Background: Timely entomological and insecticide resistance monitoring is a key to generating relevant data for vector management. We investigated the insecticide susceptibility status of Anopheles gambiae s.l. in eight rural farming communities in Southern Gombe, Nigeria. Methods: Overall, 3–5 days-old adult female Anopheles mosquitoes reared from field-collected immature stages between September and November, 2014 were exposed to the diagnostic doses of pyrethroids, organophosphate and carbamate insecticides using the Center for Disease Control Bottle bioassay. The observatory knockdown time from exposure to each insecticide was recorded up to two hours. The dead mosquitoes were then identified morphologically and by molecular assays. Results: Mortality results showed resistance in An. gambiae s.l. populations to bendiocarb (2.3–100%), deltamethrin (39–70%), pirimiphos-methyl (65–95%), dichloro-diphenyl-trichloroethane (0–38.1%), permethrin (0–46.3%) and lambda-cyhalothrin (42.5–86.4%). The few cases of full susceptibility were observed from lamdacyhalothrin exposed population of An. gambiae s.l. in Banbam and Pantami respectively. An. gambiae 177 (45%) was significantly higher (P< 0.05) than An. arabiensis 64 (16.3%), An. coluzzii 34 (8.7%) and An. gambiae/An. coluzzii hybrid 78 (19.8%). Conclusion: A strong evidence of widespread resistance in the major malaria vector species in Southern Gombe to all common classes of insecticides is a justification for the State Malaria Elimination Programme to consciously consider incorporating insecticide resistance management strategies into control programs in order to sustain the future of current control interventions
Recently, there is increasing efforts to develop newer and effective larvicides to control mosquito vectors. This study was carried out to examine the efficacy of ZnO/SiO2 nanocomposite synthesized using Gum Arabic against Culex quinquefasciatus larvae. The elemental composition, morphology, functional groups and surface plasmon resonance of the ZnO@SiO2 nanocomposite was analyzed by Energy dispersive X-ray analysis (EDX), Scanning electron microscope (SEM), FTIR and UV-Visible spectroscopy respectively. In bioassay, larvae were exposed to three different concentrations of synthesized ZnO/SiO2 nanocomposite. The mortality rates at concentrations of 10, 20 and 25 were found to be (70%, 80%, 86%), (56%, 64%, 84%) and (44%, 48%, 76%) for 1st, 2nd, and 3rd instar respectively. This study revealed that the synthesized ZnO@SiO2 nanocomposite exhibit high larvicidal activity; 1st instar (LC50=4.024, LC90= 39.273 mg/l), 2nd instar (LC50=8.767, LC90=51.069 mg/l) and 3rd instar (LC50=13.761.LC90=81.809 mg/l).
Aims: Nanoparticles are gradually gaining wide scientific interest due to their various applications in catalysis, magnetism, medicine, optics, as antibacterial and nanolarvicidal agents. This research aimed at evaluating the larvicidal activity of green synthesized Ag/Ni BMNPs from the aqueous root extract of Borassus aethiopum as the stabilizing agent as well as their spectroscopic investigation using UV-Visible and FT-IR spectroscopy. Place and Duration of Study: The study was conducted in Gombe State University between August and December, 2019. Methodology: In this study, Ag/Ni hybrid bimetallic nanoparticles was synthesized using an eco-friendly method from the secondary metabolites of Borassus aethiopum acting as the reducing agent. Results: Optical measurements using UV-Vis showed the maximum absorption wavelength at 410nm while the FT-IR result for the root extract showed peaks at 3443.26cm-1, 2929.48 cm-1, 1651.28 cm-1, and 1080.12 cm-1 corresponding to OH stretch, sp3 C-H stretch, C=C stretch and C-O-C stretching respectively. These were replaced in the spectra of the BMNPs with the absence and appearance of some others indicating that they were involved in the capping process. The lethal concentration (LC50) was found to be 5.730, 13.585 and 15.735 mg/L for 1st, 2nd and 3rd/4th instars respectively. Also, the lethal concentration (LC90) was found to be 88.444, 195.689 and 236.889 mg/L for 1st, 2nd and 3rd/4th instars respectively. Conclusion: The larvicidal bioassay result showed a dose-dependent mortality rates against Culex quinquefasciatus larvae which suggest they can be developed to control the insect population.
Cowpea is one of the common edible annual herbaceous legume. Callosobruchus maculatus is one of the common post-harvest pest of cowpea.This work was aimed at determining the protectant effect of five vegetable oils; coconut oil, cotton seed oil, groundnut oil, palm oil and sesame oil for the protection of stored cowpea against cowpea weevil (Callosobruchus maculatus).The study was conducted in Gombe State University between October, 2018 and April, 2019. Black eye seeds were used for the experiment. A completely randomized design with five replicates per treatment was used.Black eyed seeds (susceptible variety) used for the experiment were subjected to different oil treatments namely: coconut, cotton, groundnut, palm and sesame oils applied at 0.4, 0.8 and 1.2 ml/100 g of cowpea equivalent to 4, 8 and 12 kg. Effect of the oils on weight lost and seed germination was also tested.Percentage adult mortality at 12 ml/Kg revealed that all the five oils killed 100% of the insects. Among the different edible oils evaluated, cotton seed oil was more effective killing 95% of the insect at 4 ml/kg and 100% at 8 ml/kg. The lowest mortality was recorded in the treatment with palm oil with 60 and 91.67% mortality at 4 and 8 ml/kg dose treatment respectively. Minimum percentage weight loss after 90 days of storage was observed in grains treated with cotton seed oil (1.95%) followed by sesame oil (2.00%) and groundnut oil (2.38%) at 12 ml/kg grains. Cotton seed oil, groundnut oil and sesame oil at doses between 8 and 12 ml/kg could be effective for protecting cowpea in storage against cowpea weevil for 90 days of storage.All the treatments indicated minimal effect on the germination of cowpea. The 8 ml/kg of cotton seed, groundnut and sesameoils investigated are promising bio friendly preservatives that could serve as an alternative formulations to synthetic chemical based insecticides for storage of cowpea.
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