Laboratory bioassay of six pesticides, an entomopathogenic fungus, and a botanical pesticide on two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae)

Abstract

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a serious pest that infests different agricultural crops in Bangladesh. The application of different types of pesticides (botanical and chemical) with various modes of action and bio-pesticides was used for the first time to develop sustainable pest control strategies against spider mites. In this study, the effects of six chemical insecticides viz. abamectin, bifenthrin, bifenazate, etoxazole, hexythiazox, and spinosad, and entomopathogenic fungus Beauveria bassiana and botanical neem oil were evaluated against adult and egg stages of T. urticae under laboratory conditions. Treated mites were kept in controlled conditions at 25 ± 1 ℃, 60–70% RH and a photoperiod of 16:8 h (L: D). The LC50 values of all chemicals [for adults, abamectin (0.51 ml/L), bifenthrin (3.26 ml/L), bifenazate (3.82 ml/L), hexythiazox (3.27 ml/L) and spinosad (3.83 ml/L); for eggs, abamectin (0.56 ml/L), bifenthrin (3.48 ml/L), bifenazate (26.81 ml/L), hexythiazox (4.18 ml/L) and spinosad (18.28 ml/L)] suggest that they were effective against eggs and adult females of the T. urticae. Etoxazole (LC50 = 3.99 ml/L) is recommended against egg stage. The neem oil was found to be moderately effective (for adult, LC50 = 1.26%; for egg, LC50 = 1.77%) against eggs and adult females of T. urticae. The B. bassiana was also found to be effective against eggs and adult females of T. urticae. Finally, it could be concluded that all chemicals used in this study are effective for the management of two spotted spider mite but the entomopathogenic fungus B. bassiana and botanical neem oil were promising alternatives for successful management of T. urticae in IPM programs.