Sharlene Sing - Academia.edu (original) (raw)
Papers by Sharlene Sing
The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United State... more The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United States in Montana, in 1996. This agent has now become established to varying degrees after subsequent releases made at sites throughout the state. Multiple releases of M. janthinus have presented researchers with a unique opportunity to evaluate the efficacy of this agent in diverse habitats and under a variety of environmental conditions. The results presented in this paper summarize findings from long-term field data, illustrating not only the impact of M. janthinus on the target weed, Dalmatian toadflax, Linaria dalmatica (L.) P. Mill., but also on correlated plant community dynamics. These results additionally provide a valuable means to compare and contrast the biotic response and control efficacy of this agent at both a regional and sub-continental scale.
Invasive Species in Forests and Rangelands of the United States, 2021
Managing invasive species becomes increasingly difficult and expensive as populations of new path... more Managing invasive species becomes increasingly difficult and expensive as populations of new pathogens, plants, insects, and other animals (i.e., pests) spread and reach high densities. Research over the past decade confirms the value of early intervention strategies intended to (1) prevent invasive species from arriving within an endangered area or (2) detect and respond quickly to new species incursions (Baker et al. 2009; Ewel et al. 1999; Holden et al. 2016; Leung et al. 2014). The goal of such biosecurity approaches is to keep or return the density of invasive species to zero so that damages from those pests might be prevented or to confine populations to localized areas so that damage from those species might be limited (Magarey et al. 2009). Prediction, prevention, early detection, eradication, and other rapid responses, all components of proactive management, are less costly and more effective than reactive tactics (Epanchin-Niell and Liebhold 2015; Leung et al. 2002; Lodge ...
The root cause of the biological invasion problem is globalization, which has facilitated the pla... more The root cause of the biological invasion problem is globalization, which has facilitated the planet-wide breakdown of biogeographic barriers to species migration (Mooney and Hobbs 2000). In order to understand and manage the problem, coordination on a global scale is essential, and international cooperation among affected countries as well as with countries of pest origin must therefore play a critical role in virtually all aspects of research on biological invasions (Chornesky et al. 2005; McNeely et al. 2001; Perrings et al. 2010; Wingfield et al. 2015). Here we discuss key aspects of research on biological invasions, where international collaboration and coordination are important, and what infrastructures play a role in this work.
Projects to develop biological control solutions against invasive plants are midto long-term ende... more Projects to develop biological control solutions against invasive plants are midto long-term endeavors that require considerable financial support over several years. Discussions of concerns and potential conflicts of interests often occur when biological control agents are first being proposed for release into the environment. Such late discussion, which in some cases results in delays or in the halt of ongoing biological control programs, has led to uncertainty, confusion and frustration among the various stakeholder groups, including the biological control practitioners. Russian olive (Elaeagnus angustifolia L.), a small tree or multi-stemmed shrub native to south-eastern Europe and Asia, was introduced to North America in the late 19th century as a horticultural plant. It has since spread into the environment, particularly along river courses where it now occupies similar habitats as tamarisk. To date, Russian olive has become a declared noxious weed in four US states. Because o...
An exotic toadflax stem mining weevil conventionally identified as Mecinus janthinus Germar has b... more An exotic toadflax stem mining weevil conventionally identified as Mecinus janthinus Germar has become widely established on Dalmatian toadflax [Linaria dalmatica (Linnaeus) Miller] in western North America, although agent density and control efficacy are highly variable across release sites (De Clerck-Floate & Miller, 2002; McClay & Hughes, 2007; Van Hezewijk et al., 2010). Naturally-occurring and fertile hybrid toadflax (HT) populations resulting from the cross-pollination of Dalmatian toadflax (DT) and a sister species, yellow toadflax (Linaria vulgaris Miller) (YT), have been discovered in Montana (Ward et al., 2009). Genetically distinct, host-specific Mecinus species have been confirmed from native range populations (Tosevski et al., 2011). In Montana, the DT-associated M. janthiniformis Tosevski & Caldara sp.n. appears to be abundant and widespread, while the YT-associated weevil confirmed to be Mecinus janthinus Germar, 1821 appears to occur much less frequently (Tosevski, p...
![Research paper thumbnail of Ecology and management of yellow toadflax [Linaria vulgaris (L.) Mill.]](https://attachments.academia-assets.com/88139674/thumbnails/1.jpg)
](Yellow toadflax is a short-lived perennial herb native to the steppes of southeastern Europe and ... more Yellow toadflax is a short-lived perennial herb native to the steppes of southeastern Europe and southwestern Asia (Eurasia). This species spreads by both seeds and vegetative buds on its roots and creeping rhizomes (see Figure 1). Yellow toadflax was intentionally introduced in North America but has escaped cultivation as an ornamental, a source of fabric dye, and as a folk remedy to become an opportunistic invader associated with natural and anthropogenic disturbances throughout the continental United States, in all Canadian provinces and territories, and in parts of Mexico. In Montana, yellow toadflax was first reported in Flathead County in 1899 and by 2006 was reported from 32 Montana counties, mostly west of the continental divide (http://invader.dbs.umt.edu). Yellow toadflax is typically found on sites with higher moisture resources than those supporting Dalmatian toadflax infestations. Despite being designated a
Environmental Entomology, 2020
The leaf beetle Diorhabda carinulata Desbrochers (Coleoptera: Chrysomelidae) was introduced into ... more The leaf beetle Diorhabda carinulata Desbrochers (Coleoptera: Chrysomelidae) was introduced into the United States in 1999 for classical biological control of the exotic woody invader saltcedar (Tamarix spp. L. [Caryophyllales: Tamaricaceae]). The recent southern expansion of the range of D. carinulata in the United States has precipitated conflict between proponents of biological control of Tamarix and those with concerns over habitat conservation for avian species. Several semiochemicals that mediate aggregations by this species have been reported, but no repellent compounds have been recorded thus far. We now report a repellent compound, 4-oxo-(E)-2-hexenal, induced by adult D. carinulata feeding on saltcedar foliage. Collection of headspace volatiles, gas chromatography mass spectrometry, and electroantennographic analyses identified 4-oxo-(E)-2-hexenal as an insect-induced compound that is antennally active. Behavioral and exposure assays were conducted to test for repellency a...
Rangeland Ecology & Management, 2020
The Great Plains of North America encompass approximately 1,30 0,0 0 0 km 2 of land from Texas to... more The Great Plains of North America encompass approximately 1,30 0,0 0 0 km 2 of land from Texas to Saskatchewan. The integrity of these lands is under continual assault by long-established and newlyarrived 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.
Journal of Chemical Ecology, 2020
Before weed biocontrol insects are transported and released in a new area, they are commonly coll... more Before weed biocontrol insects are transported and released in a new area, they are commonly collected into small paper containers, chilled, and kept under dark conditions. This process can be termed a pre-release protocol. The influence of a prerelease protocol on establishment success of a gregarious biological control agent was assessed using the northern tamarisk beetle, Diorhabda carinulata (Desbrochers), and its exotic, invasive host plant saltcedar (Tamarix spp.). Pre-release protocol impacts on aggregation pheromone production by D. carinulata were characterized under controlled conditions. Additional experiments were undertaken to determine if deployment of aggregation pheromone lures might enhance the agent's persistence at release sites. Adults that experienced the pre-release protocol produced less aggregation pheromone compared to undisturbed adults. Olfactometer bioassays indicated that a cohort of adults subjected to the pre-release protocol were less attractive to other adults than a control cohort. Efficacy of aggregation pheromone-based lures to retain adults at release sites was evaluated by comparing capture numbers of adult beetles at paired treatment and control release sites, 10-14 days after the release of 300, 500, or 1000 individuals. A greater number of adult D. carinulata were captured where the pheromone lures had been deployed compared to control release sites. Application of aggregation pheromone when a new release of D. carinulata is planned should allow biological control practitioners to increase retention of beetles at a release site.
Annals of Applied Biology, 2018
Linaria vulgaris, common or yellow toadflax, and Linaria dalmatica, Dalmatian toadflax (Plantagin... more 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.
Glossary defines technical terms essential to communicating specifics about toadflax biological c... more Glossary defines technical terms essential to communicating specifics about toadflax biological control. Words in bold italic in text are defined in the glossary. Selected References are provided from the large body of literature on toadflax biology, ecology, and biological control. Also included is a selected list of Internet sites that provide a wealth of practical information. Appendices provides the Code of Best Practices for Classical Biological Control of Weeds, a troubleshooting guide, examples of insect release and monitoring forms, and vegetation monitoring forms (these forms may be reproduced for use as needed).
Pest management science, 2018
Semiochemicals for monitoring, attracting or repelling pest and beneficial organisms are increasi... more Semiochemicals for monitoring, attracting or repelling pest and beneficial organisms are increasingly deployed in agricultural and forest systems for pest management. However, the use of aggregation pheromones and host-plant attractants for the express purpose of increasing the efficacy of classical biological control agents of weeds has not been widely reported. Therefore, we conducted field-based assays to determine if a specialized wax-based matrix impregnated with an aggregation pheromone of the northern tamarisk beetle Diorhabda carinulata (Desbrochers) or host-plant volatiles could increase the efficacy of D. carinulata. The aggregation pheromone and host-plant volatiles were formulated for field application using a wax-based matrix. Reported release rates suggest that this matrix is a viable formulation for enhancing D. carinulata aggregations under field conditions. Pheromone-treated saltcedar plants (Tamarix spp.) not only had higher densities of adult and larval D. carinul...
Invasive Plant Science and Management, 2016
Gene flow between Dalmatian toadflax (DT) and yellow toadflax (YT), both aggressive invaders thro... more Gene flow between Dalmatian toadflax (DT) and yellow toadflax (YT), both aggressive invaders throughout the Intermountain West, is creating hybrid populations potentially more invasive than either parent species. To determine the direction of gene flow in these hybrid populations, species-diagnostic cytoplasmic markers were developed. Markers were based on polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) polymorphisms in the trnT-D chloroplast DNA (cpDNA) region digested with Alu1, and single-nucleotide polymorphisms (SNPs) in the matK and trnL-F chloroplast-barcoding regions. Four hybrid toadflax populations sampled from Colorado, Montana, and Washington contained both DT and YT cytoplasm, with YT predominating; 25 individuals from a fifth hybrid population from Idaho all had identical YT cpDNA haplotypes. Thirteen plants from two Colorado populations, assumed to be DT based on morphology and geographic isolation from any known YT population, were found...
Journal of Entomological Science, 2011
Our study reports the results of field and garden experiments designed to quantitatively evaluate... more Our study reports the results of field and garden experiments designed to quantitatively evaluate the impact of herbivory by a weed biological control agent, the stem-mining weevil Mecinus janthinus Germar, on the growth of its exotic host Dalmatian toadflax, Linaria dalmatica (L.) Miller. Herbivory by M. janthinus under both natural and manipulated environmental conditions inhibited L. dalmatica growth. Reductions in stem length, biomass, and growth were more pronounced for plants subjected to both exophagous (adult) and endophagous (larval) feeding injury than for plants exposed only to adult folivory. Decreases we observed in root biomass could additionally inhibit shoot production from lateral roots. This provides a plausible mechanism explaining anecdotal reports correlating the reduced spread of L. dalmatica with attack by M. jan thin us. Our results indicate that L. dalmatica growth is compromised once a threshold density equivalent to 5 M. janthinus larvae per stem is exceeded. The consistency of growth responses observed in this study suggests that a mechanistic/quantitative approach, such as measuring the impact of M. jan thin us herbivory on L. dalmatica, is a robust and relevant method for postrelease evaluations of weed biocontrol efficacy.
Tansy ragwort, a member of the Asteraceae taxonomic family, is a large biennial or short-lived pe... more Tansy ragwort, a member of the Asteraceae taxonomic family, is a large biennial or short-lived perennial herb native to and widespread throughout Europe and Asia. Stems can grow to a height of 5.5 feet (1.75 meters), with the lower half simple and the upper half many-branched at the inflorescence. Reproductive stems produce up to 2,500 bright golden-yellow flowers. Capitula (flowerheads) arranged in 20-60 flat-topped, dense corymbs per plant are composed of ray and disc florets; both produce achenes containing a single seed. Rosettes formed of distinctive pinnately-lobed leaves attain a diameter of up to 1.5 feet (0.5 meter). First reported in Montana in 1979 in Mineral County, tansy ragwort has since spread into Flathead, Lincoln, and Sanders Counties. Soils with medium to light textures in areas receiving sufficient rainfall (34 inches or 860 millimeters/year) readily support populations of tansy ragwort. This species is a troublesome weed in decadent pastures, waste areas, clear-...
Invasive Plant Science and Management, 2009
Although there is evidence that interspecific hybridization can initiate invasion by nonnative pl... more Although there is evidence that interspecific hybridization can initiate invasion by nonnative plants, there are few documented examples of novel hybridization events between introduced plant species already exhibiting invasive behavior. We conducted morphometric and molecular analyses of toadflax plants with intermediate morphology found at two sites in Montana, which were co-invaded by yellow toadflax and Dalmatian toadflax. Field-collected putative hybrid plants had intermediate morphometric scores (mean 0.47, on a scale of 0.0 = indistinguishable from Dalmatian toadflax to 1.0 = indistinguishable from yellow toadflax) for a suite of phenotypic traits that differentiate the parent species (leaf length : width ratio, growth form, seed morphology, inflorescence type, and ventral petal shape). Inter-simple sequence repeat (ISSR) analysis of a subset of these putative hybrids revealed combinations of species-diagnostic bands, confirming the presence of DNA from both parent species. C...
Proceedings of the XII International Symposium on Biological Control of Weeds, La Grande Motte, France, 22-27 April, 2007
The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United State... more The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United States in Montana, in 1996. This agent has now become established to varying degrees after subsequent releases made at sites throughout the state. Multiple releases of M. janthinus have presented researchers with a unique opportunity to evaluate the efficacy of this agent in diverse habitats and under a variety of environmental conditions. The results presented in this paper summarize findings from long-term field data, illustrating not only the impact of M. janthinus on the target weed, Dalmatian toadflax, Linaria dalmatica (L.) P. Mill., but also on correlated plant community dynamics. These results additionally provide a valuable means to compare and contrast the biotic response and control efficacy of this agent at both a regional and sub-continental scale.
A close relative of spotted knapweed in the Asteraceae taxonomic family, diffuse knapweed is typi... more A close relative of spotted knapweed in the Asteraceae taxonomic family, diffuse knapweed is typically biennial, reproducing exclusively by seed. It forms a rosette with a central crown and tap root in the juvenile stage and a single upright stem one to three feet (0.3 to 0.9 m) tall with numerous spreading branches at maturity. White (occasionally purple) flowers are borne in heads with spiny bracts (see Figure 1). It is generally found on more arid sites than spotted knapweed. Native to the Mediterranean region, diffuse knapweed was first recorded in Montana from Mineral County in 1951 and by 2008 had been reported from 39 of Montana's 56 counties. Its dense, spiny overstory reduces the availability of desirable forage plants to livestock and wildlife, and grass production can be reduced by over 90% in heavy infestations. Declines in diffuse knapweed populations in western North America have been attributed to the lesser knapweed flower weevil (Larinus minutus), one of 14 app...
The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United State... more The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United States in Montana, in 1996. This agent has now become established to varying degrees after subsequent releases made at sites throughout the state. Multiple releases of M. janthinus have presented researchers with a unique opportunity to evaluate the efficacy of this agent in diverse habitats and under a variety of environmental conditions. The results presented in this paper summarize findings from long-term field data, illustrating not only the impact of M. janthinus on the target weed, Dalmatian toadflax, Linaria dalmatica (L.) P. Mill., but also on correlated plant community dynamics. These results additionally provide a valuable means to compare and contrast the biotic response and control efficacy of this agent at both a regional and sub-continental scale.
Invasive Species in Forests and Rangelands of the United States, 2021
Managing invasive species becomes increasingly difficult and expensive as populations of new path... more Managing invasive species becomes increasingly difficult and expensive as populations of new pathogens, plants, insects, and other animals (i.e., pests) spread and reach high densities. Research over the past decade confirms the value of early intervention strategies intended to (1) prevent invasive species from arriving within an endangered area or (2) detect and respond quickly to new species incursions (Baker et al. 2009; Ewel et al. 1999; Holden et al. 2016; Leung et al. 2014). The goal of such biosecurity approaches is to keep or return the density of invasive species to zero so that damages from those pests might be prevented or to confine populations to localized areas so that damage from those species might be limited (Magarey et al. 2009). Prediction, prevention, early detection, eradication, and other rapid responses, all components of proactive management, are less costly and more effective than reactive tactics (Epanchin-Niell and Liebhold 2015; Leung et al. 2002; Lodge ...
The root cause of the biological invasion problem is globalization, which has facilitated the pla... more The root cause of the biological invasion problem is globalization, which has facilitated the planet-wide breakdown of biogeographic barriers to species migration (Mooney and Hobbs 2000). In order to understand and manage the problem, coordination on a global scale is essential, and international cooperation among affected countries as well as with countries of pest origin must therefore play a critical role in virtually all aspects of research on biological invasions (Chornesky et al. 2005; McNeely et al. 2001; Perrings et al. 2010; Wingfield et al. 2015). Here we discuss key aspects of research on biological invasions, where international collaboration and coordination are important, and what infrastructures play a role in this work.
Projects to develop biological control solutions against invasive plants are midto long-term ende... more Projects to develop biological control solutions against invasive plants are midto long-term endeavors that require considerable financial support over several years. Discussions of concerns and potential conflicts of interests often occur when biological control agents are first being proposed for release into the environment. Such late discussion, which in some cases results in delays or in the halt of ongoing biological control programs, has led to uncertainty, confusion and frustration among the various stakeholder groups, including the biological control practitioners. Russian olive (Elaeagnus angustifolia L.), a small tree or multi-stemmed shrub native to south-eastern Europe and Asia, was introduced to North America in the late 19th century as a horticultural plant. It has since spread into the environment, particularly along river courses where it now occupies similar habitats as tamarisk. To date, Russian olive has become a declared noxious weed in four US states. Because o...
An exotic toadflax stem mining weevil conventionally identified as Mecinus janthinus Germar has b... more An exotic toadflax stem mining weevil conventionally identified as Mecinus janthinus Germar has become widely established on Dalmatian toadflax [Linaria dalmatica (Linnaeus) Miller] in western North America, although agent density and control efficacy are highly variable across release sites (De Clerck-Floate & Miller, 2002; McClay & Hughes, 2007; Van Hezewijk et al., 2010). Naturally-occurring and fertile hybrid toadflax (HT) populations resulting from the cross-pollination of Dalmatian toadflax (DT) and a sister species, yellow toadflax (Linaria vulgaris Miller) (YT), have been discovered in Montana (Ward et al., 2009). Genetically distinct, host-specific Mecinus species have been confirmed from native range populations (Tosevski et al., 2011). In Montana, the DT-associated M. janthiniformis Tosevski & Caldara sp.n. appears to be abundant and widespread, while the YT-associated weevil confirmed to be Mecinus janthinus Germar, 1821 appears to occur much less frequently (Tosevski, p...
Yellow toadflax is a short-lived perennial herb native to the steppes of southeastern Europe and ... more Yellow toadflax is a short-lived perennial herb native to the steppes of southeastern Europe and southwestern Asia (Eurasia). This species spreads by both seeds and vegetative buds on its roots and creeping rhizomes (see Figure 1). Yellow toadflax was intentionally introduced in North America but has escaped cultivation as an ornamental, a source of fabric dye, and as a folk remedy to become an opportunistic invader associated with natural and anthropogenic disturbances throughout the continental United States, in all Canadian provinces and territories, and in parts of Mexico. In Montana, yellow toadflax was first reported in Flathead County in 1899 and by 2006 was reported from 32 Montana counties, mostly west of the continental divide (http://invader.dbs.umt.edu). Yellow toadflax is typically found on sites with higher moisture resources than those supporting Dalmatian toadflax infestations. Despite being designated a
Environmental Entomology, 2020
The leaf beetle Diorhabda carinulata Desbrochers (Coleoptera: Chrysomelidae) was introduced into ... more The leaf beetle Diorhabda carinulata Desbrochers (Coleoptera: Chrysomelidae) was introduced into the United States in 1999 for classical biological control of the exotic woody invader saltcedar (Tamarix spp. L. [Caryophyllales: Tamaricaceae]). The recent southern expansion of the range of D. carinulata in the United States has precipitated conflict between proponents of biological control of Tamarix and those with concerns over habitat conservation for avian species. Several semiochemicals that mediate aggregations by this species have been reported, but no repellent compounds have been recorded thus far. We now report a repellent compound, 4-oxo-(E)-2-hexenal, induced by adult D. carinulata feeding on saltcedar foliage. Collection of headspace volatiles, gas chromatography mass spectrometry, and electroantennographic analyses identified 4-oxo-(E)-2-hexenal as an insect-induced compound that is antennally active. Behavioral and exposure assays were conducted to test for repellency a...
Rangeland Ecology & Management, 2020
The Great Plains of North America encompass approximately 1,30 0,0 0 0 km 2 of land from Texas to... more The Great Plains of North America encompass approximately 1,30 0,0 0 0 km 2 of land from Texas to Saskatchewan. The integrity of these lands is under continual assault by long-established and newlyarrived 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.
Journal of Chemical Ecology, 2020
Before weed biocontrol insects are transported and released in a new area, they are commonly coll... more Before weed biocontrol insects are transported and released in a new area, they are commonly collected into small paper containers, chilled, and kept under dark conditions. This process can be termed a pre-release protocol. The influence of a prerelease protocol on establishment success of a gregarious biological control agent was assessed using the northern tamarisk beetle, Diorhabda carinulata (Desbrochers), and its exotic, invasive host plant saltcedar (Tamarix spp.). Pre-release protocol impacts on aggregation pheromone production by D. carinulata were characterized under controlled conditions. Additional experiments were undertaken to determine if deployment of aggregation pheromone lures might enhance the agent's persistence at release sites. Adults that experienced the pre-release protocol produced less aggregation pheromone compared to undisturbed adults. Olfactometer bioassays indicated that a cohort of adults subjected to the pre-release protocol were less attractive to other adults than a control cohort. Efficacy of aggregation pheromone-based lures to retain adults at release sites was evaluated by comparing capture numbers of adult beetles at paired treatment and control release sites, 10-14 days after the release of 300, 500, or 1000 individuals. A greater number of adult D. carinulata were captured where the pheromone lures had been deployed compared to control release sites. Application of aggregation pheromone when a new release of D. carinulata is planned should allow biological control practitioners to increase retention of beetles at a release site.
Annals of Applied Biology, 2018
Linaria vulgaris, common or yellow toadflax, and Linaria dalmatica, Dalmatian toadflax (Plantagin... more 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.
Glossary defines technical terms essential to communicating specifics about toadflax biological c... more Glossary defines technical terms essential to communicating specifics about toadflax biological control. Words in bold italic in text are defined in the glossary. Selected References are provided from the large body of literature on toadflax biology, ecology, and biological control. Also included is a selected list of Internet sites that provide a wealth of practical information. Appendices provides the Code of Best Practices for Classical Biological Control of Weeds, a troubleshooting guide, examples of insect release and monitoring forms, and vegetation monitoring forms (these forms may be reproduced for use as needed).
Pest management science, 2018
Semiochemicals for monitoring, attracting or repelling pest and beneficial organisms are increasi... more Semiochemicals for monitoring, attracting or repelling pest and beneficial organisms are increasingly deployed in agricultural and forest systems for pest management. However, the use of aggregation pheromones and host-plant attractants for the express purpose of increasing the efficacy of classical biological control agents of weeds has not been widely reported. Therefore, we conducted field-based assays to determine if a specialized wax-based matrix impregnated with an aggregation pheromone of the northern tamarisk beetle Diorhabda carinulata (Desbrochers) or host-plant volatiles could increase the efficacy of D. carinulata. The aggregation pheromone and host-plant volatiles were formulated for field application using a wax-based matrix. Reported release rates suggest that this matrix is a viable formulation for enhancing D. carinulata aggregations under field conditions. Pheromone-treated saltcedar plants (Tamarix spp.) not only had higher densities of adult and larval D. carinul...
Invasive Plant Science and Management, 2016
Gene flow between Dalmatian toadflax (DT) and yellow toadflax (YT), both aggressive invaders thro... more Gene flow between Dalmatian toadflax (DT) and yellow toadflax (YT), both aggressive invaders throughout the Intermountain West, is creating hybrid populations potentially more invasive than either parent species. To determine the direction of gene flow in these hybrid populations, species-diagnostic cytoplasmic markers were developed. Markers were based on polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) polymorphisms in the trnT-D chloroplast DNA (cpDNA) region digested with Alu1, and single-nucleotide polymorphisms (SNPs) in the matK and trnL-F chloroplast-barcoding regions. Four hybrid toadflax populations sampled from Colorado, Montana, and Washington contained both DT and YT cytoplasm, with YT predominating; 25 individuals from a fifth hybrid population from Idaho all had identical YT cpDNA haplotypes. Thirteen plants from two Colorado populations, assumed to be DT based on morphology and geographic isolation from any known YT population, were found...
Journal of Entomological Science, 2011
Our study reports the results of field and garden experiments designed to quantitatively evaluate... more Our study reports the results of field and garden experiments designed to quantitatively evaluate the impact of herbivory by a weed biological control agent, the stem-mining weevil Mecinus janthinus Germar, on the growth of its exotic host Dalmatian toadflax, Linaria dalmatica (L.) Miller. Herbivory by M. janthinus under both natural and manipulated environmental conditions inhibited L. dalmatica growth. Reductions in stem length, biomass, and growth were more pronounced for plants subjected to both exophagous (adult) and endophagous (larval) feeding injury than for plants exposed only to adult folivory. Decreases we observed in root biomass could additionally inhibit shoot production from lateral roots. This provides a plausible mechanism explaining anecdotal reports correlating the reduced spread of L. dalmatica with attack by M. jan thin us. Our results indicate that L. dalmatica growth is compromised once a threshold density equivalent to 5 M. janthinus larvae per stem is exceeded. The consistency of growth responses observed in this study suggests that a mechanistic/quantitative approach, such as measuring the impact of M. jan thin us herbivory on L. dalmatica, is a robust and relevant method for postrelease evaluations of weed biocontrol efficacy.
Tansy ragwort, a member of the Asteraceae taxonomic family, is a large biennial or short-lived pe... more Tansy ragwort, a member of the Asteraceae taxonomic family, is a large biennial or short-lived perennial herb native to and widespread throughout Europe and Asia. Stems can grow to a height of 5.5 feet (1.75 meters), with the lower half simple and the upper half many-branched at the inflorescence. Reproductive stems produce up to 2,500 bright golden-yellow flowers. Capitula (flowerheads) arranged in 20-60 flat-topped, dense corymbs per plant are composed of ray and disc florets; both produce achenes containing a single seed. Rosettes formed of distinctive pinnately-lobed leaves attain a diameter of up to 1.5 feet (0.5 meter). First reported in Montana in 1979 in Mineral County, tansy ragwort has since spread into Flathead, Lincoln, and Sanders Counties. Soils with medium to light textures in areas receiving sufficient rainfall (34 inches or 860 millimeters/year) readily support populations of tansy ragwort. This species is a troublesome weed in decadent pastures, waste areas, clear-...
Invasive Plant Science and Management, 2009
Although there is evidence that interspecific hybridization can initiate invasion by nonnative pl... more Although there is evidence that interspecific hybridization can initiate invasion by nonnative plants, there are few documented examples of novel hybridization events between introduced plant species already exhibiting invasive behavior. We conducted morphometric and molecular analyses of toadflax plants with intermediate morphology found at two sites in Montana, which were co-invaded by yellow toadflax and Dalmatian toadflax. Field-collected putative hybrid plants had intermediate morphometric scores (mean 0.47, on a scale of 0.0 = indistinguishable from Dalmatian toadflax to 1.0 = indistinguishable from yellow toadflax) for a suite of phenotypic traits that differentiate the parent species (leaf length : width ratio, growth form, seed morphology, inflorescence type, and ventral petal shape). Inter-simple sequence repeat (ISSR) analysis of a subset of these putative hybrids revealed combinations of species-diagnostic bands, confirming the presence of DNA from both parent species. C...
Proceedings of the XII International Symposium on Biological Control of Weeds, La Grande Motte, France, 22-27 April, 2007
The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United State... more The toadflax stem mining weevil, Mecinus janthinus Germar, was first released in the United States in Montana, in 1996. This agent has now become established to varying degrees after subsequent releases made at sites throughout the state. Multiple releases of M. janthinus have presented researchers with a unique opportunity to evaluate the efficacy of this agent in diverse habitats and under a variety of environmental conditions. The results presented in this paper summarize findings from long-term field data, illustrating not only the impact of M. janthinus on the target weed, Dalmatian toadflax, Linaria dalmatica (L.) P. Mill., but also on correlated plant community dynamics. These results additionally provide a valuable means to compare and contrast the biotic response and control efficacy of this agent at both a regional and sub-continental scale.
A close relative of spotted knapweed in the Asteraceae taxonomic family, diffuse knapweed is typi... more A close relative of spotted knapweed in the Asteraceae taxonomic family, diffuse knapweed is typically biennial, reproducing exclusively by seed. It forms a rosette with a central crown and tap root in the juvenile stage and a single upright stem one to three feet (0.3 to 0.9 m) tall with numerous spreading branches at maturity. White (occasionally purple) flowers are borne in heads with spiny bracts (see Figure 1). It is generally found on more arid sites than spotted knapweed. Native to the Mediterranean region, diffuse knapweed was first recorded in Montana from Mineral County in 1951 and by 2008 had been reported from 39 of Montana's 56 counties. Its dense, spiny overstory reduces the availability of desirable forage plants to livestock and wildlife, and grass production can be reduced by over 90% in heavy infestations. Declines in diffuse knapweed populations in western North America have been attributed to the lesser knapweed flower weevil (Larinus minutus), one of 14 app...