Antennal transcriptome and odorant binding protein expression profiles of an invasive mealybug and its parasitoid

Olfaction is fundamental to insect survival due to its roles in host location and interspecific communications. Here, we analysed the transcriptomes of odorant binding proteins (OBPs) from the invasive mealybug Phenacoccus solenopsis and its endoparasitoid Aenasius bambawalei through RNA-Seq. The antennal transcriptomes of P.solenopsis and A.bambawalei were assembled, and gene ontology (GO) annotation indicated that the relative abundance of transcripts associated with specific GO terms was highly similar between the two species. We obtained 12 putative odorant binding proteins (OBPs), four chemosensory proteins (CSPs), four odorant receptors (ORs), one gustatory receptor (GR) and one sensory neuron membrane protein (SNMP) from P.solenopsis. There were 54 putative OBPs, 226 ORs, 41 GRs and three SNMPs in A.bambawalei. PsolOBPs exhibited high expression in the third instar nymph and varied expression in female adults of P.solenopsis. Almost all candidate AbamOBPs were expressed at high levels in the sensory organs (antennae, heads and legs) of adult A.bambawalei of both sexes. Among them, AbamOBP31 exhibited an obvious female antennal-specific expression pattern. AbamOBP1, AbamOBP23, AbamOBP24 and AbamOBP30 were expressed at high levels in male antenna. This study for the first time identified the chemosensory genes and determined their expression patterns in different tissues of the two species. Our results provide important molecular information for the exploration of chemosensory mechanisms in these two species.