Control of the larvae ofConorhynchus mendicus (Col.: curculionidae) bySteinernema carpocapsae andSteinernema feltiae (nematoda,steinernematidae) in the gharb area (Morocco)

Two entomopathogenic nematodes,Steirnernema carpocapsae andS. feltiae were evaluated in the laboratory and under field conditions against larvae ofConorhynchus mendicus, a pest of sugar beet in the Gharb area of Morocco. Nematodes were applied in an artificially infested field using a knapsack sprayer either during the day or in the evening after sunset. The number of insect cadavers recovered from both soil and sugar beet plants was greater in the treated plots compared with the untreated ones. The percent reduction in live larvae was significantly greater in theS. carpocapsae treated plots (89.5% and 59.5% for night an day application respectively) compared with those treated withS. feltiae (68.5% and 28% respectively). The efficacy of entomopathogenic nematodes was therefore increased by application at night particularly in the case ofS. carpocapsae where control was maintained for 45 days.