Evaluation of Phytoseiidae mites and Chrysoperla carnea (Stephens) on the control of Tetranychus urticae in Carica papaya L.

In order to evaluate the establishment and biological effectiveness of the predators Phytoseiulus persimilis, Neoseiulus californicus and Chrysoperla carnea on populations of Tetranychus urticae, a trial was established at the farm “La Pola” (with a cumulative precipitation of 445.9 mm), located in the municipality of Roldanillo, Valle del Cauca, Colombia. An experiment was performed under field conditions between September 2017 and May 2018 and using the papaya hybrid Tainung-1 between the stages of vegetative growth and fruit filling. Four treatments were established: T1: 12 releases of P. persimilis and N. californicus; T2: 10 releases of C. carnea; T3: treatment with no predator releases (control); and T4: grower’s practice (15 applications of pesticides) in a randomized complete block design with three replicates per treatment. Samples were collected every eight days by measuring the following variables: infestation percentage, number of fruits/plant, population of T. urticae, P. persimilis, N. californicus, and C. carnea/leaf and the diameter of the stem (every 30 d). The largest T. urticae populations were found in T3 and the lowest ones in T4. The populations of immature and adult T. urticae did not show significant differences between T1 and T2 but there were significant differences between T3 and T4. The variables diameter of the stem, number of leaves per plant, percentage of infestation, and number of fruits per plant showed significant differences between treatments. The T1 and T2 were equal to T3. T4 had the highest number of leaves and fruits per plant. The released predators did not control the populations of the mite T. urticae under the conditions of the present experiment.