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

Only a few habitats are stable enough to support continuous yearly development. Temperate regions are characterized by harsh winters and moderate summers, while tropical areas have alternating dry and wet seasons. To avoid stress, small organisms, such as insects, enter diapause–a resting state triggered by environmental signals before ecological deterioration occurs. Euschistus stink bugs (Hemiptera: Pentatomidae) are significant pests in the Americas, found in both 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 regarding 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 is induced under short-daylight conditions in E. servus, E. taurulus, and E. heros, while E. crenator does not enter diapause under the tested conditions. The RNA-seq analyses identified 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. The knockdown of ftz led to very high mortality across all species. We conclude that in Euschistus stink bugs, the facultative diapause and related gene functions are only partially shared between Nearctic and Neotropical species.