BackgroundIn recognition of the threat of insecticide resistance in vectors of malaria, the WHO Global Malaria Programme recommends the development of an appropriate and comprehensive response to insecticide resistance. In principle, good resistance management practice requires the application of multiple insecticides of different modes of action, for example, in rotations and mixtures. Insecticides recommended by the World Health Organization for indoor residual spraying and long-lasting insecticide nets are limited. It is, therefore, judicious to prevent the rapid spread of insecticide resistance by evaluating new insecticides formulations with different modes of action and long residual effect.MethodsFludora® Fusion, a new neonicotinoid IRS formulation (a mixture of 500 g/kg clothianidin and 62.5 g/kg deltamethrin applied 200 mg ai/sqm + 25 mg ai/sqm, respectively) was tested. Small scale field evaluation of this product was conducted in the district of Dangbo in Benin, to compare its efficacy and residual effect on cement and mud walls against those of clothianidin 200 mg ai/sqm (WG 70) alone, and of deltamethrin 25 mg ai/sqm (WG 250) alone. WHO wall cone bioassays were conducted monthly with laboratory susceptible Anopheles “Kisumu” and wild Anopheles gambiae sensu stricto (s.s.) population from Dangbo. The induced mortality by each treatment per wall substrate for 24 h, 48 h, and 72 h post exposure were recorded every month and analysed.ResultsFludora® Fusion and clothianidin WG 70 showed mortality rates over 80% WHO bio-efficacy threshold on cement walls either with susceptible or resistant An. gambiae s.s. over a period of 10 and 9 months, respectively. Treatment with Fludora® Fusion and clothianidin WG 70 on the mud walls showed residual effect for 6 months and 5 months respectively against both susceptible and resistant mosquitoes. During the whole evaluation period, deltamethrin WG 250 showed mortality rates below 80% against resistant Anopheles population. Furthermore, the knock down rates observed with the Fludora® Fusion combination were significantly higher (p < 5%) than those induced by Clothiandin WG 70.ConclusionBoth the Fludora® Fusion combination and clothianidin alone showed very good and lasting efficacy for IRS against resistant Anopheles with some residual benefit provided by the combination. The residual efficacy of the Fludora® Fusion combination evaluated at 10 months shows this product is a good candidate for IRS interventions.Electronic supplementary materialThe online version of this article (10.1186/s12936-018-2633-6) contains supplementary material, which is available to authorized users.

No abstract

Background: Progress made in the control of malaria vectors globally is largely due to the use of insecticides. However, success in the fight against malaria has slowed down or even stalled due to a host of factors including insecticide resistance. The greatest burden of the disease is felt in Africa, particularly Nigeria. Unfortunately, adequate information on insecticide resistance is lacking in many parts of the country, particularly the SouthEast Zone. Hence, this study aims to bridge the information gap in the Zone. Methods: The study was conducted from April to December 2016. Anopheles gambiae (s.l.) larvae and pupae were collected from one community each, in the five states of the SouthEast Zone and reared to the adult stage. The adults were subjected to bioassays for insecticide resistance in accordance with the World Health Organization test procedures, across the four classes of insecticides used in public health. The mosquitoes were also subjected to molecular identification to the species level, and genotyped for West African knockdown resistance mutation (L1014F) and insensitive acetylcholinesterase-1 resistance mutation (G119S). Results: The mosquitoes were susceptible (100%) to bendiocarb but resistant to pirimiphos-methyl (39.6%), deltamethrin (57%) and dichlorodiphenyltrichloroethane (DDT) (13%). Molecular analysis revealed that only An. gambiae (sensu stricto) was found in all the states except for Ebonyi, where only Anopheles coluzzii was present. High frequencies (0.6-0.9) of the L1014F mutation were found across the zone. The L1014F mutation was significantly higher in An. gambiae (s.s.) than in An. coluzzii (P < 0.0001). A relatively low frequency (0.2) of the G119S mutation was found in An. coluzzii, and only in Ebonyi State. Conclusion: The results show that mosquitoes collected from the SouthEast Zone of Nigeria were resistant to all insecticides used, except for bendiocarb. The presence of L1014F and G119S resistance mutations reported in this study calls for urgent attention to stop the growing threat of insecticide resistance in the country.

No abstract

Background: In 2011, Benin's National Malaria Control Programme (NMCP) organized a nationwide mass distribution campaign of LLINs throughout the country. Following this intervention, it was important to assess whether the level of susceptibility of malaria vectors to insecticides had remained the same as compared to the pre-intervention period. The current study investigated this. Methods: Larval collections were conducted in Ifangni, Sakété, Pobè and Kétou districts located in Plateau department, Southeastern Benin before (2009) and after (2012-2013) LLIN distribution. Anopheles gambiae sensu lato (s.l.) larvae from the 4 study districts were reared to adulthood and WHO susceptibility tests were conducted. The insecticides tested were deltamethrin (0.05%), permethrin (0.75%), bendiocarb (0.1%) and DDT (4%). Molecular species identification as well as, the characterization of the kdr L1014F mutation were also performed in the An. gambiae s.l. complex using PCR method. Results: Overall, a significant decrease in mortality rates of An. gambiae s.l. to deltamethrin (0.05%), permethrin (0.75%) and DDT (4%) was observed post-LLIN distribution, respectively: (100% vs 80.9%, p < 0.0001), (77.5% vs 70%, p = 0.01) and, (47.8% vs 4.4%, p < 0.0001). By contrast, susceptibility of vectors to bendiocarb (0.1%) remained the same (100% mortality in the WHO susceptibility tube tests) pre-and post-intervention. An increase in the kdr L1014F frequency was observed post-LLIN distribution [F(kdr) = 0.91)] compared to the pre-intervention period [F(kdr) = 0.56], p < 0.0001. Anopheles coluzzii and An. gambiae were the two molecular species identified in the study area. Conclusion: The decrease susceptibility to pyrethroids and DDT as well as, the increase in the frequency of the kdr L1014F mutation after the intervention stressed at the time, the need for the development and implementation of effective insecticide resistance management strategies. At present, an update of the vectors resistance status in the area is also necessary for decision-making.