Abstract
The efficiency of three species of parasites, Aphidius colemani, Lysiphlebus japonicus and Aphelinus abdominalis, in suppressing the population density of the melon aphid, Aphis gossypii, was compared at 25°C, 16L8D in plastic cages (Width 34cm×Depth 25.6cm×Height 34cm). Ten apterous female adults of A. gossypii and 2 to 50 wasps of each species were released together on the leaves of four cucumber seedlings in each cage. A. colemani was the most effective for suppressing the density of the aphids among the three species. The efficiency of A. colemani in suppressing the density of the aphids is thought to decrease after stocking the parasites at 5°C for several days.
