Nontarget effects of a weed biological control agent on a native plant in Northern Australia

Nontarget herbivory by a weed biocontrol insect is limited to spillover, reducing the chance of population‐level impacts

“…It is intuitive that reduced preference and performance together decrease the chance an agent will use a nontarget plant as a ''prime host'' (Zwo¨lfer and Harris 1984), because isolated patches of lower-ranked hosts should be only weakly attractive sinks to dispersing agents and a poor source of new agent generations (Dias 1996). Indeed, most studies describe nontarget herbivory in weed biocontrol as mild (McEvoy and Coombs 1999, Louda et al 2003, Dudley and Kazmer 2005, Andreas et al 2008, Paynter et al 2008, Diaz et al 2009, Moran et al 2009, transient (Baker et al 2004, Dhileepan et al 2006, Moran 2010, or localized (Schooler et al 2003, Russell et al 2007, Taylor et al 2007, Paynter et al 2008. However, the extent of nontarget herbivory by the thistle biocontrol weevils Rhinocyllus conicus Fro¨lich (deliberately introduced in the 1960s), and the accidentally introduced but deliberately redistributed Larinus planus Fabricius in North America has stimulated a challenge to the validity of the reduced preference and performance premise.…”

Risk to plant health in the EU territory of the intentional release of the bud‐galling wasp Trichilogaster acaciaelongifoliae for the control of the invasive alien plant Acacia longifolia

“…These non-target attacks on A. melanoxylon and P. lophantha were unexpected; however, further communications with South African researchers (Fiona Impson, October 2014, Plant Protection Research Institute, South Africa, personal communication) revealed that at sites where galling on A. melanoxylon was initially observed as relatively common, galls are now rare and hard to find or, in one case, completely absent, even though galls persist on local A. longifolia. This is most likely to be what practitioners of biological control refer to as a "spill-over effect" (Taylor et al, 2007). As such, a plant that is within the physiological host range of the potential BCA is attacked but only under conditions where the agents are present at a very high population during the initial outbreak period.…”

“…This is most likely to be what practitioners of biological control refer to as a "spill-over effect" (Taylor et al, 2007). As such, a plant that is within the physiological host range of the potential BCA is attacked but only under conditions where the agents are present at a very high population during the initial outbreak period.…”

“…After the initial population peak, galling on A. melanoxylon and P. lophantha has not been re-observed (Fiona Impson, October 2014, Plant Protection Research Institute, South Africa, personal communication). This type of attack has been termed "spill-over" (Taylor et al, 2007).…”

Benefit–risk assessment of biological control in wildlands

“…(Breiter and Seastedt, 2007), and melaleuca (M. quinquenervia) . In other cases, sustained feeding on non-target species at varying levels was detected in some cases, such as projects directed against the invasive species Mimosa pigra L. (Taylor et al, 2007), lantana (Lantana camara L.) (Snow and Dhileepan, 2008), houndstongue (Cynoglossum officinale L.) (Andreas et al, 2008), leafy spurge (Euphorbia estula L.) (Baker and Webber, 2008; but cf. Wacker and Butler, 2006), and old man's beard (Clematis vitalba L.) (Paynter et al, 2008).…”