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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY BASED MANAGEMENT OF BOLL WEEVILS AND OTHER ROW CROP PESTS UNDER TRANSITION TO BOLL WEEVIL ERADICATION IN TEMPERATE REGIONS

Location: Insect Control and Cotton Disease Research Unit

Title: The Molecular Characterization of the Kinin Transcript and the Physiological Effects of Kinins in the Blood-Gorging Insect Rhodnius prolixus

Authors
item Bhatt, Garima -
item Da Silva, Rosa -
item Nachman, Ronald
item Orchard, Ian -

Submitted to: Peptides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 18, 2013
Publication Date: N/A

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. Research was conducted that identifies the genetic blueprint and maps its locations of the ‘insect kinins’ in the assassin bug, an insect that transmits Chaga’s disease to humans. Unlike the natural neuropeptides, two synthetic mimics of the insect kinins show irreversible effects on gut contractions as well as activity at extremely low concentrations. This discovery provides a template for the design of neuropeptide-like compounds capable of disrupting the critical life function of digestion in these insect pests. This work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling insect pests that transmit deadly diseases in an environmentally friendly fashion.

Technical Abstract: The dramatic feeding-related activities of the Chagas' disease vector, Rhodnius prolixus are under neurohormonal regulation of serotonin and various neuropeptides. One such family of neuropeptides, the insect kinins, possess diuretic, digestive and myotropic activities in many insects. In this study, we have cloned and examined the spatial expression of the R. prolixus kinin (Rhopr-kinin) transcript. In addition, in situ hybridization has been used to map the distribution of neurons expressing the kinin transcript. Physiological bioassays demonstrate the myostimulatory effects of selected Rhopr-kinin peptides and also illustrate the augmented responses of hindgut contractions to co-application of Rhopr-kinin and a R. prolixus diuretic hormone. Two synthetic kinin analogs have also been examined on the hindgut. These reveal interesting properties including a relatively irreversible effect on hindgut contractions and activity at very low concentrations.

Last Modified: 4/16/2014