Management of Vine Mealybugs in California's San Joaquin Valley Through the Integration of Chemical and Biological Controls

Final Report for SW02-020

Project Type: Research and Education
Funds awarded in 2002: $117,286.00
Projected End Date: 12/31/2004
Region: Western
State: California
Principal Investigator:
Kent Daane
Division of Insect Biology, UC Berkeley
Co-Investigators:
Walter Bentley
UC Statewide IPM Project
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Project Information

Abstract:

The vine mealybug is a severe, new vineyard pest in California. Typical treatment relies on application(s) of organophosphate or carbamate insecticides. We investigated the use of less-disruptive insecticides, releases of natural enemies, and mating disruption as alternative control strategies. Results show a systemic application of imidacloprid or a foliar application of buprofezin reduces crop damage. Inoculative release of a parasite (Anagyrus pseudococci) also reduced crop damage; currently, this natural enemy is not commercially available. Similarly, mating disruption using a synthetic sex pheromone can suppress mealybug populations, but the sprayable formulation is not yet registered in the United States. There is great potential in both augmentation and mating disruption, which are being further developed for commercial use.

Project Objectives:
  1. (1) Improve timing, dosage, and delivery methods for “least-disruptive” insecticides (e.g., Admire) that target early-season vine mealybug populations.

    (2) Test inoculative release(s) of Anagyrus pseudococci in vineyards using “least-disruptive” insecticides and compare parasitoid effectiveness in vineyards with “least-disruptive” and “standard” organophosphate insecticide applications.

    (3) Test and develop a mating disruption program using the synthetic sex pheromone.

    (4) Involve collaborating growers, farm managers, and Cooperative Extension personnel in on-farm experiments and parasitoid rearing operations; conduct field days to extend information to a larger audience; and produce research- and grower-oriented publications to improve extension.

Introduction:
Indroduction

The mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), has spread from its likely origins in the Mediterranean basin to become a primary insect pest of vineyards in California (Godfrey et al. 2003, Daane et al. 2005), South Africa (Walton et al. 2004), and Mexico (González-Hernández et al. 2006). In the early 1990s, the vine mealybug was accidentally introduced into Coachella Valley (Godfrey et al. 2003), probably from Mexico or Argentina table grape vineyards. This invasive pest quickly spread to grape-growing regions in the San Joaquin Valley (1998), Central Coast (1999), North Coast (2001), Sacramento Valley (2002), Sierra foothills (2002) and Monterey area (2002) (Daane et al. 2005). As of fall 2005, the vine mealybug had been found in 17 California counties, and it is likely that more infestations have not been detected (Daane et al. 2006). Its rapid spread since arriving in southern California in the early 1990s was most likely facilitated by the spread of infested nursery material (Haviland et al. 2005).

When left uncontrolled, vine mealybug populations can build to such levels as to destroy the crop and even kill the vine. Besides infesting the grape clusters, the mealybugs excrete large quantities of honeydew that encrusts the leaves, canes, and clusters, resulting in further crop damage, defoliation, and the growth of sooty molds and bunch rots. Moreover, vine mealybug is a vector of several viral diseases (Engelbrecht and Kasdorf 1990) and therefore is considered an economic pest even at low infestation levels. Because of the serious consequences of vine mealybug infestations, tolerance levels are relatively low, compared to those for other mealybug species, and as a result even low vine mealybug densities are cause for repeated insecticide applications. In California, the suggested insecticide treatments for vine mealybug include a delayed-dormant application and / or post harvest application of an organophosphate (chlorpyrifos), and one or more in-season applications of an organophosphate (dimethoate), carbamate (methomyl) (Bentley et al. 2004). Similar programs are used in South Africa (Walton 2003) and Mexico (González-Hernández et al. 2006), typically with even greater reliance on organophosphate materials.

Insecticides are limited in their effectiveness, however, because vine mealybug population can feed on all sections of the vine (Daane et al. 2003, Godfrey et al. 2003) and a proportion of the population remains protected from insecticide sprays under the bark or on the roots. Repeated insecticide use also adversely impacts mealybug natural enemies (Walton and Pringle 1999). For these reasons, effective, species-specific, and environmentally safe control tools to work in combination with or as an alternative to insecticide programs need to be developed (Daane et al. 2006). In response to the serious consequences of vine mealybug infestations in California, a consortium formed of University, private, and county and state personnel have initiated regional trapping and control efforts (Daane et al. 2004a). These eradication efforts have largely failed, and the grape industry realizes the need to develop alternative control strategies. Here, we present results of field research and extension directed toward the development of more sustainable controls that may work in combination with or as alternatives to standard insecticide programs.

First, we studied the effectiveness of two insecticides considered less disruptive than the organophosphate and carbamate materials, these are: (1) imidacloprid (Admire, Bayer Corp.), a systemic, nicotinoid insecticide and (2) buprofezin (Applaud, Nichino America), an insect growth regulator.

Second, we investigated methods to improve the biological control of the vine mealybug. Natural enemies attacking the vine mealybug in California vineyards include the encyrtid parasitoids Anagyrus pseudococci (Girault), Allotropa sp. and Leptomastidea abnormis (Girault); several species of green and brown lacewings; and coccinellid beetles, including the mealybug destroyer, Cryptolaemus montrouzieri (Mulsant). Of these, A. pseudococci was the most effective natural enemy of the vine mealybug in the San Joaquin Valley; as many as 90% of the exposed mealybugs collected near harvest time were parasitized (Daane et al. 2004b). However, the parasitoid’s effectiveness is hampered by at least three factors: i) from October to April vine mealybug resides primarily underneath the bark, where they are protected from foraging parasitoids; ii) Anagyrus overwinter as immatures inside the mealybug and adults do not emerge until late spring, further reducing their early-season densities (Daane et al. 2004b); iii) foraging ants protect mealybugs from parasitoids (Daane et al. 2006). We tested inoculative releases of Anagyrus as a possible mechanism to overcome some of these barriers.

Third, we began development of a mating disruption program. The mealybug sex pheromone, which is produced by the female to attract the adult winged male, was initially identified by Hinkens et al. (2001) and then commercially developed and successfully employed in pheromone-baited monitoring traps (Millar et al. 2002, Walton et al. 2004). The effectiveness of the synthetic pheromone, and its relatively inexpensive means of production, presented the opportunity to investigate its use for mating disruption. To date successful mating disruption programs have most often targeted lepidopteran (Cardé and Minks 1995, Suckling 2000) and occasionally coleopteran (Sciarappa et al. 2005) pests, but researchers in Israel have suggested that this control technique may be effective for Planococcus species (Franco et al. 2004). We conducted field trials to evaluate the effects of a microencapsulated formulation of the synthetic sex pheromone on vine mealybug population densities and pest status.

References:

Bentley, W. J., F. G. Zalom, J. Granett, R. J. Smith, L. G. Varela, and A. H. Purcell. 2004. Univ. Calif. IPM Pest Management Guidelines: Grape, Insects and Mites. Univ. California, Agricul. Natr. Resc. Publ. 3448. Oakland, CA.

Cardé, R. T., and A. K. Minks. 1995. Control of moth pests by mating disruption – successes and constraints. Annu. Rev. Entomol. 40: 559–585.

Daane, K. M., R. Malakar-Kuenen, M. Guillén, W. J. Bentley, M. Bianchi, and D. Gonzalez. 2003. Abiotic and biotic refuges hamper biological control of mealybug pests in California vineyards, pp. 389-398. In R. vanDriesch [ed.]. Proceedings, 1st International Symposium on Biological Control of Arthropods. USDA Forest Service Publication FHTET-03055.

Daane, K. M., Bentley, W. J., and Weber, E. A. 2004a. Vine mealybug: A formidable pest spreads throughout California vineyards. Practical Winery Vineyard 3:35–40.

Daane, K. M., R. Malakar-Kuenen, and V. M. Walton. 2004b. Temperature development of Anagyrus pseudococci (Hymenoptera: Encyrtidae) as a parasitoid of the vine mealybug, Planococcus ficus (Homoptera: Pseudococcidae). Biol. Control 31: 123-132.

Daane, K. M., Sime, K. R., Hogg, B. N., Cooper, M. L., Bianchi, M. L., Rust, M. K., and Klotz, J. H. 2006. Evaluation of low dose insecticides on Argentine ant in California’s coastal vineyards. Crop Protection. (in press, available on-line)

Daane, K. M., R. H. Smith, K. M. Klonsky, and W. J. Bentley. 2005. Organic vineyard management in California. Organic-Research Com. 5: 37-55.

Daane, K. M., W. J. Bentley, V. M. Walton, R. Malakar-Kuenen, G. Y. Yokota, J. G. Millar, C. A. Ingels, E. A. Weber, and C. Gispert. 2006. Sustainable controls sought for the invasive vine mealybug. Calif. Agric. 60: 31-38.

Engelbrecht, D.J., and G. G. F. Kasdorf. 1990. Transmission of grapevine leafroll disease and associated closteroviruses by the vine mealybug Planococcus ficus. Phytophylactica 22: 341-346.

Franco, J. C., P. Suma, E. B. da Silva, D. Blumberg, and Z. Mendel. 2004. Management strategies of mealybug pests of citrus in Mediterranean countries. Phytoparasitica 32: 507-522.

Geiger, C. A., and K. M. Daane. 2001. Seasonal movement and sampling of the grape mealybug, Pseudococcus maritimus (Ehrhorn) (Homoptera: Pseudococcidae) in San Joaquin Valley vineyards. J. Econ. Entomol. 94: 291-301.

Geiger, C. A., K. M. Daane, and W. J. Bentley. 2001. Sampling program for grape mealybugs improves pest management. Calif. Agric. 55(3): 19-27.

Godfrey, K., J. Ball, D. Gonzalez, and E. Reeves. 2003. Biology of the vine mealybug in vineyards in the Coachella Valley, California. Southwestern Entomol. 28: 183-196.

Haviland, D. R., W. J. Bentley, and K. M. Daane. 2005. Hot water treatments to control Planococcus ficus (Hemiptera: Pseudococcidae) in grape nursery stock. J. Econ. Entomol. 9: 1109-1115.

Hinkens, D. M., J. S. McElfresh, and J. G. Millar. 2001. Identification and synthesis of the sex attractant pheromone of the vine mealybug, Planococcus ficus. Tetrahedron Let. 42: 1619-1621.

Millar, J. G., K. M. Daane, J. S. McElfresh, J. Moreira, R. Malakar-Kuenen, M. Guillen, and W. J. Bentley. 2002. Development and optimization of methods for using sex pheromone for monitoring the mealybug Planococcus ficus (Homoptera: Pseudococcidae) in California vineyards. J. Econ. Entomol. 95: 706-714.

Suckling, D. M. 2000. Issues affecting the use of pheromones and other semiochemicals in orchards. Crop Prot. 19: 677-683.

Systat. 2000. SYSTAT Version 10.0. Evanston, IL, SPSS Inc.

Walton, V. M., 2003. Development of an integrated pest management system for vine mealybug, Planococcus ficus (Signoret), in vineyards in the Western Cape Province, South Africa. University of Stellenbosch, PhD Dissertation.

Walton, V. M., and K. L. Pringle. 1999. Effects of pesticides used on table grapes on the mealybug parasitoid Coccidoxenoides peregrinus (Timberlake) (Hymenoptera: Encyrtidae). S. Afr. J. Enol. Viticult. 20: 31-34.

Walton, V. M., K. M. Daane, and K. L. Pringle. 2004. Utilizing the sex pheromone of Planococcus ficus to improve pest management in South African vineyards. Crop Prot. 23: 1089-1096.

Research

Materials and methods:

Research and extension activities began in spring 2002, ahead of schedule, because of the rapid spread of the vine mealybug throughout California, the great need for improved vine mealybug control tools, and grower interest in education forums (see the list of presentations). Research initially targeted WR SARE objectives 1 and 2, as outlined. Results from 2002 suggested that three additional control tools needed further investigation: monitoring vine mealybug with sex pheromones, mating disruption, and least-toxic ant controls. Research for these additional topics has been coordinated with the WR SARE research, with additional funding provided by commodity boards (California Table Grape Commission, American Vineyard Foundation, California Raisin Marketing Board) and federal or state programs (California Competitive Program for Enology and Viticulture, Viticulture Consortium, UC/USDA Exotic Pests and Diseases Program). Work on mating disruption was added to the WR SARE objectives as part of the combined impact of alternative controls and biological controls.

Insecticide Applications (Objective 1).

The vine mealybug is difficult to control with insecticides because there is always a portion of the population located in hidden locations near- or underground on the roots or trunk, where the mealybug find protection from most foliar insecticide applications. To improve control options with less-toxic insecticides, we conducted a series of experiments that compared materials, delivery systems and application timing.

Systemic insecticide. In 2002, we tested the effectiveness of imidacloprid –as a systemic insecticide (applied through in the irrigation water and taken up by the vine roots) at different timings. The study was conducted in two vineyards, one with drip and the other with furrow irrigation, near Del Rey (Fresno County), CA. The vineyards were mature (more than 20 years old) Thompson seedless blocks, planted in a well-drained, sandy-loam soil and managed for raisin grapes.

In each vineyard, imidacloprid was applied at full label rate in a randomized complete block with five blocks, each containing the following five treatments: 32 ounces imidacloprid per acre applied in (1) April, (2) May or (3) June; (4) 16 ounces imidacloprid per acre applied in both April and May; and (5) a no-insecticide control. Treatment plots were three rows by 80 to 125 vines (0.5 to 0.7 acres), running the length of each row. In the drip-irrigated vineyards, a 4- to 6-hour pretreatment irrigation prepared the soil, imidacloprid was then applied through the irrigation system, and a 6- to 8-hour post-treatment irrigation was used to move the insecticide into the root zone. The furrow-irrigated vineyards were prepared by French plowing the berm and furrow area to expose surface roots, followed by a 1 day pretreatment irrigation. Imidacloprid was then applied into the furrows using an herbicide spray rig, and the application was followed by a 1 day post-treatment irrigation.

Mealybug density was monitored before treatment application (between March 13 and 19, 2002) by a field dissection of two spurs per vine on 25 randomly selected vines per plot for a total of 625 vines per vineyard (described in Geiger et al. 2001). To determine treatment effect, crop damage was evaluated at harvest using a 0 to 3 cluster rating system, where 0 = no mealybug damage, 1 = honeydew (indicating the presence of mealybugs), 2 = honeydew and mealybugs but the cluster is harvestable, and 3 = unmarketable (described in Geiger and Daane 2001). In each treatment plot, 25 vines were randomly selected and nine clusters per vine were sampled.

Foliar treatments.

In 2003, we tested five treatments in the existing 2002 drip-irrigated and flood-irrigated plots. The five treatments were: (1) 32 ounces imidacloprid per acre, applied in May 2003 to plots that had received the same treatment in April 2002; (2) no insecticide applied in 2003 to plots that had received 32 ounces imidacloprid per acre in May 2002; (3) 12 ounces buprofezin per acre, applied in June 2003 to plots that had received 32 ounces imidacloprid per acre in June 2002; (4) 2 quarts chlorpyrifos per acre, applied in February 2003 to plots that had received 16 ounces imidacloprid per acre in both April and June 2002; and (5) no-insecticide control plots (same plots as in 2002). Because the 2002 plots were retreated, we conducted a more detailed spring survey to determine if the pre-existing mealybug density would affect the 2003 treatments.

Mealybug density was determined in March 2003 using a 5-minute search on each of five randomly selected vines per plot (described in Geiger et al. 2001). To determine treatment effect, crop damage was evaluated at harvest, as described previously.

Augmentative Biological Control (Objective 2).

We tested inoculative releases of Anagyrus as a possible mechanism to overcome some of these barriers. Field studies were conducted in five mature ‘Thompson Seedless’ vineyards that were managed for raisin grapes and located near Del Rey, CA. Treatments were Anagyrus release and a no-release control, with 1-acre treatment plots set in a randomized split plot design, and each vineyard serving as a replicate. Anagyrus were provided by the Foothill Agricultural Research (FAR) Insectary. We released 10,000 Anagyrus per acre on June 12, July 3 and 30, 2003, scheduled to occur when the mealybugs were in exposed locations on the vine (e.g., on the leaves).

Throughout the season, vine mealybug density was determined by a 5-minute search on each of 10 randomly selected vines per treatment plot. Mealybug numbers were recorded by development stage (e.g., first, second, or third instar and adult). Parasitoid activity was evaluated by collecting 100 mealybugs from each treatment plot, which were recorded by development stage and location, categorized either as “protected” (e.g., underground, under the bark of the trunk) or as “exposed” (e.g., on leaves or clusters). When possible, we selected mealybugs in a one-to-one ratio from exposed and protected locations. The collected mealybugs were stored in gelatin capsules and held for parasitoid emergence, and then percentage parasitism and parasitoid species were recorded. Crop damage was evaluated at harvest using the cluster rating system (method described previously), with the exception that we sampled 50 randomly selected vines per treatment plot and five clusters per vine.

Mating Disruption (Objective 3).

Trials were conducted from 2003–2004 in commercial vineyards located near Del Rey, Sanger, and Fowler (Fresno County, CA). The vineyards ranged in size from 5–12 ha, and each was furrow-irrigated, clean-cultivated, and planted on a Hanford sandy loam soil. The vines were mature (>10-yr-old), caned-pruned Thompson Seedless cv., with canes supported by a T-trellis (2 or 4-wire) system. In each vineyard, we established two treatment-plots for either the microencapsulated pheromone or a no-pheromone control. In each vineyard, the treatment plots were separated by buffer strips of ca. 20–120 m, depending on the vineyard size, to minimize pheromone drift into the no-pheromone control. Mating disruption and control treatments were then randomly assigned, utilizing a split-plot design. The synthetic pheromone used was racemic lavandulyl senecioate (details on chemical production in Millar et al. 2002), produced by Kuraray Fine Chemicals (Tokyo, Japan). The synthetic pheromone was microencapsulated by Suterra Inc. (Bend, OR), with the formulation containing 20% (a.i.) by weight of the pheromone. The pheromone application rate, application dates, plot size, and insecticide treatments varied each year, as follows.

In 2003, the sprayable pheromone was mixed with water (1 ml: 7.6 liter) and applied at a rate of 19.78 g (a.i.) per ha per application in each of five vineyard blocks. Application dates were on or between 12–15 May, which was before any adult male mealybugs were caught in pheromone traps, then 19 June, and 2–4 August. In total, 59.3 g (a.i.) per ha per season were applied in the mating disruption plots. Plot size varied from 1.5–2.2 ha per treatment plot (20–35 vine rows by 50–100 vines), with approximately 50–120 m between plots in each vineyard. In addition to the pheromone applications, a delayed dormant application of an organophosphate (chlorpyrifos) was applied at the full label rate, uniformly to all plots between 17–25 February 2003.

In 2004, sprayable pheromone was mixed with water (1 ml: 7.6 liter) and applied at a rate of 19.78 g (a.i.) per ha per application in each of five vineyard blocks. Applications dates were 20 April, 19 May, 16 June, and 19 July. In total, 79.1 g (a.i.) per ha per season were applied in the mating disruption plots. Plot size varied from 0.15–0.29 ha per treatment plot (5–10 vine rows by 25–50 vines), with approximately 20–30 m separating plots in each vineyard. In addition to the pheromone applications, an in-season application of an insect growth regulator (buprofezin) was applied at 50% of the full label rate, uniformly to all plots between 10–16 June 2004. We also note that mating disruption using plastic dispensers was tested in these same vineyard blocks, using similarly sized plots and buffer zones as reported for the sprayable formulation.

To monitor male mealybug flight periods and densities, three red Pherocon Delta IIID sticky traps baited with sex-pheromone lures (Suterra, Bend, OR) were placed in each treatment plot. Traps and lures were replaced every 2–4 wk, depending on the seasonal period. Trapped insects were counted using a dissecting microscope. Mealybug population densities were determined using a 3-min timed visual count, as described previously. In each plot, 2–4 vines were randomly selected in each of 3–5 rows (10 vines per plot per sample date, vines and rows on the plot edges were not sampled). Mealybug crop damage was rated using a 0–3 scale, as described previously. In 2003, crop damage was evaluated for five clusters on 20 (2 plots) or 50 (3 plots) randomly selected vines per plot (950 clusters per treatment). Sampling in 2003 indicated that mealybug distribution within the vineyard tended to be clumped, and to reduce sample variation resulting from a clumped distribution this procedure was modified in 2004 so that more vines were sampled. A single cluster was sampled on each of 100 vines (500 clusters per treatment). The vines were located in the center three rows of each plot, with vines randomly selected in each sampled row. Clusters located near the trunk and, when possible, touching either the trunk or cordon were preferentially sampled because they are more susceptible to mealybug infestation (Geiger and Daane 2001).

Results in 2003 indicated that the mating disruption treatment had little or no effect in vineyards with relatively high mealybug population densities. We modified are methods in 2004 to better follow pheromone-treatment effects on different mealybug population densities; our goal was to sample vines that had different initial mealybug densities within the same vineyard throughout the season. To select vines, we surveyed each vineyard on 7 April, before treatments were applied, using the 3 min visual search of randomly selected vines. The vines were classified as having low, medium, or high level mealybug densities based on the following criteria. Low infested vines had no visible mealybug infestation and, additionally, these vines were treated with an insect growth regulator (buprofezin) at the full label rate on 12 April. Medium infested vines had no ant activity or discoloration of the vine resulting from honeydew, with < 10 mealybugs found during a 3-min visual search. Highly infested vines had some tending ant activity (Formica aerata [Françoeur]), honeydew or sooty mold blackened trunk or cordon sections, and >10 mealybugs found during a 3-min visual search. In each treatment plot, we selected 4 vines of each category to repeatedly sample throughout the season. Because the 3-min sampling method is destructive and can alter mealybug densities through the removal of bark or canes (Geiger and Daane 2001), we used a non-destructive leaf sample to enumerate population changes in the vine canopy. For every 2 wk throughout the season, two basal leaves were sampled on each vine and all mealybugs were recorded.

Extension of Results (Objective 4).

See “Publications/Outreach” section

Statistics.

For all studies (insecticides, natural enemies and mating disruption), the results are presented as means per treatment. Treatment impacts are compared using Analysis of Variance (ANOVA), with the means separated using Tukey’s HSD test (P < 0.05) for three or more treatments or using a T-test for two treatments. Treatment influences on cluster damage, as measured by the rating scale, were compared in a 2 X 2 contingency table with treatments separated using Pearson’s chi-square (P = 0.05); differences among specific treatments were evaluated as a series of pairwise comparisons, adjusting the critical value using the standard Bonferroni technique (P = 0.01). Repeated measures ANOVA analyses were used to determine season-long differences in mealybug densities, percentage parasitism, and pheromone trap catches. The data were transformed (log[x +1] or (sqrt(x+0.5)) to stabilize the variance, when needed.

Research results and discussion:
Results

Insecticide trial results.

Systemic insecticide. In the drip-irrigated vineyard, there was a significant treatment impact on cluster damage (χ2 = 1085.4, df = 12, P < 0.0001). All treatments receiving imidacloprid, regardless of application date, had significantly less cluster damage than the control (Fig. 1A, available on hard copy). Average cluster damage ratings in the April, May, and April/June imidacloprid treatments were a significant 90.5%, 92.5%, and 92.4% lower than in the control, respectively. Average cluster damage in the June imidacloprid treatment was a significant 67.9% lower than that in the control, but significantly higher than that in imidacloprid treatments applied earlier in the season. In the furrow-irrigated, cluster damage ratings in all treatments with imidacloprid were significantly lower than the control (χ2 = 221.58, df = 12, P < 0.0001); however, there was a greater separation of the imidacloprid treatments (Fig. 1B, available on hard copy). Cluster damage in the May treatment was 59.3% lower than the control, and significantly lower than all treatments. Whereas the April and April/June treatments were only 21.3 and 31.0% lower, respectively, than the control. Average cluster damage rating in the June application of imidacloprid was 14.8% lower than the control, but significantly higher than all other imidacloprid treatments. The results show imidacloprid provided the greatest reduction in cluster damage when applied in April or May through a drip-irrigation system. Imidacloprid was less effective when delivered through the furrow-irrigation system. We believe furrow-irrigated blocks have a more wide-spread root zone, which makes delivery of the insecticide to the entire root zone difficult and results in a more dilute application and poorer uptake of the applied imidacloprid. Irrigation both pre- and post-imidacloprid application is also critical, and this too is more difficult to properly manipulate with furrow irrigation. It is important to note that these studies were conducted in the San Joaquin Valley on a sandy-loam soil; soil structure may change the efficacy of systemically applied materials. Imidacloprid, and other systemic chloronicotinyls, are moved with the irrigation water into the soil, picked up by the vine’s root system, and then moved through the vine in its xylem. For this reason, proper delivery of imidacloprid may vary greatly among vineyards depending on soil and vine conditions. For example, there is evidence that the insecticide can bind with soil particles above the root zone when there is too little soil moisture, especially in heavier soils that have higher clay content. In contrast, the insecticide may be flushed too quickly through and out of the root zone when too much water is applied in sandy soils. Once in the vine, imidacloprid must be delivered to sections where the mealybugs are feeding. Because all vineyard mealybugs are phloem feeders, there will be sections of the vine where the concentration and effectiveness of systemic insecticides will vary (for example, the concentration of a systemically-delivered insecticide may be higher in canes and lower in grape clusters). Researchers are currently investigating the uptake of systemic chloronicotinyls in the vine (N. Toscano, personal communication) and this information, developed for glassy-winged sharpshooter (Homalodisca coagulata [Say]), will greatly benefit mealybug control strategies. Systemic vs. foliar insecticides. In spring 2003, there were no significant pretreatment differences in mealybug densities among treatment plots in either the drip- or furrow-irrigated vineyards (drip: F = 0.922, df = 4, 145, P = 0.453; furrow: F = 1.518, df = 4, 145, P = 0.200). Therefore, treatment impact was not obscured by pretreatment differences resulting from the previous year’s insecticide application. In the drip-irrigated vineyard, there was a significant treatment impact on cluster damage ratings (χ2 = 221.58, df = 12, P < 0.0001). Pairwise comparisons of individual treatments cluster damage ratings were a significant 87.3%, 82.7%, and 85.0% lower in the imidacloprid-2003, buprofezin and chlorpyrifos treatments, respectively, as compared to the control (Fig. 2A, available on hard copy). There was no difference between the imidacloprid-2002 application and the control. In the furrow-irrigated vineyard, there was a significant treatment impact on cluster damage ratings (χ2 = 132.96, df = 12, P < 0.001; Fig. 2B, available on hard copy). The most effective treatments were imidacloprid-2003 and buprofezin, where cluster damage 70.7 and 85.6% lower than the control, respectively. There was a significant 44.1% reduction in the chlorpyrifos treatment, whereas cluster damage in the imidacloprid-2002 treatment was not significantly different from that in the control. That there was no significant difference between imidacloprid applied in 2002 and the control suggests that there was not an adequate year-to-year carry-over of imidacloprid in the soil or root systems for vine mealybug control. The poor control achieved with chlorpyrifos in the furrow-irrigated block may be due to the location of the vine mealybug population on these in this vineyard, which had older vines (more than 30 years) that provided many protective areas under the bark of the trunk and spurs where mealybugs remained hidden during much of the spring. Parasitoids help control mealybug. Mealybug season-long density was significantly lower in the Anagyrus release than in the control treatment (Fig. 3, available on hard copy) (repeated measures ANOVA: F = 13.27, df = 1, 76, P < 0.001). Average cluster damage rating was 57% lower in the Anagyrus release (0.22 +/- 0.03) than in the control (0.51 +/- 0.05) treatment (t = 5.52, df = 1, 444, P < 0.001). However, we are unable to conclude that the released Anagyrus were solely responsible for this reduction. First, while there was no treatment difference in vine mealybug density on March 27 (t-test = 1.66, P = 0.101), which was when treatment plots were randomly assigned, there were fewer mealybugs on June 5 (t-test = 3.70, P < 0.001), which was just before the Anagyrus release. Second, there was no season-long difference in percentage parasitism (repeated measures ANOVA: F = 2.11, df = 1, 521, P = 0.15), although this is often an unreliable tool to measure the impact of natural enemies. Nevertheless, the results provide encouraging information for the commercial use of Anagyrus to control vine mealybug. From 7458 mealybugs collected and held in gelatin capsules, 1978 were parasitized (26.5%) and 1235 parasitoid were reared to the adult stage. The parasitoids reared were A. pseudococci, L. abnormis, Allotropa sp. and Chartocerus sp. (the Chartocerus is a hyperparasitoid, which is probably attacking A. pseudococci). Anagyrus was the dominant adult parasitoid, comprising more than 93% of the total (table 1). Third-instar mealybugs were most commonly attacked, reflecting the host preference of Anagyrus. Mealybug size affected the gender of the reared Anagyrus: first- and second-instar mealybugs yielded primarily males (100 and 83.3 +/- 1.1%, respectively), whereas third-instar and adult mealybugs yielded primarily females (95.4 +/- 1.1 and 92.9 +/- 2.2%, respectively). Season-long percentage parasitism, with data separated by date and location of collected mealybugs, shows the importance of timing augmentative releases after mealybugs have moved from protected locations (Fig. 4, available on hard copy). While the season-long percentage parasitism of mealybugs collected from protected locations (such as under the bark) never exceeded 20%, there was a consistent season-long rise in parasitism of mealybugs collected from exposed locations (such as on the leaf). Season-long percentage parasitism was significantly higher in exposed than hidden locations for both control (repeated measures ANOVA: F = 247.3, df = 1, 273, P < 0.001) and release (repeated measures ANOVA: F = 501.5, df = 1, 249, P < 0.001) treatments. On the June 1 sampling date, which was prior to Anagyrus release, no mealybugs could be found in exposed locations. After releases began, there was significantly greater percentage parasitism of exposed mealybugs in release than in control plots on the initial sample. Parasitism rose steadily in both release and control plots because of the strong resident population of A. pseudococci in this untreated field, reaching more than 80% by late August, after which we could find no live mealybugs in exposed locations. In summary, resident Anagyrus pseudococci are providing significant reductions in late-season vine mealybugs, which form the base for the following season’s mealybug population. In fact, we have recorded a year-to-year decline in mealybug abundance in sampled vineyards near Del Rey. We are also enthusiastic about the commercial potential of Anagyrus and note the low rating for average cluster damage in the release treatment, which showed an average of 78% of all clusters were clean and the remaining 22% having only minor honeydew damage. The results of Anagyrus percentage parasitism and mealybug host stage preference will also help develop future release strategies. The fact that 100% of the live mealybugs in the September and October samples were in protected locations of the vine, we believe greatly reduces the ability of foraging adult Anagyrus to locate and parasitize vine mealybugs that will constitute the overwintering parasitoid population. Furthermore, we reared primarily male Anagyrus from first- and second-instar mealybugs. These results show that Anagyrus releases should be timed to coincide not only with the presence of mealybugs in exposed locations, but also with the presence of third-instar mealybugs, which are needed to support production of female Anagyrus. Mating disruption Mealybug Male Flight. In 2003 and 2004, the sprayable pheromone was applied throughout the field season. In the control blocks, male flight activity, as recorded by the pheromone-baited traps, was first detected in May, with trap counts rising to a peak in late July, and steadily declining thereafter (Fig. 5, available on hard copy). Season-long trap catches were significantly lower in the mating disruption plots than in the control plots in 2003 (F = 83.24, df = 1,8, P < 0.001) but not in the 2004 season (F = 4.08, df = 1,8, P = 0.078). However, trap catches were not completely shut down and while numbers were lower overall, the seasonal flight pattern was similar to that in the controls. A particularly strong indication of the treatment impact is the number of male mealybugs per trap per week from June through August, during the most active period, which were a significant 17.6 and 4.4 times greater in the control than the mating disruption treatment in 2003 and 2004, respectively (2003: t = 3.86, df = 25, P < 0.001; 2004: t = 2.74, df = 29, P = 0.01). Mealybug Population Density. In 2003 and 2004, mealybug populations were detected throughout the sampling period (April through October), reflecting the year-round presence of the mealybug in the tested vineyards. Population density, as determined by the 3 min search, increased rapidly from April to June, followed by a decrease from late July into August. In 2003, there was no season-long treatment impact on the density of settled mealybugs (2nd instar to adult mealybugs) in the 2003 season (F = 0.19, df = 1,6, P = 0.68), whereas in 2004, there were significantly fewer mealybugs in the mating disruption treatment than the control in the 2004 season (F = 5.77, df = 1,8, P = 0.04) (Fig. 6, available on hard copy). Parasitoid Activity. In 2003, of 2654 mealybugs isolated in gelatin capsules, 41.4 +/- 1.0% were parasitized. The mealybug developmental stage isolated influenced percentage parasitism, with the third and second instars more commonly parasitized (51.1 +/- 1.7 and 56.3 +/- 2.1%, respectively) than the first instar and adult stages (29.0 +/- 2.5 and 28.7 +/- 1.4%, respectively). Of the parasitoids reared to the adult stage (n = 593), A. pseudococci was the most common (86.3 +/- 1.4%), followed by Allotropa sp. (Platygastridae) (11.5 +/- 1.3%) and Leptomastidea abnormis (Girault) (Encyrtidae) (2.2 +/- 0.6%). There were no differences in levels of parasitoid activity, as measured by either numbers of mummies counted during the 5 min search on vines (Fig. 7, available on hard copy), or the percentage of mummies obtained from mealybugs collected and isolated in gelatin capsules. In 2004, of 4390 mature mealybugs (third instar and adults) isolated in gelatin capsules, only 2.8 +/- 0.3 were parasitized, all by A. pseudococci. There was no significant difference in parasitism levels between mating disruption and control treatments on any sample date (n = 9). Similarly, there was no season-long difference in levels of parasitoid activity, as measured by numbers of mummies counted during the 5 min search of vines (F = 0.17, df = 1,8, P = 0.69). Crop Damage. Significantly lower crop damage ratings were recorded in mating disruption than control treatments in 2003 (Pearson Chi-square = 54.81, df= 3, P < 0.001) and 2004 (Pearson Chi-square = 37.39, df= 3, P < 0.001) (Fig. 8, available on hard copy). Of key interest to vineyard managers is that fewer grape clusters were rated as having “moderate” or “severe” damage in mating disruption blocks (3.1 and 4.0% in 2003 and 2004, respectively) compared with the controls (9.1 and 11.8% in 2003 and 2004, respectively). Effect of Mealybug Density. Throughout the 2004 season, we repeatedly sampled vines that had been previously categorized as having low, moderate, or high mealybug densities. For data analysis, we first plotted the season-long mealybug density in the control plots for each of these categories. There was a significant difference in mealybug density on vines in the control plots, which followed the predicted pattern of low, medium, and high mealybug densities (Fig. 9, available on hard copy). Average mealybug counts per leaf on vines in control plots categorized as having low, moderate, or high mealybug densities during a survey on 19 April 2004. Mealybug density, as determined by Repeated Measures ANOVA using sampling dates between 16 May to 29 June, differed significantly among each category (F = 18.70, df = 2,9, P < 0.001), with pairwise comparisons showing a significant difference between low vs. high (F = 61.83, df = 1,6, P < 0.001) and medium vs. high (F = 27.86, df = 1,6, P = 0.002), while there was no difference between low vs. medium (F = 2.87, df = 1,6, P = 0.14) categories. We then compared the change in mealybug densities on leaves in the mating disruption blocks, as compared with the control blocks. The percentage reduction of mealybugs varied significantly among mealybug density categories (F = 5.88, df = 2, 12, P = 0.016), and was greater in the low vs. high density category (the medium vs. high density category was P = 0.069). Mealybug densities were reduced by 86.3 +/- 6.3% compared to controls on vines previously categorized as having a low mealybug density , whereas the reduction on vines categorized as having a high mealybug density, where there was only a 9.0 +/- 35.7% reduction in densities compared to controls. We observed a significant reduction in the number of male mealybugs caught in traps. This result is an indication of pheromone effects, but does not necessarily signify successful mating disruption; the reduction in trap catches amongst treatments is not always proportional to the reduction of crop damage or changes in pest population density. In fact, when we later measured mealybug population density on the vines, we found that the level of mealybug reduction as measured by pheromone trap catches was much greater than that recorded by visual counts of mealybugs. Most important was the reduction of mealybugs and their damage in the grape clusters, which were significantly lower in combination mating disruption and insecticide treatments, compared with insecticide treatment alone. Parasitism levels were not disrupted by the mating disruption treatment, a result that was unexpected. In contrast, earlier studies with the P. ficus pheromone showed that the parasitoid A. pseudococci was attracted to the pheromone traps (Millar et al. 2002), and we saw an increase in parasitism levels in mating disruption trials in South Africa (Walton and Daane, unpublished). In the current study, two factors may have influenced parasitism, reducing the difference between treatments. First, in 2003 trials the vineyards had high levels of parasitism in both treatments, a result of reduced insecticide use and inoculative release of A. pseudococci in adjacent vineyards from 2001–2003. Second, in 2004 trials the vineyards received an in-season application of the insect growth regulator in June, which is a critical period for the overwintered A. pseudococci to locate and oviposit in exposed hosts (Daane et al. 2004b). There have been mixed reports of natural enemy activity in mating disruption programs.

Research conclusions:
Impact of Results

There has been a reduction of organophosphates used in vineyards where managers have switched to nicotenoids or insect growth regulators for mealybug controls.

Program development is continuing for mating disruption, with target dates for registration in 2007-08.

The biological control program will be continued. To date, natural enemies are being spread throughout the California, but are not relied upon for control. This is, in part, because of the recent “goal” of vine mealybug eradication in the coastal regions.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:
Publications and Outreach

The results of this vine mealybug research have been made available as they are developed. Furthermore, grower collaborators will maintain records of chemical use and labor costs for the different treatments imposed. These two measurements (damage and dollars) will provide a “bottom-line” assessment of the program for growers. During the project period (2002-2004) Daane and Bentley have made about >50 presentations on the vine mealybug. Both popular and refereed publications from this work have been completed and more are in preparation.

We have also developed a mealybug website

Presentations

DAANE (2002-2004)

Abiotic and biotic refuges hamper biological control of mealybug pests in California vineyards. 1st International Symposium on Biological Control of Arthropods. Honolulu, HI. Jan 2002.

Description, biology and chemical suppression of the vine mealybug. Sun-Maid Growers of California Annual Best Pest Management Practices. Selma, CA. Jan 2002.

Vine mealybug and its parasitoids compared between the San Joaquin Valley and Coachella Valley vineyards. Madera Lunch and Vineyard Management Series. Jan 2002. Madera, CA.

The increasing spread of the vine mealybug, a new pest in the San Joaquin Valley. Sun Maid Best Pest Management Seminar. Selma, CA. Jan 2002.

Biological control of the vine mealybug in California vineyards (USA): using Anagyrus pseudococci y Leptomastidea abnormis. Taller Internacional de Control Biologico Manejo integrado del piojo harinoso de la vid – Planococcus ficus. Hermosillo, Sonora, Mexico. Jan 2002.

Monitoring beneficial insects in tree and vine crops: is it more difficult to count the good bugs? 36th Annual Conference – Association of Applied Insect Ecologist: IPM and Monitoring – Back to the Basics with New Technology. Berkeley, CA. Feb 2002.

Biology and control of mealybugs in vineyards. Monterey County’s Central Coast Winegrape Seminar. Salinas, CA. Feb 2002.

Insect ecology, invasive species biology and biological control: Mealybugs in California vineyards as an example. Division of Insect Biology’s Graduate Student Seminar Series. Berkeley, CA. Apr 2002.

Mealybug and scale pests of grapevines. Napa Valley Vineyard Technical Group. Napa, CA. Apr 2002.

Vine mealybug distribution and biology. Special Meeting on the Vine Mealybug – Kern County Cooperative extension. Arvin, CA. May 2002.

Vine mealybug pheromone trapping. Special Meeting on the Vine Mealybug – Kern County Cooperative extension. Arvin, CA. May 2002.

Field identification and biology of mealybug and scale pests of grapevines. Special Meeting of UCCE personnel in Napa and Sonoma County. Sonoma, CA. May 2002.

Cover crops in vineyard management. Health, wealth and successful winegrape production: managing vineyards for environmental and economic sustainability. Madera, CA. Jun 2002.

Vine mealybug in the Coachella Valley. 86th Annual Meeting of the Pacific Branch of the Entomological Society of America. South Lake Tahoe, CA. Jun 2002.

Vine mealybug, a new pest in the San Joaquin Valley. 86th Annual Meeting of the Pacific Branch of the Entomological Society of America. South Lake Tahoe, CA. Jun 2002.

Population dynamics of the vine mealybug in the Coachella Valley. 86th Annual Meeting of the Pacific Branch of the Entomological Society of America. South Lake Tahoe, CA. Jun 2002. POSTER presentation.

Vine mealybug distribution, biology and control in raisin vineyards. Sun Maid Mite and Insect Field Meeting. Caruthers, CA. Jun 2002.
Mealybug pests in California vineyards. 2002

Annual Meeting and Report, Central Coast Vineyard Team, Mealybug Educational Meeting. Santa Maria, CA. Aug 2002.

Predator – prey relationships in grape vineyards: Do early-season parasitoid densities relate to late-season pest densities. Association of Applied Insect Ecologist mid-Summer Roundtable. Aug 2002. Modesto, CA.

Development and optimization of methods for using sex pheromones for monitoring vine mealybug in California vineyards. International Organization of Biological Control – Pheromone and Semiochemical Working Group. Florence, Italy. Sept 2002. (second with Jocelyn Millar)

Mealybug pests in California vineyards. 2002 Annual Meeting, Lodi-Woodbridge Winegrape Commission. Lodi, CA. Oct 2002.

Vine mealybug population abundance and distribution in the San Joaquin Valley. UCCE Riverside County, Vine Mealybug Seminar. Indio, CA. Oct 2002.

What you need to know about the vine mealybug in the Coachella Valley. UCCE Riverside County, Vine Mealybug Seminar. Indio, CA. Oct 2002.

Vine mealybug in California vineyards. Napa Valley Viticultural Fair, Napa Valley Grape Growers Association. Napa, CA. Nov 2002.

Mealybugs in California vineyards. Kings-Tulare County CAPCA Continuing Education. Tulare, CA. Nov 2002.

Mealybugs in California vineyards. Simposio Internacional: Piojos Harinosos, XXV Congreso Nacional de Control Biologico. Hermosillo, Sonora, Mexico. Nov 2002.

The Argentine ant and grape mealybug pest complex in Sonoma County, California: Ant baiting trials. 50th Annual Meeting of the Entomological Society of America. Fort Lauderdale, FL. Nov 2002.

Mealybug pests in Central Coast vineyards – the encroaching vine mealybug in California. Central Coast Vineyard Team. Shell Beach, CA. Nov 2002.

Vine mealybug in California vineyards. 2002 Unified Winegrape Symposium: Pests and Pest Management. Sacramento, CA. Jan 2003.

Update on vine mealybug biology and control. San Joaquin Valley Grape Symposium. Easton, CA. Jan 2003.

Sugar Bait / Insecticides for Argentine Ant Control to Improve Biological Control of Scale and Mealybug Pests 37th Annual Conference – Association of Applied Insect Ecologist: The Urban-Ag Interface and the Future of Agriculture. San Luis Obispo, CA. Feb 2003.

Vine mealybug in California vineyards. 2003 Northern San Joaquin Valley Grape Day (Modesto and Merced Counties). Turlock, CA. Feb 2003.

Monitoring vine mealybugs with pheromones to find and control new infestations: developing a statewide program. California Agricultural Production Consultants Association (CAPCA). Santa Paula, CA. Mar 2003

Monitoring vine mealybug with pheromones to find and control new infestations. Grape Day 2003 – Yolo/Solano/Sacramento county UCCE and Clarksburg Wine Growers Association. Walnut Grove, CA. Mar 2003.

Monitoring vine mealybugs with pheromones to find and control new infestations: developing a statewide program. Winegrape Pest Management Alliance. San Luis Obispo, CA. Mar 2003.

Controlling Argentine ants (Hymenoptera: Formicidae) with aqueous baits. 87th Annual Meeting of the Pacific Branch of the Entomological Society of America. Tucson, AZ. Mar 2003. (junior w/ M Rust).

Vine mealybug in California – understanding its potential for statewide dissemination. California State University, Fresno (contact Joe Browde). Fresno, CA. Apr 2003

Vine mealybug in California – understanding its potential for statewide dissemination. California Association of Winegrape Growers. Fresno, CA. Apr 2003

Monitoring vine mealybugs with pheromones to find and control new infestations. California Agricultural Production Consultants Association (CAPCA). Lodi, CA. Apr 2003

Monitoring vine mealybugs with pheromones to find and control new infestations. Lodi Woodbridge Winegrape Commission. Lodi, CA. May 2003.

Life cycle of the vine mealybug; an update on research efforts. UCCE San Joaquin County (Verdegaal). Ripon, CA. May 2003.

Vine mealybug control strategies and successes. UCCE San Joaquin County (Verdegaal). Ripon, CA. May 2003. (second with W. J. Bentley)

Mealybug pests in vineyards. California Polytechnic State University. Grape Pest Management (Fruit Science 414). San Luis Obispo, May 2003.

Developing sustainable insect pest management systems in California vineyards. 54th Annual Meeting, American Society for Enology and Viticulture. Reno, NV. Jun 2003.

How to prevent the spread of vine mealybug during grape havesting. UCCE Sacramento County (Ingels) and San Joaquin (Verdegaal) County and Lodi Woodbridge Winegrape Commission “Field Day”. Lodi, CA. Aug 2003.

Monitoring vine mealybugs with pheromones to find and control new infestations. California Alliance of Pest Control Advisors (CAPCA). Tulare, CA. Aug 2003.

Can a statewide “sustainable agriculture” system be developed for California vineyards: biological control of the vine mealybug as a case study. Departmental Seminar (ESPM Colloquium Series), Environmental Science, Policy and Management, University of California, Berkeley, CA. Sept 2003.

Biological control of invasive species in California: insectary and quarantine operations. ESPM 198. Berkeley, CA Sept 2003.

Integrated pest management of leafhoppers and the vine mealybug. Mendocino College 6th Annual Pest Management Seminar. Ukiah, CA Nov 2003.

Developing a statewide sustainable agriculture program for vineyards: control of the vine mealybug as a case study. Departmental Seminar (Ent 250), Entomology, University of California, Riverside, CA. Nov 2003.

Identification and biology of the vine mealybug: is eradication feasible for the north coast winegrape region? American Vineyard Foundation: Vine Mealybug Workshop, UCCE Napa County, Napa, CA. Nov 2003.

Identification and biology of the vine mealybug: is eradication feasible for the central coast winegrape region? Paso Robles, American Vineyard Foundation: UCCE San Luis Obispo Vine Mealybug Workshop. Paso Robles, CA Dec 2003.

Identification and biology of the vine mealybug: is eradication feasible for the central coast winegrape region? Napa County and the American Vineyard Foundation. Napa, CA Jan 2004.

The vine mealybug as an invasive pest of California vineyards. Unified Winegrape Sympoisum, Sacramento, CA Jan 2004.

Vine mealybug biology and management in the San Joaquin Valley: Benefits of using pheromone traps. Vine Mealybug Workshop, Fresno County. Fresno, CA. Feb. 2004.

Vine mealybug biology and management in the San Joaquin Valley: Benefits of using pheromone traps. Canneros Region Winegrape Growers: Vine Mealybug Taskforce, CA. Mar. 2004.

After vine mealybug insecticide programs: Is there a “Sustainable” program for use in the North Coast winegrape region? North Coast BIFS. Mar. 2004.

Research on natural enemy biology of insect pests in the Central Valley. Kearney’s 40th Aniversary and New Research Greenhouse Dedication. May 2004.

Vine mealybug biology and management in the San Joaquin Valley using biological control agents. Sun Maid’ VMB Workshop. Parlier, CA. May 2004.

Vine mealybug update. UCCE Napa County Vine Mealybug: Management Strategies for Vintners and Growers. Yountville, CA. Jun. 2004.

Grape IPM and biological control in California organic vineyards. XXII International Congress of Entomology. Brisbane, Australia. Aug. 2004.

Temperature-dependent development of Anagyrus pseudococci reared on the vine mealybug. XXII International Congress of Entomology. Brisbane, Australia. Aug. 2004. (POSTER)

An overview of the University “Cooperative Extension and Research” programs for the vine mealybug. University of California President Dynes’ Tour of UCCE Outreach Programs. Sept. 2004. Buena Vista Vineyards, Sonoma County, CA.

Vine mealybug: research and advances in management. Central Valley Grape Expo. Easton, CA, Nov. 2004. 20 min presentation,

Vine mealybug: research advances in management. Napa Valley Viticulture Fair. Napa, CA, Nov. 2004.

Utilizing vine mealybug sex pheromone for control: progress update. UCCE Kern County 2004 Grape Pest Management.Bakersfield, CA

The vine mealybug in California. Critical Issues in Vineyard Health (UC Davis Extension Course). Davis, CA, Nov. 2004.

Ant biology and control in grapes. Bayer CropScience: 2005 Grape Pest Control Strategies. Carmel Valley, CA. Jan. 2005.

Impact of the Argent ant on mealybug pests and their natural enemies. America Vineyard Foundation Update. Paso Robles, CA. Jan. 2005.

BENTLEY (2002-2004)

Review of key grape insect pests and research. Kern County Grape Meeting. Bakersfield, CA. Feb 2002.

Review of key grape insect pests and research. Fresno County Grape Meeting. Fresno, CA. Feb 2002.

Monitoring and treatment strategies for vine mealybug. Vine Mealybug Mtg., UCCE Kern County, Arvin, CA. May 2002.

Ant exclusion and its impact on grape mealybug infestation. USDA Lunch Seminar, Parlier, CA. May 2002.

Vine mealybug management in coastal wine grapes. Napa Valley Viticultural Fair, Napa Valley Grape Growers Assn., Napa, CA. Nov 2002.

Managing vine mealybug in California, Crop Care Associates Training Mtg., Carmel Valley, CA. Feb 2003.

Vine mealybug management for central coast vineyards. Central Coast Winegrape Seminar, UCCE Monterey County, Salinas, CA. Feb 2003.

Vine mealybug update. San Joaquin Valley Table Grape Seminar, Calif. Table Grape Commission, Visalia, CA. Feb 2003.

Detection and management of vine mealybug in wine grapes. UCCE Calaveras County, Grape Grower mtg., Murphys, CA. Mar 2003.

Chemical control of vine mealybug. Yolo/Solano/Sacramento County UCCE & Clarksburg Wine Grape Association mtg., Walnut Grove, CA. Mar 2003.

Identification and management of vine mealybug. Vine mealybug training session, UCCE/Lodi-Woodbridge Wine Commission, Lodi, CA. Apr 2003.

Monitoring and managing vine mealybug. UCCE Madera County, Madera, CA. Apr 2003.

Vine mealybug management. Vine Mealybug Workshop, UCCE El Dorado County, Placerville, CA. Apr 2003.

Control of vine mealybug. Grape Day 2003, UC KAC, Parlier, CA. Aug 2003.

Grapevine mealybug. Central Valley CAPCA Fall CE Meeting, Modesto, CA. Oct 2003.

Effective methods of control for the vine mealybug. American Vineyard Foundation, Vine Mealybug Workshop, UCCE Napa County, Napa, CA. Nov 2003.

Insect & mite pests: spider mites, mealybugs. VEN 118, Grapevine Pests, Diseases & Disorders, Williams, University of California, Davis, CA. Nov 2003.

Chemical management of vine mealybug. American Vineyard Foundation, Vine Mealybug Workshop, UCCE San Luis Obispo County, Paso Robles, CA. Dec 2003.

Monitoring and management of vine mealybug, new developments. Bayer Crop Science Grape Day, Carmel Valley, CA. Jan 2004.

Emerging insect problems and pest management approaches for grape growers. San Joaquin Valley Grape Symposium, Easton, CA. Jan 2004.

Vine mealybug update on monitoring and control. UCCE Annual Lodi Grape Day, Lodi, CA. Feb 2004.

Insect pest management in trees and vines. Tulare-Kings CAPCA Farm Show Mtg, Tulare, CA. Feb 2004.

Management strategies to control vine mealybug. Central Coast Winegrape Seminar, UCCE Monterey County, Salinas, CA. Feb 2004.

Detection and control of vine mealybug. Grape Day 2004, UCCE. Sacramento Co., Walnut Grove, CA. Mar 2004.

Vine mealybug update. SCGGA Vineyard Manager’s Mtg., Conoma County Grape Growers Assn., Healdsburg, CA. Mar 2004.

New and emerging pests in California viticulture. Integrated Grape Production Workgroup, UC Davis, Davis, CA. Apr 2004.

Vine mealybug management in California vineyards. Vine Mealybug Mgmt Seminar, Sun Maid Growers of California, Parlier, CA. Apr 2004.

Vine mealybug monitoring and management. Kearney Greenhouse Opening. Parlier, CA. May 2004.

Vine mealybug monitoring and management . Friend’s Day, Duarte Nursery, Modesto, CA. May 2004.

Overview of grape pests and management. Viticulture 100, CSU Fresno, CA. May 2004.

Mites , Mealybugs and leafhoppers. Madera Co. Grape Grower/PCA Mtg., UCCE, Madera, CA. May 2004.

Insect and mite pests: spider mites, mealybugs. VEN 118 lecture, Larry Williams, UC Davis, CA. Nov 2004.

Mealybug Articles:

Millar, J. G., Daane, K. M., McElfresh, J. S., Moreira, J., Malakar-Kuenen, R., Guillen, M., and Bentley, W. J. 2002. Development and optimization of methods for using sex pheromone for monitoring the mealybug Planococcus ficus (Homoptera: Pseudococcidae) in California vineyards. Journal of Economic Entomology 95(4): 706-714.

Millar, J. G., Daane, K. M., McElfresh, J. S., Moreira, J. A., and Bentley, W. J. Development and optimization of methods for using sex pheromones for monitoring vine mealybug in California vineyards. International Organization of Biological Control – Pheromone and Semiochemical Working Group. Florence, Italy. Sept 2002.

Daane, K. M., Mills, N. J., and Tauber, T. J. 2002. Biological Pest Controls: Augmentative Controls, pp. 36-38. In D. Pimentel [ed.]. Encyclopedia of Pest Management. Marcel-Dekker, Inc., New York, NY.

Godfrey, K. E., Daane, K. M., Bentley, W. J., Gill, R. J, and Malakar-Kuenen, R. 2002. Mealybug in California vineyards. University of California Division of Agriculture and Natural Resources Publication 21612. Oakland, CA.

Daane, K. M., R. Malakar-Kuenen, W. J. Bentley, and M. Guillén. 2002. Mealybugs in California vineyards, pp. 28-33. In H. G. Hernádez, A. F. Castillo, and R. B. Sañudo [eds.]. Proceedings, Simposeio Internacional de Piojos Harinosos, 25th Congreso Nacional de Control Biologico. Hermosillo, Sonora, Mexico. Nov 2002.

Daane, K. M., Malakar-Kuenen, R., Bentley, W. J., Guillén, M., Martin, L. A., Millar, J. G., Krugner, M., Yokota, G. Y. 2003. Population dynamics of the vine mealybug and its natural enemies in the Coachella and San Joaquin Valleys. In. 2002-2003 California Table Grape Commission Annual Reports, Vol. 31, 30 pages.

Millar, J., Daane, K., and Bentley, W. 2003. Pheromones for sampling major mealybug pests in California vineyards. In 2002-2003 Viticulture Research Reports, California Table Grape Commission Annual Reports, Vol. 31, 6 pages.

Millar, J. G., Bentley, W. J., Malakar-Kuenen, R., Martin, L. M., Krugner, M., Daane, K. M. 2003. Mating disruption of vine mealybug in California vineyards. In 2002-2003 Viticulture Research Reports. California Table Grape Commission Annual Reports, Vol. 31, 7 pages.

Daane, K. M., Malakar-Kuenen, R. Guillén, M., Bentley, W. J., Bianchi M., and D. Gonzalez. 2003. Abiotic and biotic refuges hamper biological control of mealybug pests in California vineyards, pp. 389-398. In R. vanDriesch [ed.]. Proceedings, 1st International Symposium on Biological Control of Arthropods. USDA Forest Service Publication FHTET-03055.

Daane, K. M., Malakar-Kuenen, R., Bentley, W. J., and Guillén, M. 2003. Update on vine mealybug biology and control, pp. 8-15. In S. Vasquez [ed.]. Proceedings, San Joaquin Valley Grape Symposium. Easton, CA. Jan 2003.

Daane, K. M., Bentley, W. J., Macmillan, C., and Walton, V. W. 2003. New control programs for the vine mealybug. Wine Business Monthly 10(8): 24-28.

Millar, J., Daane, K., and Bentley, W. 2004. Pheromones for sampling major mealybug pests in California vineyards. In 2003-2004 Viticulture Research Reports (California Table Grape Commission Annual Reports), Vol. 32, 5 pages.

Daane, K. M., Walton, V. M., Guillén, M., Malakar-Kuenen, R., Krugner, M., Gispert, C., Yokota, G. Y., Bentley, W. J., Millar, J. G. 2004. Population dynamics of the vine mealybug and its natural enemies in the Coachella and San Joaquin Valleys. In. 2002-2003 Viticulture Research Reports. California Table Grape Commission Annual Reports, Vol. 32, 28 pages. (same report to California Raisin Marketing Board)

Daane, K. M., Bentley, W. J., Walton, V. M., Krugner, M., Millar, J. G., Yokota, G. Y., and Malakar-Kuenen, R. 2004. Mating disruption of vine mealybug in California vineyards. In 2003-2004 Viticulture Research Reports. California Table Grape Commission Annual Reports, Vol. 32, 16 pages. (same report to California Raisin Marketing Board)

Daane, K. M., Malakar-Kuenen, R., and Walton, V. M. 2004. Temperature development of Anagyrus pseudococci (Hymenoptera: Encyrtidae) as a parasitoid of the vine mealybug, Planococcus ficus (Homoptera: Pseudococcidae). Biological Control 31(1): 123-132.

Haviland, D., Daane, K., Bentley, W. 2004. IPM in action: developing IPM strategies for the vine mealybug. CAPCA Advisor 6: 24-26.

Daane, K. M.., Weber, E. A., and Bentley, W. J. 2004. Vine mealybug – formidable pest spreading through California vineyards. Practical Winery & Vineyard. May/June: (www.practicalwinery.com)

Millar, J. G., Daane, K. M., McElfresh, J. S., Moreira, J. A., and Bentley, W. J. 2005. Chemistry and applications of mealybug sex pheromone, pp 11-27. In R. J. Petroski, M. R. Tellez, and R. W. Behle [eds.]. ACS Symposium Series 906, Semiochemicals in Pest and Weed Control. American Chemical Society, Washington, D.C.

Walton, V. M., Daane, K. M., and Pringle, K. L. 2004. Utilizing the sex pheromone of Planococcus ficus to improve pest management in South African vineyards. Crop Protection 23: 1089-1096.

Mills, N. J., and Daane, K. M. 2005. Non-pesticide alternatives (biological and cultural controls) can suppress crop pests. California Agriculture 59(1): 23-28.

Daane, K. M., Bentley, W. J., Walton, V. M., Yokota, G. Y., and Millar, J. G. 2005. Mating disruption of vine mealybug in California vineyards. In 2004-2005 Viticulture Research Reports. California Table Grape Commission Annual Reports, Vol. 33, 27 pages. (same report to California Raisin Marketing Board)

Millar, J., Daane, K., and Bentley, W. 2005. Pheromones for sampling major mealybug pests in California vineyards. In 2004-2005 Viticulture Research Reports (California Table Grape Commission Annual Reports), Vol. 33, 3 pages.

Bentley, W., and K. Daane. 2005. Vine mealybug, Planococcus ficus, management and movement, pp. 8-16. In California Table Grape Commission [sponsor]. Proceedings, San Joaquin Valley Table Grape Seminar. Visalia, CA. Feb 2005.
Daane, K. M., Bentley, W. J., Klonsky, K. M., Smith, R. H. 2005. Organic vineyard management in California. Organic-Research.com 5: 37-55.

Godfrey, K., Haviland, D., Erwin, J., Daane, K., and Bentley, W. 2005. Vine mealybug: What you should know. University of California, Division of Agriculture and Natural Resources, Publication 8152.

Haviland, D. R., Bentley, W. J., and Daane, K. M. 2005. Hot water treatments to control Planococcus ficus (Hemiptera: Pseudococcidae) in grape nursery stock. Journal of Economic Entomology 98(4): 1109-1115.

Bentley, W. J., Varela, L. G., and Daane, K. M. 2005. Grapes, insects ecology and control, pp. 1-8. In Encyclopedia of Pest Management. DOI: 10.1081/E-EPM-120041132. Taylor & Francis, NY.

Millar, J. G., Midland, S. L., McElfresh, J. S., and Daane, K. M. 2005. (2,3,4,4-tetramethylcyclopentyl)methyl acetate, a sex pheromone from the obscure mealybug: First example of a new structural class of monoterpenes. Journal of Chemical Ecology 31(12):2999-3005.

Daane, K. M., Bentley, W. J., Walton, V. M., Malakar-Kuenen, R., Millar, J. G., Ingels, C. A., Weber, E. A., Gispert, C. 2006. New controls investigated for vine mealybug. California Agriculture 60(1): 31-38.

Daane, K. M., Sime, K. R., Hogg, B. N., Cooper, M. L., Bianchi, M. L., Rust, M. K., and Klotz, J. H. 2006. Evaluation of low dose insecticides on Argentine ant in California’s coastal vineyards. Crop Protection. (in press, available on-line)

Walton, V. M., Daane, K. M., Bentley, W. J., Millar, J. G., Larsen, T. E., and Malakar-Kuenen, R. Pheromone-based mating disruption of Planococcus ficus (Hemiptera: Pseudococcidae) in California Vineyards. Journal of Economic Entomology. (submitted, December 2005)

Project Outcomes

Project outcomes:
Economic Impacts

Imidacloprid provided the greatest reduction in cluster damage when applied in April or May through a drip-irrigation system. We recommend that imidacloprid be applied near 70% bloom, typically in late April to mid-May. As noted, imidacloprid was less effective when delivered through the furrow-irrigation system. Even when properly timed (May) and delivered (pre- and post-application irrigation), a single imidacloprid application did not locally extirpate vine mealybugs. In fact, the vine mealybug population recovered in all imidacloprid treatment plots between summer 2002 and spring 2003. This is presumably because imidacloprid cannot reach all parts of the vine, which leaves small pockets of mealybugs that can recolonize. We note again that there was no year-to-year carry-over impact of imidacloprid. Imidacloprid is the most expensive of the insecticide materials and, for this reason, is not used by many growers. Buprofezin is less expensive and provided excellent control, comparable to both imidacloprid and chlorpyrifos, and can be used effectively in vineyards with furrow-irrigation systems. We recommend that buprofezin be used as an alternative to in-season organophosphate treatments. Because buprofezin is an insect growth regulator, it is most effective on smaller mealybugs undergoing insect molts, and will be less effective as a postharvest application later in the season when insect development is nearly complete.

Our results suggest that Anagyrus release can be used in combination with Admire applications (data not presented shows that Anagrus can not be used with buprofezin, but may be a good combination with mating disruption programs). These results are corroborated by laboratory data of A. pseudococci survival on grape leaves treated with Admire, which showed no mortality, compared with A. pseudococci survival on leaves treated with Lorsban, which had >80% mortality. The combined impact of both controls was not significantly lower than the application of Admire alone. Costs for Admire application (at label rate) range from $70-120 per acre, and we released A. pseudococci at rates between 50,000 adults per acre, which we estimate to cost near $100 per acre as well. For this reason, it is unlikely that vineyard managers would use both control programs concurrently as costs for Applaud or Lorsban are less than $70 per acre. More likely, Admire applications would be used to vine mealybug densities that were high enough to cause immediate crop damage, and this practice might be followed by parasitoid release.

The synthetic pheromone formulated for mating disruption is not yet registered for use. We are working closely with commercial producers toward registration, including a cost analyses – with a target cost of between $35-75 per acre. For commercialization of a sprayable formulation to be adopted, the effective field lifetime of the formulations must be improved. The efficacy of the sprayable formulation used in our studies clearly declined after only 3 wk, with the pheromone totally depleted after 5 wk. The short field lifetime of the formulation may explain, in part, the better performance of the mating disruption program in 2004, where there were four applications, as compared with 2003, when only three applications were made. We suggest that problems with effective lifetime can be overcome with better formulation of the microencapsulated particles. Improvement of the effective field lifetime is clearly required in order to develop a robust and reliable control program.

Farmer Adoption

This research will contribute much-needed information toward the development of sustainable controls, as well as the biology and ecology of mealybugs and their key parasitoids. It should also provide additional information on the seasonal abundance and age structure of the mealybug populations, which will aid in the development of sampling plans and IPM programs. Our work with less-disruptive insecticides has had an immediate impact, as documented by the rapid adoption of our recommendations by the majority vineyard managers. A smaller proportion of growers, particularly in the coastal wine grape regions, are eager to use augmentative release of natural enemies and mating disruption, when these practices are commercially available.

Recommendations:

Areas needing additional study

Future Research Needs

New tests with systemic and foliar insecticides that will work in combination with parasitoid releases are underway. Research will focus not only on the immediate kill, but on season-long control of pests, residual impact on beneficial insects, application timing and movement of material throughout the vine. We have also opened two new research avenues to work in conjunction with parasitoid releases: ant controls and mating disruption. There is also a need to find a material that will kill the mealybugs under the bark, especially during the dormant season.

A key factor in successful biological is the reduction of the ant populations in the vineyard. Ants disrupt mealybug biological control by closing tending Homoptera for their honeydew and, in return, interfering with parasitoid activity. We have tested a 25% sugar-water and small amounts (0.0001%) of neoticotinoid insecticides placed in bait dispensers throughout the vineyard blocks. Results were very promising, with a significant season-long reduction of ant activity in baited plots. There was also a late-season response of mealybugs, with significantly fewer mealybugs and less crop damage in baited plots.

We are currently working with the USDA and California Department of Food and Agriculture on the importation and evaluation of new parasitoids. This work will be critical to the long-term control of the vine mealybug.

Our research identifies several key factors requiring further improvement for a commercially successful mating disruption program and suggests further experimental studies to better reflect the potential of this program. Most evident was the effect of mealybug density on the effectiveness of mating disruption: the proportional reduction of mealybug density was much greater on vines with low initial mealybug densities. It is well known that the performance of mating disruption can decline with increased pest population density. For this reason, a combination of control tactics may prove more effective than a single tactic, as revealed in other pest systems. Our results are consistent with codling and fruit moth studies, and suggest that commercialization of this program may include some use of insecticides or other practices to lower the initial mealybug density to a level at which the mating disruption is effective. Further studies are also needed to determine the optimal application rates and intervals. We also used a formulation of >99% chemically pure lavandulyl senecioate, which greatly increased production costs. If similar levels of efficacy could be obtained with much cheaper and less pure technical grade material, overall costs of a mating disruption program could be greatly reduced. Further study and manipulation of the formulation to enhance longevity may show that mating disruption is an effective, economical, and sustainable tool to be implemented as part of a mealybug management program.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.