2018 ASHS Annual Conference

Tomatoes (Solanum lycopersicum) are susceptible to a wide array of arthropod pests. Varieties on the market do not have pest resistance incorporated to allow for a reduction of pesticides used on the crop. In protected culture, using biological control agents is a critical part of IPM, especially for the control of the two major pests: whiteflies and aphids. Limited research is available on the effect of OMRI approved insecticides on biological control agents in producted culture. We evaluated the selectivity of five OMRI approved insecticides against 2^nd instar larvae of the generalist beneficial control agent, Chrysoperla rufilabris, in triple exposure and behavioral assays. Triple exposure assays were conducted with thirty 2^nd instar larvae per treatment with positive and negative controls and five insecticides applied at the highest rate on the label. Insects were monitored daily for mortality and developmental time points. All insects treated with the positive control, DEET, died within an hour. Two thirds of the Azatin-O® treated larvae pupated and delay of a day and a half was statistically different from the control and four other insecticides, EcoTec®, M-Pede® PyGanic® and SucraShield®. None of the Azatin-O® treated larvae produced adults compared to over 90% for the other treatments.

Behavioral assays were conducted with the same treatments versus a control using thirty 2^nd instar larvae per treatment with the ViewPoint™ tracking system, where data was collected on ambulatory time, distance walked, velocity, and proportion of time spent in each half of the arena for 10 minutes. This assay violates ANOVA assumptions of normality and homoscedasticity thus, the Wilcoxon rank sum test was used to test the significance of differences in treatment response. C. rufilabris larva expressed repellency characteristics upon contact of DEET in the paired behavioral assays based on Wilcoxon Signed-Rank Test for ambulatory time, distance and % time, but not velocity. The acetone control showed no significance for any parameter. Larvae exposed to Azatin-O® had a significant response to the distance traveled. While PyGanic® had a significant effect on the velocity of the larvae, which was no surprise since if they encountered PyGanic they died on that side of the arena.

Care must be taken when applying insecticides in combination with beneficial insects. Our work found one impeded insect development and foraging ability (Azatin-O®), but others only reduced foraging ability of the larvae on sprayed surfaces (PyGanic®). Three of OMRI approved insecticides (Ecotec®, M-Pede® and SucraShield®) did not affect green lacewing larvae development or foraging ability.