Fatty acid-binding protein gene is indispensable for molting process in Heortia vitessoides(Lepidoptera:Crambidae)

As intracellular fatty acid(FA) carriers,FA-binding proteins(FABPs) widely participate in the absorption,transport,and metabolism of FAs.It is a key protein in insect lipid metabolism and plays an important role in various physiological activities of insects.An FABP gene(HvFABP) was cloned from the transcriptional library of Heortia vitessoides Moore(Lepidoptera:Crambidae),and its expression patterns were determined using reverse transcription quantitative PCR(RTqPCR).Stage-and tissue-specific expression profiles indicated that HvFABP highly expressed from prepupal to adult stages and in larval midgut and adult wings.HvFABP expression may be induced through starvation,mRNA expression was downregulated at 24 and 48 h and upregulated at 72 h after starvation.Furthermore,20-hydroxyecdysone can induce the upregulation of its expression.RNA interference-mediated silencing of Hv FABP significantly inhibited HvFABP expression,resulting in delayed development,abnormal molting or lethal phenotypes,and a significantly reduced survival rate.These results indicate that HvFABP plays a key role in the molting of H.vitessoides.

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.