PermaNet® 3.0 is an insecticide synergist-combination long-lasting insecticidal net designed to have increased efficacy against malaria vectors with metabolic resistance, even when combined with kdr. The current study reports on the impact of this improved tool on entomological indices in an area with pyrethroid-resistant malaria vectors in Nigeria.

Mosquito samples were collected from rural and urban communities in three selected major towns in Southwestern Nigeria to determine the impact of urbanization on the diversity and abundance of Anopheles species associated with malaria transmission in human habitations. A total of ten Anopheles species were identified in the rural communities, while eight Anopheles species were identified in the urban communities. Out of the ten Anopheles species identified, only four species, Anopheles gambiae (Giles), Anopheles funestus (Giles), Anopheles moucheti (Evans), and Anopheles nili (Theobald), were established to be vectors of malaria occurring in greater than 50% of the rural communities. Only A. gambiae occurred in all the urban communities, while the other three major vectors occurred in not more than 20% of the urban communities. Margalef's and Shannon-Wiener indices showed that diversity and species richness were higher in the rural compared to the urban. Comprehensive information on malaria vector abundance and diversity in rapidly changing communities is an important tool in planning and implementing successful vector control programs.

Resistance monitoring is essential in ensuring the success of insecticide based vector control programmes. This study was carried out to assess the susceptibility status of urban populations of Anopheles gambiae to carbamate insecticide being considered for vector control in mosquito populations previously reported to be resistant to DDT and permethrin.

Background. PermaNet® 3.0 (PN 3.0) is a combination long-lasting insecticidal net (LLIN) designed to have increased efficacy against pyrethroid-resistant malaria vectors. Field testing of this new tool under normal use has been limited. Here we report on a small-scale village trial carried out at two localities where malaria vectors were resistant to pyrethroid insecticides. Methods. Nets were distributed to cover all sleeping spaces and evaluated for insecticidal activity. Households were visited to assess net usage and reported side effects. Entomological data were collected on a monthly basis for 12 months. Results. Bioassays repeated on domestically used PN 3.0 over 12 months showed persistent bioefficacy although bioefficacy of Olyset decreased over this period ( 65% mortality) compared to the Olyset nets (< 45%). Conclusion. This study provides persuasive evidence on the increased efficacy of PN 3.0 against malaria vectors with kdr only and kdr plus metabolic-based pyrethroid resistance mechanisms under realistic LLIN use scenarios.

Objective: To investigate the susceptibility status of the major malaria mosquito in selected rural, semi-urban and urban areas of Nigeria to DDT and Permethrin based insecticides used in vector control. Methods: Two to three day old unfed adult female Anopheles mosquitoes raised from larvae collected across three ecological zones in Nigeria were exposed to 4 % DDT impregnated papers. To find out the possibility of DDT – pyrethroid cross-resistance, susceptibility tests were carried out using 0.75% Permethrin. Mosquitoes tested were identified to species level using PCR assays. Knockdown resistance assays were also carried out on all specimens. Results: At all three locations, the principal species was A. gambiae s.s constituting more than 80% of mosquitoes analysed. The 24 hour post-exposure mortality for Permethrin ranged from 51.7 to 100% with resistance observed in five out of the 19 communities tested. DDT resistance was observed at all of the 12 communities tested with mortality ranging from 9.8% to 80%. Incidence of Permethrin resistance was associated with urban communities compared to DDT resistance which was widespread in all the communities. Resistance was recorded in the A. gambiae s.s, however DDT resistance was observed in A. arabiensis from five study communities. Conclusions: Indications of differential susceptibility to Permethrin and high frequency of DDT resistance in A. gambiae was observed which highlights the need for baseline information prior to the use of DDT for indoor residual spray in Nigeria. It also highlights the need for an effective insecticide resistance management programme.