Toxicity of precocene-2 for the american dog tick, Dermacentor variabilis (Acari: Ixodidae) [Ageratum houstonianum]

The plant derivative precocene-2 (2,6-dimethoxy-2,2-dimethyl chromene) was found to be toxic to immature D. variabilis ticks. Contact treatment with doses of 1.0 mu g/cm super(2) was lethal for most unfed larvae and nymphs. When exposed to lesser doses, many more surviving larvae failed to feed than...

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Veröffentlicht in:Journal of medical entomology 1982-01, Vol.19 (6), p.734-742
Hauptverfasser: Dees, W H, Sonenshine, D E, Breidling, E, Buford, N P, Khalil, G M
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Sprache:eng
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Zusammenfassung:The plant derivative precocene-2 (2,6-dimethoxy-2,2-dimethyl chromene) was found to be toxic to immature D. variabilis ticks. Contact treatment with doses of 1.0 mu g/cm super(2) was lethal for most unfed larvae and nymphs. When exposed to lesser doses, many more surviving larvae failed to feed than did untreated larvae or those exposed only to acetone. Contact treatment of engorged larvae resulted in ecdysial delay, ecdysial mortality, or death without molting. Treatment of engorged nymphs resulted in ecdysial mortality without ecdysial postponement (1.0 mu g/cm super(2)) or induced a slow-death syndrome. In the latter case, adult characters developed normally but the treated nymphs failed to molt, and many remained in the nymphal skin for weeks or even months before eventual death. An inverse relationship was found between the developmental state of the immature ticks and their sensitivity to precocene-2.
ISSN:0022-2585
1938-2928
DOI:10.1093/jmedent/19.6.734