Odorant receptor BtauOR74a Is Essential for Attraction of Bactrocera tau to Host Volatiles

Bactrocera tau(Walker) (Diptera: Tephritidae), a highly invasive horticultural pest, threatens more than 80 crop species. The environmentally friendly strategy based on behavioral response of flies to host plant volatiles is a promising alternative to chemical insecticides. Here, we found BtauOR74a, one antennae highly expressed odorant receptor of B. tau, was responsible for detecting six host volatiles in a dose-dependent manner. Among these, (E)-2-octen-1-ol or (Z)-6-nonen-1-ol exhibited significant attraction to female or male, respectively. Furthermore, the preference of female B. tau for (E)-2-octen-1-ol and that of male B. tau for (Z)-6-nonen-1-ol were significantly decreased after silencing of BtauOR74a by RNAi. Additionally, a significant reduction was observed in the EAG responses of B. tau to these host volatiles in both male and female. These results not only provide the molecular basis of the olfactory recognition mechanism of B. tau to host volatiles, but also offer the potential for development of eco-friendly management strategies.