Dietary Antioxidants Impact DDT Resistance in \u3cem\u3eDrosophila melanogaster\u3c/em\u3e

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

Comparison between the toxicity of nano and bulk formulations of imidacloprid against wheat aphid, bird cherry-oat aphid, Rhopalosiphum padi L

Recently, nano-insecticide formulations and new insecticide application methods are promised in pest control improvement. Wheat crop is infested by many sucking pests, such as cereal aphids in Upper Egypt. The toxicity of the recommended dose of imidacloprid (70% WS GAUCHO®) as positive control, the full and half recommended dose of nano and bulk imidacloprid 25% WP (BEST®) formulations were investigated under laboratory and field conditions against bird cherry-oat aphid, Rhopalosiphum padi L. The leaf-dip bioassay results indicated that the nano-imidacloprid formulations had higher potency ratio than the bulk formulations by 2.53 to 7.17 folds. Significant reduction percentage of aphids was recorded in seed treatments of field wheat crops, the aphid reductions reached 95% after 60 days. All insecticide treatments showed significant increasing in grain yield ranging from 10.55% to 22.02% higher than the control. The results concluded that the nano-imidacloprid formulation is promising formulation in cereal aphid control. Moreover, the seed-treatment is better than foliar treatment as a pest control tool for protecting the wheat seedling against sucking insect pests

Seasonal incidence and efficacy of nano-thiamethoxam on tomato leaf miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae)

Seasonal incidence of tomato leaf miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae), and evaluation of the new nano-formulation of thiamethoxam insecticide under climatic factors that supplying the vital knowledge for successful integrated pest management (IPM) programs. This study was conducted in two successive seasons 2017-18/ 2018-19 on variety (no. 765) of tomato that cultivated at the plant protection experimental Farm, Faculty of Agriculture, Assiut University, Assiut, Egypt. The numbers of mines on the tomato leaf were recorded from the first of November to the first of the February in the two seasons. The highest peak of mines was 28.34 mines/ plant in the 13th of December, 2018, while, it was 41.8/ plant in the January1st, 2019. Further, the climatic factor analysis during the two studied seasons demonstrated that the relative humidity was the most efficient factor (52.49 % out of 91.46 %), while the temperature was the least effective one (8.67% out of 91.46%). The nano thiamethoxam at the recommended dose (1x) of neonicotinoid insecticide significantly reduced the mines compared to traditional thiamethoxam. Furthermore, the half recommended dose of nano thiamethoxam in the two tested seasons was equal in the efficacy to the traditional thiamethoxam (1x). The reduction percentages were 86.87, 75.81 and 68.67 for nano-thiamethoxam (1x), thiamethoxam (1x), and nano- thiamethoxam (½ x), respectively, in 2017-18 for the first spray. In the same corresponding treatments, the values recorded were 78.94, 65.61and 62.75% in the second spray. Results of the second season (2018-19) were in the same line, where, the reduction percentages were 84.23, 76.43 and 62.43% at first spray, while the second spray were 72.95, 65.40 and 59.31% for nano-thiamethoxam (1x), thiamethoxam (1x) and nano- thiamethoxam (½ x), respectively. These results suggested that, the relative humidity was the main climatic factor effect on the mines population of Lirimyza trifolii. The nano-thiamethoxam was significantly reduced the pest population. Results of this study highly recommend using nano formulation in applying of IPM leaf miner programs

Dietary antioxidants impact DDT resistance in Drosophila melanogaster.

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