Several studies have shown that non-target species are attacked in the field by introduced biological control agents. However, Hopper (1998) pointed out that few studies demonstrated that such attack had any impact on population density of a non-target species.
Stanley and Julien (1998) noted that too few biological control programmes continued their efforts to the point where pre-release predictions were validated by post-release studies of biological control agents. Also Holt and Hochberg (2001) concluded from theoretical studies that attack rates alone do not adequately describe risk to non-target species.
A literature review for biological control of insects showed that data on post-release impacts were reported for less than 2% (of over 5000) of classical biological control introductions (Lynch et al. 2001). Extrapolating from their data, they estimated that just under 10% of instances of non-target attack may have led to population impacts, and hence over 600 non-target insect species may have been affected at the population level throughout the history of biological control. The authors of the review suggested that there exists major under-reporting of adverse effects of biological control agent introductions.
For weed biological control, the safety record appears to be very high, with only two of over 300 species that have been released worldwide affecting non-target species at the population level. Post-release monitoring is not routine in weed biological control programmes, and so under-reporting of non-target effects may exist; however, herbivores and their impact on plants are easier to assess than effects of parasitoids, invertebrate predators or entomopathogens.
Desirability of monitoring
The EPA does not normally apply controls to release approvals requiring post-release monitoring because controls are intended to reduce risk. However, the EPA encourages post-release monitoring because the data would help validate decisions, and hence inform future decisions on biological control agents. Furthermore the EPA does have a requirement under Section 148b to monitor effectiveness of HSNO on reducing impacts.
Funding for monitoring
Post-release monitoring is not normally used as a condition of approval for biological control agents, mainly because it does not manage risk, since the release has already been made. Furthermore, the EPA is aware that monitoring depends upon adequate funding that cannot always be guaranteed. However, some post-release monitoring research, and retrospective studies of pervious decisions is being carried out in the research programme Better Border Biosecurity (B3) [http://www.b3nz.org] in a sub-programme "Improved Biosafety for EPA Decisions". This work is funded by a research collaboration made up of AgResearch, Plant and Food Research, Scion, Landcare Research, and also Lincoln University. Other sources of funding for work like this could come from the beneficiaries of the biological control programme, who perhaps want to monitor post-release impacts on the target pest, and adding non-target species to this work can sometimes be quite cost-effective.
Holt R.D. and Hochberg M.E. (2001). Indirect interactions, community modules and biological control: a theoretical perspective. Pp. 13-37 In: Evaluating indirect ecological effects of biological control, E. Wajnberg, J. K. Scott and P. C. Quimby (Ed.) CABI Publishing, Wallingford, Oxon., UK
Hopper K.R. (1998). Assessing and improving the safety of introductions for biological control. Pp. 501-510 In: Pest Management - Future Challenges: Proceedings of the 6th Australasian Applied Entomological Research Conference, M. Zalucki, R. Drew and G. White (Ed.) The Cooperative Research Centre for Tropical Pest Management.
Lynch L.D., Hokkanen H.M.T., Babendreier D., Bigler F., Burgio G., Gao Z.-H., Kuscke S., Loomans A., Menzler-Hokkanen I., Thomas M.B., Tommasini G., Waage J.K., Van Lenteren J.C. and Zeng Q.-Q. (2001). Insect biological control and non-target effects: a European perspective. Pp. 99-125 In: Evaluating indirect ecological effects of biological control, E. Wajnberg, J. K. Scott and P. C. Quimby (Ed.) CABI Publishing, Wallingford, Oxon., UK.
Stanley J.N. and Julien M.H. (1998). The need for post-release studies to improve risk assessments and decision making in classical biological control. Pp. 561-564 In: Pest Management - Future Challenges: Proceedings of the 6th Australasian Applied Entomological Research Conference, M. Zalucki, R. Drew and G. White (Ed.) The Cooperative Research Centre for Tropical Pest Management.