A retrospective analysis of known and potential risks associated with exotic toadflax-feeding insects

Abstract

Hansen, Richard W.; and Markin, George P., "A retrospective analysis of known and potential risks associated with exotic toadflax-feeding insects" (2005 AbstractTo date, eight exotic toadXax-feeding insect species have been accidentally or intentionally introduced to North America. Reports on their establishment and impact have been recorded for more than 60 years. Environmental risks linked to biological control of toadXax were identiWed in terms of host resources and undesirable impacts on the target species through the critical review of this record. Data gaps revealed during this retrospective analysis are addressed through suggestions for future research and associated experimental methodologies. Known and potential impacts of toadXax-feeding insects on both invasive toadXax and non-target species are examined. Recent programmatic demands for demonstrated agent eYcacy and stringent host selectivity during the prerelease screening process clearly illustrate that classical biological control of invasive toadXax in North America is progressing beyond the so-called lottery approach. 

Biology and host specificity of Rhinusa pilosa, a recommended biological control agent of Linaria vulgaris

“…Their presence is due both to unintentional and intentional introductions from Europe, along with their hosts L. vulgaris or the congeneric weedy species, Linaria dalmatica (L.) Miller and L. genistifolia (L.) Mill. Three adventitiously introduced seed-feeding beetles, Brachypterolus pulicarius (Linnaeus, 1758) (Coleoptera: Nitidulidae), Rhinusa antirrhini (Paykull, 1800) (formerly Gymnetron antirrhini), and Rhinusa neta (Germar, 1821) (formerly Gymnetron netum) (Coleoptera: Curculionidae), are now ubiquitous on North American L. vulgaris, either self-dispersed or intentionally spread as part of the North American toadflax biological control program (De Clerck-Floate and McClay 2013;De Clerck-Floate and Turner 2013;Sing et al 2005;Wilson et al 2005).…”

“…Despite the use of the mentioned insect species against invasive toadflaxes beginning in the 1960s (McClay and De Clerck-Floate 2002;Sing et al 2005;Wilson et al 2005;De Clerck-Floate and McClay 2013;De Clerck-Floate and Turner 2013), the reported efficacy of the majority of these on L. vulgaris has been minimal, with only M. janthinus recently showing some promise since its first releases in the 1990s in both the USA and Canada De Clerck-Floate and McClay 2013). Since 2000, several other European insects have been investigated for potential use against L. vulgaris, and the first of these, the shoot-galling weevil, Rhinusa pilosa (Gyllenhal) (Coleoptera: Curculionidae), was petitioned for release in the USA andCanada in 2012 (De ClerckFloate andMcClay 2013).…”

Immature stages of Palearctic Mecinus species (Coleoptera, Curculionidae, Curculioninae): morphological characters diagnostic at genus and species levels

“…The larvae develop inside the ovaries, stems, or roots of the host plants and are sometimes able to induce the formation of galls (Hoffmann 1958;Caldara 2001;Toševski et al 2011). Several species of the genus have been the subject of detailed ecological studies (De Clerck-Floate and Harris 2002;De Clerck-Floate and Miller 2002;McClay and De Clerck-Floate 2002;Sing et al 2005;Toševski et al 2011) as potential biological control agents for some species of toadflax (Linaria spp.) that were introduced into North America and have since become invasive (Vujnovic and Wein 1997).…”

Rhizosphere bacterial communities associated with insect root herbivory of an invasive plant, Euphorbia esula/virgata .

“…This aspect has not been investigated previously. It has been increasingly accepted within the field of biological control that microbial interactions are a considerable, significant factor in the biological control of invasive plants (Bacher et al, 2002;Lym and Carlson, 2002;Sing et al, 2005;Butler et al, 2006). This complements a large body of literature showing that exotic plant invasion is both affected by and affects the soil microbial ecology (Belnap and Phillips, 2001;Ehrenfeld et al, 2001;Ehrenfeld, 2003;Kourtev et al, 2002Kourtev et al, , 2003, including effects on plant succession (Van der Putten et al, 1993;Bever et al, 1997).…”