Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 2, 2005
Publication Date: July 21, 2005
Citation: Caesar, A.J. 2005. Melding ecology, weed biocontrol and plant microbial ecology can inform improved practices in invasive plant species biocontrol. Biological Control. 35(3):240–246. Interpretive Summary: The revisiting or reanalysis of data from past studies, called retrospective studies, can lead to improvement in 'best practices' in weed biocontrol methods. The use of methods that place the greatest emphasis on screening for agents with the highest level of impact by biological control agents will serve to reduce unintended effects such as attacks on native species and changes in how available food resources are balanced among associated plants and animals. Additional benefits from applying data from past studies to improve biological control are the reductions in the number of releases of unsuccessful agents by restricting releases to those with demonstrated ability to interact with microbes and the related cost savings to programs. The paper examines underemphasized data from past studies leading to successful weed biocontrol, and recent studies showing the effects of the soil microbial community on plant communities and vice versa. It draws a relationship between such findings from past studies, which indicate a likely microbial role in the successes achieved, and the more recent body of ecological literature on the interplay of microbes and plant community composition. Both the ecological literature and the underemphasized findings in past biocontrol literature provide data that support development of prerelease studies that seek to assess impact through capacity to synergize and reduce costs and unintended negative effects on the ecology of native plant communities.
Technical Abstract: Early research leading to the successful biological control of such invasive species as Opuntia spp. and Hypericum perforatum set examples and provided data useful for programs that would follow. However, this work failed to become established as a source of applicable principles for later workers in weed biocontrol. Recently, to enhance future programs in weed biocontrol, retrospective and parallel studies have been suggested as a means to reengage with earlier work to derive useful ideas and data. Parallel studies of the nature of feedback elicited by plant species in their invaded and native range by workers in the field of plant community ecology have shown the importance of soil microbial communities in effecting the feedback observed. Retrospective reexamination of previous studies would likely provide clues to other insect/plant pathogen interactions in addition to those described previously by the author and others. The effects of invasive species in profoundly altering soil microbial communities point to the need for further studies on key species contributing to or effecting the impact of biocontrol, and possible follow-on effects of biocontrol measures and attempts at restoration. These collective data suggest that the desired goal of selecting for and utilizing stronger agents to reduce non-target effects and increase the impact of programs would be served best by prerelease studies that assess the propensity of a candidate agent for direct or indirect interaction with other agents, using survival analysis. Over all, empirical parallel studies and retrospective studies should be a necessary part of how biological control is practiced.