摘要或動機

The purpose of this project is to control the Aphis craccivora Koch. on the cow pea Vigna unguiculata (L.) by using two predators, the earwigs (black) beetle, Proeus simulans Stallan and the ladybird beetle, Micraspis discolor (F.). The experiments were carried out in the closed system in the laboratory and in the opened field with various ages of Proeus simulans Stallan and Micraspis discolor (F.) from the 1st - 4th stage of embryo to the adult form. Prior to the study in the field, the capability of the predators, Proeus simulans Stallan and Micraspis discolor (F.), that can eat the Aphis craccivora Koch. within a period of time was set up in the laboratory. The result showed that the 1st-4th stage of embryo of Micraspis discolor (F.) can eat 8.46+1.25 – 12.50+0.60, at 95% confidence, Aphis craccivora Koch. per day, while its adult can eat at the average number of 43.66 + 0.78, at 95% confidence, per day. The 1st–3rd stage of Proeus simulans Stallan embryo and the adult form can eat Aphis craccivora Koch. at the average number of 2.37+0.33 – 3.74+0.29 and 9.84+0.36, at 95% confidence, per day, respectively. This data showed that Micraspis discolor (F.) was more efficiency as predator than Proeus simulans Stallan. The insecticide activity of these two predators in the closed field (8 m x 9 m) was then determined. The number of Aphis craccivora Koch. on the plant was randomly counted everyweek for 10 weeks. It was found that the number of Aphis on the experimented and control groups were 16.20+4.30 and 2,582.00+102.40, at 95% confidence, per plant, respectively. The result support the efficiency of the two predators in controlling the pest. When the experiment was set up at the two opened field (6 m x 30 m, each field), 27.51+2.74 and 52.11+5.21, at 95% confidence, of Aphis craccivora Koch. were found on the plant of experimented and control groups, respectively, at the 10th week. The lower number of Aphis on the control plant might possilbly due to the interference from natural predators. From this study, the biological control of Aphis craccivora Koch. on the cow pea Vigna unguiculata (L.) could be achieved by using Proeus simulans Stallan and Micraspis discolor (F.). To avoid the use of chemical insecticides, biological control should be trained to farmers to help reduce the environmental problem.