Development of resistance by different malaria vector populations to insecticides has become a big threat to malaria vector elimination. This study evaluated the susceptibility of Anopheles mosquito populations in Akwa Ibom State, Nigeria to permethrin (0.75%), deltamethrin (0.5%), lambdacyhalothrin (0.5%), alphacypermethrin (0.75%), Dichlorodiphenyltrichloethane (DDT), propoxur, bendiocarb and pirimiphosmethylin in World Health Organization (WHO) test tubes following standard protocols. The mosquitoes were obtained as aquatic forms and reared under laboratory conditions to adults. The adults were subjected to WHO susceptibility bioassays following standard procedures. Malaria vectors across the study sites were resistant to permethrin, deltamethrin, lambdacyhalothrin and alphacypermethrin insecticides. Full susceptibility to propoxur and bendiocarb was recorded across the sites. Full susceptibility to pirimiphosmethyl was recorded in populations from three sites. Nevertheless, population of the malaria vectors collected from Oron was resistant to pirimiphosmethyl. KDT50 and KDT95 estimated for each insecticide using a log-time probit model revealed that knockdown was more rapid for deltamethrin, lambdacyhalothrin, alphacypermethrin, propoxur, bendiocarb and pirimiphosmethyl than for DDT and permethrin  across the study sites. Morphological identification of all the mosquito samples used revealed that they were female Anopheles gambiae s.l. Sustained susceptibility of malaria vectors to pyrethriod is necessary for successful malaria control with insecticide treated nets and Indoor Residual Spraying (IRS). Emergence of focal points with insecticide resistance gives serious concern especially with the scale-up in distribution of pyrethriod treated nets to these areas. This may increase selection pressures due to overexposure. Further study to identify the exact resistance mechanism(s) of malaria vectors from these sites is recommended.

Background: This study investigated the dynamics in pyrethriod resistance and the presence/frequencies of L1014F knockdown resistance mutant allelles in Culex quinquefasciatus vector populations from Uruan Local Government Area of Akwa Ibom State, Nigeria. Methods: Centre for Disease Control (CDC) bioassay was used to evaluate resistance to permethrin, deltamethrin and alphacypermethrin insecticides following standard protocols. Allele-Specific Polymerase Chain Reaction (AS-PCR) was used in detecting target site insensitivity in the vector populations. Results: Results obtained revealed that vectors from all the study sites were resistant to permethrin insecticide (mortality rate: 18% - 23%). Suspected resistance (mortality rate: 90% - 93%) to deltamethrin and low resistance (mortality rate: 82% - 85%) to alphacypermethrin insecticides were detected. knockdown was more rapid with deltamethrin and alphacypermethrin than with permethrin across the study sites considering their KDT50 and KDT95. The frequency of the resistant phenotypes ranged between 35.14 % to 55.3 % across the study sites with a net of 45.1 % resistant phenotype recorded in this study. The 1014F allelic frequency calculated from Hardy-Weinberg principle for vector populations across the study sites ranged from 0.5 (50 %) to 0.7763 (77.63 %). All populations witnessed significant (p < 0.05) deviations from Hardy-Weinberg equilibrium in the distribution of these alleles. Conclusion: The findings of this study show that there is a tendency to record an entire population of resistant vectors in this study area over time due to natural selection.

Rapid emergence in insecticide resistance among malaria vector populations to commonly used public health insecticides poses a challenge to current malaria vector control strategies and interventions in sub- Saharan Africa. This study was conducted to determine the susceptibility status of female An.gambiae s.l to Propoxur (0.01%) and bendiocarb (0.1%) (carbamate) and pirimiphosmethyl (0.25%) (organophosphate) insecticides in Uyo Metropolis, Akwa Ibom State, Nigeria. The larvae of An. gambiae s.l were collected from natural water bodies and other potential breeding sites from different sites in Uyo Metropolis. Insecticide susceptibility bioassays were performed according to the World Health Organization standard operating procedures on 2-3 days old, sugar-fed but none blood fed female Anopheles mosquitoes. Post exposure mortality after 24 hours and knockdown values for KDT50 and KDT95 were calculated. Knock-down at 1 hour insecticide exposure ranged from 94 % to 100 %. Mortality after 24 hours post exposure was 100% for all insecticides except Propoxur which was 98 %. There was high variability in KDT50 and KDT95 values (in minutes) with propoxur (4.337 and 15.620), Bendiocarb (9.523 and 20.996) and pirimiphosmethyl (39.908 and 61.722) respectively. Adopting the WHO criteria, the mosquitoes were not resistant to any of the insecticides tested. The results therefore showed that vector control campaigns employing the use of any of these insecticides in the study area would not be compromised. However, there is need for continued monitoring to ensure early detection of resistance. Keywords: Anopheles gambiae; insecticide susceptibility; Uyo; Akwa Ibom State; Nigeria.

Effects of aqueous seed extracts of Sphenostylis stenocarpa on the reproductive indices of male rats were investigated. A total of 104 adult rats were used for the experiment, and were divided into 4 groups (group A – D) and replicated in triplicate. Group A served as the normal control, while groups B, C and D received three graded doses (800mg/kg, 1200mg/kg and 1600mg/kg) of the extracts, respectively, by oral intubation. The gonad characteristics, sperm parameters and hormonal analyses of the male rats were determined using standard procedures. These were ascertained prior to the commencement of treatment, and on weekly basis. Data were analyzed statistically using SPSS and R software at 95% confidence interval. An overall dose and time dependent showed significant differences in the mean weekly gonad characteristics of the male rats in the treatment groups when compared with the control. There was a significant reduction (p < 0.05) in the body weights of the male rats, but a significant increase (P < 0.05) in the testes weights, gonad somatic index, sperm count and sperm motility in the rats. The gonadal hormone testosterone, responded to the plant extracts, while follicle-stimulating and luteinizing hormones were largely undetected. There were significant increases in the testosterone levels of all the treated rats. Conclusively, aqueous seed extracts of Sphenostylis stenocarpa seems to possess ability to enhance reproductive health in male rats.

Vector control has proved to be a successful strategy for reducing incidences of mosquito borne-diseases. This study evaluated the repellent and larvicidal efficacy of A. muricata against An. gambiae. Oil was extracted from the seeds using the solvent extraction method. For the repellency test the oil (0.38 ml) was topically applied on the right arms of 10 human volunteers to evaluate its effect against adult female An. gambiae. The left arms of the volunteers were treated with 1 ml of 20% acetone (control). Ethanol leaf extract was used for phytochemical screening and preparation of n-hexane, ethyl acetate and aqueous fractions. These were used for larvicidal assays. From the stock solution (5 g each in 100 ml of water), 0.15, 0.30, 0.45, 0.60 and 0.75%w/v concentrations were obtained. In the control experiment, larvae were exposed to 100 ml tap water and nutrients only. Test concentrations and controls had 5 replicates each. Each larvicidal experiment consisted of 20 third instar larvae of Anopheles gambiae. Repellency and larvicidal experiments were carried out at the Malaria Vector Research Laboratory and Insectary, University of Uyo and National Arbovirus and Vectors Research Centre, Enugu, Nigeria, respectively. Repellency of the oil reduced with increased exposure time, in each case. The number of mosquito landings on the control arms was higher than landings on the treated arms. Mosquitoes that landed on the treated arms could not bite, suggesting that A. muricata oil could possess feeding deterrent property. Phytochemical screening revealed the presence of some plant metabolites. The ethanol leaf extract and aqueous fractions had no larvicidal activity at the highest concentration. However, n-hexane and ethyl acetate fractions were larvicidal. N-hexane fraction was the most potent with 48hLC50 value of 0.41%w/v, while ethyl acetate fraction had 48hLC50 value of 0.79% w/v. Results suggest that A. muricata has promising repellent and larvicidal potentials against An. gambiae.