Abstract L. vulgaris is a perennial flowering plant with a spreading root system. It forms dense mats which can compete with crops and suppress native vegetation, reducing pasture productivity and/or biodiversity (ISSG, 2015). Native to temperate areas of Europe and Asia, it has been widely introduced to North America, Australia, New Zealand and South Africa, and is regarded as noxious in many of these countries. By inclusion in indexes of invasive species it is regarded as invasive widely in Canada and in the USA (Alberta Invasive Species Council, 2014; Invasive Plant Atlas of the United States, 2015). L. vulgaris received an invasive index of 69 (out of a maximum of 100) in Alaska, USA (ANHP, 2011). It is also regarded as invasive within its native range in Serbia (Dzigurski and Nikolic, 2014).

Abstract V. rossicum is a herbaceous perennial climbing vine native to Ukraine and southwestern European Russia. It was introduced into North America for ornamental purposes and has spread extensively throughout the lower Great Lakes Basin, particularly Lake Ontario, including New York State, USA and Ontario, Canada. Self-fertility and large numbers of wind-borne seeds ensure rapid dispersal of V. rossicum to new sites. Small patches of V. rossicum can coalesce to form very large, monospecific stands which can outcompete native vegetation resulting in a change in habitats and a decrease in biodiversity. V. rossicum is allelopathic and can alter the microbial composition in the rhizosphere preventing the growth of sensitive plant species. In the USA, competition from V. rossicum is putting pressure on the rare and endangered species Asplenium scolopendrium var. americanum. In addition to this, V. rossicum has been shown to decrease insect biodiversity and may have negative impact on the reproduction of the Monarch butterfly, Danaus plexippus.

Abstract V. nigrum is a herbaceous climbing vine native to south-western Europe (Italy, France, Portugal and Spain). It has spread extensively throughout New England, the lower Hudson River basin and south-eastern Pennsylvania, USA. V. nigrum produces a large number of wind-borne, self-fertile seeds which readily disperse to new sites. Small patches of V. nigrum can coalesce to form large, monospecific stands that outcompete with native vegetation and alter habitats. In Vermont and New Hampshire, USA, the endemic and endangered species, Astragalus robbinsii var. jesupii, is under pressure by an expanding population of V. nigrum. In addition to this V. nigrum may have negative impact on the monarch butterfly, Danaus plexippus.

This datasheet on Linaria dalmatica covers Identity, Overview, Distribution, Dispersal, Hosts/Species Affected, Diagnosis, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.

A combined taxonomic, morphological, molecular and biological study revealed that stem-galling weevils from the genus Rhinusa associated with toadflaxes from the genus Linaria (Plantaginaceae) are composed of three different species: Rhinusa pilosa, Rhinusa brondelii and Rhinusa rarasp.n. The authentic field host plants are respectively, Linaria vulgaris, Linaria purpurea and Linaria genistifolia/ Linaria dalmatica. These weevil species can be distinguished from each other by a few subtle morphological characteristics, mainly in the shape of the rostrum and of the integument. An analysis of the mitochondrial [cytochrome oxidase subunit II gene (COII) and 16S ribosomal RNA gene (16S)] and nuclear (elongation factor-1, EF-1) sequence data revealed high genetic divergence among these species. Uncorrected pairwise distances on mtCOII gene were 14.3% between R. pilosa and R. brondelii, 15.7% between R. pilosa and R. rara, while R. brondelii and R. rara were approximately 11% divergent from each other. Divergences obtained on 16S and nuclear EF-1 genes were congruent. However, substantial intraspecific mitochondrial divergence was recorded for all studied populations of R. pilosa s.s. showing two mtDNA lineages, with estimated COII and 16S divergences of 4% and 1.6%, respectively. Nuclear pseudogenes (Numts) and Wolbachia influence, although recorded within both lineages, were excluded as possible causatives of the mtDNA divergence, while EF-1 indicated absence of lineage sorting. Species from the R. pilosa complex are estimated to have diverged from each other approximately 7.2 million years ago (mya; late Miocene), while R. brondelii and R. rara diverged from each other about 4.7 mya (early Pliocene). This published work has been registered in ZooBank, .

In this paper, we describe five successful classical biological weed control agents released in the United States. For each of the five arthropod species, we compared data from prerelease studies that experimentally predicted the agent's host range with data collected postrelease. In general, experimental host range data accurately predicted or overestimated risks to nontarget plants. We compare the five cases with insects recently denied for introduction in the United States and conclude that none of the discussed agents would likely be approved if they were petitioned today. Three agents would be rejected because they potentially could attack economic plants, and two because of potential attack on threatened or endangered plants. All five biocontrol agents have contributed significantly to the successful management of major weeds with no or minimal environmental risk. We believe that the United States may miss opportunities for sustainable and environmentally benign management of weeds using biological control if the regulatory framework only considers the risks of agents as potential plant pests and treats any host-range data regarding economic or threatened and endangered species as a binary decision (i.e., mandates rejection if there is any chance of feeding or development). As a way forward we propose the following: (1) the addition of risk and benefit analyses at the habitat level with a clear ranking of decision-making criteria as part of the U.S. Department of Agriculture Animal and Plant Health Inspection Service Technical Advisory Group's evaluation process of biocontrol agents; (2) recognition of the primacy of realized host range data for potential agents that considers the insect's host selection behavior instead of emphasizing fundamental host range data during release evaluations, and (3) development of formalized postrelease monitoring of target and nontarget species as part of the release permit. These recommendations may initially be advanced through reassessment of current policies but may in the longer term require the implementation of dedicated biocontrol legislation.

A combined taxonomic, morphological, molecular and biological study revealed that the species presently named M ecinus heydenii is actually composed of five different species: M . heydenii Wencker, 1866; M. raphaelis B aviera & C aldara sp. n., M . laeviceps Tournier, 1873; M. peterharrisi Toševski & Caldara sp. n. and M . bulgaricus Angelov, 1971. These species can be distinguished from each other by a few subtle characteristics, mainly in the shape of the rostrum and body of the penis, and the colour of the integument. The first four species live on different species of L inaria plants, respectively, L . vulgaris (L.) P . Mill., L . purpurea ( L .) P . Mill. L . genistifolia ( L .) P . Mill. and L . dalmatica ( L .) P . Mill., whereas the host plant of M . bulgaricus is still unknown. An analysis of mt COII gene sequence data revealed high genetic divergence among these species, with uncorrected pairwise distances of 9% between M . heydenii and M . raphaelis , 11.5% between M . laeviceps, M . heydenii and M . raphaelis , while M . laeviceps and M . peterharrisi are approximately 6.3% divergent from each other. M ecinus bulgaricus exhibits even greater divergence from all these species and is more closely related to M . dorsalis Aubé, 1850. Sampled populations of M . laeviceps form three geographical subspecies: M . laeviceps laeviceps , M . laeviceps meridionalis Toševski & Jović and M . laeviceps corifoliae Toševski & Jović. These subspecies show clear genetic clustering with uncorrected mt DNA COII divergences of approximately 1.4% from each other.

Linaria vulgaris Mill. (Plantaginaceae), common or yellow toadflax, is a Eurasian short-lived perennial forb invasive throughout temperate North America. Rhinusa pilosa (Gyllenhal) (Coleoptera, Curculionidae) is a univoltine shoot-galling weevil found exclusively on L. vulgaris in Europe. Under no-choice test conditions, 13 non-native Linaria species exposed to R. pilosa were accepted for oviposition and most were found to be suitable, to varying degrees, for gall and larval development. Adult feeding and survival was minimal on native North American species in the plant tribe Antirrhineae which includes the target plant. In no-choice tests with 63 native North American species and 24 other non-target species outside Linaria , oviposition was limited to four native North American species. Only three larvae developed to the adult stage on Sairocarpus virga (A. Gray) D.A. Sutton, with no negative impact on plant growth. Risks to native flora from the release of R. pilosa are therefore expected to be minimal. The Technical Advisory Group for the Biological Control of Weeds (TAG—BCW) has recommended release of R. pilosa in September 2013.

This chapter focuses on common tansy (Tanacetum vulgare) which increasingly colonizes pastures and hay fields, especially in Alberta, Canada. It provides an overview of the insects and fungi that are potentially useful for its management. Future research prospects are recommended.

Several populations of the stem-mining weevil Mecinus janthinus Germar species complex (Mecinini, Curculionidae), identified based on morphological characteristics, have been introduced in North America for the biological control of invasive toadflaxes of European origin: Linaria vulgaris Miller and L. dalmatica (L.) Miller (Plantaginaceae). According to the mitochondrial cytochrome oxidase subunit II (COII) gene haplotype divergence of Mecinus janthinus species complex, a total of 20 M. janthinus s.s. , 3 M. janthinus s.l. of the ‘speciosa’ genotype and 29 M. janthiniformis haplotypes have been recorded across their native range in central and southeastern Europe. A polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) diagnostic assay of COII gene using Hpy 188III and Mnl I enzyme-mix, was developed for fast and cost-effective discrimination of these morphologically very similar cryptic weevil species. It is shown that digestion generates unique 4-fragment restriction profile in M. janthinus s.s. , 2-fragment profile in M. janthiniformis and 3-fragment profile in M. janthinus s.l. ‘speciosa’ group of haplotypes, allowing precise identification of each species or genotype. The proposed method represents a practical tool for fast and accurate identification of the target biocontrol agents and should prevent using inappropriate weevil species in redistribution programs for biological control of invasive toadflax species.

High genetic diversity of introduced plant populations may pose a key advantage under changed selection pressures but may also have important implications for biological control of such plants. However, molecular markers employed to measure genetic variation do not necessarily reflect variations in phenotypic traits such as plant chemical composition, which may be similarly important for both the invasion success of a plant and the establishment of biological control agents. The Asteraceae species Tanacetum vulgare is of Eurasian origin, but was introduced to North America, where it became invasive in some areas. This species varies greatly in terpene composition, forming different chemotypes. To assess the genetic diversity of T. vulgare in relation to its chemical diversity, we grew populations originating from different sources of the native and introduced ranges under standardized conditions. Using inter simple sequence repeat markers, we found indications for an increased genetic diversity in plants of the introduced compared to the native range. Analyses of volatile profiles of these individuals indicated similarly high chemical diversities in native and introduced populations. Clustering analyses revealed a considerable amount of unique geno- and chemo-types on both continents. No significant relation between the genetic and chemical data could be detected, demonstrating that the genetic structure of invasive populations does not necessarily offer information on its chemical diversity and vice versa. Knowledge of both the genetic structure and the actual variation in plant chemistry allows biological control research to consider factors potentially interfering with the success of biocontrol agents prior to release.

Biological control is often an effective technique deployed to tackle invasive plant species by the release of highly specialized enemies. However, variation in plant chemistry due to high plasticity and/or evolved during the introduction process needs to be considered when testing the efficacy of potential biocontrol agents. The tortoise beetle, Cassida stigmatica Suffrian (Coleoptera: Chrysomelidae), is a potential biological control agent selected to control the chemically highly variable and invasive plant species Tanacetum vulgare L. (Asteraceae). This study was conducted to test whether or not plants of different chemical profiles (terpene chemotypes) are equally accepted by C. stigmatica . Therefore, female oviposition and feeding choice behaviour were examined using one pure chemotype (β‐thujone type) and three mixed chemotypes (camphor/1,8‐cineole, β‐thujone/camphor, and camphor/camphene types) in various paired‐choice combinations. Furthermore, larval survival and adult body mass were compared when beetles were reared on the four chemotypes. Overall, C. stigmatica females showed a clear preference for the pure β‐thujone chemotype over the mixed chemotypes containing camphor, and no preferences when only mixed chemotypes were offered in choice tests. However, they were able to use all offered chemotypes for oviposition and feeding. No differences in larval survival and adult body mass could be detected when reared on the various chemotypes. The study demonstrates that knowledge of the acceptance of chemically variable host species is essential when testing for applicability of biocontrol agents.

Cirsium arvense (L.) Scop. is a perennial herb indigenous to Eurasia that is now present throughout temperate regions of the world where it is considered one of the worst weeds of pastoral and agricultural systems. Classical biological control has been attempted in both North America (NA) and New Zealand (NZ). However, nearly 50years after the first agent releases there are no indications of successful control. We review the status of the five agents deliberately released for control of C. arvense in NA and NZ, plus the species unintentionally introduced, and the occurrence of insects native to NA on C. arvense. We retrospectively evaluate C. arvense as a target weed, critique the agents selected for release, and contrast the different situations in NA and NZ. In retrospect, we see justification for the agents released in NA, but it is evident that these agents would not meet the more stringent host specificity requirements necessary to be released today. The failure of the program in NA is attributed to compromised safety, and lack of impact. Non-target impacts by one of the released agents, Rhinocyllus conicus, have raised safety concerns for native thistle plants. The other released agents either failed to establish, or if established, had no impact on the weed. In contrast, the situation in NZ is quite different because there are no related native thistles (Cardueae), and thus little chance of non-target impacts. Thus far, failure in NZ is attributed to lack of effectiveness due to non-establishment, or no impact, of released agents. In the past, the same agents that were released in NA were subsequently released in NZ, without considering whether or not these were the best choices. Thus, the past failure in NZ might be due to the previous lack of a NZ-specific approach to biocontrol of thistles in general and C. arvense in particular. A new approach taking into consideration the absence of native Cardueae has resulted in the release of agents more likely to be effective, and has potentially set NZ on track towards successful biological control of C. arvense, and other thistles.

A combined morphological, molecular and biological study shows that the weevil species presently namedMecinus janthinusis actually composed of two different cryptic species:M. janthinusGermar, 1821 andM. janthiniformisToševski & Caldarasp.n.These species are morphologically distinguishable from each other by a few very subtle morphological characters. On the contrary, they are more readily distinguishable by both molecular and biological characters. A molecular assessment based on the mitochondrial DNA cytochrome oxidase subunit II gene revealed fixed differences between the two species with p‐distances between samples of both species ranging from 1.3 to 2.4%. In addition to this, the larvae of the two species are found to develop on different species within the genusLinaria(Plantaginaceae):M. janthinusis associated with yellow toadflax (L. vulgaris) andM. janthiniformiswith broomleaf toadflax (L. genistifolia) and Dalmatian toadflax (L. dalmatica). Molecular and host use records further suggest the occurrence of a third species associated withL. vulgariswithinM. janthinus,sampled from north Switzerland, central Hungary and east Serbia. The significance of these new findings is of particular importance because species of theM. janthinusgroup are used, or are potential candidates, for the biological control of invasive toadflaxes in North America.

The European leaf-feeding moth Abrostola asclepiadis and root-feeding beetle Eumolpus asclepiadeus are promising biological control agents for two European swallow-worts (Vincetoxicum rossicum and Vincetoxicum nigrum) in North America, however, their impact on plant performance is uncertain. Densities of each herbivore were manipulated in a common garden to determine whether leaf and root herbivory affect the performance of these plants. During the second year of the experiment, V. rossicum and V. nigrum unexpectedly became infected with the fungal pathogens Ascochyta sp. and Cercospora sp. (Ascomycota), respectively. Although pathogen infection mainly reduced shoot height and delayed reproduction, herbivore effects on plant growth were still evident. Leaf herbivory by A. asclepiadis had no effect on plant growth 1year after defoliation. Root herbivory by E. asclepiadeus reduced shoot height and plant biomass and decreased the ability of plants to compensate for pathogen attack. Pathogen infection prevented detection of herbivore effect on reproduction. Due to its substantial impact on plant biomass, E. asclepiadeus should be further evaluated as a biological control agent against Vincetoxicum spp. populations invading open habitats in North America. Further research is needed to evaluate the impact of A. asclepiadis in combination with E. asclepiadeus and plant competition under high and low light conditions.

Common buckthorn, Rhamnus cathartica L., is a small tree or shrub of Eurasian origin that has become invasive in North America. A survey was conducted during 2010 to evaluate occurrence of buckthorn witches' broom (BWB) disease symptoms induced by Candidatus Phytoplasma rhamni' in the native range of R. cathartica. The distribution of phytoplasma-infected trees was identified over a large expanse of Europe, from south-west Switzerland to north-east Serbia. Although 25% of analyzed buckthorn trees were infected with phytoplasma (34 out of 133 plants), all plants were symptomless, indicating a commensal relationship between the phytoplasma and its plant host without negative effects which would lead to disease development.

Mechanisms contributing to the invasive success of plants are still only partly understood. A main assumption is that an escape from specialized enemies in introduced ranges allows a reduction of chemical defences resulting in an increase in growth and reproduction and thus increased competitive ability of introduced plants. Not only variation in concentration but also variation in composition of chemical compounds between individuals may be a key advantage for plants introduced to novel areas impeding adaptation of different plant antagonists. To investigate quantitative and qualitative variation of putative defence compounds and investment of resources in growth, we conducted a common garden experiment in the native range with seeds of 13 native and 9 introduced populations of Tanacetum vulgare, an aromatic plant forming different chemotypes. After 3.5 months, plants of introduced populations had similar biomass but more stems and higher concentrations of volatile secondary compounds (mainly terpenes) than plants of native populations. Both native and invasive T. vulgare populations exhibited high chemotypic variation with nine chemotypes occurring on both continents, whereas several were found exclusively either in plants originating from the native (n = 10) or invasive (n = 2) range. Due to the known negative effects of many mono-and sesquiterpenes on various organisms, we propose that high concentrations of these secondary compounds accompanied by high chemotypic diversity may facilitate the invasion success of a plant species.

Plant feeding insects and the plants they feed upon represent an ecological association that is thought to be a key factor for the diversification of many plant feeding insects, through differential adaptation to different plant selective pressures. While a number of studies have investigated diversification of plant feeding insects above the species level, relatively less attention has been given to patterns of diversification within species, particularly those that also require plants for oviposition and subsequent larval development. In the case of plant feeding insects that also require plant tissues for the completion of their reproductive cycle through larval development, the divergent selective pressure not only acts on adults, but on the full life history of the insect. Here we focus attention on Rhinusa antirrhini (Curculionidae), a species of weevil broadly distributed across Europe that both feeds on, and oviposits and develops within, species of the plant genus Linaria (Plantaginaceae). Using a combination of mtDNA (COII) and nuclear DNA (EF1-alpha) sequencing and copulation experiments we assess evidence for host associated genetic differentiation within R. antirrhini. We find substantial genetic variation within this species that is best explained by ecological specialisation on different host plant taxa. This genetic differentiation is most pronounced in the mtDNA marker, with patterns of genetic variation at the nuclear marker suggesting incomplete lineage sorting and/or gene flow between different host plant forms of R. antirrhini, whose origin is estimated to date to the mid-Pliocene (3.77 Mya; 2.91-4.80 Mya).

From examination of type specimens the authors establish that Rhinusa hispida sensu auctorum is not the same species as R. hispida (Brullé, 1832), which is instead synonymous with R. tetra (Fabricius, 1792) (syn. n.). Moreover, under the name R. hispida sensu auctorum two distinct taxa are confused, which can be distinguished from each other by taxonomic, biological and genetic differences: R. pilosa (Gyllenhal, 1838) and R. brondelii (Brisout, 1862), stat. n. (= R. lanuginosa (Wollaston, 1875), syn. n.). Gymnetron vulpes Lucas, 1849 (= G. marmota Fairmaire, 1883, syn. n.), previously placed under synonymy of R. hispida (Brullé), is transferred to the genus Mecinus and considered a distinct species. A neotype of G. pilosum brondelii Brisout and lectotypes of G. hispidum Brullé, G. pilosum Gyllenhal, G. vulpes Lucas and G. lanuginosum Wollaston are designated.