| The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), which is the most important pest of soybeans, Glycine max (L.) Merr. It feeds primarily on soybean by sucking, from the leaves, stems and pods, which causes leaves yellowing and curling, plants stunting, poor pod filling, and results in poor yields and seed quality. These aphids are also known to spread a number of plant virus diseases, including soybean mosaic. With the changing of the atmosphere, the outbreak of the soybean aphid is becoming more and more frequent and the damage heavier and heavier. Since 2000, the soybean aphid has been found in America and Australia. Along with the expansion of distribution, it is of great significance on studying population geography distribution of soybean aphid, and of important application value on effective control measure, to find out whether or not its population ecology adaptability changes.Adult soybean aphids were collected from soybean plants in Guangzhou, Guangdong Province, Langfang, Hebei Province, Jinan, Shandong Province and Harbin, Heilongjiang Province, which were named as GD, SD, HB and HLJ, respectively. Each aphid was cultured on soybean seedlings at 24℃, RH 70%, with a photoperiod of 13:11(L:D). The morphological variation of growth and development, the relationship between emergence of sexual morphs and photoperiod (L:D=8:16 and L:D=10:14) at 18℃, 16℃, 14℃, the life parameters of these populations at different temperatures were evaluated.The main results are as follows:In the first part of the study with asexual aphids, morphological parameters were evaluated and the results showed that there were no significant differences in morphology at different temperatures, expect 15℃, and the size of the adult soybean aphids of one population increased as the temperature decreased. And, the surface area of the soybean aphid was the same. But there were no significant differences on the surface area at different temperatures.In the second part of the study, the results are as follows:①The soybean aphids were found to survive normally at temperatures ranging from15℃to 30℃,but they died quickly in nymph stage at 35℃.②There were no significant differences in nymph duration among the 4 populations, but the nymph duration of one population showed an increasing trend with the decrease of the temperature. At l5℃, the duration of adult aphids showed an increasing trend with the increase of latitude of location.③There were no significant differences in the average fecundity among the 4 populations, too. But the average fecundity of adult soybean aphids of the same population had increased with the decrease of the temperature, expect 15℃.④The innate capacity of increase of soybean aphids had no significant differences which can be observed at the same temperature, but it decreased with the decreasing temperatures.In the third part of the study on sexual aphids, the results showed that the various morphs of soybean aphids could be induced successfully at the temperatures (18℃, 16℃, 14℃), and photoperiods (L:D=8:16 and L:D=10:14).We could found that 16℃was the best temperature for inducing the gynoparae female and androparae male which we intended. The shorter photoperiod we designed, the more virginoparae could be reproduced. And there was a decreasing trend of the reproductive duration with the increasing latitude of location.
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