Effect of entomopathogenic nematodes under laboratory conditions on Cylas puncticollis pest of sweet potato in Benin
Sweet potato is an economic crop. Unfortunately, it is greatly affected by Cylas puncticollis. To control this pest, farmers use insecticides. Today, find a biological control method against this pest is necessary. Thus, the pathogenicity of ten isolates of entomopathogenic nematodes Heterorhabditis has been tested under laboratory conditions using three local varieties of sweet potato. Ten sliced sweet potato of each variety have been placed in Petri dishes and have been infested with 3 males and 7 females of Cylas puncticollis. After two weeks, the rings have been inoculated with 20 or 40 nematodes and Petri dishes were arranged in a completely randomized design. Washers that received no inoculum of nematodes and insects and those fed only insects were the control treatments. Analysis of variances using the SAS programme showed that the effect of weevils on tuber slice’s quality is significantly higher compared with its effect on the amount of tuber. All isolates of nematodes used were effective and significantly reduced the emergence of adult insects. Moreover, these entomopathogenic nematodes were more effective on weevil larvae than other development stages. The isolates 63c, 62b and 5d have distinguished themselves by their effectiveness. In addition, all isolates of nematodes have the potential to multiply and thus to persist.
Keywords: Biological control, Ipomoea batatas, Cylas puncticollis, Heterorhabditis, pathogenicity