Repellence of δ‐nonalactone in German cockroaches of different stages, sexes, and ages

Abstract

δ-Nonalactone is a cyclic ester of hydroxycarboxylic acid with a six membered ring. It is present in several fruits and animal products consumed by humans. The aim of this study was to investigate the behavioral response of the German cockroach, Blattella germanica Linnaeus, to repellence produced by δ-nonalactone, and how this behavior varies relative to its stage, age, sex and absence of antennae. A cockroach was placed on a circle of filter paper, half of which was treated with δ-nonalactone in acetone and the other half, with acetone alone. The cockroach behavior was quantified using Ethovision XT 10.1 software. Values of Distribution Coefficient (DC) were calculated: DC = (Tt – TA) / Tt, where Tt is the experimental time and TA is the time the nymph spent in the area treated with the repellent. DC can vary between 0 and 1; values higher than 0.5 indicate repellency. Small, medium, and large nymphs, as well as male and female adults, were exposed to δ-nonalactone. Small nymphs were most sensitive to the repellent effect of δ- nonalactone (DC = 0.84). There were no differences between the response of males and females (DC = 0.74 and 0.75, respectively), nor in adult males between the age of less than 6 h and 90 days. The repellent effect was not manifested in antennectomized cockroaches. The results of the present study encourage us to further our investigations on the possibility of using δ-nonalactone as a tool in the integrated pest management of German cockroaches.