Microbial pesticides characteristics

Part 158 in Title 40 of the Code of Federal Regulations was finalized in 1984 (14). In the final rule, the term Biorational Pesticide was dropped and the term Biochemical and Microbial Pesticides was adopted to describe this class of pest control agents (Figure 4). The general characteristics of biochemical and microbial pesticides remained essentially unchanged. 

Competitiveness. Unlike chemical pesticides, microbial pesticides are living entitles which may survive, replicate and compete with other species for space and food sources. These factors, alaie, do not constitute a hazard, but do require an evaluation for which there is no coutiterpart for chemical pesticides. Such an analysis must consider whether characteristics have been engineered into a microorganism v ich may permit it to establish itself in new environmental niches. If so, then its potential to exert adverse effects ai nontarget species must be considered. 

Formulation development for microbial pesticides is often the results of efforts from two opposing directions. One direction is from the production side that begins with production of the active agent that provides a technical product with specific characteristics. For example the fungus Beauveria bassiana is produced by solid media culture and provides a powdered product containing a high concentration of hydrophobic spores. In contrast, e bacteria Bacillus... 

Pesticides vary widely in their chemical and physical characteristics and it is their solubility, mobility and rate of degradation which govern their potential to contaminate Controlled Waters. This, however, is not easy to predict under differing environmental conditions. Many modern pesticides are known to break down quickly in sunlight or in soil, but are more likely to persist if they reach groundwater because of reduced microbial activity, absence of light, and lower temperatures in the sub-surface zone. 

The presence of natural solids can significantly modify the rates of transformation in aqueous systems—relative to the rates observed in homogeneous solution—for many pesticide compounds, but may have little effect on others (Barbash and Resek, 1996). Factors that can influence the rates and mechanisms of transformation of pesticide compounds at the water/solid interface include the structure of the compound of interest (e.g.. Torrents and Stone, 1991 Baldwin et al., 2001), the composition and surface structure of the mineral phase (e.g., Kriegman-King and Reinhard, 1992 Wei et al., 2001 Carlson et al., 2002), the solid-phase organic-carbon content (e.g., Wolfe and Macalady, 1992), and the characteristics, health, and size of the resident microbial community. 

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