Laboratory testing of the effects of a natural insecticide made with neem extracts (Azadirachta indica A. Juss) on Glossina fuscipes fuscipes Newstead, 1910 (Diptera: Glossinidae)

Abstract

Azatin EC®, an extract from neem (Azudirachta indica A. Juss) seeds, has been tested to examine its potential role in tsetse fly control by rural communities. Laboratory tests were performed on Glossina fuscipes fuscipes by topic applications or tarsal contacts. The topic application of Azatin EC® (30 g of azadirachtin per liter), induced a low mortality rate at higher dosages only (2.61 µg of azadirachtin/fly) in Young males (DL50 = 0.747 µg) and old gravid females (DL50 = 2.516 µg). Productivity (number of pupae/female) decreased 4.5-fold at higher dosages and the pupa weight was significantly lower at the beginning of the pupa period. These parameters did not significantly differ from control thereafter. The emergence rate was significantly lower at dosages higher than 0.261 µg/fly. Flying and probing difficulties were observed at, and above, 0.261 µg/fly, indicating a probable muscular physiological unbalance. However, tarsal contact with a piece of material treated with 3.9 g/m²,  azadirachtin had no effect on the mortality and emerging rates, or productivity, for the three periods of time tested (1, 2 or 3 min). A strong repellent effect has nevertheless been noticed after coating the host ear with a 0.3 g/l azadirachtin solution. At this concentration, 70 % and, at 3 g/l concentration, 90 % of the flies did not feed on the host. As regards the results obtained, the possible use of this natural product in the field is discussed, in particular as a repellent for the protection of cattle in infested areas.