Final report for GNE22-288
Project Information
Lycorma delicatula, spotted lanternfly (SLF), is an invasive plant hopper from Asia and a major pest to the agricultural and forestry industries in the Mid-Atlantic region that was first detected in New Jersey in 2018. It is present at over 75% of vineyards throughout the state, with most experiencing populations high enough to warrant treatment. SLF is a highly polyphagous species that feeds on the plant phloem of over 100 plant taxa. A key host is cultivated grape which SLF adults congregate on in late summer/early fall. Feeding on grapevines has been associated with decreased grape growth rates, overwintering ability, and reduced crop yield. An economic threshold of 10 SLF adults/vine used in South Korea has been exceeded in many New Jersey vineyards, with some experiencing pressure of 200 SLF/vine. Waves of SLF adults colonize vines for 4-8 weeks, requiring multiple insecticide applications. Growers apply 2 to 6 insecticide sprays on average just for managing SLF adults during this short period of time. This project assessed the efficacy of insecticides currently used in vineyards against SLF and the in-field residual activity of each for resistance management. This study builds on previous research that has identified peak dispersal time and residence time in New Jersey grapes as well as caged insecticide trials. Research conclusions from this study included ranking the efficacy of four foliar insecticides labeled for SLF management in vineyards, and identifying SLF feeding risk on vines under current field conditions and insect pressure. Results of this study have been disseminated directly to farmers through grower conferences and Rutgers extension blog posts. Results of this study have helped guide grower decisions on the timing of insecticide applications and materials used that match pre-harvest restrictions.
- Evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults.
Three pyrethroids and one noenicitinoid will be tested that have varying reported residual activity. One application will be made at the peak of SLF movement into vineyards. Using decease individuals and live counts on vines percent mortality will be tracked over the course of 26 days for each of the tested insecticides to identify its efficacy over time. The study was conducted for two consecutive years at one research station vineyard and one commercial vineyard in 2022 and 2023. Residual efficacy of the insecticides were ranked each year from best/longest to shortest/least effective. Materials ranked differently between years. This discrepancy is hypothesized to be due to weather extremes experienced in 2022. Insecticide ranking in 2023 was more consistent with the results previously reported in controlled experiments and are hypothesized to be more accurate. This will help guide grower decisions for materials used within their vineyards.
- Assess SLF female physiological state during movement.
Dead individuals collected will be sexed and ranked based on the percent fat shown on the exterior of their abdomen to assess fat body accumulation over time. Females will be dissected to identify mated status over 26 days. This will allow us to equate fat body accumulation with timing of SLF movement into vineyards. There are currently no quantifiable metrics to predict exact time of movement.
During dissection the specimens were considered too desiccated for accurate identification.
- Quantify SLF feeding impact on primary bud growth.
Primary bud formation metrics were recorded on vines exposed to SLF feeding from fall 2022 at vineyard edge and vineyard center. These metrics were conducted on two grape varieties (chardonnay and chambourcin). Neither variety showed any significant bud death associated with SLF adult feeding based on the natural populations that were tracked during the fall 2022 growing season. This will help equate vine damage with feeding density providing insight into potential SLF feeding thresholds.
The purpose of this project was to evaluate the residual efficacy of foliar-applied insecticides on grapevines against adult SLF to reduce the number of insecticide applications reducing environmental impact and increasing worker safety. Our results have guided grower decisions on compounds used for insecticide application that incorporate label pre-harvest intervals. Peak adult SLF dispersal into vineyards occurs in early September and continues for several weeks. This movement coincides with pre-harvest and harvest periods with increased human activity within the vineyard. The compounded effects of gregarious feeding over the span of several years can result in significant economic losses for growers. SLF density increases feeding pressure on grapevines acting as a plant stressor and is associated with decreased grape growth rates, overwintering ability (Song 2010), and reduction of crop yield (Urban 2019, Leach and Leach 2020).
Since its first detection in 2018, approximately 75% of New Jersey vineyards have some level of SLF pressure resulting in many growers apply 2 to 6 additional insecticide applications targeting SLF. Based on our surveys, vineyards in New Jersey with high SLF population densities can have upwards of 200+ SLF/vine for multiple weeks despite insecticide applications.
Penn State evaluated the efficacy and residual activity of several of the proposed insecticides on growing grape terminals with variable results. Their trials involved sleeve cages with 10 adults exposed to the material for 24 hours before removal. This process was repeated for eight times points between 1 to 26 days (Leach 2021). Their results have helped shape management recommendations, however, SLF behavior is altered when enclosed in a cage and SLF at this critical time stage are feeding on canes and trunks rather than the shoots were sleeve clogs were faceted. A more a curate evaluation on residual activity is needed to effectively manage the new waves of adults dispersing into the vineyard. The insecticides identified with the longest residual by Penn State plus the insecticide most commonly used pre-harvest was evaluated in consideration with their pre- -harvest interval. SLF adult pressure coincides with harvest for grapes and all three of these factors need to be considered when choosing which insecticide to apply. The results of the residual effects of these compounds have guided grower application as part of their management program. Identifying effects of adult feeding on vines after one year using New Jersey's current environment factors and SLF pressures can help growing make more educated decision on SLF population threshold in within their vineyards.
References:
Leach H, Leach A. (2020). Seasonal Phenology and Activity of Spotted Lanternfly (Lycorma delicatula) in Eastern Us Vineyards. Journal of Pest Science. 93(4):1215-24. doi: 10.1007/s10340-020-01233-7
Leach H. (2021). Evaluation of Residual Activity of Insecticides for Control of Spotted Lanternfly in Grape, 2020. Arthropod Management Tests, Volume 46, Issue 1, 2021, tsaa123, https://doi.org/10.1093/amt/tsaa123
Song M-G. (2010). Damage by Lycorma delicatula and Chemical Control in Vineyards: Chung-buk National University Graduate School.
Urban, J. M. (2019). Perspective: shedding light on spotted lanternfly impacts in the USA. Pest Manag. Sci. 76: 10–17.
Cooperators
- (Researcher)
Research
- Evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults.
To evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults four insecticides will be assessed. The treatments to be evaluated are a neonicotinoid, thiamethoxam (Actara) and three pyrethroids, cypermethrin (Mustang Max), fenpropathrin (Danitol), and bifenthrin (Brigade). These insecticides were selected based on their previously reported residual activity. Our study added to current information available about these insecticides using controlled assays by testing them against SLF using methods that would reflect conditions experienced by growers. Neonicotinoids demonstrated > 60% mortality up to 5 days after application while pyrethroids had a much longer residual efficacy lasting up to 15-21 days after application (Leach 2021). Treatments will be applied to mature grapes using a hand-held CO2 pressurized sprayer. Each of the four insecticides will be applied once at the start of peak SLF movement. An additional treatment will be included for a potential grower spray program using the residual results found by Leach (2021) such as 1) Danitol 2) Actara 3) Mustang Maxx 4) Brigade post-harvest (Table 1) that integrates PHI with expected residual activity. Insecticide treatments were applied to three vines with an additional three vines left untreated between treatments. SLF exposure to insecticide will be based on the natural influx of SLF adults moving into the vineyard. Nielsen (unpublished) has reported SLF adult persistence within the vineyard for 3 weeks using mark-release-recapture methods. Percent mortality was assessed 3 times per week for 28 days (Leach 2021). Dead individuals were removed and frozen for the treatment areas at each check day and used for objective 2. A mixed model for each treatment was used comparing efficacy of the four treatments by day.
|
Trade Name |
Active Ingredient |
Class |
Rate per acre (oz.) |
PHI (days) |
REI (hrs) |
Residual Activity (days) |
Max. use per season (oz) |
|
Actara 25WDG |
thiamethoxam |
Neonicotinoid |
3.5 |
5 |
12 |
<21 |
7 |
|
Mustang Maxx 0.8EC |
cypermethrin |
Pyrethroid |
4 |
1 |
12 |
<7 |
24 |
|
Danitol 2.4EC |
fenpropathrin |
Pyrethroid |
21.33 |
21 |
24 |
>26 |
42.66 |
|
Brigade 10WSB |
bifenthrin |
Pyrethroid |
8-16 |
30 |
12 |
21 |
16 |
- Assess timing of SLF movement into vineyards with fat body accumulation.
To assess fat body accumulation and mated status, dead individuals will be sexed, measured, and dissected from each of the treatments and check points. Only females will have their yellow abdominal area measured (Urban unpublished) and dissected for mated status. Wolfin et al. (2019) showed a relationship between increased yellow abdomen area with limited flight capability and mated status. Presence of the male spermatophore and oocyte development will also be recorded. A one-way ANOVA will be used for analysis.
This objective was removed from the study due to the desiccation of dissection specimens.
- Quantify SLF feeding impact on primary bud growth.
To determine SLF feeding impact on primary bud development density of individuals was recorded for each vine during the duration of adult presence within the vineyard. A series of bud formation metrics were used to measure primary, secondary, and tertiary bud mortality in the spring 2023. Fifteen vines from two varieties were assessed (chardonnay and chambourcin). Three vines were cut at the end of March and allowed to sit in bucks of water for 48 hours. 50 buds from each vine were selected for dissection. A linear regression comparing SLF density with bud mortality. There was no significant association with natural SLF density on vines recorded in 2022 to bud mortality seen on those vines in 2023.
References:
Leach H. (2021). Evaluation of Residual Activity of Insecticides for Control of Spotted Lanternfly in Grape, 2020. Arthropod Management Tests, Volume 46, Issue 1, 2021, tsaa123, https://doi.org/10.1093/amt/tsaa123
Wolfin, M.S., Binyameen, M., Wang, Y. et al. (2019). Flight Dispersal Capabilities of Female Spotted Lanternflies (Lycorma delicatula) Related to Size and Mating Status. J Insect Behav 32, 188–200. https://doi.org/10.1007/s10905-019-09724-x
Objective 1: Complete
Evaluate the residual efficacy of foliar-applied insecticides in vineyards against SLF adults. SAREupdate1.15.23graphs
The insecticide trial was conducted in the Summer of 2022 at RAREC on two grape varieties (chardonnay and chambourcin). Chemicals assessed included Actara, Mustang Maxx, Danitol, and Brigade. Treatments were checked three times per week for live SLF on vines and dead insects collected and stored in the freezer for future dissection. The trial lasted for a total of 27 days. Materials with shorter residual activity were reapplied as needed in accordance with the label instructions. This resulted in three sprays for Mustang Maxx, two sprays for Danitol, and one spray for Actara and Brigade for the duration of the experiment.
All insecticides had a high initial knockdown effect, with Bridage and Danitol performing the best. All insecticides showed large oscillations in their residual efficacy. We suspect this volatility may be a result of extremes in temperature despite time of sampling being consistent throughout the trial. Days with higher temperatures had greater SLF movement and resulting in lower average percent mortality. Extended periods of cold, rain, wind, or hurricane conditions hindered SLF movement and percent mortality resulting in higher average percent mortality.
General observations showed an overall higher number of SLF in the Actara (neonicotinoid) treatments then with other insecticides (pyrethroids). Insecticides were ranked for best residual efficacy as follows: 1) Brigade, 2) Actara, 3) Danitol, and 4) Mustang Maxx. However, there were no statistically significant differences between the insecticide’s residual efficacies. Based on previous studies, Danitol was expected to have higher residual efficacy longer than 13 days. Actara outperformed expectations and previously predicted residual efficacy duration.
|
Treatment (active ingredient) |
Rate per acre (oz.) |
Percent Mortality |
|
||||||||||||
|
|
|
Base pop. per vine |
1 DAT |
3 DAT |
6 DAT |
8 DAT |
10 DAT |
13 DAT |
15 DAT |
17 DAT |
20 DAT |
22 DAT |
24 DAT |
27 DAT |
|
|
Actara 25WDG (thiamethoxam) |
3.5 |
35 |
89.9 |
78.6 |
56.3ab |
34.0ab |
47.6 |
43.7 |
27.2 |
11.3 |
27.1 |
29.5b |
22.5 |
9.6 |
|
|
Brigade 2EC (bifenthrin) |
3.2 |
25 |
98.4 |
83.3 |
14.9b |
13.5b |
44.8 |
31.9 |
33.7 |
25.8 |
66.1 |
72.9a |
28.5 |
31.7 |
|
|
Danitol 2.4EC (fenpropathrin) |
21.33 |
24 |
98.7 |
87.3 |
82.6a |
54.5ab |
43.1 |
24.3 |
x |
x |
x |
x |
x |
x |
|
|
Mustang Maxx 0.8EC (cypermethrin) |
4.0 |
21 |
83.2 |
61.3 |
40.5ab |
95.0a |
29.2 |
14.8 |
x |
x |
x |
x |
x |
x |
|
|
F ratio |
|
|
1.45 |
2.57 |
4.40 |
5.14 |
0.35 |
1.94 |
0.06 |
4.95 |
1.99 |
15.94 |
0.79 |
0.99 |
|
|
Degrees of freedom |
|
|
3 |
3 |
3 |
3 |
3 |
3 |
1 |
1 |
1 |
1 |
1 |
1 |
|
|
P-value |
|
|
0.2556 |
0.4886 |
0.0157 |
0.0130 |
0.7920 |
0.1666 |
0.8120 |
0.0766 |
0.2199 |
0.0112 |
0.4147 |
0.3650 |
|
An additional year of data for 2023 needed to be collected due to environmental extremes during the course of the trial in 2022. Differences in residual efficacy were observed between insecticides by sampling year. Data analysis for this data is still in progress.
In 2023 the experiment was repeated at a different location (Cedar Rose) due to a SLF population drop at RAREC in 2023. Insecticide ranking was different from that of the 2022 results but in alignment with the results previously reported in controlled studies using these same insecticides.
|
Treatment (active ingredient) |
Rate per acre (oz.) |
Percent Mortality |
||||||||||
|
|
|
Base pop. per vine |
1 DAT |
3 DAT |
6 DAT |
8 DAT |
10 DAT |
13 DAT |
15 DAT |
17 DAT |
20 DAT |
22 DAT |
|
Actara 25WDG (thiamethoxam) |
3.5 |
16 |
79.3 |
41.5B |
61.8 |
25.1 |
16.0B |
28.5 |
51.7A |
21.3 |
17.2 |
10.4 |
|
Brigade 2EC (bifenthrin) |
3.2 |
13 |
97.8 |
82.8A |
63.5 |
34.7 |
26.8Ab |
13.8 |
20.8B |
6.7 |
21.2 |
5.8 |
|
Danitol 2.4EC (fenpropathrin) |
21.33 |
18 |
67.7 |
58.1Ab |
53.0 |
28.7 |
35.7A |
22.6 |
22.4B |
20.6 |
12.1 |
6.9 |
|
Mustang Maxx 0.8EC (cypermethrin) |
4.0 |
16 |
89.5 |
43.5B |
47.0 |
24.6 |
7.8b |
20.1 |
2.6B |
12.5 |
9.2 |
4.4 |
|
F ratio |
|
|
1.93 |
4.95 |
0.73 |
0.31 |
5.59 |
0.87 |
10.18 |
1.44 |
1.25 |
0.60 |
|
Degrees of freedom |
|
|
3 |
3 |
3 |
3 |
3 |
3 |
3 |
3 |
3 |
3 |
|
P-value |
|
|
0.1390 |
0.0045 |
0.5382 |
0.8215 |
0.0023 |
0.4620 |
0.0002 |
0.2561 |
0.3133 |
0.6229 |
Objective 2: Removed
Assess timing of SLF movement into vineyards with fat body accumulation.
- During dissection specimens were deemed too desiccated for accurate assessment and this objective was removed from the study.
Objective 3: Complete
Quantify SLF feeding impact on primary bud growth.
To asses damage caused by adult feeding of overwintering vines SLF counts were done weekly for the same 30 vines at RAREC for the duration of adult feeding in fall of 2022. This was done for two grape varieties; Chardonnay (15 vines) and Chambourcin (15 vines). Three shoots were collected at random from each sampled vine in March of 2023. Shoots were stored in buckets with water for 48 hours, to increase accuracy of identification of bud death. 50 buds were dissected for each shoot and assessed for bud primary, secondary and tertiary mortality. Percent mortality for buds was identified for each vine. We analyzed bud mortality via regression against the average number of SLF feeding on vines and found no significant correlation between SLF density and bud mortality (P Value= 0.4590). bud mortality
There was variability with residual efficacy within chemicals tested between years. This variability has been hypothesized to be associated with weather extremes observed in 2022.
In 2022, all compounds showed high efficacy directly following the spray with more than 96% morality on day one. Actara and Brigade had the highest residual efficacy by day 24 with more than 20% mortality. Danitol and Mustang Max had the lowest residual efficacy by day 13.
In 2023, all compounds showed high efficacy directly following the spray on day one. Actara had the highest residual efficacy by day 15 with over 50% mortality. Mustang Max had the lowest residual efficacy by day 15 with less than 3% mortality.
Information from these efficacy trials is currently in preparation for publication and data obtained from these trials is being used to provide growers with insecticide application recommendations.
We were not able to identify a direct correlation between adult feeding and bud mortality, likely due to low naturally occurring populations and moderate temperature fluctuations experienced in southern New Jersey. Our study does not dispute that SLF adult feeding causes damage to grapevines, but simply notes that based on our SLF populations in 2022 no association with bud mortality was detected.
Education & Outreach Activities and Participation Summary
Participation Summary:
Results obtained from these studies will be published in two Arthropod Management Tests and presented at professional conferences such as Cumberland Shenandoah fruit workers conference 2022 and 2023 the Entomological Society of America Eastern Branch meeting in 2023. To make this information easily accessible to growers, these results will be presented at grower meetings including New Jersey grape camp New Jersey Fruit and Vegetable EXPO, and in-season twilight meetings. Online publications will be posted on the Rutgers NJAES blog website “Plant Pest Advisory”. Data obtained from this study will be applicable across different states as the spread of SLF unfolds. Grower recommendation website postings will be written to reach a wider audience.
Project Outcomes
The results of this study can provide additional information to growers to help guide insecticide applications during peak adult movement in New Jersey. I hope the results of this study allow for the decrease in the frequency of insecticide applied. A decrease in insecticide application will positively affect growers financially as well as benefit the environment.
During this project I have learned that abiotic conditions are out of my control and can have a substantial effect on the results of an experiment. To combat this, flexibility is imperative as location may have to be changed or the trial may need to be repeated, as both happened for the first objective of my project. I also learned the value of approaching an issue (in my case insecticide efficacy) from various angles in both controlled and non controlled settings to obtain a more comprehensive picture of the results. The interpretation of these results can provide the necessary information to guide grower recommendations.
My passion remains in identifying solutions to provide growers with current pest issues they face. For the duration of my dissertation I will focus on SLF but hope to expand my research to include additional insect pests in the future. I am currently working on publishing two Arthropod Management Test reports for the for the first objective of this study looking at efficacy. I hope to include the results of SLF feeding impact of grapevines in a larger manuscript in the future. The results of this study have been reported at Rutgers within our department, at grower meetings, working groups specific to SLF, as well as local and national conferences.