Biological control of Tetranychus urticae Koch (Acari: Tetranychidae) with Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) on roses in the Sabana of Bogota

Abstract

The present and tries to contribute to the knowledge on the habits of Phytoseiulus persimilis under the conditions of the Sabana of Bogota through the evaluation of three dif­ferent levels of this species (5, 15 and 45 predators per plant) for the control of Tetranychus urticae in roses, seven month­old cv. Madame Delbard. The plots were in­fested with T urticae to obtain a level of approximately 40 spider mites (eggs + mobile forms) / leaflet before the release of P persimilis. Analysis of the data from the main­tenance layer of the plants showed a tendency toward control as of week 5. However, in the treatment 5 predators/plant, a significant popu­lation increase was observed prior to its con­trol. By week 8, averages of the treatments 15 and 45 predators/plants were near the O pest population. Results from the production layer of the plants showed that in all treatments the pest mite moved upwards. On the other hand, the upwards movement of the predators was also observed with an ensuing control of the pest. In all treatments, a good level of control was observed by week IO. The authors suggest that this predator is a good candidate for the con­trol of T urticae under the conditions of the Sabana of Bogota. The initial level of infes­tation by T urticae was found to be too high for rapid control by P persimilis. As the treat­ments 15 and 45 predators/plant obtained similar results, it is assumed that a little over 15 predators/plant is sufficient to obtain the same results.