不同寄主植物对草地螟的营养作用及消化酶的影响

植食性昆虫可以在取食后通过消化分解和吸收从食物中获得营养从而进行正常的生长发育。不同植物中营养物质成分在质和量上都有很大差别。本文通过用藜(灰菜)、大豆、向日葵、玉米和马铃薯叶片分别饲喂草地螟,发现取食不同寄主植物不仅显著影响草地螟幼虫的相对取食量、相对生长率和食物利用率(P0.05),而且中肠消化酶活性也不相同。幼虫取食最喜食的藜时,各项营养指标均显著高于其他处理的幼虫,其中肠消化酶活性也最高;而饲喂草地螟幼虫不喜食的马铃薯和玉米时,幼虫无论取食量、生长率还是食物利用率均显著低于其他处理组(P0.05),中肠消化酶活性较低,但是某些酶活性随取食时间的增加而升高,这可能是昆虫对不适寄主的一种适应。

Influences of different host plants on the nutrition and digestive enzymes of Loxostege sticticalis

To understand the arthropod community structure and diversity of Pugionium cornutum, the arthropod community diversity in P. cornutum fields were investigated with visual method and net method from May to August of 2013. The results showed that there were 4 080 individuals belonging to 74 species in 44 families of 10 orders. Individuals of Hemiptera and Lepidoptera were more numerous than other orders, accounting for more than 70% of the total number; the species numbers of Hymenoptera and Diptera were the richest. The seasonal dynamics of arthropod community and the change of diversity index indicated that the highest number of individuals and species occurred in June, and the diversity index and evenness index were high in August. By dividing these species into different functional groups, the results of diversity analysis showed that the group of natural enemies had high indices of diversity in time, while the group of pests had higher number of individuals during different growing stages. Among them, Plutella xylostella, Phyllotreta striolata, Myzus persicae, Lipaphis erysimi and Brevicoryne brassicae were the main pests, and became the dominant species in the field during different periods. This study might be helpful for understanding the ecological system of P. cornutum and the integrated management of the pest.