Biological efficiency of mite predator Phytoseiulus persimilis (Acarina: Phytoseidae) against two-spotted spider mite Tetranychus urticae (Acarina: Tetranychidae)
Praslicka, J.(Univerzita Konstantina Filozofa, Nitra (Slovak Republic) | Bartekova, A.Univerzita Konstantina Filozofa, Nitra (Slovak Republic))
The aim of the study was to observe the biological efficiency of Phytoseiulus persimilis against Tetranychus urticae on the cucumber Cucumis sativus L. under greenhouse conditions (temperature 23-27 deg C and relative humidity 70-90 %) with leaf damage index of IPL-1 (0.5 individuals of T. urticae per square centimeter, area damage less than one fifth of leaf area) and IPL-2 (1.9 exemplars of T. urticae per square centimeter, area damage to two fifth of leaf area). By IPL-1 were applied five individuals and by IPL-2 ten individuals of Ph. Persimilis to each plant. The average biological efficiency by IPL-1 was 74.47 % seven days and 84.55 % fourteen days after the application. It can be concluded that Ph. persimilis adequately reduced the number of T. urticae on the observed plants of cucumber. The average biological efficiency by IPL-2 was 49.64 % seven days and 54.90 % fourteen days after the application. Because of insufficient biological efficiency it was necessary to perform another application by IPL-2 on the plants. After the second application, the biological efficacy was only 54.41 % on the 7th day and 57.35 % on the 14th day. Even though the number of T. urticae was greatly reduced, the survived individuals remain danger with respect to plant damage. It is recommended to performe the application of Ph. persimilis after the initial occurrence of T. urticae on greenhouse plants.
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