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Title: Effect of seasonality and perisulfakinin on engorgement by Tabanus nigrovittatus (Diptera: Tabanidae) in the laboratory

item Nachman, Ronald

Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2006
Publication Date: 3/1/2007
Citation: Downer, K.E., Nachman, R.J., Stoffolano, Jr., J.G. 2007. Effect of seasonality and perisulfakinin on engorgement by Tabanus nigrovittatus (Diptera: Tabanidae) in the laboratory. Annals of the Entomological Society of America. 100:251-256.

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 a finding that the feeding inhibition activity of the sulfakinin neuropeptide class in the salt marsh horse fly is dependent on the feeding technique used. A deeper understanding of how these neuropeptides regulate the critical processes of satiety and digestion in insects will aid in the design of strategies to disrupt insect populations. The above results suggest that development of metabolically stable versions of the sulfakinins could lead to agents capable of disrupting the feeding process in insect pests. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling pest insects in an environmentally friendly fashion.

Technical Abstract: The horse fly Tabanus nigrovittatus Macquart (Diptera: Tabanidae), a hematophagous insect, is a nuisance pest along the Atlantic Coast. A description of the engorgement pattern throughout the season is lacking in the literature for this species. The percentage of the flies engorging a bloodmeal in the laboratory throughout the season was recorded, and here we demonstrated that sulfakinins, a vertebrate homologue of cholecystokinin, function in feeding inhibition as a satiety factor. We found that groups of flies injected with one nanomole of perisulfakinin were inhibited from blood feeding by 45-60%. The satiation of feeding reported here is in agreement with the previous research by using nonhematophagous species. When groups of flies were injected with 10 nmol of perisulfakinin, the percentage of flies engorging was increased relative to the sham-injected flies, although not significantly. The stimulation of engorgement by sulfakinin has not previously been demonstrated, and its mode of action remains unclear.