Spray deposition and efficacy of four petroleum-derived oils used against Tetranychus urticae (Acari: Tetranychidae).

Petroleum-derived spray oils (PDSOs) offer an interesting alternative to acaricides to control the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), a key pest of clementine mandarins, Citrus reticulata Blanco. However, there is a lack of knowledge on how these products should be used. In this study, we evaluated the efficacy of four PDSOs (Sunspray Ultrafine, Volck Miscible, Texaco D-C-Tron Plus, and Agroaceite) at five concentrations (0.5, 1.0, 1.5, 2.0, and 3.0%) against eggs, protonymphs, and adults of T. urticae. We also characterized the PDSOs deposition pattern to find out the possible relationship between this factor and efficacy. In general, for all PDSO assayed, the higher the concentration, the higher the coverage, the mean area of impacts and efficacy on T. urticae. The biggest mean area of the impacts corresponded to Texaco D-C-Tron Plus. This PDSO was the most effective one and its efficacy was independent of concentration for concentrations higher than 1.0%. The same applied for concentrations higher than 1.5-2.0% for Agroaceite, Volck Miscible, and Sunspray Ultrafine, with high efficacies against eggs, protonymphs, and adults. PDSOs are highly effective against T. urticae, the use of these products should be encouraged in integrated citrus pest management programs in Spain. The next step will be to ascertain the efficacy under real field conditions.