Abstract
Background Insecticide resistance among the vector population is the main threat to existing control tools available. The current vector control management options rely on applications of recommended public health insecticides, mainly pyrethroids through long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Regular monitoring of insecticide resistance does not provide information on important factors that affect parasite transmission. Such factors include vector longevity, vector competence, feeding success, and fecundity. This study investigated the impacts of insecticide resistance on longevity, feeding behaviour, and egg batch size of Anopheles gambiae s.l. Method The larval sampling was conducted in rice fields using a standard dipper (350 ml) and reared to adults in field insectary. A WHO susceptibility test was conducted using standard treated permethrin (0.75%) and deltamethrin (0.05%) papers. The susceptible Kisumu strain was used for reference. Feeding succession and egg batch size were monitored for all survivors and control. Results The results revealed that mortality rates declined by 52.5 and 59.5% for permethrin and deltamethrin, respectively. The mortality rate for the Kisumu susceptible strain was 100%. The survival rates of wild An. gambiae s.l. was between 24 and 27 days. However, the Kisumu susceptible strain blood meal feeding was significantly higher than resistant colony (t = 2.789, df = 21, P=0.011). Additionally, the susceptible An. gambiae s.s. laid more eggs than the resistant An.gambiae s.l. colony (Χ2 = 1366, df = 1, P ≤ 0.05). Conclusion It can, therefore, be concluded that the wild An. gambiae s.l. had increased longevity, blood feeding, and small egg batch size compared to Kisumu susceptible colonies.
Highlights
Malaria is still one of the most prevalent human vectorborne disease that threatens the world’s population living in areas where there is a risk of infectious bites with 228 million morbidity and 405 000 mortality cases reported in 2018 [1]
Vector control measures remain a main intervention strategy for the global malaria eradication programme [16,17,18,19]. e core vector control measures that are Journal of Tropical Medicine widely used include long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) [1]. e strategy aimed to reduce the risk of malaria infection by targeting indoor biting mosquitoes [1, 20]
It was important to explore these factors from the natural environment. e present study investigated the impact of insecticide preexposure on longevity, feeding behaviour, and egg batch size of An. gambiae s.l. from northern Tanzania
Summary
Malaria is still one of the most prevalent human vectorborne disease that threatens the world’s population living in areas where there is a risk of infectious bites with 228 million morbidity and 405 000 mortality cases reported in 2018 [1]. Malaria vectors have the ability to produce high amount of enzyme naturally, which enable them to metabolize the insecticide and become functionless [30] Other insects modify their cuticle or the digestive track by slowing down or prevent the absorption of the insecticides penetrations [31], while behavioural resistance occurs after a long time exposure of insects to an insecticide [24, 27, 32, 33]. Most other important factors that determine the ability of the vector to transmit the parasites are underexplored during the day-to-day insecticide resistance monitoring activities Such factors include vector longevity, biting behavior, and vector competence of the insecticide-resistant malaria vectors, and their impact on malaria epidemiology is underexplored [41, 42]. It was important to explore these factors from the natural environment. e present study investigated the impact of insecticide preexposure on longevity, feeding behaviour, and egg batch size of An. gambiae s.l. from northern Tanzania
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