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Evaluation of insecticide‐treated cattle as a barrier to re‐invasion of tsetse to cleared areas in northeastern Zimbabwe
Author(s) -
Warnes M. L.,
Van Den Bossche P.,
Chihiya J.,
Mudenge D.,
Robinson T. P.,
Shereni W.,
Chadenga V.
Publication year - 1999
Publication title -
medical and veterinary entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 82
eISSN - 1365-2915
pISSN - 0269-283X
DOI - 10.1046/j.1365-2915.1999.00148.x
Subject(s) - clearance , deltamethrin , biology , trypanosomiasis , veterinary medicine , tsetse fly , african trypanosomiasis , field trial , herd , toxicology , ecology , agronomy , virology , pesticide , medicine , urology
Summary A field trial in Zimbabwe investigated the efficacy of insecticide‐treated cattle as a barrier to prevent the re‐invasion of tsetse, Glossina morsitans and G. pallidipes (Diptera: Glossinidae), into cleared areas. The original tsetse barrier consisted of insecticide‐treated odour‐baited targets, at an operational density of four to five targets per km 2 , supported by insecticide‐treatments of cattle with either deltamethrin dip (Decatix ® , Coopers) at two‐weekly intervals, or deltamethrin pour‐on (Spoton ® , Coopers) at monthly intervals, in a band ≈ 20 km wide from the re‐invasion front. Tsetse catch, and trypanosomiasis incidence in nine sentinel herds was recorded for 7–8 months, respectively, before the targets were removed, leaving only the insecticide treatment of the local cattle to stem the re‐invasion of tsetse. After the removal of the target barrier, the tsetse readily invaded the trial area and the incidence of trypanosomiasis in sentinel herds increased, while their PCVs decreased. After seven months without the targets in place, trypanosomiasis prevalence in the local stock had reached alarmingly high levels; the trial was terminated prematurely and the target barrier re‐deployed. Immediately after the re‐deployment of the target barrier, the tsetse catch in the trial area reverted to acceptable levels along the re‐invasion front, and trypanosomiasis incidence in the sentinel cattle decreased. It is concluded that, under the conditions of the field trial, the insecticidal treatment of local cattle did not in itself form an effective barrier to tsetse re‐invasion. By contrast, the target barrier performed as was predicted by mathematical and experimental analysis, and readily cleared the tsetse infestation and reduced trypanosomosis incidence in the trial area.