Browsing by Author "Ojo James Adebayo"

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    Dietary antioxidants impact DDT resistance in Drosophila melanogaster
    (PloS ONE, 2020) Ojo James Adebayo
    Insects experience a diversity of subtoxic and/or toxic xenobiotics through exposure to pesticides and, in the case of herbivorous insects, through plant defensive compounds in their diets. Many insects are also concurrently exposed to antioxidants in their diets. The impact of dietary antioxidants on the toxicity of xenobiotics in insects is not well understood, in part due to the challenge of developing appropriate systems in which doses and exposure times (of both the antioxidants and the xenobiotics) can be controlled and outcomes can be easily measured. However, in Drosophila melanogaster, a well-established insect model system, both dietary factors and pesticide exposure can be easily controlled. Additionally, the mode of action and xenobiotic metabolism of dichlorodiphenyltrichloroethane (DDT), a highly persistent neurotoxic organochlorine insecticide that is detected widely in the environment, have been well studied in DDT-susceptible and -resistant strains. Using a glass-vial bioassay system with blue diet as the food source, seven compounds with known antioxidant effects (ascorbic acid, β-carotene, glutathione, α-lipoic acid, melatonin, minocycline, and serotonin) were orally tested for their impact on DDT toxicity across three strains of D. melanogaster: one highly susceptible to DDT (Canton-S), one mildly susceptible (91-C), and one highly resistant (91-R). Three of the antioxidants (serotonin, ascorbic acid, and β-carotene) significantly impacted the toxicity of DDT in one or more strains. Fly strain and gender, antioxidant type, and antioxidant dose all affected the relative toxicity of DDT. Our work demonstrates that dietary antioxidants can potentially alter the toxicity of a xenobiotic in an insect population.
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    Efficacy of extracts of Tithonia diversifolia (Hemsl.) A. Gray as protectant against maize weevil (Sitophilus zeamais [Motsch.]) and cowpea weevil, Callosobruchus maculatus F. on stored grains
    (Nigerian Journal of Entomology, 2021) Ajao Adeyemi Mufutau; Ojo James Adebayo; Adeoye Abubakar Abdullahi; Ibraheem Mufliah Ololade; Babarinde Tosin Michael
    This study sought to determine the efficacy of Tithonia diversifolia (Mexican Sunflower) as pesticides against maize weevil Sitophilus zeamais and cowpea weevil Callosobruchus maculatus. The research was conducted to ascertain the toxicity potency of T. diversifolia on insects’ mortality, repellency, adult emergence, seed damage and weight loss for the treatment of stored products and determine their minimum effective dosage for application. T. diversifolia collected from the premises of Kwara State University, Malete were air-dried, ground and dissolved in 50 g to 600 ml of four different extracts (Ethanol, Methanol, n-Hexane and aqueous). S. zeamais and C. maculatus were reared in the laboratory at 60-75% relative humidity and 25-35 oC. After the whole extraction, ten unsexed S. zeamais and C. maculatus were infested in 10 g of grains and replicated three times in each application of extracts with different treatment levels. The mortality and other parameters were counted posttreatment. The mean results of the parameters studied were significantly different at (P<0.05). N-hexane extracts was most toxic to S. zeamais while Methanol extract was most toxic to C. maculatus. Thus, all the extracts were potent, and they reduced insects’ oviposition, increased mortality, improved repellence, inhibited reproduction, grain damage and weight loss in storage compared to the untreated control. Subjected to the qualitative phytochemical screening, active compounds discovered to be present in T. diversifolia include tannin, flavonoid, saponin, phenol, terpenoid, glucosides and alkaloid. The study proffers the use of T. diversifolia, a readily available, safe and ecofriendly biopesticide for farmers as short and long-term storage of the stored produce.