The effects of three fungicides on the emergence rate of Tetrastichus brontispae Ferrière and Asecodes hispinarum Bouček.
Coconut leaf beetle Brontispa longissima Gestro is an important invasive pest on palm plants. The release of parasitoid wasps can effectively control the pest. The effects of fungicides, including methylthiazolam, chlorothalonil and imidamine, on the emergence rates of parasitic wasps, Tetrastichus brontispae Ferriere and Asecodes hispinarum Bouček, were measured using the dipping method. The results showed that chlorothalonil slightly reduced the emergence rate of the wasps when treated to the early pupae of T. brontispae and A. hispinarum. In contrast, imidamine had no effect on emergence of the two parasitic wasp species. Notably, significant decline in the emergence rate was recorded with methylthiazolam treatment to the middle stage pupae of T. brontispae. In addition, methylthiocyanidin had significant lethal effects on the early and middle stage pupae of T. brontispae and A. hispinarum. Therefore, it is recommended that the methylthiophenol and chlorothalonil should be used at regular intervals when the parasitic wasps are released in the field, whereas the methylamine is safe for the two parasitic wasps and can be used in combination with the wasps. The present results are significant for the control of coconut leaf beetle using parasitoids and control of diseases using fungicides on palm plants.