Avalation of toxic effects of meliaceae aqueous extract and by-products on Tetranychus urticae (KOCH) (Acari, Tetranychidae)

Abstract

The two-spotted spider mite Tetranychus urticae is resistant to several pesticides. Thus, an integrated strategy of control measures is needed. One of these possible measures is the utilization of botanic substances with toxic activity against mites. Several by-products of species of Meliaceae including the neem tree (Azadirachta indica), the most studied insecticide-plant in the world, have toxic activity against T. urticae. The objective of this study was to assess the effects of aqueous extracts and by-products of three Meliaceae species on the mite survival, fecundity and damage on Canavalia ensiformis leaf disks, in laboratory. The aqueous extracts of leaves and branches of Trichilia pallida (5% w/v), leaves, branches and fruits of Melia azedarach (5% w/v), leaves (1 and 5% w/v), branches (5% w/v) and seeds (5% w/v) of neem and the neem oil (0.5; 1 and 2% v/v) were toxic for T. urticae. The mortality caused by Nimkol-L^® a commercial formula of neem leaves (0.5; 1 and 2% i.a. v/v) was not different than that of the control. The aqueous extracts of neem leaves and seeds and branches of T. pallida reduced female fecundity and mites damage to leaf disks. The results confirm the value of the extracts of Meliaceae for the control of T. urticae. The toxic effect and the abundance of original material are key elements for the practical use of aqueous extracts of leaves of neem and branches of T. pallida.