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Glycoprotein hormone receptors mediate a diverse range of physiological functions in vertebrate and invertebrate organisms. The heterodimeric glycoprotein hormone GPA2/GPB5 and its receptor LGR1, constitute a recently discovered invertebrate neuroendocrine signaling system that remains to be functionally characterized. We previously reported that LGR1 is expressed in the testes of adult Aedes aegypti mosquitoes, where its immunoreactivity is particularly regionalized. Here, we show that LGR1 immunoreactivity is associated with the centriole adjunct of spermatids and is observed transiently during spermatogenesis in mosquitoes, where it may act to mediate the regulation of flagellar development. RNA interference to downregulate LGR1 expression was accomplished by feeding mosquito larvae with bacteria that produced LGR1-specific dsRNA, which led to defects in spermatozoa, characterized with shortened flagella. LGR1 knockdown mosquitoes also retained ∼60% less spermatozoa in reproductive organs and demonstrated reduced fertility compared to controls. To date, the endocrine regulation of spermatogenesis in mosquitoes remains an understudied research area. The distribution of LGR1 and detrimental effects of its knockdown on spermatogenesis in A. aegypti indicates that this heterodimeric glycoprotein hormone signaling system contributes significantly to the regulation of male reproductive biology in this important disease-vector.

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Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) is one of the most aggressive pests of stored grains, causing significant decrease in the nutritional quality of the grains and major losses in economic trade. The ability of this pest to damage grains and other products is directly related to the morphology of the alimentary canal. Considering the importance of the foregut in the digestion, this study aimed to describe the morphology of the crop and proventriculus in S. zeamais adults. The tissues were isolated, processed, and analyzed by using light microscopy, scanning electron microscopy, and transmission electron microscopy. The crop functioned as a storage organ, and its cells showed functional characteristics related to protein synthesis. High densities of prokaryotic microorganisms and spicules were found in the lumen. The proventriculus exhibited eight chitinous teeth, which were responsible for grinding and filtering food particles. This organ formed the stomodeal valve, which controlled the unidirectional flow of food through the alimentary canal. The alimentary canal is the primary surface of contact between the external environment and an insect's internal environment, and knowledge of its morphology is required to better understand the physiology of stored-grain insect pests.

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