Aqueous neem seed kernels extracts (NSKE) were used to treat flea-infested goats in Morogoro, Tanzania to determine their efficacy for flea control. Mean population densities of the insects were significantly lower in the treated goats compared to their untreated counterparts (P < 0.05). It was concluded that NSKE has potential in controlling livestock fleas, but further studies are needed to determine the active principals against fleas and their mode of action.

The influence of post-treatment temperature on the insecticidal activity of Azadirachta indica (A. Juss) seed extract against the desert locust, Schistocerca gregaria (Forskål) is reported. In tests on adults, the toxicity of crude A. indica seed extract increased by about 10-fold when the post-treatment temperature was raised from 22°C to 40°C. This temperature-dependent toxicity was observed in insects treated either topically or via injection. This phenomenon could partly explain the wide variability in efficacy of neem extracts reported by different investigators.

The oviposition-deterrent and toxic effects of seven plant species with known biological effects were tested against the Adzuki bean beetle, Callosobruchus chinensis L. (Goleoptera: Bruchidae) on stored faba bean seeds for two years at Holetta Research Centre, Ethiopia. Oils of Azadirachta indica, Milletiaie ferrnginea and Chrysanthemum cineraraefolium were the most effective in partially or completely preventing egg laying, and no bruchids emerged from the few eggs laid. The Phytolacca dodecandra, Hagenia abyssinica and Schinus molle treatments had no significant effect on the bruchids and most of the eggs laid developed into adults. Eucalyptus globulus seed powder treatment caused the death of only emerging adult beetles.

The effects of neem seed kernel extract (NSKE), neem oil (NO) and nucleopolyhedrovirus (NPV) of the Spodoptera litura Fabricius (Lepidoptera: Noctuidae) on the mortality, feeding and development of S. litura were evaluated in the laboratory. Dose-dependent mortality was evident after NPV treatment, which also depended on larval age at treatment. Upon combining NPV with neem products, the percentage mortality was enhanced threefold even at reduced concentrations. The NSKE and NO significantly inhibited the growth and development of S. litura, and extended the duration of its larval and pupal stages. Oviposition period, adult longevity and fecundity were significantly reduced following treatment with neem products and with neem + NPV treatment. The efficiencies of conversion of ingested food (ECI) and digested food (ECD) were also significantly decreased by treatment with NSKE, NO and NPV, either alone or in combination.

Gas-liquid chromatography was used to analyse the saponifiable and unsaponifiable fractions of petroleum ether (PE) extracts of neem fruits and leaves. Both fractions, as well as a crude PE extract, were assayed for biological activity against third instar cotton leafworm, Spodoptera littoralis.

In neem fruits, eighty-eight percent (88%) of the saponifiable matter consisted of saturated fatty acids, while 12% was composed of unsaturated fatty acids. In the neem leaves, the corresponding proportions were 62 and 38%, respectively. Unsaponifiable matter of both fruits and leaves contained varying amounts of hydrocarbons and sterols. All the tested extracts demonstrated significant larvicidal effects against leafworm larvae. They also prolonged larval duration, caused malformations of the resulting pupae and significant adverse effects on the fecundity of resulting adults.