Side effects of biological control agents in agriculture : does the bacteria Bacillus amyloliquefaciens affect the earthworm Aporrectodea longa?

Abstract: Pathogenic microorganisms pose a big threat towards food production. Meanwhile, negative impacts on humans and environment are seen by the use of pesticides. Biological control agents are an alternative to the use of chemical pesticides, and plant-growth promoting rhizobacteria, such as Bacillus amyloliquefaciens has been shown to have good properties as biocontrol agents. Before these bacteria can be used commercially their impact on other soil organisms has to be evaluated. This thesis looks into what biocontrol bacteria are and how they might affect earthworms. The thesis consists of a literature review and an experiment where earthworms (Aporrectodea longa), kept in natural soil, were exposed to the bacteria B. amyloliquefaciens. Earthworms were exposed to the bacteria in three ways; contact with skin, gut or both, they were either directly dipped in the bacterial solution or the solution was added to the soil. Earthworm growth, mortality and reproduction were measured to evaluate bacterial impact. Though neither of the treatments affected the earthworms negatively further research to test other means of bacterial exposure is needed before the bacteria can be used in agricultural management. Amongst others it is suggested to investigate how earthworms are affected by eating crop residues treated with the bacteria and to study if earthworms show avoidance behavior when exposed to the bacteria.