Image: Fig 2 from Cock et al. (2016) BioControl.
Finally, there is an update to Greathead & Greathead’s (1992) database on classical biological control of insects! Cock et al. (2016) present a nice update in BioControl of Greathead & Greathead’s seminal paper, and they allude to more papers and analyses to come. Awesome!
This update is important because so many changes have occurred in the last couple decades regarding ecological risk assessment of classical biological control agents. We value biodiversity and ecological processes and systems much more highly than they did prior to the 1970s. These changes in values have resulted, among other things, in changes in regulatory processes and in the research behind biological control agent releases. As Cock et al. demonstrate (see their Fig 1 below), these changes in values have corresponded with a major decrease in the number of introductions made each year. While I’m happy to live in an era where higher value is placed on the natural world (though not high enough!), this reduction in classical biological control releases is unfortunate, I think, because the rate of arrival of new invasive species will likely continue to increase (Hulme 2009 J. Appl. Ecol.), and classical biological control remains one of our best management strategies available.
On the flip side, the authors suggest that our increased attention to ecological processes and our corresponding research has resulted in an increased proportion of establishments and successful control by biological control agents that are released (see Fig 2 at the top of the post). The overall trend since the 1970s of increased rates of successful biological control is pretty great, but note the little down tick we see between the 1990s and 2000s… Is this indicative of a newer change? Aversion to risk of classical biological control agents really heightened through the 1990s, and I wonder if our total focus on extreme specialists or the longer wait times in quarantine (in the U.S., at least) have reduced the “quality”, and ultimately the efficacy, of agents we release. There is some evidence to support this (e.g. Gariepy et al. 2015 Biolog. Control). The down tick from the 1990s to 2000s might alternatively be due to a publication lag. I doubt it’s just random variation, though, because they put the standard errors at <1% for each time bin after the 1880s.
Anyway, I’m on the lookout for this group’s forthcoming papers!