Evaluation of the efficacy of an indigenous Peruvian entomopathogenic nematode Heterorhabditis sp. to control the Andean potato weevil Premnotrypes suturicallus Kuschel under field conditions

摘要

The Andean potato weevil (APW) (Coleoptera: Curculionidae) is one of the most important pests of potato (Solanum sp.) and other root and tuber crops cultivated in the Andean region; its distribution extends from Argentina to Venezuela covering a widemountainous territory about 5,000 km in length between 2,800 and 4,700 m a.s.l. Most of the APW species occur in the highlands of Peru and Bolivia, which are considered the centre of origin. The species Premnotrypes vorax Mustache, P. suturicallus Kuschel and P. latithgrax, (Pierce) are the most important species with regard to distribution, predominance and damage caused. Most damaging are APW larvae, which feed and develop in potato tubers. At present, the application of highly toxic insecticides (laand Ib according to the WHO classification) is the most frequent control method applied by farmers. Mean damage rates vary between 16 and 45% while without insecticides up to 100% of tubers might be damaged. In 2003, an entomopathogenic nematode of the genus Heterorhabditis was discovered in Peru that proved to be highly pathogenic to all developmental stages of P. suturicallus. We tested the hypothesis that entomopathogenic nematodes could be integrated into APW management programs. A series of experiments were performed in the Central Highlands of Peru over a period of three years to determine the efficacy under (i) semi-field conditions with controlled numbers of APWs released per potato plant, and (ii) under field conditions with natural APW infestation and applications of nematodes in aqueous suspensions and infected cadavers.