The control of Malpighian tubule secretion in a predacious hemipteran insect, the spined soldier bug Podisus maculiventris (Heteroptera, Pentatomidae)

Authors: COAST, GEOFFREY - University Of London; Nachman, Ronald; Lopez, Juan De Dios

Submitted to: Peptides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2010
Publication Date: 11/18/2010
Citation: Coast, G.M., Nachman, R.J., Lopez, J. 2010. The control of Malpighian tubule secretion in a predacious hemipteran insect, the spined soldier bug Podisus maculiventris (Heteroptera, Pentatomidae). Peptides. 32(3):493-499.

Interpretive Summary: Because of problems with the development of resistance to conventional pesticides, there is a critical need for new concepts and alternative approaches in controlling insect pests. The basic premise of this research is that neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions. New, selective control measures may be developed by designing metabolically stable mimics of these neuropeptides that actively inhibit or over-stimulate functions regulated by them, resulting in disruption of the internal environment of the insect. We report on how neuropeptides regulate the critical processes of water and mineral balance in a beneficial insectivorous stink bug (the spined soldier bug) and compare that with herbivorous stink bug species, pests of cotton and soybean. The work identifies some similarities and some differences between the neuropeptide regulation of water balance in the two types of insects. While the ‘CAP2b’ neuropeptide class stimulates water loss in flies, it prevents water loss in both herbivorous and insectivorous stink bugs. Conversely, neuropeptides of the ‘DH’ class stimulate water loss in the insectivorous species to a much greater degree than in the herbivorous species. Maintenance of proper water balance is critical to insect survival and differences between the neuropeptide regulatory systems of the two bugs can be exploited to selectively develop metabolically stable NP-based agents capable of disrupting this important survival mechanism in herbivorous agricultural pests without harm to beneficial insects. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling stink bug pests in an environmentally friendly and selective fashion.

Technical Abstract: Spined soldier bugs, Podisus maculiventris, are heteropteran insects that feed voraciously on other insects, particular the soft bodied larval forms of Lepidoptera and Coleoptera. The response of P. maculiventris Malpighian tubules (MT) to serotonin and known diuretic and antidiuretic peptides has been investigated, and is compared with that of MT from the hematophagous and phytophagous heteropteran bugs Rhodnius prolixus and Acrosternum hilare, respectively. A CRF-related peptide diuretic hormone (DH) from the termite Zootermopsis nevadensis (Zoone-DH) stimulated MT secretion, which was reversed by a member of the CAP2b family of peptides from A. hilare (Acrhi-CAP2b -2), an antidiuretic effect. Serotonin had no effect on secretion, neither did a representative calcitonin-like DH, kinin, tachykinin-related peptide, and an antidiuretic factor from the mealworm Tenebrio molitor (Tenmo-ADFb) in both P. maculiventris or A. hilare. Serotonin is a DH in R. prolixus, and its lack of effect on MT from P. maculiventris and A. hilare suggests this is an adaptation to hematophagy. On the other hand, the antidiuretic activity of members of the CAP2b family in all three bugs is consistent with this being a heteropteran feature rather than a specialism for hematophagy.