Mwangala, Kaposhi, & Choongo

 

The Effect of Acaricides on Oviposition in a Strain of Boophilus decoloratus (Koch) Resistant to Toxaphene and Dioxation, by F.S. Mwangala, C.K.M. Kaposhi, J.C. Purakal and H. Choongo, Zambia Journal of Science & Technology, Vol.9, no.1, September 1991, Pg. 6-13

ABSTRACT

The effect of widely used acaricides on oviposition in a strain of Boophilus decoloratus (Koch resistant to toxaphene and dioxathion was investigated. Engorged female ticks were dipped in acaricidal test solutions for 10 minutes within 24 hours after dropping from host animals. The acaricides used were toxaphene, dioxathion, chlorfenvinphos and amitraz; and were tested at the manufacturer's recommended concentration(field usage rates, FUR) and at 75% of FUR. Both concentrations of chlorfenvinphos and amitraz had a strong inhibitory effect on oviposition (95% inhibition) and harchability of eggs. Toxaphene and dioxathion has less effect on ovipostion (26% inhibition) and egg harchability. Most of ticks exposed to toxaphene, dioxathion and amitraz were still alive after four weeks, while 30% of those exposed to chlorfenvinphos died within the first week. These results suggest that the mode of action of amitraz was entirely on oviposition, probably by preventing the conversion of blood meal into eggs, or the release of eggs from the ovaries. The effect of chlorfenvinphos, on the other hand, was indirect as the ticks were killed before eggs could be laid. Most ticks were affected by this acaricide in the first week, although they were still alive.

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