Temperature dependent virulence of the entomopathogenic nematodes against immatures of the oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae)

Abstract

Fruit flies have a great influence on fruit and vegetable industry of Pakistan. Bactrocera dorsalis Hendel (Tephritidae) is a polyphagous pest in large number of fruit and vegetable crops worldwide. Virulence of 4 entomopathogenic nematodes (EPNs) species, Heterorhabditis bacteriophora, H. indica, Steinernema carpocapsae, and S. asiaticum, was evaluated at different temperature degrees (15, 20, 25, 30 and 35 °C) against the immature stages of fruit fly species, B. dorsalis. The tested EPNs species showed a temperature dependent virulence against the fruit fly immatures. All EPNs showed a poor infectivity at the lowest temperature (15 °C) and a high infectivity at the highest temperature (35 °C). In overall, H. bacteriophora performed the best against the fruit fly larvae and pupae at all temperature degrees. At 35 °C, all the EPNs caused more than 95% mortality in fruit fly maggots, but H. bacteriophora and S. carpocapsae performed better than the others. The EPNs infectivity increased with increasing the temperature and exposure time. Similar results were recorded in case of pupae. H. bacteriophora and S. carpocapsae caused more than 70% pupal mortality rates at 35 °C.