Summary: | The excessive use of synthetic chemicals for <i>Megalurothrips usitatus</i> (Bagrall) management has resulted in the development of insecticide resistance as well as adverse effects to the natural ecosystem. This has driven the need to develop alternative pest control strategies. This study reports a synergistic interaction between the entomopathogenic fungus <i>Akanthomyces attenuatus</i> (Zare & Gams) and the botanical insecticide matrine against <i>M. usitatus</i>. The results revealed that the germination rate and colony growth of <i>A. attenuatus</i> were inhibited by higher matrine concentrations. Percentage mortalities of <i>M. usitatus</i> following application of <i>A. attenuatus</i> and matrine showed a dose mortality effect. After five days of treatment, all concentrations of matrine combined with different concentrations of <i>A. attenuatus</i>, except one combination (matrine 0.25 mg/mL + 1 × 10<sup>7</sup> conidia/mL), showed synergistic effect. The activities of acetylcholinesterase and antioxidant enzymes (superoxide dismutase, catalase and peroxidase) in <i>M. usitatus,</i> in response to individual or combined application of <i>A. attenuatus</i> and matrine at the end of the experimental period, were significantly lower than controls. The findings confirm the synergistic action of <i>A. attenuatus</i> and matrine against <i>M. usitatus</i> along with the biochemical phenomenon possibly regulating the synergistic effect.
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