Oviposition Selectivity and Competitive Research on Bactrocera cucurbitae (Coquillett) and Bactrocera tau (Walker)

Purpose The aim of this study was to determine the host selectivity of adult oviposition and interspecific competition of melon fruit flyBactrocera cucurbitae (Coquillett) and South Asian fruit flyBactrocera tau (Walker).Methods Selection tests on adult's oviposition of B.cucurbitae (Coquillett)and B.tau (Walker) were conducted in lab in 2015, and fruits of seven host plants, Cucumis sativus, Sechium edule,Luffa cylindrical, Lycopersicon esculentum, Cucurbita moschata, C.pepo, Momordica charantia were used as hosts. Also,the interspecific competition of these two fruit flies were tested on fruits of three host plants, C.sativus, C.pepo and C.moschata.Results The host selectivity of adult's oviposition between these two species of fruit flies were different among different fruits of host plants. The oviposition amount sequence (from high to low) of B.cucurbitae (Coquillett) on the intact fruits was C.sativus > M.charantia > L.cylindrica > C.pepo > S.edule > L.esculentum and C.moschata. The oviposition sequence (from high to low) of this fruit fly on peeled fruits was C.moschata > C.sativus > M.charantia > C.pepo > L.cylindrica > S.edule > L.esculentum. The oviposition sequence (from high to low) of B.tau (Walker) on the intact fruits was C.pepo > L.cylindrica > C.sativus > M.charantia > S.edule > L.esculentum and C.moschata. The oviposition sequence (from high to low) on the peeled fruits was C.pepo > C.moschata > L.cylindrica > M.charantia > C.sativus > S.edule > L.esculentum. The competitive ability of B.cucurbitae and B.tau were different when host plants and population densities were different. The rate of emergence between these two fruit flies in the lowest population density wasn't obvious, when these two fruit flies in the highest density (8:8), the emergence rate of B.Cucurbitae feeded by C.sativus was significant higher(PB.tau, and the emergence rate of B.tau feeded by C.pepo and C.moschata is significant higher(PB.cucurbitae.Conclusion Adult's oviposition of B.cucurbitae (Coquillet) and B.tau (Walker) was different when hosts were different, and it was also different when fruits peeled or not. The competitive ability of B.tau was stronger than B.cucurbitae in lab.