Browsing by Author "Sing, Sharlene E."

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Field demonstration of a semiochemical treatment that enhances Diorhabda carinulata biological control of Tamarix spp.
(2019-09) Gaffke, Alexander M.; Sing, Sharlene E.; Dudley, Tom L.; Bean, Daniel W.; Russak, Justin A.; Mafra-Neto, Agenor; Peterson, Robert K. D.; Weaver, David K.
The northern tamarisk beetle Diorhabda carinulata (Desbrochers) was approved for release in the United States for classical biological control of a complex of invasive saltcedar species and their hybrids (Tamarix spp.). An aggregation pheromone used by D. carinulata to locate conspecifics is fundamental to colonization and reproductive success. A specialized matrix formulated for controlled release of this aggregation pheromone was developed as a lure to manipulate adult densities in the field. One application of the lure at onset of adult emergence for each generation provided long term attraction and retention of D. carinulata adults on treated Tamarix spp. plants. Treated plants exhibited greater levels of defoliation, dieback and canopy reduction. Application of a single, well-timed aggregation pheromone treatment per generation increased the efficacy of this classical weed biological control agent.
An Herbivore-Induced Plant Volatile From Saltcedar (Tamarix spp.) Is Repellent to Diorhabda carinulata (Coleoptera: Chrysomelidae)
(2020-10) Gaffke, Alexander M.; Sing, Sharlene E.; Millar, Jocelyn G.; Dudley, Tom L.; Bean, Daniel W.; Peterson, Robert K. D.; Weaver, David K.
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 and toxicity in adults and larvae. Headspace volatiles were also collected from adult males exposed to 4-oxo-(E)-2-hexenal to determine the impact exposure might have on the emission of the aggregation pheromone. 4-Oxo-(E)-2-hexenal elicited electrophysiological responses in adults of both sexes. Behavioral responses indicated repellency across multiple doses for reproductive D. carinulata adults but not in nonreproductive adults. Exposure assays indicated altered behaviors in first instar larvae and adults, but not in third instar larvae. Collection of headspace volatiles indicated that exposure to 4-oxo-(E)-2-hexenal did not alter emission of the D. carinulata aggregation pheromone by adult males. The continued development and field deployment of this repellent compound may provide a new tool for the management of D. carinulata.
Managing invasive plants on Great Plains grasslands: A discussion of current challenges
(2020-05) Gaskin, John F.; Espeland, Erin; Johnson, Casey D.; Larson, Diane L.; Mangold, Jane M.; McGee, Rachel A.; Milner, Chuck; Paudel, Shishir; Pearson, Dean E.; Perkins, Lora B.; Prosser, Chadley W.; Runyon, Justin B.; Sing, Sharlene E.; Sylvain, Zachary A.; Symstad, Amy J.; Tekiela, Daniel R.
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.
Retrospective use of integrative taxonomy in classical biological control: The unintentional introduction of the weevil Rhinusa dieckmanni to North America
(Elsevier BV, 2023-08) Toševski, Ivo; Sing, Sharlene E.; Caldara, Roberto; Weaver, David K.; Jović, Jelena; Krstić, Oliver; Hinz, Hariet L.
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.
Semiochemicals to enhance herbivory by Diorhabda carinulata aggregations in saltcedar (Tamarix spp.) infestations
(2018-01) Gaffke, Alexander M.; Sing, Sharlene E.; Dudley, Tom L.; Bean, Daniel W.; Russak, Justin A.; Mafra-Nato, Agenor; Grieco, Paul A.; Peterson, Robert K. D.; Weaver, David K.
BACKGROUND: Semiochemicals for monitoring, attracting or repelling pest and beneficial organisms are increasingly deployed in agricultural and forest systems for pest management activities. 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. RESULTS: The aggregation pheromone and host plant volatiles were formulated for field application using a wax based matrix. Reported release rates suggest 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. carinulata, but also sustained greater levels of foliar damage than control plants. Increased damage from the focused feeding of D. carinulata caused an increase in foliar dieback and decrease in live canopy volume of semiochemical-treated plants. CONCLUSION: Field deployment of these semiochemical formulations could be useful in directing populations of D. carinulata for increased impact on Tamarix spp.
Twenty-five years after: post-introduction association of Mecinus janthinus s.l. with invasive host toadflaxes Linaria vulgaris and Linaria dalmatica in North America
(2018-07) Tosevski, Ivo; Sing, Sharlene E.; De Clerck-Floate, Rosemarie; McClay, Alec; Weaver, David K.; Schwarzländer, Mark; Krstic, Oliver; Jovic, Jelena; Gassmann, A.
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.