Assessment of the host-range and impact of the mite, Aculus crassulae, a potential biological control agent for Australian swamp stonecrop, Crassula helmsii

PM 6/5 (1) Host specificity testing of non‐indigenous (classical) biological control agents used against invasive alien plants

“…The series of tests that is detailed in the following sections follows a tiered approach that allows the assessment of the physiological and the realized host range of the invertebrate organism. In most CBC programmes, the minimum sequence performed will be no‐choice (Section 6.1.2) followed by choice tests (Section 6.1.3), although there are exceptions (see Varia et al., 2022). The testing sequence progressively reduces the number of plants exposed based on results of preceding tests, essentially removing unaccepted plant species at each stage, until only a few species remain to be tested under conditions which are as natural as feasible.…”

“…In recent years, CBC programmes have been implemented against a small number of invasive alien plant species in the EPPO region. Such programmes have included the control of Reynoutria japonica (formerly Fallopia japonica ; Japanese knotweed) using the psyllid Aphalara itadori (Shinji) (Hemiptera: Aphalaridae) (Djeddour & Shaw, 2010); the control of Acacia longifolia (Sydney golden wattle) using the gall forming wasp Trichilogaster acaciaelongifoliae (Froggatt) (Hymenoptera: Pteromalidae) (López‐Núñez et al., 2021); the control of Crassula helmsii (Australian stonecrop) using the mite Aculus crassulae Knihinicki & Petanović & Cvrković & Varia (Acarida: Eriophyidae) (Varia et al., 2022); and the control of Hydrocotyle ranunculoides (floating penny‐wort) using the weevil Listronotus elongatus (Hustache) (Coleoptera: Curculionidae) (Walsh & Maestro, 2017). Additionally, a fungal BCA, Puccinia komarovii var.…”

Knowledge and perceptions of invasive plant biocontrol in Europe versus the rest of the world

“…(Polygonaceae) in 2010 (UK) and 2020 (NL), the rust fungus Puccinia komarovii var glanduliferae against Impatiens glandulifera Royle (Balsaminaceae) in 2014 (UK) (Tanner et al, 2015;Varia et al, 2018), the gall wasp Trichilogaster acaciaelongifoliae (Froggatt) against Acacia longifolia (Andrews) Willd. (Fabaceae) in 2015 (Portugal) (Marchante et al, 2017) and the gall-forming mite Aculus crassulae Knihinicki & Petanović versus Crassula helmsii (Kirk) Cockayne (Crassulaceae) (Knihinicki et al, 2018;Varia et al, 2022). Most recently in 2020, again in the UK, the weevil Listronotus elongatus (Hustache) was released against Hydrocotyle ranunculoides L. f. (Apiaceae) (D. Djeddour pers.…”