Impact of Predators and Parasitoids of Major Insect Pests on Groundnut
Ohio State University
Makerere University, Serere Agricultural and Animal Research Institute, Kumi District Agriculture Office (Uganda); Virginia Tech, Ohio State University (US)
J. Mark Erbaugh
M.B.T.Munyuli, S.Kyamanywa,V. Odeke, E. Adipala, G. Epieru (Uganda); G. Luther, Ronald Hammond (US)
Studies to determine the effect of groundnut cropping systems and insecticide applications on the abundance and diversity of predator and parasitoids, were conducted during the first rains (May-August) of 2003(2003A), in Bukedea, Kumi district. The efficacy of spider predators against groundnut pests was assessed under laboratory conditions during the same period. Population density of predators was monitored bi-weekly using pitfall traps, sweep net and visual / opportunistic observations of plants. Leaf miner pupae and larvae and aphid mummies/adults were reared in the laboratory to allow parasitoids to emerge. Results showed that aphids/leaf miner parasitoid activities and parasitism (%) were significantly affected by the rate of insecticide spray. The abundance and diversity of predators, was significantly (P<0.05) affected by the cropping system, the time of sampling and the level of insecticide spray. Groundnut genotypes had no significant effect on population densities of predatory fauna. Overall, the voracity of spiders varied according to prey species. A spider consumed daily 8-9 aphids, 2.1 thrips and 4.2 leafminers. The predation efficiency and acceptability of prey (aphids, leafminers and thrips) by spider predators were low, compared to that of earwigs on aphids.
To identify the natural enemies of groundnut pests (leafminers, aphids, thrips) and to assess the impact of insecticides, groundnut genotypes and groundnut cropping systems on the population of native natural enemies in Eastern Uganda.