Evaluation of local isolates of entomopathogenic nematodes for the management of black cutworm, Agrotis ipsilon Hufnagel (Lepidoptera: Noctuidae)

Abstract

The black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) is considered to be one of the serious polyphagous pests that spend a large part of its life in the soil environment, where many microorganisms live including entomopathogenic nematodes (EPNs) (Rhabditida: Steinernematidae and Heterorhabditidae). EPNs have been long used for suppressing the soil-dwelling insects like cutworms and are successful biological control agent against A. ipsilon larvae. In the present study, the efficacy of local EPNs isolates against the fourth larval instar of A. ipsilon was evaluated at different concentrations (10, 25, 50, 100 IJs/larva/Petri dish and 25, 50, 100 IJs/cm2 soil) in two different experiment environments including filter papers in Petri dishes and soil in plastic containers under laboratory conditions at 25 ± 1 °C. Larval mortalities of A. ipsilon were recorded first, second, third, and fourth day post inoculation where the mortality rates increased by increasing the concentrations. The maximum mortality rate (100%) was reached within 2 days after inoculation, inoculating the Heterorhabditis bacteriophora FLH-4-H and H. indica 216-H isolates at concentrations of 50 and 100 IJs/cm2, in the plastic container experiment. The highest mortality rate (90%) was obtained by Steinernema carpocapsae E76-S isolate at a concentration of 100 IJs/larva/Petri on the fourth day after inoculation, in the Petri dish experiment. The lethal concentration values (LC50 and LC90) of the A. ipsilon larval population were 52 IJs and 129 IJs, respectively, for S. feltiae E76-S isolate in the Petri dish tests. In the plastic container experiment, the lowest LC50 and LC90 values found to be 17 IJs and 23 IJs, respectively, for H. bacteriophora FLH-4-H isolate. The results showed that all indigenous EPN isolates had good potentials in the management of A. ipsilon.