Male Attractants in Tephritidae (Diptera) Species: A Comparative Behavioural and Electrophysiological Study

Male attractants are widely used to detect and control Tephritidae pest species. When naturally ingested by males, these compounds modify the sex pheromone composition, enhancing male attractiveness to females and thereby increasing individual reproductive success. The evolutionary origin of this sexual selection is uncertain, as male attractants differ across species. To investigate this, we compared the olfactory responses of males from nine Tephritidae species-Bactrocera dorsalis, Bactrocera zonata, Ceratitis capitata, Ceratitis catoirii, Ceratitis quilicii, Dacus ciliatus, Dacus demmerezi, Neoceratitis cyanescens, and Zeugodacus cucurbitae-to compounds known to attract males in at least one species within the family. Using a six-way olfactometer and a high-throughput Flywalk behavioural assay, we found species-specific attraction profiles. Species were globally separated into methyl eugenol responders, cuelure responders, and non-responders, with small variations observed within the groups. Using three-point electroantennography and electropalpography, we found most compounds elicited peripheral responses in males across all species, with weak connection to behavioural preferences. Consistently, peripheral responses did not predict behavioural groups. Notably, among the two species attracted to methyl eugenol, only B. zonata showed a stronger antennal response to this compound than other species, whereas cuelure peripheral responses were weak across all species. Our findings suggest that male attraction in Tephritidae may have evolved through pre-existing signal reinterpretation in the central nervous system, leading to novel behavioural outputs. Overall, this study provides valuable behavioural and electrophysiological data for understanding olfactory mechanisms underlying responses to semiochemicals used in pest management.