Identification and Expression Profile Analysis of Odorant Binding Proteins in the Oriental Fruit Fly Bactrocera dorsalis

Olfaction is crucial in many insects for critical behaviors, including those regulating survival and reproduction. Insect odorant-binding proteins (OBPs) function in the first step of the olfactory system and play an essential role in the perception of odorants, such as pheromones and host chemicals. The oriental fruit fly, Bactrocera dorsalis, is a destructive fruit-eating pest, due to its wide host range of up to 250 different types of fruits and vegetables, and this fly causes severe economic damage to the fruit and vegetable industry. However, OBP genes have not been largely identified in B. dorsalis. Based on our previously constructed B. dorsalis cDNA library, ten OBP genes were identified in B. dorsalis for the first time. A phylogenetic tree was generated to show the relationships among the 10 OBPs of B. dorsalis to OBP sequences of two other Dipteran species, including Drosophila melanogaster and the mosquito Anopheles gambiae. The expression profiles of the ten OBPs in different tissues (heads, thoraxes, abdomens, legs, wings, male antennae and female antenna) of the mated adults were analyzed by real-time PCR. The results showed that nine of them are highly expressed in the antenna of both sexes, except BdorOBP7. Four OBPs (BdorOBP1, BdorOBP4, BdorOBP8, and BdorOBP10) are also enriched in the abdomen, and BdorOBP7 is specifically expressed in leg, indicating that it may function in other biological processes. This work will provide insight into the roles of OBPs in chemoreception and help develop new pest-control strategies.