Study of the Efficacy of Oberon 240SC (Spiromesifen) and D-C-TronPlus on the Red Spider Mite (Tetranychus spp) on Tomatoes(Lycopersicon esculentum) (Mill) and their Effect on Predatory Mite (Phytoseiulus persimilisi (Athias Henriot)
The overall objective of this study was to establish a cost effective and environmentally friendly control strategy of the red spider mites, Tetranychus spp, in tomatoes using Oberon 240SC and D-C- Tron Plus mineral oil. The efficacy of the two products, their mixture and a rotation was tested against the red spider mites (T. evansi, Baker and Pritchard) in the laboratory, green house and field conditions. The effect of the treatments on the beneficial capacity of the predatory mite (Phytoseiulus persimilis Athias Henriot) was also assessed in the laboratory and the mite species associated with the damage and loss on tomatoes in major tomato growing areas in Kenya were identified. The ovicidal effect of Oberon 240 SC on the red spider mite (T. evansi) was 100%. The product however did not have acute toxicity on the motile stages of the mites, but completely deterred the adult females from laying eggs. D-C- Tron Plus caused mortality to the motile stages and reduced the percentage of eggs that hatched. The results for the mixture and the rotation were similar to those of Oberon 240SC alone. All the treatments were incompatible with the P. persimilis. Both in the green house and the field Oberon 240 SC, its rotation and mixture with D-C- Tron Plus showed very high ability to reduce the mite population and the results compared well with Dynamec 1.8EC a standard acaricide. The effect on fecundity of the mites and the ovicidal activity of Oberon 240SC lowered the mite population drastically in the field conditions. The mites species associated with damage on tomatoes in Loitokitok, Kimana, Rombo and Maili Tatu areas of Kajiado District were a mixed population of T. evansi and T. urticae (Koch), while in Mwea, in Kirinyaga District T. urticae was found. In Subukia and Bahati of Nakuru District T. evansi was identified.