|Anhalt, Jennifer - IOWA STATE UNIVERSITY|
Submitted to: American Society of Microbiologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 3, 1999
Publication Date: N/A
Technical Abstract: Imidacloprid (NTN) [1-[(6-chloro-3-pyridinyl)methyl]-N-nitro- 2-imidazolidinimine], a chloronicotinyl insecticide used to control biting and sucking insects, is very persistent in the environment with a half life of greater than 100 days. Objectives in this study were to determine the biological and chemical factor governing NTN persistence. Soil-free enrichments are being monitored for NTN degradation. Enrichments were made using four different surface soils. Two grams of each soil was put into a carbon-limited, a nitrogen-limited, and a general nutrient broth, all containing 83 mg L-1 of NTN. Dilutions were made from these soil slurries to yield soil-free enrichments which contain a mixture of fungi and bacteria. After two weeks 43% and 16% of the NTN applied to NTN-13 and NTN-16, respectively, was degraded. Chloronicotinic acid, which is a degradation product of NTN, was also detected in these samples and not in the others. Enrichments without microorganisms had no loss of NTN. All enrichments that show NTN degradation are in N-limited broth. Two months later daughter cultures of NTN-13 and NTN-16 were still able to degrade NTN, but not as quickly. In a concurrent experiment surface and subsurface soils, from California and Indiana, were treated in triplicate with 0.1 mg kg**-1 **14C-methylene-imidacloprid. Soils were incubated for 400 days in the dark at « bar moisture content and 25 degrees C. Cumulative **14CO2 production after 217 d was less than 0.5% of applied **14C in all treatments.