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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
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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