Assessing matting patterns, chromosome composition, host suitability, and diapause expression of >i<Euschistus>/i< (Hemiptera: Pentatomidae) strains and species

Abstract

Assessing matting patterns, chromosome composition, host suitability, and diapause expression of Euschistus strains and speciesBrazil has become a prominent agricultural producer, contributing significantly to the global food supply. Stink bugs of the Pentatomidae family are a group of insects common in Brazil that feed on crops, causing decreased production and quality. Historical and contemporary demographic and adaptive factors associated with agricultural practices are important in determining which arthropods, native or invasive, will positively or negatively impact agroecosystems from a human point of view. For example, the Neotropical brown stink bug, Euschistus heros (Fabricius), a species rarely found in soybean fields until the 1970s, quickly evolved into a major soybean pest in just a few decades. The discovery of two allopatric strains of E. heros in South America, with a secondary contact area in central Brazil, has raised questions about its impact on pest dynamics in Brazil. Furthermore, E. heros has recently become a significant threat to cotton crops. Additionally, several species of Euschistus have been recorded in the Neotropical region on soybeans, but only E. heros has become highly prevalent in soybean fields. This study aimed to investigate the causes of a possible process of pre-zygotic isolation in the asymmetric gene flow between the two strains of E. heros, as well as to characterize the meiotic behavior and satellite DNA dynamics of the two strains of E. heros and their hybrid progeny and compare them with the sister species E. crenator (Fabricius) and E. taurulus Berg. We also characterized the host preference and suitability of the two E. heros strains and their reciprocal hybrids. In addition, we tested soybean and cotton suitability and insecticide susceptibility in three Euschistus species (natural hybrid population of E. heros, E. taurulus, and E. crenator) reported on soybean in Brazil and characterized diapause expression/termination of E. heros (both strains), E. taurulus and E. crenator. Finally, we employed a functional and molecular approach to characterize the transcript profile of E. heros and E. taurulus submitted to different photoperiod conditions, functionally validating the candidate genes related to diapause in E. servus (Say), a Nearctic species. We found that the SS strain is larger and darker, while the NS strain is smaller and has a lighter brown color. In addition, we found that E. heros mates assortatively with larger insects, favoring the SS, and the reciprocal hybrids (NS females mated with SS males) showed a reduced frequency of chiasmas. In addition, satDNAs were accumulated differently, mainly on the Y chromosome, in the two strains of E. heros; however, they did not promote reproductive isolation between the strains. Our bioassays revealed that the SS strain prefers soybeans over cotton, while the NS strain chose soybeans and cotton randomly. The reciprocal hybrid strains (HSN and HNS) behaved similarly to NS, choosing randomly between cotton and soybean...