Diapause variation among Nearctic and Neotropical Euschistus (Hemiptera: Pentatomidae) species

Only a few habitats are stable enough to support continuous annual development. Temperate regions are characterized by harsh winters and moderate summers, while tropical areas have alternating dry and wet seasons. To avoid stress, insects enter diapause before ecological deterioration occurs. Euschistus stink bugs (Hemiptera: Pentatomidae) are significant pests in the Americas, found in both the Nearctic and Neotropical regions. Despite their importance, only a limited number of species have had their diapause phenotypes thoroughly characterized, and there is a lack of molecular analysis of this phenotype within this group. Therefore, our objectives were to: 1) assess the diapause expression of four Euschistus species (E. servus = Nearctic, and E. heros, E. crenator, and E. taurulus = Neotropical); 2) identify diapause-associated genes in ovarian tissue (RNA-seq) and characterize selected genes (RNAi). We found that diapause occurs under short-daylight conditions in E. servus, E. taurulus, and E. heros, whereas E. crenator does not enter diapause under the tested conditions. RNA-seq analysis revealed three candidate diapause genes: nuclear receptor ftz-f1 (ftz), juvenile hormone epoxide hydrolase (jheh), and farnesyl pyrophosphate synthase (fpps). RNA interference targeting fpps and jheh induced a diapause phenotype in E. servus and E. taurulus but not in E. heros or E. crenator. Knocking down ftz caused very high mortality across all species. We conclude that in Euschistus stink bugs, facultative diapause and related gene functions are only partly shared between Nearctic and Neotropical species.