The bioassay uses living organisms either in the laboratory or under semi-controlled greenhouse conditions to test products for effects on the target pest organism and/or the various crop plants for which it’s development is intended. These experiments normally use topical applications or dietary incorporation of increasing rates of the test substance. In the former case, the pesticide bioassay is the mainstay for determining commercial rate ranges to begin field testing for efficacy results against target organisms, as well as plant safety validation. In some cases, the effective pest control rate range is above the safety threshold for phytotoxicity, and therefore, the product must be reformulated prior to development. This line of investigation determines these specific values and conditions for each candidate crop plant in the development program.

The bioassay is also essential in monitoring field populations for pesticide resistance. Here, Pacific Ag technicians collect field samples of infected plant parts in the case of plant pathogens, or insect specimens directly from infested crops, and establish laboratory colonies from these discrete samples. Rate responses are then determined through exposure protocols that have been developed at Pacific Ag. These may then be compared to previous data from these same agricultural areas, allowing the client to monitor the degree of sensitivity of pest populations to their product in the districts where it is being sold. The bioassay is thus a true measuring device for product effectiveness, and one which every management team needs to navigate their development efforts.