Appraisal of growth inhibitory, biochemical and genotoxic effects of Allyl Isothiocyanate on different developmental stages of Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae)

Abstract

Allyl isothiocyanate (AITC), a glucosinolates’ hydrolytic product, was studied for its anti-insect potential against an economically important, destructive tephritid pest, Zeugodacus cucurbitae (Coquillett). The first, second and third instar maggots of the pest were fed on artificial diets amended with varied concentrations of AITC viz. 5 ppm, 25 ppm, 50 ppm, 100 ppm, 150 ppm and 200 ppm with DMSO (0.5%) as control. Results revealed high larval mortality, alteration of larval period, prolongation of pupal and total developmental periods in all instars of the maggots treated with AITC as compared to controls. Percent pupation and percent adult emergence decreased in all larval instars. Growth indices viz. Larval Growth Index (LGI) and Total Growth Index (TGI) were negatively affected. Anti-nutritional/post ingestive toxicity of AITC was also revealed by the decrease in Food Assimilation (FA) and Mean Relative Growth rate (MRGR) values with respect to control. Profiles of PO (Phenol oxidase) and other detoxifying enzymes including SOD (Superoxide dismutases), CAT (Catalases), GST (Glutathione-S-transferases), EST (Esterases), AKP (Alkaline phosphatases) and ACP (Acid phosphatases) were also significantly influenced. The genotoxic effect of AITC was also evaluated by conducting comet assays at LC30 and LC50. Significant DNA damage in hemocytes was reflected by increase in Tail length (μm), Percent Tail DNA, Tail Moment (TM) and Olive Tail Moment (OTM) as compared to controls. The results indicated high potential of AITC as biopesticide for pest management.