Responses of Bactrocera invadens (Diptera:Tephritidae) to Volatile Emissions of Fruits from Three Hosts
Bactrocera invadens is an invasive fruit fly species of Asian origin that was first detected in Kenya in 2003 and now has been reported in many parts of the African continent. The responses of B. invadens towards odour blends emitted from three host fruits, namely mango (Mangifera indica), marula (Sclerocarya birrea), and Indian almond (Terminalia catappa) growing in Nguruman and Embu in Kenya, were monitored in a dual choice olfactometer. Three mango varieties were tested (sensation, apple and kent), each at immature, mature unripe and ripe stages. Marula and Indian almond fruits were tested when mature, both when unripe and ripe. Results showed that, both male and female B. invadens were attracted equally to mature unripe and ripe mango fruits. However, in all cases attraction to immature fruits was significantly lower (P < 0.05). Two-way comparisons showed no significant difference between sensation and apple, but both attracted significantly more flies than kent. There were no significant different in attraction when M. indica, T. catappa and S. birrea were compared between each other. The results indicate that mature host fruits emit volatile constituents that are attractive to the fruit flies and if characterized may be useful in monitoring and managing B. invadens.