Monday, December 11, 2006 - 8:47 AM

Evaluation of timing and frequency of releases for Neoseiulus californicus as a biological control agent for Tetranychus urticae Koch in North Florida strawberry fields

Aimee B. Fraulo, and Oscar E. Liburd, University of Florida, Entomology and Nematology Department, Bldg 970 Natural Area Drive, Gainesville, FL

Laboratory and field experiments were conducted to determine the effect of timing on inundative releases of Neoseiulus californicus (McGregor) for the control of twospotted spider mite (TSSM) in strawberries and to asses the effect of mite damage on photosynthetic processes. In the laboratory experiment 4 treatments were evaluated in a completely randomized block design (CRBD) with 5 replicates. The treatments included the release of predatory mites at different periods throughout the experiment 1) day 0, 2) day 5, 3) day 10, and 4) a control (no predatory mites). The ratio of predators to TSSM was 1:10 respectively. Experimental units consisted of screened cages (30.48 cm in height, 13.97 cm in diameter). The results indicated that the release on day 0 achieved the highest level of control. In the field experiment the same 4 treatments were evaluated. However, the predatory mites were released over a longer period of time. Treatments included 1) early-season release 1 month after planting, 2) mid-season release 2 months after planting, 3) a late-season release 5 months after planting, 4) a control (no predators). The experimental design was a CRBD with 6 replicates using 1:10 predator to TSSM ratio. The results indicated that one early-season release has potential for managing TSSM populations throughout the entire season. In addition, the use of hyperspectral imagery was evaluated to show the effect of mite damage on the photosynthetic processes within strawberry leaves. Results indicate that TSSM damage may be detected at a cellular level.

Species 1: Acari Phytoseiidae Neoseiulus californicus
Species 2: Acari Tetranychidae Tetranychus urticae (two-spotted spider mite)