Speaker
Description
The insect olfactory system has evolved to guide species toward specific mating partners, food sources, and oviposition sites. However, how species-specific repertoires of odorant receptors (ORs)—which mediate the detection of volatile cues—have been shaped by ecological pressures remains poorly understood. Fruit flies of the Tephritidae family (Diptera) exhibit highly diverse host preferences due to multiple host switches throughout their evolutionary history, making them ideal models to explore this question.
In this study, we used RNA sequencing to identify the OR repertoires of thirteen Tephritidae species with varying host ranges: Bactrocera curvipennis, Bactrocera dorsalis, Bactrocera psidii, Bactrocera tryoni, Bactrocera umbrosa, Bactrocera zonata, Ceratitis capitata, Ceratitis catoirii, Ceratitis quilicii, Dacus ciliatus, Dacus demmerezi, Neoceratitis cyanescens, and Zeugodacus cucurbitae. Through manual curation, we annotated 60 to 80 OR transcripts per species, including the obligatory coreceptor Orco, and identified a total of 698 new OR sequences. Differential expression analyses revealed some organ- and sex-biased OR expression patterns. Importantly, we found significant correlations between certain OR repertoire characteristics and host range. Specifically, both the sequence and relative expression levels of several ORs were more conserved in polyphagous than in oligophagous species. Additionally, certain ORs were uniquely present in polyphagous species. These findings provide molecular insights into the ecological forces shaping OR evolution in Tephritidae fruit flies.
