Toxicidade de acaricidas a Atheloca bondari Heinrich (Lepidoptera: Pyralidae) e seus efeitos na sobrevivência e comportamento

Abstract

The coconut tree moth, Atheloca bondari, and the coconut mite Aceria guerreronis are two species of pest herbivores that co-occur in the coconut fruit. Due to both species share the same resource, A. bondari is exposed to the contact of acaricides used for control A. guerreronis. This study had as objective evaluate biological and behavioral aspects of A. bondari larvae when exposed to acaricide abamectin, azadirachtin, fenpyroximate, and pyridaben in laboratory conditions. Three methodologies (Wooden stick, triangle, and mesocarp fragmente) were tested for toxicity experiments, comparing the mortality caused by abamectin at its label-recommended concentration with the control. The wooden stick method provided higher larvae survival in the control, proving to be more suitable for the toxicity test. Subsequently, the mortality caused by those acaricides was evaluated through label-recommended concentration, after that, the toxicity was evaluated through rate-response curves. The residual effect of acaricides on fruit preference and walking behavior was also evaluated. Abamectin and pyridaben were the most toxic products, being estimated LC50 of 1.35 mg/L and 141 mg/L, respectively. The tested acaricides did not affect the preference of the larvae to fruit (treated or untreated). A.bondari larvae showed a lower movement speed when exposed to the treated surface with the acaricides abamectin, azadirachtin, and fenpyroximate when compared to the control, and shoed less distance traveled when exposed to the fenpyroximate- treated surface. A. bonrari larvae remained less time on the abamectin-treated surface characterizing an irritation effect.