黄野螟群体大小对幼虫个体生存和发育的影响

幼虫聚集取食是一些鳞翅目昆虫提高幼虫生长和存活的手段。通过对聚集取食的黄野螟Heortia vitessoides Moore幼虫在室内条件下进行饲养,探究黄野螟幼虫的群体数量大小（分别为30、60、90头幼虫）对幼虫体长、发育速度、达末龄（5龄）时的存活率的影响。分析发现在排除天敌捕食和食物缺乏的前提下,从3龄开始,大群体（90头）的体长显著大于小群体（30头）,大群体的幼虫发育速度显著快于小群体,大群体对幼虫前4个龄期时的成活率没有显著提高,尽管大群体的存活率在均值上高于小群体,但是幼虫总体存活率在不同群体中差异不显著。黄野螟幼虫的聚集取食对幼虫的生长的促进作用明显,显著促进了幼虫的生长,加快了幼虫的发育。     

Knockdown of β‐N‐acetylglucosaminidase gene disrupts molting process in Heortia vitessoides Moore

β‐N‐acetylglucosaminidase (NAG) is a key enzyme in insect chitin metabolism and plays an important role in many physiological activities of insects. The HvNAG1 gene was identified from the Heortia vitessoides Moore (Lepidoptera: Crambidae) cDNA library and its expression patterns were determined using quantitative real‐time polymerase chain reaction. The results indicated that HvNAG1 mRNA levels were high in the midgut and before molting, and 20E could induce its expression. Subsequently, the HvNAG1 gene was knocked down via RNA interference to identify its functions. We found that 3 μg of dsNAG1 resulted in optimal interference at 48 and 72 hr after injection, causing a decrease in NAG1 protein content, which resulted in abnormal or lethal phenotypes, and a sharp decrease in the survival rate. These results indicate that HvNAG1 plays a key role in the molting process of H. vitessoides. However, the silencing of HvNAG1 had no significant effect on the chitin metabolism‐related genes tested in this study. Our present study provides a reference for further research on the utility of key genes involved in the chitin metabolic pathway in the insect molting process.     

RNA interference of a trehalose-6-phosphate synthase gene reveals its roles in the biosynthesis of chitin and lipids in Heortia vitessoides(Lepidoptera:Crambidae)

Trehalose 6-phosphate synthase(TPS),an enzyme that hydrolyzes two glucose molecules to yield trchalose,plays a pivotal role in various physiological processes.In this study,we cloned the trehalose-6-phosphate synthase gene(HvTPS)and investigated its expression patterns in various tssues and d:velopmental stages in Heortia vitessoides Moore(Lepidoptera:Crambidac).HvTPS was highly expressed in the fat body and after pupation or before molting.We knocked down TPS in H.vitessoides by RNA interference and found that 3.0μg of dsHvTPS resulted in optimal interference at 24 h and 36 h post-injection and caused a sharp decline in the survival rate during the 5th instar larval-pupal stage and obviously abnormal or lethal phenotypes.Additionally.compared to the controls,TPS activity and trehalose contents were significantly lower and the glucose content was significantly higher 24 h or 36 h after injection with 3.0μg of dsHIvTPS.Furthermore,the silencing of HvTPS suppressed the cxpression of six key genecs in the chitin biosynthesis pathway and one key gene related to lipid catabolism.The expression levels of two genes associated with lipid biosynthesis were upregulated.These results strongly suggest that HvTPS is essential for the normal growth and development of H.vitessoides and provide a reference for further studies of the utility of key genes involved in chitin and lipid biosynthesis for controlling insect development.