Insect-corn kernel interaction: Chemical signaling of the grain and host recognition by Sitophilus zeamais (Coleoptera: Curculionidae)

Abstract

In living organisms, the cuticle has structural functions and is involved through chemical signaling in biological interactions such as plant-insect and provides protection against biotic and abiotic factors, thereby avoiding desiccation or predators'attack. The objective of this study was to investigate the participation of the epicuticle in the interaction of the maize kernel and the maize weevil Sitophilus zeamais. For this study the extraction ofepicuticle was carried on and the extract was analyzed by GC-MS. Digital photographs ofcross sections of grains with and without epicuticle were taken, and behavior bioassayswere carried out with both grains with and without epicuticle and epicuticle extracts. TheGC-MS analysis of the epicuticle extract demonstrated the presence of aliphatichydrocarbons, alcohols, ethers, fatty acids, sterols and their derivatives. The results ofpreference bioassays showed that the epicuticle of maize has a primordial role in itsinteraction with S. zeamais participating in the recognition and attraction to the foodsource. According to these results, in the assay of kernels' susceptibility to insect attack,kernels without epicuticle were significatively less damage than kernels with epicuticle. In progeny assays, the exposition of S. zeamais adults to kernels without epicuticle caused a reduction in progeny, indicating that it could regulate the reproduction of S. zeamais. In addition, the compounds present in the epicuticle extract may act assignalling molecules and developmental regulators. This study reveals the effect of the maize kernel epicuticle on Sitophilus behavior and contributes to the understanding of their interaction.