An acetone extract of Clausena anisata may be a potential control agent for flies encountered in cutaneous myiasis.

Clausena anisata is a medicinal plant used traditionally to treat myiasis and as an insect repellent by various communities. We have previously demonstrated the effects of C. anisata extracts on blowfly feeding and development in our laboratory. The impact of C. anisata leaf extracts on populations of different fly species on farms in Mpumalanga, South Africa was investigated in this study under field conditions. Flies were exposed to liver baits treated with acetone leaf extracts of C. anisata (150 mg/mL). Fly numbers and composition on two farms, with and without C. anisata treated liver, were compared during a period of 12 weeks when fly populations were expected to be high. Observations were made on fly behaviour and development, adult sizes and numbers. The flies exposed to liver treated with the leaf extract of C. anisata had a decreased rate of development, prolonged larval period, smaller body sizes and more sluggish behaviour compared to those subjected to the control treatment. No significant differences were, however, found between the numbers and sizes of flies on the treated and on the control farm, which was most likely due to the limited nature of the baiting programme we followed. The effects of C. anisata extracts on blowfly behaviour and development observed in previous laboratory studies were confirmed in this field evaluation. Although the extracts did not have a significant effect on the overall population size in this experiment, we believe that the C. anisata leaf extract could be useful in integrated pest management based on its effect on larval development. In addition, species such as Lucilia cuprina and Chrysomya marginalis seemed to have been repelled by the C. anisata treated liver; as a result, further work should explore this aspect and how it can be used for the protection of animals.

Repellent and mosquitocidal effects of leaf extracts of Clausena anisata against the Aedes aegypti mosquito (Diptera: Culicidae).

Mosquitoes are rapidly developing resistance to insecticides that millions of people relied on to protect themselves from the diseases they carry, thereby creating a need to develop new insecticides. Clausena anisata is used traditionally as an insect repellent by various communities in Africa and Asia. For this study, the repellency and adulticidal activities of leaf extracts and compounds isolated from this plant species were evaluated against the yellow fever mosquito, Aedes aegypti. In the topical application assays, using total bites as an indicator, repellency was dose dependent, with the acetone crude extract (15 %) having 93 % repellence and the hexane fraction (7.5 %) 67 % repellence after 3 h. Fractionation resulted in a loss of total repellence. As mosquito-net treating agents, the acetone and hexane extracts of C. anisata, both at 15 %, had average repellences of 46.89 ± 2.95 and 50.13 ± 2.02 %, respectively, 3 h after exposure. The C. anisata acetone extract and its hexane fraction caused mosquito knockdown and eventually death when nebulised into the testing chamber, with an EC50 of 78.9 mg/ml (7.89 %) and 71.6 mg/ml (7.16 %) in the first 15 min after spraying. C. anisata leaf extracts have potential to be included in protection products against mosquitoes due to the repellent and cidal compounds contained therein.