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Title: Maximizing the contribution of native-range studies towards the identification and prioritization of weed biocontrol agents

item Goolsby, John

Submitted to: Australian Journal of Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2006
Publication Date: 12/1/2006
Citation: Goolsby, J., Palmer, B., Van Klinken, R. 2006. Maximizing the contribution of native-range studies towards the identification and prioritization of weed biocontrol agents. Australian Journal of Entomology. 45:276-285.

Interpretive Summary: Foreign exploration is conducted in the native range of an exotic weed to discover and evaluate insects and pathogens to use as biological control agents. The candidate biological control agents with the greatest potential demonstrate both a narrow host range (feed only on one or a few closely related plant species) and the potential to be damaging to their host plant. Intensive studies in the native range are needed to determine these key characteristics. The benefits of conducting these studies are that agents with the greatest potential are identified up front in the program which maximizes the chances for a successful biological control program and minimizes the risks incurred from releasing multiple agents. In particular, field studies in the native range can measure the potential damage that a candidate agent may cause to the target weed which can be used to predict its impact in the introduced range. Many new scientific tools are now available to foreign explorers to identify the genetic match of the invasive weed in the native range. This information is used to direct foreign exploration in the part of the native range where the genetically similar populations of the weed occur. Molecular tools can also be used to sort out genetic differences between herbivores plant that look very similar but may actually be separate species with unique biologies. Software program are also available which can be used to find climate matches between the native and introduced range of a weed. This is important because the most successful biological control agents often come from climates that are similar to the introduced range of a weed. In summary, native range studies greatly enhance the likelihood that the best candidate agents for an exotic will be discovered, evaluated and released as biological control agents.

Technical Abstract: Effective study in the native range to identify potential agents underpins all efforts in classical biological control of weeds. Good agents that demonstrate both a high degree of host specificity and the potential to be damaging are a very limited resource and must therefore be carefully studied and considered. The overseas component is often operationally difficult and expensive but can contribute considerably more than a list of herbivores attacking a particular target. While the principles underlying this foreign component have been understood for some time, recently developed technologies and methods can make very significant contributions to foreign studies. Molecular and genetic characterizations of both target weed and agent organism can be increasingly employed to more accurately define the identity and phylogeny of them. Climate matching and modeling software is now available and can be utilized to better select agents for particular regions of concern. Relational databases can store collection information for analysis and future enquiry while quantification of sampling effort, employment of statistical survey methods and analysis by techniques such as rarefaction curves contribute to efficient and effective searching. Obtaining good and timely identifications for discovered agent organisms is perhaps the most serious issue confronting the modern explorer. The diminishing numbers of specialist taxonomists employed at the major museums while international and national protocols demand higher standards of identity exacerbates the issue. Genetic barcoding may provide a very useful tool to overcome this problem. Native-range work also offers under-exploited opportunities for contributing towards predicting safety, abundance and efficacy of potential agents in their target environment.