SAFETY OF MICROORGANISMS INTENDED FOR PEST AND PLANT-DISEASE CONTROL - A FRAMEWORK FOR SCIENTIFIC EVALUATION

Microorganisms are enormous but largely untapped natural resources for biological control of pests and diseases. There are two primary reaso ns for their underployment for pest or disease control: (1) the techni cal difficulties of using microorganisms for biological control, owing to a lack of fundamental information on them and their ecology, and ( 2) the costs of product development and regulatory approvals required for each strain, formulation, and use. Agriculture and forestry benefi t greatly from the resident communities of microorganisms responsible for naturally occurring biological control of pest species, but additi onal benefits are achieved by introducing/applying them when or where needed. This can be done as (1) an inoculative release, (2) an augment ative application, or (3) an inundative application. Because of their specificity, different microbial biocontrol agents typically are neede d to control different pests or the same pest in different environment s. Four potential adverse effects are identified as safety issues (haz ards) associated with the use of microorganisms for the biological con trol of plant pests and diseases. These are: (1) displacement of nonta rget microorganisms, (2) allergenicity to humans and other animals, (3 ) toxigenicity to nontarget organisms, and (4) pathogenicity to nontar get organisms. Except for allergenicity, these are the same attributes that contribute to the efficacy of microbial biocontrol agents toward the target pest species. The probability of occurrence of a particula r adverse nontarget effect of a microbial biocontrol agent may be a fu nction of geographic origin or a specific trait genetically added or m odified, but the safety issues are the still the same, including wheth er the microorganism intended for pest or disease control is indigenou s, nonindigenous (imported and released), or genetically modified by t raditional or recombinant DNA (rDNA) technology. Likewise, the probabi lity of occurrence of a particular adverse nontarget effect may vary w ith method of application, e.g., whether as an aerosol, soil treatment , baits, or seed treatment, and may increase with increased scale of u se, but the safety issues are still the same, including whether the mi croorganism is used for an inoculative release or augmentative or inun dative application. Existing practices for managing microorganisms in the environment (e.g., plant pathogens, Rhizobium, plant inoculants) p rovide experience and options for managing the risks of microorganisms applied for pest and disease control. Moreover, experience to date in dicates that any adverse nontarget effects, should they occur, are lik ely to be short-term or transitory effects that can, if significant, b e eliminated by terminating use of the microbial biocontrol agent. In contrast, production agriculture as currently practiced, such as the u se of tillage and crop rotations, has significant and long-term effect s on nontarget organisms, including the intentional and unintentional displacement of microorganisms. Even the decision to leave plant pests and diseases unmanaged could have significant long-term environmental effects on nontarget organisms. Potential safety issues associated wi th the use of microbial biocontrol must therefore be properly identifi ed and compared with the impact of other options for managing the pest or leaving the pest unmanaged. This paper provides a scientific frame work for this process. (C) 1996 Academic Press, Inc.