Toxicity and biochemical effects of emamectin benzoate combined with some common insecticides on Tuta absoluta (Lepidoptera: Gelechiidae)

Taleh, Mohsen (2021) Toxicity and biochemical effects of emamectin benzoate combined with some common insecticides on Tuta absoluta (Lepidoptera: Gelechiidae). Doctoral thesis, University of Mohaghegh Ardabili.

Text 95@.pdf Download (2MB)

Abstract

Research Aim: In this study, toxicity and biochemical effects of emamectin benzoate combined with azadirachtin, indoxacarb, imidacloprid, acetamiprid, thiacloprid, eforia, lambda-cyhalothrin, and hexaflumuron on 2nd instar larvae and toxicity and biochemical effects of emamectin benzoate combined with acetamiprid, eforia, and hexaflumuron on 4th instar larvae of Tuta absoluta (Lepidoptera: Gelechiidae) and lethal and sublethal effects of these insecticides were conducted. Research method: The experiments were carried out in the growth chamber at 25 ± 2 °C, 65 ± 5% RH and photoperiod of 16:8 (L:D) h. The tomato leaves were dipped into five different concentrations of each insecticide and twenty 2nd and 4th instars larvae of Tuta absoluta was transferred on treated leaves. The mortality of larvae was recorded at time of 72 h after treatments. For life-table experiments, 2nd instar larvae that had been fed with insecticide-treated leaves for 24 h were transferred to non-treated tomato leaves and duration of different stages was recorded daily. The 2nd and 4th instars of T. absoluta was exposed to mixtures of emamectin benzoate with azadirachtin, indoxacarb, imidacloprid, acetamiprid, thiacloprid, eforia, lambda-cyhalothrin and hexaflumuron and mixtures of emamectin benzoate with acetamiprid, eforia, and hexaflumuron, respectively, at LC10:LC10, LC15:LC15, LC25:LC25 and LC50:LC50 using the leaf-dip method. Also the mixtures of tested insecticides with emamectin benzoate were estimated on esterase, GST, α-amylase activity and protein content of 2nd instar larvae and the esterase and protein content of 4th instar larvae. Zymogram of α-esterase activity and glutathione S-transferase of 2nd instar larvae was tested. Finding: Based on the results, Female fecundity and adult longevity reduced in all insecticides except hexaflumuron and lambda-cyhalothrin. In all insecticides, oviposition period decreased, which was significantly different from control. The results showed that the intrinsic rate of increase (rm) was the least in emamectin benzoate and indoxacarb. In all insecticides except hexaflumuron, lambda-cyhalothrin and thiacloprid the net reproductive rate (R0) was significantly lower than control. The emamectin benzoate mixed with azadirachtin and indoxacarb at LC15:LC15 ratio, with azadirachtin, indoxacarb and imidacloprid at LC25:LC25 ratio and also with azadirachtin, indoxacarb, imidacloprid and acetamiprid at LC50:LC50 ratio showed synergistic effects. All mixtures of emamectin benzoate with lambda-cyhalothrin and hexaflumuron showed an antagonism interaction on 2nd instar larvae. The emamectin benzoate mixed with acetamiprid at LC50:LC50 ratio, showed synergistic effects and it mixed with hexaflumuron showed an antagonism interaction on 4th instar larvae. The highest activity of alpha-esterase of 2nd instar larvae was in the combination of emamectin benzoate with imidacloprid, acetamiprid, eforia, and thiacloprid. The combination of emamectin benzoate with azadirachtin reduced the enzyme activity. The highest and least activity of glutathione S-transferase enzyme was observed in the combination of emamectin benzoate with acetamiprid and indoxacarb, respectively. The highest and least activity of alpha-amylase enzyme was observed in the combination of emamectin benzoate with eforia and azadirachtin, respectively. The highest activity of alpha-esterase of 4th instar larvae was in the combination of emamectin benzoate with acetamiprid and eforia. Conclusion: Based on the results, it can be concluded that the combination of emamectin benzoate with common insecticides can reduce T. absoluta population. This study showed that mixture of tested insecticides can alter the biochemical properties of T. absoluta larvae.

Actions (login required)

View Item