|COAST, GEOFFREY - University Of London
|TEBRUGGE, VICTORIA - University Of Toronto
|Lopez, Juan De Dios
|LANGE, ANGELA - University Of Toronto
|ORCHARD, IAN - University Of Toronto
Submitted to: Peptides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2009
Publication Date: 3/10/2010
Citation: Coast, G.M., Tebrugge, V.A., Nachman, R.J., Lopez, J., Aldrich, J.R., Lange, A., Orchard, I. 2010. Neurohormones implicated in the control of Malpighian tubule secretion in plant sucking Heteropterans: The stink bugs Acrosternum hilare and Nezara viridula. Peptides. 31:468-473.
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 two stink bug species, pests of cotton and soybean. The work demonstrates that while neuropeptides of the ‘CAP2b’ class stimulate water loss in flies, they prevent water loss in stink bugs. Neuropeptides of the ‘DH’ class stimulate water loss in both flies and stink bugs. Maintenance of proper water balance is critical to stink bug survival. The above results suggest that development of metabolically stable versions of these two classes of neuropeptides could lead to agents capable of disrupting this important survival mechanism in these agricultural pests. 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 fashion.
Technical Abstract: Plant sucking heteropteran bugs feed regularly on small amounts of K+rich plant material, in contrast to their hematophagous relatives which imbibe large volumes of Na+-rich blood. It was anticipated that this would be reflected in the endocrine control of MT secretion. To explore this, neuroendocrine factors known to influence MT secretion were tested on MT of the pentatomid plant sucking stink bugs, A. hilare and N. viridula, and the results compared with previously published data from R. prolixus. Serotonin had no effect on N. viridula MT, although it stimulates secretion by R. prolixus MT >1000-fold, and initiates a rapid diuresis to remove excess salt and water from the blood meal. Kinins had no effect on stink bug MT, but secretion was increased by Zoone-DH, a CRF-like peptide, although the response was a modest 2-3 fold acceleration compared with a greater than 100-fold in R. prolixus. Native CAPA peptides, which have diuretic activity in dipteran flies, had antidiuretic activity in MT of the stink bug (Acrhi/Nezvi-CAPA-1 and -2), as previously shown with Rhopr-CAPA-2 in R. prolixus. The antidiuretic activity of Rhopr-CAPA-2 has been linked with terminating the rapid diuresis, but results with stink bugs suggest it is a general feature of heteropteran MT.