Olfactory responses of the blister beetle Epicauta atomaria, a polyphagous crop pest, to host, non-host, and conspecific odors

Abstract

The blister beetle Epicauta atomaria (Germar) (Coleoptera: Meloidae) is a phytophagous pest of various agricultural crops, especially in Amaranthaceae, Solanaceae, and Fabaceae. Currently, this insect is managed through the spraying of synthetic insecticides that cause serious human health and environmental damage. To reduce the use of synthetic insecticides, the integrated pest management (IPM) programs for other crop pests rely on the use of semiochemical compounds, such as pheromones, kairomones, and allomones, to manipulate the insects' behavior to prevent crop damage. However, studies on semiochemical compounds related to E. atomaria have never been carried out. For this reason, the aim of this study was to explore the chemical communication of E. atomaria. This includes the existence of (i) a sex and/or an aggregation pheromone, (ii) attractant volatile kairomones from host plants, and (iii) repellent volatile allomones from non-host plants. Tests were carried out using olfactometers and an experimental arena. First, olfactometer tests failed to show the existence of volatile sex and/or aggregation pheromones of these insects. Second, olfactometer and experimental arena tests failed to demonstrate attraction of E. atomaria via volatile kairomonal compounds from host plants (chard, bell pepper, and cock's-eggs). However, olfactometer tests showed that non-host plants of E. atomaria (thyme and lavender) emit allomonal volatile compounds with repellent activity. This work represents a first step toward the elucidation of the chemical ecology of E. atomaria and suggests that volatiles from non-host plants help shape the host preferences of these insects. Those volatiles could be used as a “push” component in a “push–pull” strategy against this pest.