OVIPOSITION SITE SELECTION BY TETRANYCHUS URTICAE KOCH (ACARI: TETRANYCHIDAE) IN RESPONSE TO FENVALERATE AND PERMETHRIN RESIDUES ON SOYBEAN

The oviposition site selection of Tetranychus urticae Koch in response to fenvalerate and permethrin residues on soybeans was examined in the laboratory. Five leaf treatment regimes were evaluated on potted soybeans (half-area vs. whole area and partial coverage vs. complete coverage) plus a distilled water control. Over 95% of the eggs were deposited on untreated halves of leaflets on which the other half was treated with either fenvalerate or permethin. Similar oviposition behavior was observed for both partial spray coverage, ca. 10% of the leaf area, or total coverage of the treated half leaflet. Over 95% of the eggs were observed on the leaf surface in the control, whereas, 40% and 30% of the eggs were suspended off the leaf surface that was totally covered with permethrin and fenvalerate, respectively. No differences were observed in the vertical distributions of eggs between control, and the permethrin and fenvalerate half-leaf treatments. More than 95% of the total eggs were observed on the leaf surface; however, few eggs were laid on the leaflet half containing the pyrethroid residue.