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item Vercruysse, L.
item Gelman, Dale
item Raes, E.
item Hooghe, B
item Vermeirssen, V.
item Van Camp, J.
item Smagghe, E.

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2004
Publication Date: 11/1/2004
Citation: Vercruysse, L., Gelman, D.B., Raes, E., Hooghe, B., Vermeirssen, V., Van Camp, J., Smagghe, E. 2004. Ace inhibitor captopril reduces oviposiiton and ecdysteroid levels in lepidoptera. Archives of Insect Biochemistry and Physiology. 2004 v 57. p.123-132

Interpretive Summary: Currently, chemical pesticides are the most frequently used compounds to limit insect damage, damage that causes billions of dollars in crop losses annually. The development of pesticide resistance, concern for environmental safety and pesticide-associated destruction of natural enemies has made the reduction of pesticide use a primary goal for agriculture. Increased availability of insect-specific biopesticides would reduce dependency on chemical pesticides. Information concerning the nature, action and interaction of insect regulatory molecules would facilitate the development of such biopesticides; however, such information is seriously lacking. In this study, the role of a potent regulatory molecule, angiotensin converting enzyme (ACE) was investigated. Results showed that ACE is involved in insect metamorphosis and also controls egg production by two different and independent pathways, one via the activity of the insect molting hormone, and the second by influencing the production of the protein-digesting enzyme, trypsin. Information should be useful to scientists, especially for designing new strategies for insect control based on the disruption of insect development and reproduction.

Technical Abstract: The role of ACE in metamorphic- and reproductive-related events in the Egyptian cotton leafworm, Spodoptera littoralis (Lepidoptera, Noctuidae) was studied by using the selective angiotensin converting enzyme (ACE) inhibitor captopril. Although oral administration of captopril had no effect on larval growth, topical administration to new pupae resulted in a large decrease of successful adult formation. Oviposition and overall appearance of adults emerging from treated larvae did not differ significantly from those emerging from non-treated larvae. In contrast, topical or oral administration of captopril to newly emerged adults caused a reduction in oviposition. By evaluating the effect of captopril on ecdysteroid titers and trypsin activity, we revealed an additional physiological role for ACE. Captopril exerted an inhibitory effect on ecdysteroid levels in female but not male adults. Larvae fed a diet containing captopril exhibited increased trypsin activity. A similar captopril-induced increase in trypsin activity was observed in female adults. In male adults, however, captopril elicited reduced levels of trypsin activity. Our results suggest that captopril downregulates oviposition by two independent pathways, one through ecdysteroid biosynthesis regulation, and the other through regulation of trypsin activity. Apparently, fecundity is influenced by a complex interaction of ACE, trypsin activity and ecdysteroid levels.