The importance of cryptic species and subspecific populations in classic biological control of weeds: a North American perspective

Authors: SMITH, LINCOLN; CRISTOFARO, MASSIMO - ENEA CASACCIA RESEARCH CENTER; BON, MARIE-CLAUDE - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); DE BIASE, ALESSIO - UNIVERSITY OF ROME SAPIENZA; PETANOVIC, RADMILA - UNIVERSITY OF BELGRADE; VIDOVIC, BILJANA - UNIVERSITY OF BELGRADE

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2017
Publication Date: 6/1/2018
Citation: Smith, L., Cristofaro, M., Bon, M., De Biase, A., Petanovic, R., Vidovic, B. 2018. The importance of cryptic species and subspecific populations in classic biological control of weeds: a North American perspective. Biocontrol. 3(417-425). doi.org/10.1007/s10526-017-9859-z.
DOI: https://doi.org/10.1007/s10526-017-9859-z

Interpretive Summary: Classical biological control is a cost-effective, sustainable, and environmentally friendly method to control invasive alien weeds. The method involves searching for insects that attack target weeds in their region of origin, testing them to be sure that they do not attack other nontarget plants, and releasing them to control the target weed. Safety depends on finding agents that are highly host specific. This requires correctly understanding the identity of the target plant to direct where to search for potential agents. Behavioral experiments and DNA analysis have helped to identify hidden species or biotypes of plants that differ in important biological characters, such as susceptablity to attack by biological control agents. This combined approach has likewise revealed that some species of insects and mites previously thought to attack multiple species of plants really consist of multiple biotypes or species, some of which are highly host specific. This indicates that there may be more potential biological control agents than we think because they may be hidden in groups of indistinguishable 'cryptic' species. This raises the question of how such populations should be classified, and how to confirm the identity of live insects and mites before releasing them as classical biological control agents. The existence of biotypes or cryptic species may greatly increase the number of prospective biological control agents available; however, it may also create new challenges for governmental regulation.

Technical Abstract: Classical biological control of weeds depends on finding agents that are highly host specific. This requires not only correctly understanding the identity of the target plant, sometimes to the subspecific level, in order to find suitable agents, but also identifying agents that are highly host specific. Behavioral experiments and molecular genetic tools have revealed that some arthropod species previously thought to be polyphagous really consist of multiple biotypes, some of which are more host specific. Recent examples include Psylliodes chalcomera (Chrysomelidae), Ceutorhynchus assimilis (Curculionidae), Trichosirocalus horridus (Curculionidae), and some eriophyid mites. This raises the question of how such populations should be classified, and how to confirm the identity of live arthropods before releasing them as classical biological control agents. The existence of biotypes or cryptic species may greatly increase the number of prospective biological control agents available; however, it may also create new challenges for governmental regulation.