| Summary: | Autophagy is a highly conserved and regulated process in eukaryotic cells and remodels cytoplasm, recovers essential nutrients, and disposes of unwanted cytoplasmic components. Autophagy-related gene (ATG) 8, identified in <i>Heortia vitessoides</i> Moore, which is an oligophagous pest of <i>Aquilaria sinensis</i> (Lour.), was characterized (<i>HvATG8</i>). Multiple sequence alignment showed that <i>HvATG8</i> possesses highly conserved domain structures. Stage- and tissue-specific expressions indicated that <i>HvATG8</i> is highly expressed in prepupal, pupal, and adult stages and in the midgut of larvae and abdomen of adults. Lack of function of <i>HvATG8</i> by RNA interference resulted in a significant decrease in survival rate and an increase in abnormal or nonviable phenotypes in <i>H</i>. <i>vitessoides</i>. Transition rate from larval to pupal stages was 33.0% and from pupal to adult stages was 15.0% after injection. Reduction of ATG8 expression reduced survival of <i>H</i>. <i>vitessoides</i>. Therefore, <i>HvATG8</i> possibly plays a key role in normal growth stage of <i>H</i>. <i>vitessoides</i>. <i>HvATG8</i> suppression downregulates <i>HvATG3</i> expression, suggesting that the two genes are interconnected. Further, <i>HvATG8</i> expression increased by 20-hydroxyecdysone treatment, starvation, and extreme temperature exposure. Starvation also altered expression of other ATGs in <i>H</i>. <i>vitessoide</i>. This study may be used to guide research on molecular mechanisms of autophagy in insects.
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