Different processing of CAPA and pyrokinin precursors in the giant mealworm beetle Zophobas atratus (Tenebrionidae) and the boll weevil Anthonomus grandis grandis (Curculionidae)

Authors: NEUPERT, SUSANNE - University Of Cologne; MARCINIAK, PAWEL - Adam Mickiewicz University; KOHLER, RENE - University Of Cologne; Nachman, Ronald; Suh, Charles; PREDEL, REINHARD - University Of Cologne

Submitted to: General and Comparative Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2017
Publication Date: 2/8/2018
Citation: Neupert, S., Marciniak, P., Kohler, R., Nachman, R.J., Suh, C.P., Predel, R. 2018. Different processing of CAPA and pyrokinin precursors in the giant mealworm beetle Zophobas atratus (Tenebrionidae) and the boll weevil Anthonomus grandis grandis (Curculionidae). General and Comparative Endocrinology. 258:53-59.

Interpretive Summary: Insect pests have developed resistance to several conventional pesticides, and new approaches are needed for pest management. Although neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions, the neuropeptides hold little promise as pest control agents because they can be degraded in the target pest. New, selective control agents may be developed by designing mimics of these neuropeptides that resist degradation and either inhibit or over-stimulate critical neuropeptide-regulated life functions. We report on the identification of neuropeptides of several classes from the central nervous system of the boll weevil, a major pest of cotton. In addition, we have mapped neuropeptide storage and release sites and characterized the structures of seven distinct peptide hormones in the nervous system of these insect pests. The study identified a hormone in the boll weevil that has a unique structure, which could allow for the development of stable versions that can act as control agents specific to the cotton pest. This information will aid in determining the functional roles of these different classes of neuropeptides in boll weevils and other related insect pests, which may lead to development of practical neuropeptide-like substances that can effectively and specifically control pest insects in an environmentally friendly fashion.

Technical Abstract: Capa and pyrokinin (pk) genes in hexapods share a common evolutionary origin. Using transcriptomics and peptidomics, we analyzed products of these genes in two beetles, the giant mealworm beetle (Zophobas atratus; Tenebrionidae) and the boll weevil (Anthonomus grandis grandis; Curculionidae). Our data revealed that even within Coleoptera, which represents a very welldefined group of insects, highly different evolutionary developments occurred in the neuropeptidergic system. These differences, however, primarily affect the general structure of the precursors and differential processing of mature peptides and, to a lesser degree, the sequences of the active core motifs. With the differential processing of the CAPA-precursor in Z. atratus we found a perfect example of completely different products cleaved from a single neuropeptide precursor in different cells. The CAPA precursor in abdominal ganglia of this species yields primarily periviscerokinins whereas processing of the same precursor in neurosecretory cells of the subesophageal ganglion results in CAPA-tryptoPK and CAPA-PK. The CAPA-PK of Z. atratus represents the third putative receptor ligand encoded in the capa gene of many lineages of insects but has never been found to be processed in the CNS or elsewhere. In contrast to the processing of the CAPA precursor from Z. atratus, processing of the homologous precursor from A. g. grandis seems to be as simple as it was observed for PK precursors of both species; no hints suggesting a differential processing were found. These data suggest that rapid evolutionary changes of capa genes and their products were still going on when the different beetle lineages diverged. The sequence of the single known PVK of A. g. grandis occupies a special position within the known PVKs of insects and might serve as a basis to develop lineage specific peptidomimetics capable of disrupting physiological processes regulated by PVKs.