Sex-linked differences in semiochemical-mediated movement by Trogoderma variabile Ballion and Trogoderma inclusum LeConte (Coleoptera: Dermestidae) after exposure to long-lasting insecticide-incorporated netting

Abstract

Stored product insects are highly mobile and present in the landscape and can disperse by tracking odors of food and pheromones. A novel preventative integrated pest management (IPM) tactic to intercept dispersing insects of durable commodities (e.g., packaged goods, flour, bulk commodities), is a long-lasting insecticide-incorporated netting (LLIN) containing 0.4% deltamethrin. However, it is unknown how exposure to the deltamethrin-based LLIN (LLIN hereafter) may affect olfaction and orientation to important semiochemicals by stored product insects. In this study, our aims were to evaluate whether exposure to LLIN affected male and female (or mixed sex) populations of Trogoderma variabile and T. inclusum movement in the presence of important semiochemicals, including food kairomones and pheromones, including the major sex pheromone for Trogoderma spp. (e.g., (Z)-14-methyl-8-hexedecenal). We evaluated this with a video-tracking protocol and confirmed volatile emissions with headspace collection coupled with gas chromatography and mass spectrometry (GC/MS). Disruption in movement in this study is taken to mean a significant upregulation or downregulation in response compared to our netting without active ingredient (control). Distance moved increased 4–6-fold in T. variabile after exposure to LLIN compared to control netting, while it was reduced by a third to a half in T. inclusum. Overall, out of 40 possible olfactory and taxis patterns which could be disrupted, exposure to LLIN interrupted 68–73% of these in T. inclusum and T. variabile, respectively, compared to control netting-exposed individuals. Pheromonal stimuli were more important for males, but food and pheromones were equally important for females. Our research suggests the use of LLIN may enhance the effectiveness of other behaviorally-based management strategies when used as part of a comprehensive IPM program for these short-lived adults.