Efficacy of Entomopathogenic Nematodes and Insecticides in Managing Bactrocera dorsalis: A Laboratory Study

Abstract

Fruit flies are among the most destructive pests, causing significant economic losses worldwide, including in Pakistan. Various management strategies have been explored, with entomopathogenic nematodes (EPNs) emerging as promising biocontrol agents. This study evaluated the effectiveness of two EPNs, Steinernema glaseri and Heterorhabditis bacteriophora, along with two insecticides, lufenuron and bifenthrin, against Bactrocera dorsalis under laboratory conditions. EPNs were cultured and reared in the lab on the last larval instar of Galleria mellonella. Fruit fly larvae were collected from the field and reared in the lab to ensure a sufficient population for bioassays. Different concentrations of insecticides and EPNs alone and in combination were applied to larvae and pupae of B. dorsalis. Both insecticides and EPN revealed higher mortality rates against fruit flies with increased exposure time and higher concentrations. Alone treatment of both insecticides produced 100% of the mortality of both larvae and pupae at their highest concentrations. The maximum mean mortality of individual larvae (9.75 individuals) and pupae (10.00 individuals) have been produced by H. bacteriophora. While S. glaseri produced the mean mortality of 9.00 individual larvae and 9.25 individual pupae after 144h of treatment application. The combined treatments of insecticides and EPNs also caused mortality, the effectiveness was comparatively lower than that observed with individual treatments of either insecticides or EPNs. The maximum mean mortality has been produced by H. bacteriophora+ bifenthrin 8.75 individual larvae and 9.25 individual pupae. These results suggest that synergistic or additive effects may occur under certain conditions.