# Electroantennographic and Behavioral Response of Female Moroccan locusts [Dociostaurus maroccanus (Thunberg, 1815) (Orthoptera: Acrididae)] to Male-Specific Aldehydes

## TL;DR

The study explores how male-specific aldehydes affect the behavior of female Moroccan locusts, suggesting potential pheromone roles for these compounds.

## Contribution

The study identifies three male-specific aldehydes and their differential effects on the behavior of virgin and mated female locusts.

## Key findings

- Mated females are significantly attracted to tetradecanal and pentadecanal, while virgin females prefer hexadecanal.
- The release of aldehydes by males is age-dependent, peaking 1–2 weeks after fledging.
- Electroantennographic responses of females vary with mating status and aldehyde type.

## Abstract

The Moroccan locust Dociostaurus maroccanus (Thunberg, 1815) (Orthoptera: Acrididae) is a destructive pest of grasses and crops that has traditionally been managed with synthetic chemical pesticides. However, current regulation policies on pesticides highlight the need to develop environmentally friendly control strategies. In this context, the identification of chemical compounds capable of manipulating insect behavior (semiochemicals) emerges as a promising approach. In this study we addressed the behavioral activity of male-specific aldehydes, namely tetradecanal, pentadecanal and hexadecanal, on virgin and mated females D. maroccanus under laboratory conditions. Adult males release these compounds in an age-dependent pattern, whereas they are absent from the volatile profile of fifth-instar male nymphs. Females of both mating statuses perceive these aldehydes, although differences in the behavioral response depending on the mating status are observed in double-choice olfactometric assays. While virgin females only show a preference for hexadecanal, mated individuals are significantly attracted to tetradecanal and pentadecanal. Overall, our findings provide a preliminary basis for identifying putative pheromones in the Moroccan locust, although comprehensive research is still needed to determine the role of these aldehydes in the species’ chemical communication.

The Moroccan locust Dociostaurus maroccanus (Thunberg, 1815) (Orthoptera: Acrididae) is recognized as a serious pest of pastures and crops in many Mediterranean countries. So far, the identification of chemical compounds involved in intraspecific communication has been elusive, with only one male-specific compound, namely (2E,7R,11R)-3,7,11,15-tetramethylhexadec-2-enal (2E,7R,11R-phytal), proposed as candidate sex pheromone component. Previous works reported that males also release the sex-specific long-chain aldehydes tetradecanal and hexadecanal, although no evidence of their role in chemical signaling has been presented so far. Here we additionally report another male-specific compound, viz. pentadecanal, and also report the electroantennographic and behavioral responses of virgin and mated females to these three aldehydes. We first demonstrated that their release is age-dependent, with emission overall peaking at 1–2 weeks after fledging. Solid-phase microextraction analyses from male hind legs suggest that these aldehydes are released from this body part. Overall, the antennae of virgin and mated females exhibited a dose-dependent response to increasing concentrations of each aldehyde, except for the response of virgin females to hexadecanal. Significant differences were observed between virgin and mated females at all doses of hexadecanal, while the mating status did not influence the response to tetradecanal and pentadecanal. Furthermore, the behavioral response of females varied according to their mating status. Specifically, mated females showed a significant preference for tetradecanal and pentadecanal, whereas a slight but non-significant attraction to hexadecanal was observed on virgin females. These findings provide new insights into the sexual communication of the species, although further research is needed to decipher their ecological function, especially on mated females.