Figure 52 - uploaded by Carol Bell Randall
Content may be subject to copyright.
Calophasia lunula damage: a. larvae feeding on Dalmatian toadflax leaves (Laura Parsons & Mark Schwarzländer, University of Idaho); b. larvae defoliating a Dalmatian toadflax stem (Susan Turner, British Columbia Ministry of Forests)(a,b bugwood.org)
Citations
... across a broad geographic area of their native range. Those results revealed that all four host plants were used by R. dieckmanni and thus the native geographic range of the species is wider than multiple introductions of R. antirrhini "Dalmatian host race" during the 1990s in Canada and the USA, establishment in North America was sporadic and population numbers remained low (Sing et al., 2016). Literature on R. antirrhini "Dalmatian host race" is generally associated with studies related to the biological control of invasive toadflaxes in North America (Sing et al., 2016). ...
... Those results revealed that all four host plants were used by R. dieckmanni and thus the native geographic range of the species is wider than multiple introductions of R. antirrhini "Dalmatian host race" during the 1990s in Canada and the USA, establishment in North America was sporadic and population numbers remained low (Sing et al., 2016). Literature on R. antirrhini "Dalmatian host race" is generally associated with studies related to the biological control of invasive toadflaxes in North America (Sing et al., 2016). A taxonomic review of the R. antirrhini species complex known to be associated with L. dalmatica and its closest relatives is conspicuously lacking. ...
... During the 1990 s, the "Dalmatian host race" was introduced to North America under the name R. antirrhini, but in contrast to the widespread distribution of this species (s. str.) across L. vulgaris populations in North America, the "Dalmatian host race" experienced conspicuous adversity in establishing significant populations in the adopted range, with negligible landscape-level impact on L. dalmatica (Sing et al., 2016). Difficulties with establishment were especially common in high elevation habitats with shorter summers and colder winters, although the release of such agents in this type of habitat was of primary interest (Turner, 2008). ...
A seed-feeding weevil introduced to North America (NA) as a biological control agent of the invasive toadflax Linaria dalmatica (L.) Mill., identified then as Gymnetron antirrhini "Dalmatian host race" and subsequently confirmed as established, was revealed through our study to be a separate species, i.e., Rhinusa dieckmanni (Behne) (Coleoptera: Curculionidae). This weevil species was presumed to be endemic in its native range, with a distribution restricted to Mount Rila in southwestern Bulgaria. We conducted a comprehensive study of seed-feeding weevils associated with L. dalmatica, L. dalmatica ssp. macedonica (Griseb.) D.A. Sutton, L. genistifolia (L.) Mill., and L. grandiflora Desf. across a broad geographic area of their native range. Those results revealed that all four host plants were used by R. dieckmanni and thus the native geographic range of the species is wider than expected, encompassing the Balkans and the Anatolian Plateau. Our observations suggest that phenotypes of this weevil are highly variable and dependent on the seed capsule size of the Linaria host population. The haplotype network based on mitochondrial COII, 16S genes, and nuclear EF 1-α gene genealogy confirmed the conspecific nature of geographically distant weevil populations, that is, R. dieckmanni phenotypes utilizing L. genistifolia, L. dalmatica, and L. grandiflora for larval development. Specimens collected from L. dalmatica in the northwestern USA shared the same haplotypes as samples from L. dalmatica ssp. macedonica in southwestern North Macedonia, supporting the known introduction history of the North American population. Females from these populations have relatively short rostrums, which may limit their reproductive success on North American invasive L. dalmatica with larger seed capsules.
... Yellow toadflax is native to Europe and was one of the first documented invasive plants in North America (Mack 2003). Yellow toadflax prefers relatively wet riparian environments and gullies and possesses a deep tap root that can compete for water and nutrients (Sing et al. 2016). It can spread via seed or shoot production from creeping rhizomes (McClay and De Clerck-Floate 2001;Ward et al. 2009). ...
Warming and changing water amount can alter the outcome of biotic interactions in native and exotic plants between facilitation and competition. Exotic plants may adapt better to changing environmental conditions, such that they may compete better than native plants.
We conducted competition trials for four plant species, two exotic forbs (Centaurea stoebe and Linaria vulgaris) and two grasses (exotic Poa compressa and native Pseudoroegneria spicata), commonly found in Southern interior British Columbia. We compared the effects of warming and changing water on target plant shoot and root biomass, and on pairwise competitive interactions among all four species. We quantified interactions using the Relative Interaction Intensity index, which has values from -1 (complete competition) to +1 (complete facilitation).
Key results: C. stoebe biomass was highest under low water and no competition. Facilitation of C. stoebe was found under high water and low temperatures but shifted to competition under low water and/or warming. Competition in L. vulgaris decreased due to reduced water and increased due to warming. Grasses were less competitively suppressed by warming, but more competitively suppressed by reduced water input.
The response of exotic plants to climate change can differ by plant species, moving in opposite directions for both forbs, but grasses appear to respond similarly. This has consequences for grasses and exotic plants in semi-arid grasslands.
... dalmatica (L.) Maire & Petitm.], Plantaginaceae) is an invasive alien forb that is established throughout much of North America and is especially problematic in the western half of the USA and Canada, where it displaces desirable vegetation and reduces forage for cattle (Lajeunesse, 1999;Sing and Peterson, 2011;De Clerck-Floate and Turner, 2013;Sing et al., 2016). It is a short-lived perennial that has multiple stems per taproot. ...
... Before the existence of the cryptic species was known, Jeanneret and Schroeder (1992) speculated that 'the weevil' would establish between latitudes 40 and 52 • N, which was based on the known distribution of 'Mecinus janthinus', before the discovery of the cryptic species. Successful establishment of M. janthiniformis has been documented in Alberta, British Columbia, Colorado, Idaho, Montana, Oregon, South Dakota, Utah, Washington and Wyoming (Sing et al., 2016). In California, it was first documented in the northeastern corner of the state in 2010, presumably having dispersed from Oregon since it was not permitted to be released in the State at that time (Villegas et al., 2011). ...
... On the other hand, L. dalmatica cover did not change in the year following the fire (25.5% in 2014 to 41.0% in 2015; F (10, 55) = 8.8, P < 0.0001, Tukey HSD). Although Jacobs and Sheley (2003) also observed no change in L. dalmatica cover after a fire in Montana in March 1999, it often increases after fires (Sing et al., 2016). Linaria dalmatica cover peaked in 2015 at 41.0% and decreased drastically (by 83% to 6.8% cover) by 2017 and by 99% to trace levels (0.3% cover) by 2019, which was visually evident in the field (Fig. 8). ...
Dalmatian toadflax (Linaria dalmatica) is a perennial forb that has invaded grasslands in North America. The weevil, Mecinus janthiniformis, has been released as a classical biological control agent in the western U.S. and Canada, but not in California because of concern that it might attack some nontarget native snapdragons (Antirrhinum spp.). An infestation of Dalmatian toadflax was discovered in southern California in 2004 at the Hungry Valley State Vehicular Recreation Area. In 2008, we released the weevil at three sites, and the populations increased to an average of 45 weevil pupal chambers per 100 cm of stem length in 2012, and 100% of L. dalmatica stems within 15 m were infested. Mecinus janthiniformis also spread to three nearby check sites (10-72% infestation). A wildfire in May 2013 destroyed the weevil population, but the toadflax recovered by 2014, and M. janthiniformis was released again. By 2017, the weevil populations had again increased at all release sites, with up to 47 weevil pupal chambers per 100 cm of stem length and 100% of stems infested. The weevils had dispersed at least 427 m, and population densities were similar at the release and check sites. Survivorship of immature and adult weevils overwintering inside the stems was high (92% survival), probably due to mild winter temperatures and absence of parasitism. The relatively warm climate probably allowed females to realize their maximum fecundity at this southernmost release site in North America. Dalmatian toadflax cover declined 99% from 2014 to 2019, whereas annual and perennial grasses increased, annual forbs remained abundant, and perennial forbs and shrubs remained rare.
... Grazing early in the growing season when weeds are more palatable or nutritious can provide high quality forage for livestock while creating optimal conditions for biocontrol agents with a preference for less dense stands of vegetation, such as the leafy spurge flea beetle ( Aphthona spp.) ( Bourchier et al. 2006 ). Although grazing and other non-selective methods of biomass removal can negatively impact biological control agents, species such as bison selectively feed on grasses and thus avoid harming stem dwelling agents such as the toadflax stem miners (Mecinus janthinus Germar and M. janthiniformis Tosevski & Caldara; Sing et al. 2016 ). ...
... Biological control research for some important grassland invaders is nearing the end of the research phase, and petitions for permits to release candidate agents will soon be submitted for a mite (Aceria angustifoliae Denizhan, Monfreda, de Lillo & Cobanoglu) and a moth (Anarsia eleagnella Kuznetsov) for control of seed production in Russian olive ( Sing et al. 2016 ), and a highly host-specific seed feeder for houndstongue ( Mogulones borraginis Fabricius) ( Park et al. 2018 ). A mite (Aceria drabae Nalepa) for hoary cress (Lepidium draba L.) ( De Lillo et al. 2017 ) and a stem-galling weevil (Rhinusa pilosa Gyllenhal) for yellow toadflax (Linaria vulgaris Mill.) ( Gassmann et al. 2014 ) were approved for release in 2018 and deployed in 2019. ...
The Great Plains of North America encompass approximately 1,300,000 km² of land from Texas to Saskatchewan. The integrity of these lands is under continual assault by long-established and newly-arrived invasive plant species, which can threaten native species and diminish land values and ecological goods and services by degrading desired grassland resources. The Great Plains are a mixture of privately and publicly owned lands, which leads to a patchwork of varying management goals and strategies for controlling invasive plants. Continually updated knowledge is required for efficient and effective management of threats posed by changing environments and invasive plants. Here we discuss current challenges, contemporary management strategies, and management tools and their integration, in hopes of presenting a knowledge resource for new and experienced land managers and others involved in making decisions regarding invasive plant management in the Great Plains.
... Pupation typically occurs mid-August to mid-September. Egg deposition triggers a gall to form in the seeds, causing from 8 to 17 seeds to grow to around 10 times their normal size rendering them unviable ( Sing et al. 2016). Mature larvae construct cells of loosely cemented fragments of the placentae which serve as pupal cases and subsequently as overwintering sites for the adults (Smith 1959). ...
... Adults often feed on stems of the host plant and before overwintering in soil or plant litter. Occasionally, fully developed adults may remain within the root galls throughout the fall and winter, emerging the following spring ( Sing et al. 2016). ...
... Remarks.-Rhinusa linariae was approved for release for biological control of invasive toadflaxes (Linaria spp.) in Canada in 1995and 1996(Sing et al. 2016, and after several attempts a population was established at a site in Brit- ish Columbia in 1997 (De Clerck-Floate andHarris 2002). A population from British Columbia was redistributed to Colorado in 2008(Sing et al. 2016, and Idaho, overwintering adults emerge beginning in mid-May to early June depending on elevation. ...
... Adults of M. janthiniformis emerge from exit holes in overwintered toadflax stems in early spring to mate and lay eggs into newly growing host stems, and the larvae mine internally within these stems and pupate during mid to late summer (Jeanneret and Schroeder 1992, Toševski et al. 2011, Sing et al. 2016. After completing pupation, individuals remain in host stems as adults during the autumn and winter. ...
... After completing pupation, individuals remain in host stems as adults during the autumn and winter. The dates corresponding to these general seasonal patterns can be expected to vary significantly across the wide range of latitude and local conditions where the weevil has been introduced (Sing et al. 2016). These dates, therefore, require field evaluation for individual geographical areas. ...
... Complete development from oviposition to adulthood takes approximately 50-62 d (Jeanneret and Schroeder 1992). The phenology of the weevil across western North America is similar, with larvae developing within stems from early May to early August, after which the majority of individuals occurring within stems are pupae or adults (Sing et al. 2016). However, larvae develop within stems well into October in Alberta, Canada, likely due to delayed maturation resulting from low spring temperatures (McClay and Hughes 2007). ...
The summer phenology and survivorship of the stem-mining weevil, Mecinus janthiniformis Toševski and Caldara, a biocontrol agent of Dalmatian toadflax, Linaria dalmatica (L.) Miller, was studied in 2015-2016 as it developed within host plant stems at a low elevation, open rangeland site in northern Utah. Hatching from eggs in spring and early summer, weevils occurred as larvae within stems in June. Earliest maturing adults occurred in mid-July, and the majority of individuals had completed pupal development by early August. Survivorship within stems was high, with two-thirds or more of individuals surviving from egg hatch to adulthood as assessed in mid-September. Mortality rates within stems were highest during larval development, with parasitism accounting for the majority of deaths. At least three parasitoid species (Chalcidoidea: Pteromalidae and Eupelmidae), including both endoparasitoids and ectoparasitoids, were found attacking weevils within stems. Although most surviving weevils remained as adults within stems to overwinter, some adults were found to have chewed exit holes, and in some cases had exited from stems, beginning in July; the fate of these prematurely exiting adults is unknown. Low summer mortality rates within stems should promote weevil establishment under the hot, dry conditions of northern Utah, but parasitism and premature exiting of adults from host stems merit further investigation concerning their potential to reduce biocontrol efficacy. The results presented here for M. janthiniformis phenology within host stems will contribute to the development of standardized, summer monitoring for this biocontrol agent by stem dissection.
... Hybrid Linaria populations present additional management challenges, as currently available chemical and biological controls are often less effective on these populations . Accurate taxonomic identification can be complicated by decreasing morphological differences between late-generation backcrossed hybrids and the recurrent parent (Olson et al. 2009), leading in the case of Linaria hybrids to deployment of biocontrol agents that are suboptimally matched with the host plants (Boswell et al. 2016;Sing et al. 2016). ...
Invasive populations of Dalmation toadflax [ Linaria dalmatica (L.) Mill.] and yellow toadflax ( Linaria vulgaris Mill.) are widespread throughout the Intermountain West, where gene flow between these nonnative species is producing vigorous and fertile hybrids. These hybrid toadflax populations are less responsive to herbicides than either parent species, and biocontrol agents routinely released on L. dalmatica and L. vulgaris often fail to establish on hybrid hosts. Early detection of hybrid Linaria populations is therefore essential for effective management, but resources are limited for scouting large expanses of range and wildland. We used species distribution modeling to identify environmentally suitable areas for these invasive Linaria taxa in Montana, Wyoming, and Colorado. Areas suitable for hybrid Linaria establishment were estimated using two different modeling approaches: first, based on known hybrid occurrence and associated environmental conditions, and second, based on zones environmentally suitable for co-occurrence of the parent species. This also allowed comparison of different model outputs, especially relevant when modeling emerging invasives, such as novel hybrids, with minimal occurrence data. Combining the two model outputs identified areas at greatest risk of hybrid Linaria invasion, including parts of north-central Montana, where model estimates indicate the hybrid may spread without prior co-invasion of the parents. Potential hybrid hot spots were also identified in western Montana; northwestern, northeastern, and southeastern Wyoming; and the Western Slope and Front Range of Colorado. Despite relatively few confirmed occurrences of hybrid populations to date, our results indicate that extensive spread of hybrid populations is possible within the studied area. Model-based maps of potential Linaria distributions will allow area weed managers to direct limited resources more effectively for locating and controlling these invaders.
... and Linaria dalmatica (L.) Mill. (Plantaginaceae), are perennial Eurasian forbs that have become widespread invaders of natural areas and agricultural land in North America (Vujnovic & Wein, 1997;Pauchard et al., 2003;Sing et al., 2016). Both plants are listed as a noxious or regulated weed in British Columbia, Alberta, Saskatchewan, Manitoba, Idaho, Montana, Colorado, Nevada, New Mexico, Oregon, South Dakota, Washington and Wyoming (Center for Invasive Species Management, 2014; USDA-NRCS, 2018). ...
... These two Linaria species have been the targets of classical biological control programmes in Canada and the USA since 1960s (De Clerck-Floate & Harris, 2002;McClay & De Clerck-Floate, 2002;De Clerck-Floate & McClay, 2013;De Clerck-Floate & Turner, 2013;Sing et al., 2016). Host specificity data collected during 1989-99 by CABI, Delémont Switzerland (hereafter, CABI) on a stem-mining weevil then identified as M. janthinus Germar (Coleoptera: Curculionidae) (Jeanneret & Schroeder, 1992) supported releasing the weevil against both yellow toadflax and Dalmatian toadflax in North America. ...
Linaria vulgaris, common or yellow toadflax, and Linaria dalmatica, Dalmatian toadflax (Plantaginaceae), are Eurasian perennial forbs invasive throughout temperate North America. These Linaria species have been the targets of classical biological control programmes in Canada and the USA since the 1960s. The first effective toadflax biological control agent, the stem‐mining weevil Mecinus janthinus (Coleoptera: Curculionidae) was introduced from Europe in the 1990s. This weevil has become established on L. dalmatica and L. vulgaris in both countries, although it has shown greater success in controlling the former toadflax species. Genetic and ecological studies of native range M. janthinus populations revealed that weevils previously identified as a single species in fact include two cryptic species, now recognised as M. janthinus, associated with yellow toadflax, and the recently confirmed species Mecinus janthiniformis, associated with Dalmatian toadflax. The results of a comprehensive study characterising haplotype identities, distributions and frequencies within M. janthinus s.l. native range source populations were compared to those populations currently established in the USA and Canada. The presence of both Mecinus species in North America was confirmed, and revealed with a few exceptions a high and consistent level of host fidelity throughout the adopted and native ranges. Genetic analysis based on mitochondrial cytochrome oxidase subunit II gene (mtCOII) defined the origin and records the subsequent North American establishment, by haplotype, of the European founder populations of M. janthinus (northern Switzerland and southern Germany) and M. janthiniformis (southern Macedonia), and provided population genetic indices for the studied populations. This analysis together with existing North American shipment receipt, release and rearing records elucidates probable redistribution routes and sources of both weevil species from initially released and established adopted range populations.
... Dalmatian toadflax, Linaria dalmatica (L.) Miller (Plantaginaceae), is now one such significant invasive weed in North America (Duncan et al. 2004, Sing and. First introduced as an ornamental from Eurasia in the 19th century (Sing et al. 2016), Dalmatian toadflax has subsequently invaded thousands of hectares of disturbed range and agricultural land in western North America, and it continues to spread into the southwest (Robocker 1974, Jeanneret and Schroeder 1992, Vujnovic and Wein 1997, Dodge et al. 2008, USDA 2014. The weed is a herbaceous perennial with tall erect stems that germinate in early spring and can flower at any time throughout the summer (Sing et al. 2016). ...
... First introduced as an ornamental from Eurasia in the 19th century (Sing et al. 2016), Dalmatian toadflax has subsequently invaded thousands of hectares of disturbed range and agricultural land in western North America, and it continues to spread into the southwest (Robocker 1974, Jeanneret and Schroeder 1992, Vujnovic and Wein 1997, Dodge et al. 2008, USDA 2014. The weed is a herbaceous perennial with tall erect stems that germinate in early spring and can flower at any time throughout the summer (Sing et al. 2016). It is highly competitive in many plant communities and reduces the quality of rangeland forage by displacing native and forage plants in mountain grasslands, valleys, and foothills between 1,300 and 3,100 m in elevation (Pyke 2000, Zouhar 2003. ...
... Dalmatian toadflax is not easily controlled by chemical and mechanical methods (Vujnovic and Wein 1997) and has hence been a target species for biological control. Among a number of insect biocontrol agents introduced against the weed (Sing et al. 2016), the stem-mining weevil Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae) has proved especially promising. This agent is not readily morphologically distinguishable from its close relative, the yellow toadflax stem-mining weevil Mecinus janthinus Germar, and as a result, both species were introduced in shipments of M. janthinus s.l. to North America, with the first approved releases occurring in British Columbia in 1991 (Jeanneret and Schroeder 1992, USDA-APHIS 1996, De Clerck-Floate and Harris 2002, De Clerck-Floate and Miller 2002. ...
The phenology of the stem-mining weevil Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae) as adults attacking Dalmatian toadflax, Linaria dalmatica (L.) Miller (Plantaginaceae), was studied in 2014-2015 at two low elevation sites in northern Utah. The seasonal pattern of adult weevil abundance on the host plant at the two sites was most similar between years when described by degree-day accumulation, versus calendar date. Repeated censusing over the growing season revealed that males appeared first and subsequently peaked in abundance on the host plant earlier than females did, such that the adult population was dominated by males early in the season and by females late in the season. Peak female abundance on the host plant occurred at the time when Dalmatian toadflax stems reached their maximum height and density and when they began flowering widely. Maximum toadflax stem heights and densities, and flowering activity, were markedly reduced in 2015 compared to 2014. In contrast to these host plant parameters that vary between years, degree-day accumulation can be used readily for timing collection and survey efforts for adult weevils and female adult weevils in particular. Use of degree-day accumulation can thereby facilitate implementation of redistribution and monitoring programs for M. janthiniformis as a biological control agent of Dalmatian toadflax.
... Without these enemies, invasive pests are free to establish, survive and spread in novel territories, often at the detriment of native species. The aim of classical biological control programs, centered on this hypothesis, is to reunite invasive pests with their natural co-evolved enemies from their native ranges, with the goal of "restoring the ecological balance" of pest populations that is experienced in their native ranges (Sing et al. 2016, DeBach 1964, Keane and Crawley 2002. These natural enemies or "biocontrol agents" can indeed be very effective in providing long-term and sustainable suppression of pest populations, and are often host specific to reduce negative impacts on neighboring species (Caltagirone 1981). ...
... So far, nine species of biocontrol insects have been intentionally or unintentionally introduced to feed on noxious toadflaxes in North America (Sing et al. 2016, Winston et al. 2014. All are within the orders Coleoptera and Lepidoptera (beetles 5 and moths, respectively) and five were pre-screened for suitability and host specificity by CABI Bioscience before introduction to North America (Sing et al. 2016). ...
... So far, nine species of biocontrol insects have been intentionally or unintentionally introduced to feed on noxious toadflaxes in North America (Sing et al. 2016, Winston et al. 2014. All are within the orders Coleoptera and Lepidoptera (beetles 5 and moths, respectively) and five were pre-screened for suitability and host specificity by CABI Bioscience before introduction to North America (Sing et al. 2016). Of these, the most successful biocontrol agent was Mecinus janthiniformis, a stem-mining weevil approved for release in British Columbia in 1991 as a biocontrol agent of Dalmatian toadflax (Jeanneret and Schroeder 1992, Harris et al. 2000, Nowierski 2004, Sing et al. 2016). ...
One option for long-term control of invasive weeds is biological control using natural insect enemies. Such a program has been developed for management of Dalmatian toadflax (Linaria dalmatica (L.) Miller (Plantaginaceae)) in North America using a stem-mining weevil, Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae). Although widely effective in British Columbia and in the American northwest, this insect has been slow to suppress Dalmatian toadflax in southern regions of their current range, including areas in Utah. Using field assessments of insect and plant activity over two years at sites where weevils have been slow to establish, this study aimed to provide descriptions of insect phenology and estimates of weevil mortality during a lifecycle. Interestingly, the sexes differed in their phenology in that males consistently emerged from overwintering sites and were found on Dalmatian toadflax stems considerably earlier than females in the spring. In general, both sexes tended to peak in abundance on stems in late May when Dalmatian toadflax stems reached full maturity. Overall mortality of M. janthiniformis during a lifecycle was low for all samples; approximately 83% of adults successfully emerged from overwintered stems in the following spring, and greater than 65% of larvae survived to adulthood before overwintering, although a considerable rate of parasitism was observed. Although M. janthiniformis populations were slow to establish at sites in Utah, this study indicates that the phenology and survivorship of M. janthiniformis is well suited for successful biocontrol in Utah and likely in other southern ranges of their current range.
