Whiteflies excrete non-metabolite insecticide through their honeydew

Insecticide excretion through honeydew produced by hemipterans had been reported in soybean, citrus and Christmas trees. This route of insecticide exposure can affect pollinators, predators and parasitoids because they use honeydew as food source. The objective of this study was to determine the concentrations of imidacloprid excreted through the honeydew of whiteflies in tomato plants. Imidacloprid was applied to the soil using the labeled rate. Later, honeydew excreted by whiteflies was collected at the base of each plant by placing one petri dish holding aluminum foil. Non-metabolized imidacloprid was analyzed in honeydew samples using HPLC-MS. Concentrations of imidacloprid in honeydew samples showed significant differences between treatments in both collection dates. At the 0-4 DAT (days after treatment) collection date, the imidacloprid treatment showed higher concentrations (6.01 ng/ mL) of the insecticide parent compound compared to the water control (0.16 ng/ mL). Similar concentrations were observed 5-8 DAT, imidacloprid treatment had a higher concentration (7.27 ng/ mL) compared to the control. Concentration of insecticide was not significantly different between collection dates nor imidacloprid treatments. Insecticide-tainted honeydew, produced by insect populations that survive insecticide applications, has the potential to create enemy-free space by killing their natural enemies. This could cause pest control failures and pesticide resistance. This challenging phenomenon may thus occur in many vegetable crops because whiteflies and other hemipterans that produced honeydew are problematic pests that attack several plant species and insecticide use is one of the most common control methods.