Effect of Entomopathogenic Nematodes on Acorn Weevil,?Curculio glandium?(Marsham) (Coleoptera: Curculionidae) in Field Conditions

摘要

The acorn weevil, Curculio glandium (Marsham) (Coleoptera: Curculionidae), is a major forest pest that affecting oak trees. The pest disturbs regeneration of host trees by feeding on their immature acorns.The susceptibility of?C. glandiumlastinstar grubs to two species of indigenous entomopathogenic nematodes (Steinernema carpocapsae IRAZ9 and Heterorhabditis bacteriophora IRAZ5) was examined under field conditions in Arasbaran forest. Our results suggested that the pest grubs were more susceptible to S. carpocapsae than?H. bacteriophora. The mean overall mortality by two species of nematodes was calculated 66.75% and 45.65% respectively.?Steinernema carpocapsae?caused higher grub mortality comparing to?H. bacteriophora?at all concentrations and therefore it can be introduced as appropriate candidate for biological control of?C. glandium?grubs. Regression analysis showed a direct relationship between concentrations increasing and mortality in both nematode species. LC50?values for?H. bacteriophora?and?S. carpocapsae?were calculated 1258 and 1584 IJs/ ml, respectively.