A vegetable oil-based biopesticide with ovicidal activity against the two-spotted spider mite,Tetranychus urticaeKoch

A recently developed biopesticide made of safflower and cottonseed oils has excellent ovicidal activity against the hard-to-control spider miteTetranychus urticaeKoch (Acari: Tetranychidae). It has attracted attention as a sustainable treatment for controllingT. urticaebecause it has low potential for promoting resistance and little effect on the predatory miteNeoseiulus californicus(McGregor) (Acari: Phytoseiidae), which is an important natural enemy of spider mites. Here, we investigated the mechanism of its ovicidal activity againstT. urticae. The oil droplets in the oil-in-water emulsion of the biopesticide strongly adhered toT. urticaeeggs, seeped through the chorion being cut during hatching, and inhibited the embryonic rotational movement necessary for cutting and hatching. No adverse effect was observed onN. californicuseggs even in undiluted biopesticide. We conclude that this biopesticide andN. californicuscan be used simultaneously in the integrated management ofT. urticaein oily biopesticide-tolerant plant species.