Pyrethroid Treatment of Cattle for Tsetse Control: Reducing Its Impact on Dung Fauna

Abstract

BackgroundAfrican trypansomiases of humans and animals can be controlled by attacking the vectors, various species of tsetse fly. Treatment of cattle with pyrethroids to kill tsetse as they feed is the most cost-effective method. However, such treatments can contaminate cattle dung, thereby killing the fauna which disperse the dung and so play an important role in soil fertility. Hence there is a need to identify cost-effective methods of treating cattle with minimal impact on dung fauna.Methodology/Principal FindingsWe used dung beetles to field bioassay the levels of dung contamination following the use of spray and pour-on formulations of deltamethrin, applied to various parts of the body of cattle in Zimbabwe. Results suggested that dung was contaminated by contact with insecticide on the body surface as the cattle defecated, and by ingestion of insecticide as the cattle licked themselves. Death of dung beetles was reduced to negligible levels by using only the spray and applying it to the legs and belly or legs alone, i.e., places where most tsetse feed.Conclusion/SignificanceThe restricted applications suitable for minimising the impact on dung fauna have the collateral benefits of improving the economy and convenience of cattle treatments for tsetse control. The demonstration of collateral benefits is one of the surest ways of promoting environmentally friendly procedures.

Exploring the potential of using cattle for malaria vector surveillance and control: a pilot study in western Kenya

“…Previous bioassays of the efficacy of deltamethrin against tsetse have used the Decatix formulation (Cooper Zimbabwe, Harare), a 5% (v/v) suspension concentrate (s.c.) that has been employed routinely in large-scale tsetse control operations in Zimbabwe and elsewhere [20, 38]. The Vectocid formulation of deltamethrin used in the present study had not previously been tested against mosquitoes or tsetse.…”

“…The comparative studies were carried out at Rekomitjie Research Station (16°7'60"S, 29°24'0"E) in the Zambezi valley of Zimbabwe following a standard method [20, 38] in which wild males and females of Glossina pallidipes were caught after they had fed on untreated or treated cattle. Treated cattle were sprayed with Vectocid applied to either (i) the legs and belly only (restricted protocol) or (ii) the whole body at the same concentration used in Kenya.…”

Assessing the effect of insecticide-treated cattle on tsetse abundance and trypanosome transmission at the wildlife-livestock interface in Serengeti, Tanzania

“…The insecticide reported to be widely used in this study area (alpha cypermethrin) has a half-life of approximately 1 week on vegetation or in soil [ 40 ], and in terms of contamination of dung, Vale et al . demonstrated that when insecticides are applied only to the areas where tsetse most frequently bite, death of dung beetles was reduced to negligible levels [ 41 ]. Potentially adverse environmental impacts could therefore be mitigated through informed restricted application of pyrethroids to cattle [ 6 ].…”

Environmental consequences of deltamethrin residues in cattle feces in an African agricultural landscape

“…Recommendations for increasing the environmental and economic sustainability of livestock pest and parasite management are likely to include choosing compounds and formulations that are known to be less harmful to dung beetles (Bianchin et al., ; Kryger, Deschodt, Davis, & Scholtz, , ), or treating only certain parts of the body surface where parasites prefer (Vale, Hargrove, Chamisa, Grant, & Torr, ), for example the legs and belly in the case of tsetse flies (Torr, Maudlin, & Vale, ). Staggered treatment of animals to ensure the presence of insecticide‐free refugia pats on pastures at all times targeted treatment of affected individuals, and integrated approaches may also help to minimize damage (Wall & Beynon, ).…”