J. Yang’s scientific contributions

The choice of best ratio of host and wasps when mass rearing of Chouioia cunea was studied. The result showed that 1:1 or 1:2 were the choice of the ratio of hosts and wasps when choosing fall webworm as a host and 1:50 when choosing Antheraea pernyi as a host to mass rearing C. cunea. The longevity of C. cunea reared according to this ratio was about 6 days on average in field, which could guarantee them to find suitable hosts. To improperly increase the percent of wasp would have a bad influence on the quantity or ratio of female and male of next generation.

In areas where Hyphantria cunea (Lepidoptera: Arctiidae) were a serious pest to host trees, the spatial pattern of the pest's egg cluster and the larva-web were studied in forest land and on shelter-wood trees. It was revealed that the spatial pattern of the egg clusters and larva-webs of the fall webworm belonged to Negative Binomial Distribution, which was also a kind of Aggregated Distribution. Meanwhile, Aggregated Degree Index of egg clusters and larva-webs were also studied and the results showed that the spatial patterns of fall webworm were Aggregated Distribution. Based on these studies, the theoretical sampling numbers of different density of egg clusters and larva-webs in two different kinds of forest stands were calculated too, and that will give a approximately quantity information of the fall webworm for the decision of releasing number of insect natural enemies.