Spraying with the organophosphate fenthion has been the predominant means to control the red-billed quelea (Quelea quelea), a major bird pest throughout semi-arid regions of sub-Saharan Africa, for more than forty years. A review of known effects of fenthion and other control measures used against Q. quelea on non-target organisms, provides a basis for comparisons with any alternative chemical control agents. Birds of prey, owls and passerines have been commonly reported casualties of spraying with fenthion over land. Moreover, fenthion is known to have negative effects on aquatic invertebrates, in particular on populations of crustacea, which predicates against its use near water bodies. Non-target species may be affected directly by spraying, but predatory birds, scavenging birds and even mammals can be contaminated by secondary poisoning when they eat Quelea carcasses found up to 20 km or more from the primary control site. To avoid secondary poisoning, where possible quelea carcasses should be removed from a site after spraying. The use of explosions to kill roosting quelea birds has similar effects to those of fenthion in terrestrial habitats, killing non-target species including birds of prey and owls. Another control method, harvesting quelea as a source of protein, is benign and could contribute to local nutritional and economic needs. However harvesting is unlikely to reduce quelea populations substantially. Integrated pest management (IPM) approaches are recommended to minimize environmental damage, but until these are successfully adopted, standardized procedures for comparative assessments of the effects of quelea control are required.

Gravid Lucilia treated topically with ivermectin (0.05μg/g, which represented approx. 4% of the 48 hr LD50) laid fewer viable egg batches (less than 50% of controls) and more sterile ones, when compared to untreated (P = 0.019) and acetone-treated flies (P = 0.028). This effect was also seen when mature third instar larvae were dosed with 7.6 μ g ivermectin/g (P = 0.0075 and 0.016 respectively); number of viable egg batches produced were only 25% of the number laid by the progeny of untreated larvae.

Dosage with fenthion stimulated an increase in the number of viable egg batches laid when incorporated in the original larval feeding medium at 0.2 μg/g liver; fewer viable egg batches were laid by the flies which developed from mature larvae treated with 7.6 μ g fenthion/g. Acetone solvent alone had a mild stimulatory effect on topically dosed flies.