Native Habitat Restoration, Sustainable IPM and Beneficial Insect Conservation

Native Habitat Restoration, Sustainable IPM and Beneficial Insect Conservation

Summary

Substantial progress was made in 2011 with the establishment of eight commercial vineyard demonstration sites and commencement of regular monitoring of pest and beneficial arthropod populations. In general, trends for reduced pest abundance and increased beneficial insect diversity and abundance were seen in native habitat restored (NHR) or enhanced vineyards. In contrast higher pest abundance and reduced diversity and abundance of beneficial arthropods were observed in ‘conventional’ vineyards with reduced native habitat. Diversity and abundance of butterflies was also greater in NHR vineyards. One hundred and six species of flowering perennial plants were evaluated for beneficial insect attraction, and initial results are presented.

Objectives/Performance Targets

1. Select four demonstration (Native Habitat Restoration: NHR) and four (paired control vineyards without NHR.

Four NHR demonstration and four (paired) control vineyards (without NHR) were selected in early 2011. Four viticultural sub-areas within the south-central Washington wine grape growing area were used for these sites to give a broader spread of climatic, vegetational and entomological variation.

A) Columbia Gorge AVA: Wine grapes in this sub-area are exposed to a more moderate and humid climate (adjacent to the Columbia River).

NHR site- Klickitat Winery (Robin Dobson) Syrah (two acres). NHR has been implemented at this site for 11 years.

Control site- Dry Hollow (Jose Flores) Syrah (five acres).

B) Columbia Valley AVA: Wine grapes in this sub-area exposed to hot and dry growing conditions.

NHR site- White Heron Cellars (Cameron Fries) Malbec (12 acres). NHR has been implemented at this site for eight years.

Control site – Jones of Washington (Greg Jones) Malbec (six acres).

C) Walla Walla Valley AVA: Wine grapes in this sub-area exposed to hot and dry conditions and unique terroir.

NHR site- Woodward Canyon Estate Vineyards (Rick Small) Cabernet Franc (six acres). NHR has been implemented at this site for five years.

Control site- Sevein Hills (Jon Davies) Cabernet Franc (four acres).

D) Red Mountain AVA: Wine grapes in this sub-area exposed to hot and dry conditions and unique terroir.

NHR site- Ciel du Cheval Winery (Jim Holmes) Cabernet Sauvignon. NHR is being implemented at this site (two years).

Control site- La Coye Winery (Dick Boushey) Cabernet Sauvignon.

2. Monitor pest and beneficial arthropods in NHR and control vineyards (April-September) to provide data on abundance and seasonality of pests, natural enemies, butterflies and bees.

Monitoring of pest and beneficial arthropods in the eight vineyards listed above commenced in spring 2011. Some of these data are presented in this report.

3. Establish additional refugia and native perennial ground cover plots in demonstration vineyards. Aim to increase native plant refugia area to 20-25%. Aim to establish at least three ground cover species in each vineyard.

For three of the four selected NHR vineyards, there is no need to establish additional refugia/ground covers because each already has a long history (8-11 years) of native habitat restoration/encouragement (Klickitat Winery, White Heron Cellars, Woodward Canyon Estate). The NHR status of the remaining demonstration vineyard (Ciel du Cheval) is not adequate and attempts are being made to establish some native plants at this site.

4. Conduct survey of abundance of pest natural enemies attracted to flowering native perennials in southern and central Washington. Collect data for 30-50 potential candidates for ground covers and refugia plantings.

This survey commenced in 2010 and continued in 2011. To date we have surveyed the abundance of beneficial insects associated with 106 species of flowering plants, mostly native perennials. Some of these data are presented in this report.

5. Establish native perennial ground cover candidates in field plot trial at WSU-Prosser for evaluation as natural enemy attractants. Select at least 15 species.

Three groups of replicated native plant plots have been established at WSU-Prosser, comprising 10 plants. Difficulties in establishment of some native plant species prevented a higher number being established to date, but we will continue our efforts on this objective.

6. Mass rear and release selected butterfly species in NHR vineyards using the Sustainable Prisons program.

In retrospect, the timing of this objective (commencing after six months of the project) is premature. More than six months is needed to determine the butterfly fauna of each vineyard before commencing a rear and release program. This objective is better timed to conduct in year 3 (2013). Preparations for conduct of this objective were made in 2011 with initial evaluations of vineyard butterfly fauna and establishment of rearing protocols, etc. with the Walla Walla Penitentiary (WWP), which is the facility to be involved in this project. Some preliminary rearing programs will be conducted by inmates at the WWP in 2012 to test feasibility of the concept.

7. Establish and maintain NHR website, regularly detailing progress and providing information for other vineyards wishing to adopt the program.

A website devoted to this project was established in spring 2011 and may be found at:
http://www.wavineyardbeautywithbenefits.com/ In addition, a Facebook page was also set up to provide timely information:
http://www.facebook.com/pages/Vineyard-Beauty-with-Benefits-Restoring-Habitat-for-Beneficial-Insects/112777002135559?sk=wall

Accomplishments/Milestones

Substantial progress was made in 2011 in 1) establishing and monitoring NHR and control vineyards for pest and beneficial arthropods, 2) evaluating beneficial insect attraction to native plant species, and 3) establishing replicated plots of selected native plant species and monitoring beneficial insect attraction.

Investigate native perennial flowering plants for attractiveness to beneficial insects and practicality for use as vineyard covers and refugia:

Ground covers and refugia confer a number of benefits on vineyards, including the attraction and retention of beneficial insects. A WSU/NCSFR funded study during 2005-08 demonstrated the value of some species of non-endemic annual flowering plants as ground covers to attract and retain various beneficial insects in south-central Washington vineyards, with no adverse effects on vine growth. However, germination and survival of the cover crops was generally poor, due to the characteristically dry climate of south-central Washington. A recent study in Michigan compared the attractiveness of selected perennial native plants and exotic annual plants to beneficial insects and found many native plants to be just as attractive, or more attractive than the exotics. The use of native perennial plants for ground covers and refugia has several benefits, including better adaptation to the local environment, aiding local biodiversity and avoidance of annual establishment. In addition, native perennials may provide overwintering sites for beneficial arthropods. To restore native habitat refugia to Washington vineyards to enhance IPM and biological control, plant species with optimal attraction to predators and parasitoids of grape pests need to be selected. No information is available on the attractiveness of native flowering perennial plants to beneficial insects in south-central Washington.

One hundred and six species of flowering perennial plants were evaluated for beneficial insect attraction in 2011 field studies. The vast majority of these are native, and all plants were growing wild in natural shrub-steppe landscapes in the Yakima Valley and nearby areas. Studies were primarily conducted at five to six sites near Yakima, Prosser and the Tri-Cities during April-November. The number and identity of beneficial insects attracted to different plant species was assessed using clear sticky traps (12 x 4 inches) placed either on the flowering plant or immediately adjacent to the plant. Control traps, placed on bare ground, rocks or dry non-flowering vegetation, were also positioned near target plants. The major types of beneficial insects assessed are shown in Table 1. For each assessment, a single trap was used to assess attraction to each of three separated (at least five meters) individual plants. Traps were left in the field for one to three weeks, retrieved, taken to the laboratory, stored and examined later for beneficial insects under the microscope. Most plants were evaluated at multiple sites. Insects were identified to species or family, counted and recorded. All data were converted to means per trap per trapping period.

Results

More than 1,000 traps were deployed on 106 species of flowering perennial plants during April-November 2011. To date (January 2012), traps for only five plant species (Yarrow, Gary Rabbitbrush, Green Rabbitbrush, Clematis, Milkweed) have been fully read and analyzed, with the remainder expected to be completed before April 2012. Data on the attraction of six groups of beneficial insects to these plants are shown in Figure 1. All of the species, except Green Rabbitbrush, attracted large numbers of predatory bugs. Gray Rabbitbrush was outstanding in attraction of parasitic wasps (including ichneumonids/braconids/Anagrus), with a mean of up to 380 per trap. Yarrow and Milkweed also attracted large numbers of parasitic wasps. The only species with significant attraction to beneficial flies was Yarrow, with the other species not attracting significantly more than control traps. Gray Rabbitbrush had the best overall profile of beneficial insect attraction, and Clematis had the worst (Fig. 2). Yarrow, Gray Rabbitbrush and Milkweed were also evaluated in 2010 with good results (see 2010 progress report), and it is becoming clear that these three plants are strong attractants for a number of natural enemy groups, particularly parasitic wasps and predatory bugs. Yarrow and Milkweed are potential ground cover plants for vineyards, while Gray Rabbitbrush would serve as excellent refugia plants near to vines. Most of the beneficial insect attraction to rabbitbrush occurs during August-October, and it is likely that these plants also serve as overwintering sites for beneficial insects.

Evaluation of the pest and beneficial insect fauna associated with habitat-enhanced (NHR) and habitat-reduced (control) vineyards:

Eight commercial vineyards are cooperators in this multi-season study, which commenced in spring 2011. A pair of vineyards was identified and selected in each of the Columbia Gorge, Columbia Basin, Walla Walla and Quincy-Mattawa viticultural areas. Each pair consisted of a ‘native habitat-enhanced’ (VH) and a ‘native habitat-reduced’ (C) vineyard. Habitat-enhanced vineyards are situated close to natural areas with current management practices designed to maximize colonization of native plants in and/or around grape plants. Habitat-reduced vineyards are situated away from natural areas and colonization of native plants has not been encouraged and may have been actively discouraged. Monitoring of pest and beneficial insect and mite populations commenced in all vineyards in May, continuing at two-weekly intervals until September. On each visit leaf samples were taken from grapevines and sticky yellow traps were placed in the vineyard. Leaves were examined in the laboratory for pests and beneficials, as were sticky traps. Additional sticky traps were placed in native habitats present adjacent to the habitat-enhanced vineyards.

Results

Vineyard pairs in the Columbia Gorge and Quincy-Mattawa areas showed the greatest contrast in terms of numbers of native plants species present close to grapevines, and data from these sites are presented. In both areas, the VH vineyard had a diverse immediate area flora that conservatively contained at least 30 native species occurring at medium-high density. In contrast, the C vineyards in both areas had a low-diversity flora comprising only 7-12 species.

Pest incidence/abundance. Spider mite populations were absent (Quincy) or occurred at very low density (Columbia Gorge). However, populations were significantly greater in the C vineyard than in the VH vineyard in the gorge (Fig. 3). Predatory and mildew-feeding mites (tydeids) were more common in the gorge VH vineyard along with rust mites, although the latter were substantially below levels likely to cause economic damage (Fig. 3). Leafhoppers were virtually absent in the gorge vineyards, but adults were common (mean 30 +/trap) in the Quincy VH vineyard. However, this high level of adults did not translate into economically damaging levels of nymphs on leaves (Fig. 4). Very few leafhoppers were seen at the Quincy C vineyard due to spray application.

Beneficial insect incidence/abundance. Data on abundance of four groups of beneficial insect in VH and C vineyards at Quincy and in the Columbia Gorge are shown in Figs. 5-6. Abundances in native habitat (H) areas close to the VH vineyard are also shown. In most cases, greater populations of beneficials occurred in the native habitat area (H) alongside the VH vineyard than in the C and VH vineyards. In a number of cases (e.g. predatory beetles and bugs, lacewings (Quincy only), parasitic wasps), beneficial insect populations were greater in the VH than in the corresponding C vineyard, suggesting dispersal from the adjacent habitat into the vineyard. However, with some groups of beneficials (e.g. beneficial flies, lacewings (gorge)), there appeared to be no movement from habitat into the adjacent vineyard (Figs. 5-6). These preliminary data support the hypothesis that adjacent native habitats supporting a diverse community of native plants can be an important source of some groups of predators, parasitoids and pollinators, instrumental in providing effective and sustainable ecosystem services (e.g biological control of grape pests) in vineyards. In addition to providing direct and tangible benefits to viticulture, vineyard habitat restoration also has the potential to help conserve threatened flora and fauna, including endangered native bees and butterflies. The Columbia Gorge enhanced habitat vineyard supported populations of at least nine butterfly species in 2011, at least one of which is threatened because of habitat destruction.

Ultimately, our research on attraction of beneficial insects to native flowering plants and evaluation of the influence of native habitat on vineyard IPM, will converge. Identification of the most attractive flowering plants to specific beneficial insects will enable design and tailoring of native habitat to provide needed ecosystem services in specific vineyards or viticultural regions in Washington.

What work is left to do?

Beneficial insect attraction to native plants: Another season (2012) of evaluating beneficial insect attraction to ~ 100 native plant species will be conducted. Thereafter, highest ranking species will be introduced to demonstration vineyards and WSU research vineyards for in-vineyard evaluation – entomologically and agronomically – in 2013. Replicated plot trials on selected native plant species will continue in 2012 and 2013.

Comparison of NHR demonstration and control vineyards: Monitoring of pests and beneficials in these vineyards will continue in 2012 and 2013. Rearing and vineyard releases of selected butterfly species will be conducted in 2013.

• Figure 1. Attraction of beneficial insects to Gray Rabbitbrush (GR), Milkweed (M), Green Rabbitbrush (R), Clematis (C) and Yarrow (Y) in field evaluations conducted during 2011.
• Figure 5. Mean abundance of beneficial insects in a habitat-enhanced vineyard (HV), adjacent habitat (H) and a habitat-reduced vineyard (C) in the Quincy area during 2011.
• Table 1. Beneficial insects assessed for their attraction to flowering plants
• Figure 3. Pest and beneficial mite populations on grape leaves in VH (habitat-enhanced) and conventional (C) vineyards in the Columbia Gorge in 2011.
• Figure 4. Adult and immature leafhoppers in VH (habitat-enhanced) and conventional (C) vineyards at Quincy in 2011.
• Figure 2. Beneficial insect attraction profiles for 5 native flowering perennial plants derived from field data obtained in 2011.
• Figure 6. Mean abundance of beneficial insects in a habitat-enhanced vineyard (VH), adjacent habitat (H) and a habitat-reduced vineyard (C) in the Columbia Gorge during 2011.

Impacts and Contributions/Outcomes

This research program will benefit the Washington wine grape industry by improving the efficacy and sustainability of conservation biological control of vineyard pests by restoring native habitats and associated communities of natural enemies. This will result in reduced pesticide use, production costs and environmental contamination. In addition, our research will feature and demonstrate for the first time in the western U.S., the role that agriculture can play in insect conservation. Washington vineyards will be shown to have the potential to provide habitat and refugia for threatened and charismatic insects, such as native butterflies and bees, as well as native flora. Merging the interface between agricultural production, sustainable biological control and conservation of threatened insects and flora is likely to bring substantial benefits to grapegrowers and regional communities. In addition to low input, sustainable biological control, our program will highlight marketing and tourism opportunities for wineries and the viticultural industry as a whole. Butterflies and bees may become the symbol of green viticulture in Washington State, playing a significant role in increasing sales and tourism.

Collaborators: