Economic evaluation of the successful biological control of Azolla filiculoides in South Africa

Weed biological control in the European Union: from serendipity to strategy

“…Native range surveys in North America followed by host range testing resulted in the selection and release of the frond-feeding weevil Stenopelmus rufinasus Gyllenhal (Coleoptera: Curculionidae) in 1997 (McConnachie et al 2003). Stenopelmus rufinasus is an Azolla specialist, with A. filiculoides and A. caroliniana Willd serving as host plants in the weevil's native range (Madeira et al 2013;Pemberton and Bodle 2009).…”

“…Stenopelmus rufinasus is an Azolla specialist, with A. filiculoides and A. caroliniana Willd serving as host plants in the weevil's native range (Madeira et al 2013;Pemberton and Bodle 2009). The biological control programme proved incredibly successful, with the weevil reducing the A. filiculoides population to a level at which it was no longer considered a problem within three years, with an estimated benefit:cost ratio of 15:1 by 2010 anticipated in a post-release evaluation (McConnachie et al 2003).…”

Economic evaluation of biological invasions—a survey

“…In the majority of cases it will not be appropriate to scale up regional data to a national level (as is done for instance by McConnachie et al, 2003).…”

“…Vague explanations on their source and generation generate suspicion of double-counting: (i) whether damage costs arise with or without a certain control measure (McConnachie et al, 2003) or (ii) whether government fundings are subtracted from total expenditure (Bertram, 1999).…”

“…During the course of classical cost-benefit analyses, a sensitivity analysis is mostly conducted, either by employing different discount rates (Cullen and Whitten, 1995;Pimentel et al, 2001;Tisdell, 1990) or by comparing different management regimes (McConnachie et al, 2003;Wit et al, 2001). …”