Epsilon Open Archive

Abstract

Semiochemicals are important cues in the interaction between plant and insects and between conspecific insects. Volatile compounds emitted by plants provide herbivorous insects with cues for host finding, selection and discrimination. In moths, female emitted sex pheromones enable conspecific males to find them for mating. This thesis investigated the role of semiochemicals in the behaviour of the Guatemalan potato moth Tecia solanivora (Lepidoptera: Gelechiidae), a pest insect of potato.

Identification of odours of foliage, flowers, and tubers of potato, Solanum tuberosum, were done with coupled gas chromatography-mass spectrometry and with high-performance liquid chromatography for non-volatile compounds in tubers. Antennal activity of potato volatiles was tested with electroantennographic recordings. Attraction of T. solanivora to potato volatile compounds was investigated through olfactometer, wind tunnel and field bioassays. Male behavior towards two different synthetic pheromone blends was similarly tested, to clarify their mode of action in mating disruption management.

Potato emits structure-specific volatile blends that change during the development of the plant. Tuberization stage was the preferred stage for oviposition while foliage released deterrent compounds. A three-component flower-odour mimic attracted males and females, virgin and mated, and enhanced the number of eggs laid. Female oviposition in the soil, during the tuberization stage might be guided by odours from spatially separated flowers, as an indication of suitable host vicinity. Larval survival was low in tubers with high concentrations of glycoalkaloids. This study demonstrates that odours from qualitatively different sites guide female to oviposit on tubers with high suitability for larval performance. Mating disruption was obtained with pheromone-permeated air with the two blends, but the disruption mechanism were different between them.

This first study on chemical communication between T. solanivora and its host plant showed that potato volatile compounds are perceived by the moth and act as cues in host location and oviposition. It highlights the possibility of using semiochemicals to manipulate the behavior of the moths and provides a base for further investigation and development of odour-based pest management.