Laboratory Test Methods of Exposure of Microbial Pest Control Agents by the Respiratory Route to Nontarget Avian Species

摘要

Microbial pest control agents (MPCAs) are microorganisms applied to agricultural and silvicultural environments to control proliferation and spread of insect or plant pests. During application, it is likely that nontarget plants and animals are exposed to MPCAs. Following extensive experimentation, interim protocols were developed using oral and intravenous administration of the agent to the two test species (mallard and bobwhite). These protocols are suitably designed to demonstrate pathogenicity of a microorganism in the test bird species and illustrate the potential for differences in species susceptibility. The report deals with protocols developed to evaluate the respiratory route of exposure. Respiratory exposure can be simulated by intratracheal (IT) instillation or aerosol inhalation. The pattern of deposition of microorganisms within the respiratory tract of a bird by IT instillation is quite different from inhalation of an aerosol. Therefore, both exposure methods were evaluated. A cost- effective, head-only aerosol chamber was designed and constructed. These experiments showed that more sensitive and realistic assessments can be economically and safely obtained using an aerosol exposure chamber, and it is recommended that this method be substituted for the intratracheal instillation method in the interim protocols.