2017 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. The major insect pests in protected culture of tomatoes are: whiteflies, aphids, thrips and spider mites. One of these, whiteflies, is difficult to eliminate with chemical or biological methods, thus emphasizing the importance of incorporating pest resistance into tomato varieties. Glucose esters exuded from type IV glandular trichomes mediate the resistance of Solanum pennellii to several pest species including aphids and whiteflies. Since glucose esters are non-toxic to the pests controlled, the pressure for insects to become resistant to these compounds should be less than is commonly seen for pesticides and high antibiosis-mediated plant resistance mechanisms. However, one concern is how glucose esters could affect biological control agents used to control pests in protected culture. In order to investigate the potential impacts of glucose esters on biocontrol agents, triple exposure, single exposure, and behavioral assays were undertaken on the generalist predator, green lacewing Chrysoperla rufilabris. For the triple exposure assay, three routes of exposure were assessed: oral, direct, and ingestion. This assay utilized Malathion at recommended rates as a positive control, water, as the negative control, and glucose esters at biologically relevant concentrations of 60 μg/cm². Larvae were tracked through development, and those surviving to adulthood were subjected to the single spray assay. The single spray assay treatment only evaluated the effect of glucose esters and water since Malathion resulted in 100% mortality during the triple exposure assay. There were no significant effects on mortality, developmental time, gender ratios, fertility, fecundity or longevity in triple and single exposure assays. However, since these exposure assays did not assess the possibility that glucose esters may have repellent or irritability characteristics, a behavioral assay was employed. Behavioral assays assess the sensory perception of insects to chemicals, thus affecting their ability to search for prey. A choice assay using the ViewPoint tracking system measured individual larvae for ambulatory time (walking time), percentage of time spent and distance traveled in each treatment zone. No associated repellence or irritability was exhibited to glucose esters or the acetone solvent control for lacewing larvae, however DEET treated surfaces repelled all larvae. Thus, glucose esters do not have any negative effects on C. rufilabris using both robust multiple route exposure assays and a behavioral assay.