ARS | Publication request: Cloning and characterization of an MRNA encoding an insulin receptor from the horned scarab beetle Onthophagus nigriventris (Coleoptera: scarabaeidae)

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 2012
Publication Date: December 20, 2012
Citation: Lavine, L., Hahn, Laura, Garczynski, S.F., Warren, I., Dworkin, I., Emlen, D. 2012. Cloning and characterization of an MRNA encoding an insulin receptor from the horned scarab beetle Onthophagus nigriventris (Coleoptera: scarabaeidae). Archives of Insect Biochemistry and Physiology. Vol 82(1) 43-57.

Interpretive Summary: Plum curculio and lesser shothole borers are two beetle pests of tree fruit in the Pacific Northwest. Chemical control of these pests has not proven to be successful. Scientists at the USDA-ARS Yakima Agricultural Laboratory in Wapato, WA in conjunction with Researchers at Washington State University, University of Montana and Michigan State University are conducting research to identify potential targets that can be used to control beetles. The insulin signaling pathway plays key roles in regulating embryonic development, controlling cell size and growth, metabolism, egg maturation and longevity. This manuscript provides up to date information on the cloning and characterization of a cell surface insulin receptor which initiates activation of the insulin signaling pathway. The information in this manuscript will provide scientists the information and technology they need to investigate the potential of insulin receptors as targets to control insect pests, including tree fruit pests of Washington State. This line of research will result in a better understanding of the insulin signaling pathway used by beetles in development and reproduction, perhaps leading to new methods of insect control that can be adapted for use in orchards in the Pacific Northwest as well as other agricultural crops worldwide.

Technical Abstract: The insulin signaling pathway has been implicated in the control of insect polyphenisms for some caste-forming insects and potentially has a role in horn dimorphisms in beetles. Males of the sexually dimorphic dung beetle Onthophagus nigriventris develop a magnificent thoracic horn up to twice the length of the body, provided a critical weight threshold is attained during development. Small males that do not reach the critical weight do not produce the adult thoracic horn. Females never develop a thoracic horn. The regulation of this dimorphism is known to be nutrition-dependent for males and nutrition-independent for females. However, the role of the insulin signaling pathway in this dimorphism remains unknown. We cloned and sequenced a full-length gene transcript encoding the O. nigriventris insulin receptor (OnInR), which is the receptor for circulating insulin and insulin-like peptides in animals. We show that the predicted OnInR protein is similar in overall amino acid identity to other animal insulin receptors and is most closely related phylogenetically to insulin receptors from insects. Variation in OnInR expression in developing horn tissues between male morphs indicates a role for the insulin receptor in polymorphic horn development.