Evaluation of plant species used traditionally to treat myiasis for activity on the survival and development of Lucilia cuprina and Chrysomya marginalis (Diptera: Calliphoridae)

Myiasis is a common parasitic problem of livestock responsible for severe economic losses in developing and developed countries. There are a number of challenges with the current control strategy, which depends largely on the use of pharmaceutical chemicals. These include inaccessibility, the increasing concern about pesticide accumulation in the environment and potential development of insecticide resistance in the devastating myiasis-causing flies. Consequently the search for alternatives is important. The use of plants in the treatment of wound myiasis in livestock as an alternative to commercial insecticides has been reported in resource poor areas worldwide. We therefore, undertook a study to establish the biological activity of seven plant species used against blowflies in southern Africa. A larvicidal assay was carried out in which third instar larvae of blowfly were fed meat treated with acetone leaf extracts of selected plant species. Four of the species, Aloe zebrina, Clausena anisata, Erythrina lysistemon and Spirostachys africana, induced developmental anomalies in the blowfly such as paralysis, prolongation of the prepuparium stage, reduced pupation rates, pupal malformations and reduced adult emergence. These results suggest that the plants may contain compounds that interfere with the neuroendocrine control mechanisms in the blowfly.