Modelled impact of insecticide-contaminated dung on the abundance and distribution of dung fauna

Abstract Deterministic models assessed the effects that contaminated dung from insecticide-treated cattle had on populations of three hypothetical species of dung fauna that dispersed randomly and could double their numbers every 1–28 weeks at low density. Insecticide was allowed to kill 2–98 % of adults and prevent 16–100% of breeding in pats produced immediately after cattle treatment, with toxicity declining to < 1% in pats produced 2–23 days later. Treatment intervals were 10–40 days. The modelled impact of insecticide was affected little by approximately four-fold variations in: length and density dependence of the attractive life span of pats, frequency of pat occupation by immature adults, distribution of pat toxicity during treatment interval, and changes in dispersal rates due to age and population density. Of greater importance were variations in: pat toxicity, treatment interval, frequency of pat occupation by breeding adults, density dependence of recruitment and death, natural adversity and mortality in dormancy, general rate of dispersal, and the size and shape of the area with treated cattle. Overall, it seemed that wide variations in the impact of contamination will occur in the field, but in many situations the risk to dung fauna can be substantial, especially for slow breeding beetles, and muscoids contacting insecticide on cattle. Risk extends outside the treated areas, for a distance equal to several daily displacements of the insects. Untreated refuges for species survival should be compact blocks at least 25 daily displacements wide.

[1]  T. Ridsdill‐Smith,et al.  Antiparasitic drugs, the livestock industry and dung beetles--cause for concern? , 1998, Australian veterinary journal.

[2]  J. Gaddum Probit Analysis , 1948, Nature.

[3]  J. Hargrove Tsetse dispersal reconsidered. , 1981 .

[4]  J. Hogsette,et al.  Biology and control of tabanids, stable flies and horn flies. , 1994, Revue scientifique et technique.

[5]  G. Vale,et al.  Insecticide-treated cattle for controlling tsetse flies (Diptera : Glossinidae) : some questions answered, many posed , 1999 .

[6]  G. Vale,et al.  Odour-baited targets to control tsetse flies, Glossina spp. (Diptera: Glossinidae), in Zimbabwe , 1988 .

[7]  Peter Rothery The problems associated with the identification of density dependence in population data , 1998 .

[8]  Tomas Roslin,et al.  Dung beetle movements at two spatial scales , 2000 .

[9]  C. Scholtz,et al.  Survival and reproduction of Euoniticellus intermedius (Coleoptera: Scarabaeidae) in dung following application of cypermethrin and flumethrin pour-ons to cattle , 1999 .

[10]  E. Krafsur,et al.  Bionomics of the face fly, Musca autumnalis. , 1997, Annual review of entomology.

[11]  K. Floate Off-target effects of ivermectin on insects and on dung degradation in southern Alberta, Canada , 1998 .

[12]  Wardhaugh Kg,et al.  Antiparasitic drugs, the livestock industry and dung beetles cause for concern? , 1998 .

[13]  Models to assist the evaluation of the impact of avermectins on dung insect populations , 1998 .

[14]  K. Floate Does a repellent effect contribute to reduced levels of insect activity in dung from cattle treated with ivermectin , 1998 .

[15]  J. Hargrove,et al.  The Use of Small Plots to Study Populations of Tsetse (Diptera: Glossinidae) , 1984 .

[16]  R. R. Blume,et al.  Onthophagus gazella : Mass Rearing and Laboratory Biology , 1975 .

[17]  C. Scholtz,et al.  EFFECTS OF THE PYRETHROID FLUMETHRIN ON COLONISATION AND DEGRADATION OF CATTLE DUNG BY ADULT INSECTS , 1998 .

[18]  L. Strong Avermectins: a review of their impact on insects of cattle dung , 1992 .

[19]  J. B. Jespersen,et al.  Topical treatment of calves with synthetic pyrethroids: effects on the non-target dung fly Neomyia cornicina (Diptera: Muscidae) , 2001, Bulletin of Entomological Research.

[20]  G. Fincher The potential value of dung beetles in pasture ecosystems [Texas]. , 1981 .

[21]  R. C. Wallis The Distribution and Abundance of Tsetse , 1964, The Yale Journal of Biology and Medicine.

[22]  P. van den Bossche,et al.  Evaluation of insecticide‐treated cattle as a barrier to re‐invasion of tsetse to cleared areas in northeastern Zimbabwe , 1999, Medical and veterinary entomology.

[23]  P. Skidmore Insects of the British cow-dung community. , 1991 .

[24]  W. Mulatu,et al.  Use of deltamethrin ‘pour‐on’ insecticide for the control of cattle trypanosomosis in the presence of high tsetse invasion , 2001, Medical and veterinary entomology.

[25]  M. Lacey,et al.  Effects of residues of deltamethrin in cattle faeces on the development and survival of three species of dung-breeding insect. , 1998, Australian veterinary journal.