Comparative Effects of a Genetically Engineered Insect Virus and a Growth-Regulating Insecticide on Microbial Communities in Aquatic Microcosms

Persistence of naturally occurring and genetically modified Choristoneura fumiferana nucleopolyhedroviruses in outdoor aquatic microcosms

“…The observations reported in this paper differ from a previous laboratory microcosm study in which the same two viruses were detectable in the water column for only about 3 days, although they persisted in bottom substrates until the end of the 21 day experiment 25. The authors believe this discrepancy can be explained by the existence of a floc layer in the outdoor microcosms that was not present in the laboratory microcosms.…”

“…These observations led to follow‐up depth‐specific sampling 3 years after the virus application, and resulted in the discovery that detectable amounts of virus were present only within or very near the floc layer. In the laboratory microcosm experiment referred to above, water was sampled only at mid‐depth 25. It is possible that the OBs rapidly settled to below mid‐depth (OBs were detected in bottom substrates within 3 days), thus explaining the shorter period of detection in the lab study.…”

“…The method used to lyse OBs and expose genomic DNA was a slightly modified version of a procedure that has been described elsewhere 25. Each thawed 50 mL tube was vortexed vigorously for 10 s, immediately after which a 450 µL subsample was removed and pipetted into a 2 mL microfuge tube.…”

“…The patterns of persistence of baculoviruses on foliage and in soil are well described 14–24. Much less is known about the persistence of baculoviruses in the aquatic environment 25. Nevertheless, the potential exists for baculoviral contamination of surface waters following pesticide applications through inadvertent overspray, spray drift, foliar washing or by infected insects falling from overhanging vegetation 25, 26…”

Effects of chemicals on microorganisms

“…Effects of a genetically engineered insect baculovirus and a growth-regulating insecticide, Dimilin, on indigenous aquatic microbial communities were determined in an aquatic microcosm. No significant changes were observed with the baculovirus, but Dimilin produced significant changes in community function (Kreutzweiser et al, 2001).…”