Abstract
We evaluated entomopathogenic nematodes (Steinernematidae) as potential biocontrol agents to suppress the wild population of the sweet potato weevil, Cylas formicarius (Fabricius) as part of its eradication program. The pathogenicity of Steinernema carpocapsae (‘All’ strain), S. feltiae, S. riobrave and S. glaseri (‘326’, ‘328’, ‘Mungyeong’ and ‘Dongrae’ strains) was checked against the sweet potato weevil under laboratory conditions. S. carpocapsae induced the highest mortality in both sexes of the adult sweet potato weevil (90%<). About 30–60% of pupae and larvae in the root of sweet potatoes were killed by S. riobrave, S. glaseri (‘Mungyeong’ strain) and S. glaseri (‘Dongrae’ strain). The efficacy of S. carpocapsae (‘All’ strain) on the suppression of the weevil population was then tested in a sweet potato field. Application of S. carpocapsae (‘All’ strain) successfully reduced the root damage rate and root damage index by approximately 60% and 40%, respectively, as compared with root damage in the control fields. These results suggested that S. carpocapsae (‘All’ strain) would be an appropriate and effective biocontrol agent for suppressing the weevil population.
