BackgroundDespite the increased report of insecticide resistance in malaria vectors, its impact on mosquito’s life-traits after exposure to insecticide-treated nets remains under investigated. Here, we assessed the effects of exposure to PermaNet 2.0 on several life traits of An. gambiae s.l. and An. funestus s.l. field mosquitoes in Cameroon.MethodologyFemale Anopheles mosquitoes were collected indoor using electric aspirators in southern Cameroon (Obout) in 2016. After assessing the resistance status of F1 from the field collected-mosquitoes, progeny of the first generation (An. funestus s.l.) and seventh generation (An. gambiae s.l.) were used to assess the long-term effect of exposure to PermaNet 2.0 on several life-traits of these vectors (longevity, blood feeding ability, fecundity and fertility) in comparison to untreated net. In addition, the L119F-GSTe2 mutation associated with DDT/pyrethroids resistance in An. funestus was genotyped to assess its association with increased life-span post-exposure.Principal findingsBoth An. funestus and An. gambiae were resistant to pyrethroids and DDT with a greater level in the latter. Pyrethroid-only nets PermaNet 2.0 (17.5% mortality) and Olyset (0% mortality) exhibited a significantly reduced efficacy against An. funestus in contrast to a greater efficacy for PBO-based Nets Olyset Plus (65% mortality), PermaNet 3.0 top (100% mortality). In both species, mosquitoes that survived exposure to PermaNet 2.0 exhibited a significantly reduced longevity than those non-exposed (6.95 days vs 12.46 for An. funestus P<0.001; 8.87 vs 11.25 days for An. gambiae; P<0.001). However, no significant difference was observed for blood feeding and fecundity in both species. In addition, molecular analysis of the L119F-GSTe2 mutation revealed that this mutation is associated with an increase in the chance of surviving after exposure to this net in An. funestus.ConclusionsThese results show that although the PermaNet 2.0 presents a reduced efficacy against resistant populations, it remains efficient after exposure by reducing the life expectancy of the vectors which could contribute in the reduction of malaria incidence.

Black pod rot, caused by Phytophthora megakarya, is the main cause of cocoa losses in Cameroon. A few studies have focused on describing black pod epidemics in cocoa yet numerous questions remain. Here, an epidemiological model describing the temporal evolution of cocoa black pod, taking into account the development stages of pods, is developed and studied. In particular, the relative importance of primary and secondary infection in disease dynamics is investigated. Our theoretical study shows the existence of a disease free equilibrium and at least one endemic equilibrium. We highlight two threshold parameters, related to direct and indirect infections that summarize all possible dynamics of the system. Then, based on the literature, we define a periodic pod recruitment function and provide several numerical simulations to study the impact of phytosanitary pod removal on disease dynamics. We show that intense and regular sanitary harvest could lead to complete disease eradication.Our results also highlight the importance of the environmental spores reservoir in disease dynamics, such that future field experiments and observations should focus on it. KEYWORDS analysis, black pod rot, cocoa, disease, epidemiological model, simulations 8816

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