Laboratory evaluation of three commercial coil products for protection efficacy against Anopheles gambiae from southern Ghana: a preliminary study

Residents in irrigated urban agricultural sites face numerous mosquito problems such as increased mosquito populations and reduced insecticides susceptibility due to the creation of mosquito breeding sites and agricultural use of insecticides and hence require effective protective products against them. In this study, the protection effectiveness of three pyrethroid formulated mosquito coils of Malaysian origin against Anopheles gambiae sensu lato from an irrigated urban agricultural site in Ghana were evaluated for their potential use. Sucrose fed An. gambiae s.l. were exposed to insecticide-containing coils in a 70 cm x 70 cm x 70 cm glass chamber to assess the insecticidal effect of the coils. The 0.005% metofluthrin coil caused the most rapid knockdown of 50% of the test mosquitoes. The mean lethal effect of the coils on An. gambiae s.l. were as follows; 0.005% metofluthrin (86%), 0.3% d-allethrin (74.33%), 0.15% d-trans allethrin (72%) and the 0.25% d-allethrin reference coil (69%). The 0.005% metofluthrin coil achieved the highest insecticidal effect on An. gambiae s.l. compared to the other coils and hence performed better than the others as an anti-mosquito product. All the three test coils were effective against An. gambaie s.l. from the irrigated agricultural site compared to the reference coil.

The ecology of anopheline mosquitos in northwest coastal Malaysia: larval habitats and adult seasonal abundance.

Collections of anopheline mosquitos were made twice monthly for 13 months from a cow-baited trap in two villages, Kampung Permatang Rawa and Sungai Udang Kecil, on mainland coastal Penang, Malaysia. Each collection period was six hours from sunset. Unquantified larval collections were made regularly in each area. Although the villages were only about 50km apart, and each had extensive, irrigated rice-fields in its vicinity, the species abundance and the seasonal fluctuations differed significantly. In Kampung Permatang Rawa Anopheles sinensis and An. peditaeniatus were dominant in prevalence, whereas in Sungai Udang Kecil An. indefinitus and An. lesteri paraliae were most common and An. peditaeniatus was relatively rare. The rice growing schedules in the two areas differed, but there was a moderate correlation between the abundance of several species and the rice-growing pattern. There was no correlation at either site with rainfall.

The ecology of anopheline mosquitos in northwest coastal Malaysia: host preferences and biting-cycles.

The host preferences of eight species of anophelines were studied in two coastal Malaysian villages, Kampung Permatang Rawa and Sungai Udang Kecil, by seven 12-hour catches in each village. Collections were made concurrently from a human-baited net trap, a cow-baited net trap and by human-bait landing catches. Anopheles campestris was attracted almost equally to man and cow, but An. lesteri paraliae, An. nigerrimus, An. peditaeniatus, An. sinensis, An. indefinitus, An. subpictus and An. vagus showed a strong preference for the cow bait. The human-bait landing catches were more productive than the human-baited net trap, which attracted very few mosquitos. Seven more all-night catches were made at each village employing only the cow-baited trap, and the combined data were used to plot the biting-cycles of each species at each site. Although the biting-cycles at the two localities were in general agreement, there were notable differences. At Sungai Udang Kecil, where the collection site was relatively sheltered, several species showed a steady decline in numbers from sunset to sunrise. At Kampung Permatang Rawa, on the other hand, where the site was more exposed and close to the sea, the same species showed a bimodal pattern of activity with an early evening peak followed by a decline then a period of increased activity before sunrise rising to a second, lesser peak at 0500-0600 hours.

Anopheline mosquitos of northwest coastal Malaysia.

Collections of adult anopheline mosquitos were made from a cow-baited trap in nine coastal villages located along nearly 160km of northwest peninsular Malaysia. Two collections, separated by 1.5 to 6 months, were made at each site. Nearly 6,000 anophelines of 19 species were collected. The dominant species were Anopheles peditaeniatus. An. sinensis, An. subpictus and An. lesteri paraliae. Small numbers of the malaria vectors An. maculatus (at one site) and An. campestris (at four sites) were collected, but no An. sundaicus were recorded.