Evaluation of susceptibility of the brown tail moth, Euproctis chrysorrhoea, to entomopathogenic nematodes under laboratory conditions

Abstract

The brown tail moth, Euproctis chrysorrhoea, is an important foliar pest of forest trees in most areas of Europe and Asia. Therefore, the potential of the entomopathogenic nematodes Heterorhabditis bacteriophora isolate IRAZ5 and Steinernema carpocapsae isolate IRAZ9 was assessed for biological control of third, fourth and fifth instar larvae of E. chrysorrhoea under laboratory conditions. The two entomopathogenic nematodes were tested at the rates of 0, 500, 1000, 1500, 3000, and 5000 IJs per ml of distilled water using 150 ml per well plate containing three larvae of third or fourth instar or two fifth instar larvae of the pest. Both nematode species were highly effective on last instar larvae of the pest. The greatest mortality of E. chrysorrhoea, by both nematodes, was achieved with last instar larvae at the rate of 5,000 IJs of the nematodes/ml suspension. Mean mortalities for H. bacteriophora and S. carpocapsae on the third, fourth and fifth larval stages of the pest at over all rates were 44.7, 44.0 and 51.1 and 42.2, 57.5 and 67.8, respectively. Steinernema carpocapsae caused significantly greater mortality of fourth and fifth instars of the insect compared to H. bacteriophora. LC50s were estimated at 2236, 2138 and 1592 IJs/ml for H. bacteriophora and 4472, 652 and 423 IJs/ml for S. carpocapsae on third, fourth and fifth instars, respectively.