| Proyplea japonica (Thunberg) (Coleoptera:Coccinellidae) was one of the predatory natural enemies which distributes widely in our country. The ladybird had small body size and accepted a large number of preyed species, meanwhile, it can survive under poor environmental conditions, such as starvation, high temperature and drought. So it played a positively role in biological control. In addition, P. japonica showed a high level of polymorphism in color pattern of elytral. Not only it had considerable geographic variation, but also the quantity of various phenotypes was different in the same area. By systematic field investigation and the common garden experiments, the morphologic, biological and ecological differences were compared to provide the theoretical basis that illustrating the relationship between the different phenotypes of Propylea japonica and environmental adaptation.In the field investigation, it found that there were five phenotypes distributed in the fields, which were ancora, dionea, tessellata, tessellata and marginata, respectively. Individuals of ancora were dominant in the three crops, dionea was the second, in contrast, marginata was at least. In broad bean field, the number of tessellata was similar to that of feliciae, whereas the number of tessellata was less than feliciae in the field of wheat and corn. It could be correlated with composition of aphid population in the three crops and temperature change.By comparison with distribution frequencies of these phenotypes among the three crops, individuals of ancora were dominant in all crops, which were 44.87%, and marginata was rarely, its frequency being 0.60%. In addition, the percentages of females in four main phenotypes among different crops ranged from 30.47% to 60.71%, the ratios of females in ancora were less than 50%.The measure of body size among different phenotypes showed that the body length of feliciae adults was larger than that of tessellata in the field of corn and wheat respectively, and body width of ancora female was also larger than that of tessellata in corn field. It suggested that feliciae and ancora had advantage in the body size. In addition, the same phenotype had different body sizes in the three crops. The body length of ancora adults in corn field was smaller than that in other field, and the body length of the other phenotypes female or male was also smaller in corn field. However, male collected in each crop did not show significant difference in body width among phenotypes. Meanwhile, the body size of female was larger than that of male for four phenotypes.Ancora male consumed more aphids than feliciae in 24 h, which the voracity was about 45.5 per day. Meanwhile, the feeding efficiency of feliciae females was higher than that of dionea, which was 15.1±2.4%. The results also indicated that the voracity, daily weight gain and feeding efficiency of females of these phenotypes were higher than those of males. However, there was no significant difference in heat resistance and starvation resistance among four phenotypes. In addition, our results showed the larval developmental duration of ancora was shorter than that of feliciae when the same raring condition was provided. The developmental duration was shorter in high temperature than in normal temperature. In addition, for ancora, that the developmental duration was shorter which they were feet on Aphis medicaginis Koch than which they were feet on Aphis nerii. They were 7.9±0.15d and 8.8±0.60d, respectively.It could be associated with the food preference of ancora.In the mating-choice laboratory experiments, feliciae male and tessellata female were predominantly selected for mating by female and male respectively. Ancora and tessellata females, which were darker on elytral than dionea and feliciae, were selected more easier by male. It suggested that they could be relatived to the quantity in nature.
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