Soil was taken from 23 fields in the High Plains of Texas and tested for potential of enhanced degradation of aldicarb (Temik® 15G, Bayer CropScience, Research Triangle Park, NC) with a greenhouse bioassay using western flower thrips, Franklinella occidentalis (Pergande). Soil from each field was split and one-half of the soil was autoclaved while one-half was retained with its natural microbial complement. Aldicarb was applied at 0, 0.005 and 0.008 g ai/pot. Thrips (juveniles) were counted at 3-4 day intervals to measure reproduction until 31-33 days after planting, when leaf area was measured. Rate of aldicarb and days after planting were significant main effects as well as the interaction with aldicarb rate and soil microbes when all soils were combined in one analysis. Plants from pots with no aldicarb had significantly more cumulative juvenile thrips (CJUV) than plants from pots with aldicarb, regardless of the presence or absence of microbes. Average CJUV numbers were similar in autoclaved and natural soil. Enhanced biodegradation of aldicarb was demonstrated to some degree in three fields. Enhanced degradation of aldicarb is not yet a widespread threat for producers using this product for thrips and nematode control in the High Plains of Texas.
