Background: There has been a rapid emergence in insecticide resistance among mosquito population to
commonly used public health insecticides. This situation presents a challenge to chemicals that are currently used
to control mosquitoes in sub-Saharan African. Furthermore, there is limited information on insecticide
susceptibility status of human-biting mosquitoes in some areas of Tanzania. This study aimed to determine
insecticide susceptibility status of human biting mosquitoes in a rural area of north-eastern Tanzania.
Methods: The study was conducted in two villages in Muheza district, Tanzania. Insecticide susceptibility
bioassays were performed according to the World Health Organization standard operating procedures on two
to five-day old human biting mosquitoes. The mosquitoes of each species were exposed to four classes of
insecticides commonly used for malaria vector control. Mosquito mortality rates (%) were determined after 24
hours post insecticide exposure.
Results: Mosquito species tested were Anopheles gambiae s.l., An. funestus, Aedes aegypti, and Culex
quinquefasciatus species. Real-time PCR have showed that the main sibling species of An. gambiae complex and
An. funestus group were An. gambiae s. s. (58.2%) and An. funestus s. s. (91.1%), respectively. All mosquitoes,
except Ae. aegypti formosus were susceptible to pirimiphos-methyl (0.25%). An. gambiae s. l. was found to be
resistant to permethrin (0.75%) but showed possibility of resistance to DDT (4%) and bendiocarb (0.1%). Our
findings have shown that, An. funestus was fully susceptible to all insecticide tested.
Conclusion: The present study has revealed different levels of insecticide susceptibility status to four classes of
commonly used insecticides in the most common mosquito vectors of human diseases in north-eastern
Tanzania. The findings of the present study call for integrated vector control interventions.