| Investigations into the population biology of parasitoids were conducted at four vineyards in the San Joaquin Valley of California. The study included five cropping seasons from June 1993 through December 1997. Treatments included organic, sustainable and conventional vineyards. Parasitoid sampling involved pitfall, malaise, and yellow sticky trap types. The numbers of parasitoid families was generally greater in the organic versus the conventional plots, but with fewer individuals per family. At the CSU Fresno Farm Barbera block, wasp numbers were consistently higher in the organic plots for the pitfall and malaise traps, but were about equal for the yellow sticky traps. In the statistical analysis of this trial, the two farming practice treatments were not significantly different, except for the 1996 total wasps pitfall data and the 1995 encyrtid family sticky trap data. Precipitation data showed only a slight negative correlation with wasp counts for 1994--1996. |
