Efficacy of entomopathogenic nematode,Steinernema carpocapsaeagainst the diamondback moth,Plutella xylostella(L.) in laboratory condition

In vitro studies were carried out on the diamondback moth, Plutella xylostella larvae using an insect entomopathogenic nematode isolate, Steinernema carpocapsae obtained from the Koppert company, the Netherlands. Larvae of P. xylostella were collected from cabbage farms around Mashhad city of Iran. During the study, the responses of larvae at 25 °C for three periods of 24, 48 and 72 h with different concentrations of 0, 5, 10, 20, 40, 80, 160 and 320 third instar larvae of nematode (infective stage = IJs) per insect into 10 cm Petri dishes containing filter paper soaked with 1 ml of nematodes suspension were compared. Maximum mortality caused by S. carpocapsae nematode was 88% at 24 h, and it was 100% at 48 and 72 h. With increasing nematode population level and exposure time (ET in hour), mortality of P. xylostella larvae was increased. Based on probit analysis, LC50 values of S. carpocapsae nematode in three test periods were 45.61, 12.02 and 40.80 IJs per insect, respectively. Initial ANOVA was performed for S. carpocapsae nematode. The effect of both nematode population levels (IJ) and ET on third instar larvae of the diamondback moth, P. xylostella and interaction between IJ and ET were significant. In general, it is recommended to apply this nematode in suitable condition for controlling diamondback moth.