Permethrin-impregnated bednets reduce nuisance arthropods in Gambian houses

The prevalence of bedbugs (Cimex hemipterus L.), chicken ticks (Argas persicus Oken) and headlice (Pediculus capitis De Geer) was surveyed in a rural area of The Gambia. At the beginning of the study 37.5% of children's beds were infested with bedbugs and 3.9% with chicken ticks, whilst the prevalence rate of pediculosis in children under 10 years old was 28.8%. Both bedbugs and headlice were clustered within compounds. Headlice prevalence increased with hair length and they were more common on girls than boys. Following this cross-sectional survey all bednets in the sixteen hamlets were either dipped in permethrin or a placebo. About 4 months later it was found that bedbugs and chicken ticks had disappeared from homes in which the bednets had been impregnated with permethrin. There was no reduction in hamlets with placebo-treated bednets. The rate of acquiring headlice between the two surveys was reduced by 91.1% in children who slept under insecticide-treated bednets compared with children with placebo-treated bednets. There were also significantly fewer day-flying and crawling insects, except earwigs, in homes of children who slept under insecticide-treated bednets compared with those with placebo-treated nets. These additional benefits of permethrin-treated bednets should contribute to their widespread acceptance and utilization by the community for personal protection.     

The hatching stimulus for eggs of Aedes punctor (Diptera: Culicidae)

ABSTRACT.

• 1 Eggs of the British woodland mosquito, Aedes punctor (Kirby), were subjected to a variety of media in an attempt to determine the hatching stimulus.
• 2 It was found that continuous immersion in distilled water evoked almost no hatching (0.2%); intermittent removal from the water gave low hatching (8.9%).
• 3 Slow deoxygenation of the medium by either bacterial growth or the introduction of nitrogen produced the highest level of hatching (26.0–90.0%). Eggs of A.punctor were shown to hatch within a 4 h period of the oxygen concentration in the medium reaching zero.