Abstract
Chemosensation plays a crucial role in insects life history, mediating their responses to a variety of biological and environmental chemical signals/cues to locate and select food, mates, oviposition sites and avoid predators. This PhD thesis explored chemical ecology of six tephritids and mapped their olfactomes, using a combination of different analytical (GC-MS and PTR-ToF) and electrophysiological (GC-EAD, GC-EPD) methods and techniques. This thesis is organized in three parts, each targeting a distinct aspect of tephritids chemical ecology, focusing on emission and peripheral detection (by antennae and maxillary palps) of pheromones, para-pheromones and host volatile organic compounds (VOCs). First, the diel rhythm of males and females sex-born VOCs of the olive fly Bactrocera oleae was real-time monitored and potential pheromone candidate (identified for the first time) were suggested, using a combination of GC-MS and PTR-ToF analytical techniques. Second, in order to investigate how differential olfactory sensitivities are linked to divergences and convergences in host preference, we have comparatively recorded the antennal olfactory responses of four tephritid species (Bactrocera dorsalis, Bactrocera latifrons, B. oleae and Zeugodacus cucurbitae) towards their host VOCs samples (collected in horticultural settings), using GCEAD. Despite their phylogenetic relatedness, the four species olfactory sensitivity towards host VOCs appears to be more shaped by their ecology than their phylogeny, exhibiting an overlap in terpenoids and esters detection, which suggest the importance of plant foliage VOCs in host location. Third, we have comparatively mapped palpal olfactory sensitivities of five tephritids (B. dorsalis, B. latifrons, Z. cucurbitae, Ceratitis capitata and Ceratitis cosyra) towards three fingerprint blends, to understand how maxillary palps are involved in chemoreception of tephritids and to which chemical class are tuned. These synthetic blends are composed of relevant compounds to Tephritids and Drosophilids, including spiroacetals (pheromones), phenylpropanoids (male lures), esters, pyrazines and phenols. The results reveal that maxillary palps are disproportionally tuned to spiroacetals and phenylpropanoids and their olfactory sensitivities are more likely to be shaped by their phylogeny than their ecology towards these chemicals. By employing novel tools and methods, this thesis provides insights into understanding chemical ecology of tephritids in its evolutionary and ecological contexts, as well as its practical aspects for the development of behavioral-based management tools.