Comparative efficacy of neem, Azadirachta indica, extract for- mulations and the synthetic acaricide, Amitraz (Mitac), against the two spotted spider mites, Tetranychus urticae (Acari: Tetra- nychidae), on tomatoes, Lycopersicum esculentum.

Abstract

We evaluated the efficacy of commercial formulations of neem (Azadirachta indica) extracts against the two-spotted spider mites, Tetranychus urticae (Acari: Tetranychidae), on tomatoes and compared them with the synthetic acaricide, amitraz. The neem formulations showed variable levels of protection of tomatoes against infestation by T. urticae. Neemroc EC was the most effective and the level of protection was comparable to that of amitraz. The neem formulations, except Neemros WP, showed strong ovipositional deterrence of T. urticae and suppressed the emergence of nymphs on treated leaf discs. Repeated application of the neem formulations and amitraz led to significant reduction of the population size of mites on tomatoes, compared to the control. However, Neemroc EC was the most effective in reducing leaf damage, whereas Saroneem, Neemroc Combi and Neemros WP-treated tomatoes had high leaf damage ratings associated with lower fruit weight. The high performance of Neemroc EC is attributed to the oil content in this formulation, particularly when compared with Neemroc WP whose concentration of azadirachtin was very high and yet the effectiveness against mites was very low. Neemroc EC was as effective as the standard and therefore an alternative to amitraz for protecting tomatoes against infestation by T. urticae.