Strong dissuasive effect of a synthetic capsaicinoid against whitefly infestation in avocado trees

Whitefly infestation is a major threat to horticultural crops. The control of these sap-sucking insects could be performed by application of insecticides, which may be toxic to untarget species such as honeybees and other beneficial insects. Safety of consumers is a priority and urges the development of alternatives to control pathogens and pests, thus identification of novel natural and/or synthetic products to control insect pests not harmful for humans or pollinators is an urgent need. The persistent seasonal, yearly occurrence of whitefly infestations, offered the opportunity to test promising biostimulant, non toxic molecules as dissuasive products. In this report, we show that whitefly infestation in avocado trees in the field causes the spread of chlorotic halos, blade distortion and wilt of leaves. Through serial aspersions of N-vanillyl-octanamide (ABX-I), a synthetic capsaicinoid to the avocado trees, a clear repellent effect was observed against adult whiteflies that approached the trees at sunny hours but did not feed on leaves. The number of whiteflies resting on leaves decreased in the following days after capsaicinoid application. These data reveal the possibility to control whitefly pest via application of a capsaicinoid-related compound.