Fj. Genthner et al., FATE AND SURVIVAL OF MICROBIAL PEST-CONTROL AGENTS IN NONTARGET AQUATIC ORGANISMS, Diseases of aquatic organisms, 16(2), 1993, pp. 157-162
A fully enclosed test system was developed both to assess potential ad
verse effects of microbial pest control agents on nontarget aquatic in
vertebrates and to monitor their fate and survival. Eastern oysters Cr
assostrea virginica were exposed to various microbial pest control age
nts including the vegetative bacterium Pseudomonas fluorescens, bacter
ial spores of Bacillus sphaericus, and fungal spores of Colletotrichum
gloeosporioides f. sp. aeschynomene. After an exposure of 3 d for the
fungus, 14 d f or the bacterial spores, and 7 d f or the vegetative b
acterial cells, half the oysters were placed into a fully enclosed 60
1 aquarium equipped with a recirculating water system which passed wat
er through an ultraviolet-irradiation sterilizer at a rate of 11 min-1
. The remaining oysters were placed into wire cages maintained in Sant
a Rosa Sound, Pensacola, Florida, USA. Plate counts, performed on homo
genized oyster tissues, revealed that all of the microbial pest contro
l agents were found in oysters after exposure. Oysters depurated each
microorganism at a different rate. None of the agents colonized the oy
sters. For all microbes tested, rates of clearance from the oysters in
the enclosed UV light depuration system were similar to rates of clea
rance from the oysters in Santa Rosa Sound. Histological examination o
f oyster tissues detected P fluorescens and B. sphaericus in the gut a
nd C. gloeosporioides in the gill. Spore germination was not observed
and no apparent signs of infectivity or pathogenicity were detected.