Identification of Semiochemical Candidates Involved in Glossina Palpalis Gambiensis Larviposition Site Selection and Behavioural Responses of Adult Gravid Females

Abstract

Tsetse ies (Diptera: Glossinidae) are the cyclical vectors of human and animal trypanosomes. This viviparous insect develops and produces a single larva at 10-day intervals deposited in speci c sites. In some species aggregation of larvae has been shown and seems to be mediated by both physical factors and volatile semiochemicals of larval origin. In this context, this study aims to identify chemicals emitted during the pupariation process in Glossina palpalis gambiensis. Volatile Organic Compounds (VOCs) emitted by larvae were identi ed using static headspace solid-phase microextraction and gaschromatography mass-spectrometry (GC-MS) analysis. Electrophysiology and behavioural assays were performed on gravid females to con rm VOCs behavioural activity and attractiveness. GC-MS results revealed ten chemicals emitted during the pupariation process of G. p. gambiensis larvae. Among these chemicals, gravid females were shown to detect nine of them during coupled gas chromatographyelectroantennographic detection tests. Behavioural assays highlighted two compounds were as attractive as pupae and one compound and a blend of four compounds were more attractive than pupae. Although the larval origin of some of them needs to be con rmed as they may also likely produced by micro-organisms, these compounds induced signi cant behavioural responses in the laboratory. Further experiments have to explore the biological activity and competitiveness of these compounds in the eld. This work opens interesting opportunities for behavioural manipulation and control of tsetse ies.