Identification and characterization of capa and pyrokinin genes in the brown marmorated stink bug, Halyomorpha halys (Hemiptera): Gene structure, immunocytochemistry, and differential expression

Authors: AHN, SEUNG-JOON - Oregon State University; Choi, Man-Yeon

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2018
Publication Date: 9/18/2018
Citation: Ahn, S., Choi, M.Y. 2018. Identification and characterization of capa and pyrokinin genes in the brown marmorated stink bug, Halyomorpha halys (Hemiptera): Gene structure, immunocytochemistry, and differential expression. Archives of Insect Biochemistry and Physiology. 6:e21500. https://doi.org/10.1002/arch.21500.
DOI: https://doi.org/10.1002/arch.21500

Interpretive Summary: The brown marmorated stink bug (BMSB), Halyomorpha halys (Hemiptera: Pentatomidae), is an invasive pest that was first discovered in the United States during the mid-1990s. The infestation areas of BMSB had been growing steadily, and as of 2013, has spread across 40 states including Oregon. BMSB heavily damages over 140 agricultural and ornamental crops including nursery plants. Current control methods depend on non-specific chemical insecticides that negatively impact the environment, human health and can lead to potential resistance, and should be replaced with environmentally friendly alternative approaches. It has spurred to develop various management options including pheromone-based monitoring and trapping, biological control utilizing entomopathogenic fungi, and a recent RNA interference (RNAi)-mediated approach. Scientists from USDA-ARS, and Oregon State University at Corvallis, OR identified and characterized neuropeptides related to specific endocrinal regulations and feeding behaviors will aid to find biological targets to be utilized for BMSB control. In this study, identified neuropeptides and genes are the capa and pyrokinin family peptides and genes, and they determined differential gene expressions in different nerve tissues and developmental stages. We also elucidated the immunoreactivity of FXPRL peptides in the central nervous system (CNS). The deduced amino acid sequences were compared with over 30 other hemipteran species, providing the evolutionary feature of CAPA and PK precursors in Hemiptera. The current research results provide a new insight to discover potential biological function(s) of the neuropeptides, and to assist in development of control methods for the brown marmorated stink bug.

Technical Abstract: CAPA and PK neuropeptides sharing a common PRXamide at C-terminal ends play to regulate a variety of physiological functions in insects. They are produced from two different genes, capa and pyrokinin, respectively. In this study we identified and characterized the capa and pyrokinin genes from the brown marmorated stink, bugHalyomorpha halys (Hemiptera) that is a serious invasive pest currently threatening a wide range of economic crops in the United States. In H. halys the capa gene encodes CAPA-PVK1 (DAGLFPFPRVamide), CAPA-PVK2 (EQLIPFPRVamide) and CAPA-DH (NGASGNGGLWFGPRLamide), and the pyrokinin gene encodes three PK2 peptides (QLVSFRPRLamide, SPPFAPRLamide, and FYAPFSPRLamide). The whole-mounting immunocytochemistry revealed the neurons contained PRXamide-like peptides throughout brain (Br), suboesophageal ganglion (SEG), thoracic ganglion (TG) and abdominal ganglion (AG). A pair of neurosecretory cells in the dorsal anterior part of brain and three cell clusters in the ventral part of SEG were found with the axonal projections extended through the lateral side to the median bundle of the tritocerebrum. A pair of cells immunostained are found in the TG, while three pairs of cell bodies are present in the fused AG. The expression patterns of capa and pyrokinin genes showed different in the nerve tissues including Br-SEG, TG, and AG, where capa gene was highly expressed in the AG, but pyrokinin gene was expressed most likely in the Br-SEG. During different developmental stages, however, both genes expressions were similar, the highest from the 1st nymph and decreased to the adult. The female adult always showed a lower level than male in two gene expressions. Comparative analysis of peptide sequences from pyrokinin genes over 30 hemipteran species showed, PK1 (=DH-like) peptide is lost in true bugs (Heteroptera) including H. halys, but retained in the other suborders. It suggests an ancient loss of the PK1 peptide in the pyrokinin gene might be linked in the common ancestor of the Heteroptera.