Assessment of the entomopathogenic nematodes against maggots and pupae of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), under laboratory conditions

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is one of the major insect pests which renders the fruit to become unfit for human consumption. In severe cases, losses may reach up to 100% in some fruit crops. The present study aimed to investigate the pathogenicity of entomopathogenic nematodes (EPNs), Heterorhabditis bacteriophora, H. indica, Steinernema carpocapsae, and S. asiaticum against B. dorsalis maggots and pupae under laboratory conditions. One milliliter of EPNs, having 50, 75, and 100 infective juveniles (IJs) against maggots and 100, 150, and 200 IJs against pupae, were poured into 9 cm Petri dishes with 20 g sterilized soil as supporting media. The highest maggots' mortality (70%) was obtained after 3 days of application of H. bacteriophora and S. carpocapsae and reached up to (96%) after 9 days. S. asiaticum and H. indica caused 91.16 and 85.87% mortality, respectively, after 9 days post treatment at the highest nematode concentration (100 IJs/ml). Whereas, against the fruit fly pupae, H. bacteriophora caused 69.08% mortality after 9 days at the highest concentration (200 IJs/ml). All nematode species showed high effectiveness against both stages of B. dorsalis. Their application can be further evaluated under field conditions to promote a good biological control of fruit flies for healthier fruit production.