The efficacy of long lasting insecticidal nets and piperonyl butoxides against culex mosquito species in Maiduguri, Borno State, Nigeria

This study is designed to evaluate the efficacy of LLIN and long-lasting insecticide nets plus PBO against culex mosquito species. The study was conducted at the Department of Biological Sciences research laboratory, in the University of Maiduguri, Borno State. Three brands of LLINs were used (olyset2.0, dawa2.0) and permanent plus PBO 3.0. Field sample collection of pre-adult mosquitoes culex larvae in natural habitat were identified from other mosquito’s species by their position when at rest. Identified mosquitoe larvae were brought to the laboratory for rearing. Nets samples for the bioassays were collected from the whole bed nets using the WHO procedures. WHO cone assays was conducted on 25 cm x 25 cm pieces cut from positions 2, 3, 4 and 5 of each sampled net. The efficacy of the nets was determined using standard cone bioassays method. Ten susceptible of non-blood-fed 2–5 day old culex mosquito species were exposed to each piece of netting (25cm x 25cm) for 3 minutes under standard WHO cones. After which they were held for 24 hours with access to sugar solution. Knock down was recorded for 60 minutes after exposure and mortality after 24 hours. Data obtained from the experiment was analyzed using Probit Analysis Statistical Method. The lethal dose that knock down fifty (LC50) value (with 95% Confident Limits) were calculated. The result of 1 hour knockdown effects of PBO-based LLIN (Permanent 3.0 ®) shows more potency followed by (19.82062325)> DAWA then (39.270127) > Olyset (82.54326125). The results from twenty-four hours mortality shows that, the percentage of mortality of adult Culex mosquitoes exposed to Permanent +POB 3.0®,, Dawa 2.0® and Olyset 3.0® nets were 91.53%, 65.83% and 40% respectively. The untreated which is the control bed net has only 1.75% of mortality rate. In conclusion, new generation LLINs treated with piperonyl butoxide demonstrated higher performance than LLINs without PBO. These results suggest that vector control approaches combining different types of strategies based on piperonyl butoxide, especially in LLINs, could help in solving the problems of insecticides resistance.