Improved understanding of weed biological control safety and impact with chemical ecology: a review

Authors: Wheeler, Gregory; SCHAFFNER, U - Commonwealth Agricultural Bureau International (CABI) - Switzerland

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2012
Publication Date: 3/1/2013
Citation: Wheeler, G.S., Schaffner, U. 2013. Improved understanding of weed biological control safety and impact with chemical ecology: a review. Journal of Invasive Plant Science and Management. 6:16-29.

Interpretive Summary: This review considers published research on chemical ecology as it relates to weed biological control and discusses how these two disciplines can be combined to improve the control of invasive species. Both disciplines have been operating for decades relatively independent of each other. The interface between chemical ecology and weed biological control presents a rich opportunity to exploit tightly coevolved relationships between agents and plants. The plants produce repellents or toxicants that defend against generalist insects. Specialist insects, like those used for biological control, use these same chemical compounds as cues to find and select their host for egg laying and feeding. Five topics seem relevant that if implemented could improve the predictability of safety of agents, agent establishment and impact on the target weed. We suggest that the predictability of potential agent safety can be improved with better understanding of the weed and valued plant chemistry and the potential biological control agent’s response to these compounds. Further, plants that are invasive and introduced to new areas are exposed to challenges like in their original range. Such a situation facilitates rapid evolutionary changes in weeds, which in turn may affect the outcome of biological control and other management options. Like in other plant species, weed chemistry may be highly variable. This variability, either at normal base line levels or increased in response to damage, is an important factor that potentially influences the performance of biological control agents and their impact on the target weed. Finally, the defensive plant chemistry of the plant may be used by the insect to protect against predators which would protect the biological control agent. Implementation of these techniques stands to help identify the factors responsible for the success of a biological control program. As requirements increase to better predict safety, establishment and impact of agents prior to release, the research described here stands to improve weed biological control success.

Technical Abstract: We review chemical ecology literature as it relates to weed biological control and discuss how this means of controlling invasive plants could be enhanced by the consideration of several well established research developments. The interface between chemical ecology and weed biological control presents a rich opportunity to exploit tightly coevolved relationships between agents and plants. Five topics seem relevant that if implemented could improve the predictability of host range determination, agent establishment and impact on the target weed. We suggest that the predictability of potential agent host range can be improved with better understanding of the host and test plant chemistry and the potential agent’s response to these behavioral and nutritional cues. Further, plants that are introduced to a novel environment are exposed to a new set of biotic and abiotic stressors. Such a scenario facilitates rapid evolutionary changes in phenotypic traits, which in turn may affect the outcome of biological control and other management options. Like in other plant species, weed secondary chemistry may be highly variable. This variability, either constitutive or inducible, is an important factor that potentially influences the performance of biological control agents and their impact on the target weed. Finally, sequestration of defensive plant chemistry may protect against generalist predators improving establishment of a biological control agent introduced to a new range. Implementation of these techniques stand to help identify the factors that impart success to a biological control program. As greater vigilance by biological control practitioners and the public mandates requirements to better predict specificity, establishment and impact of potential agents prior to release, the research described here stands to improve weed biological control success.