Browsing by Author "Wallingford, Anna K."

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    Expansion of the range of Pierce’s disease in Virginia
    Wallingford, Anna K.; Tolin, Sue A.; Myers, Ashley L.; Wolf, Tony K.; Pfeiffer, Douglas G. (2007)
    Pierce’s disease (PD) is a vascular disease of grapes caused by the bacterium Xylella fastidiosa Wells et al. and vectored by xylem-feeding sharpshooters (1). Symptoms of PD occur when bacteria proliferate the xylem; both the bacteria (2) and host responses to infection (3) block the flow of xylem fluid to the shoots. Affected grapevines show interveinal chlorosis, marginal necrosis with marginal yellow or red line (Figs. 1 and 2), green islands on shoot bark after normal tissue turns brown, and leaf abscission from the distal end of petioles, leaving characteristic "matchstick petioles" with necrotic tips (Fig. 3). Infection leads to vine decline, yield loss, and, within two to three years, vine death. Although the northern distribution of X. fastidiosa [* see Erratum] extends at least into New Jersey, observations of PD have been limited to vineyards on the Delmarva Peninsula and extreme southeastern Virginia; interior Virginia was considered at low risk of PD because of its low winter temperatures (lethal to the bacteria), based on the results of past research that showed lower pathogen populations in plants grown at low temperatures in a growth chamber (4). Recent warm winters have, however, increased our concerns about vulnerability of other Virginia vineyards to PD. Our objective was to conduct a state-wide survey of Virginia’s vineyards for presence of X. fastidiosa.
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    De novo formation of an aggregation pheromone precursor by an isoprenyl diphosphate synthase-related terpene synthase in the harlequin bug
    Lancaster, Jason; Khrimian, Ashot; Young, Sharon; Lehner, Bryan; Luck, Katrin; Wallingford, Anna K.; Ghosh, Saikat Kumar B.; Zerbe, Philipp; Muchlinski, Andrew; Marek, Paul E.; Sparks, Michael E.; Tokuhisa, James G.; Tittiger, Claus; Köllner, Tobias G.; Weber, Donald C.; Gundersen-Rindal, Dawn E.; Kuhar, Thomas P.; Tholl, Dorothea (2018-09-11)
    Insects use a diverse array of specialized terpene metabolites as pheromones in intraspecific interactions. In contrast to plants and microbes, which employ enzymes called terpene synthases (TPSs) to synthesize terpene metabolites, limited information from few species is available about the enzymatic mechanisms underlying terpene pheromone biosynthesis in insects. Several stink bugs (Hemiptera: Pentatomidae), among them severe agricultural pests, release 15-carbon sesquiterpenes with a bisabolene skeleton as sex or aggregation pheromones. The harlequin bug, Murgantia histrionica, a specialist pest of crucifers, uses two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol as a male-released aggregation pheromone called murgantiol. We show that MhTPS (MhIDS-1), an enzyme unrelated to plant and microbial TPSs but with similarity to trans-isoprenyl diphosphate synthases (IDS) of the core terpene biosynthetic pathway, catalyzes the formation of (15,6S,7R)-1,10-bisaboladien-1-ol (sesquipiperitol) as a terpene intermediate in murgantiol biosynthesis. Sesquipiperitol, a so-far-unknown compound in animals, also occurs in plants, indicating convergent evolution in the biosynthesis of this sesquiterpene. RNAi-mediated knockdown of MhTPS mRNA confirmed the role of MhTPS in murgantiol biosynthesis. MhTPS expression is highly specific to tissues lining the cuticle of the abdominal sternites of mature males. Phylogenetic analysis suggests that MhTPS is derived from a trans-IDS progenitor and diverged from bona fide trans-IDS proteins including MhIDS-2, which functions as an (E,E)-farnesyl diphosphate (FPP) synthase. Structure-guided mutagenesis revealed several residues critical to MhTPS and MhFPPS activity. The emergence of an IDS-like protein with TPS activity in M. histrionica demonstrates that de novo terpene biosynthesis evolved in the Hemiptera in an adaptation for intraspecific communication.
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    Performance of Insecticides on Brown Marmorated Sting Bug on Vegetables
    Kuhar, Thomas P.; Doughty, Hélène; Kamminga, Katherine; Philips, Chris; Aigner, John D.; Wallingford, Anna K.; Wimer, Adam Francis; Lilliston, Logan; Aigner, Benjamin L.; Nottingham, Louis B.; Lohr, Ashley; Fread, Elizabeth; Jenrette, James (Virginia Cooperative Extension, 2011)
    Lists the rankings of insecticides used in a series of experiments in terms of percentage of mortality for Brown Marmorated Stink Bug nymphs and adults.
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    Sesquiterpene pheromone biosynthesis in stink bugs: An isopentenyl diphosphate synthase like protein produces the cyclic sesquiterpene alcohol precursor of the aggregation pheromone murgantiol in harlequin bug (Murgantia histrionica)
    Lancaster, Jason; Khrimian, Ashot; Young, Sharon; Lehner, Bryan; Luck, Katrin; Wallingford, Anna K.; Ghosh, Saikat Kumar B.; Zerbe, Philipp; Muchlinski, Andrew; Marek, Paul E.; Sparks, Michael E.; Tokuhisa, James G.; Tittiger, Claus; Köllner, Tobias G.; Weber, Donald C.; Gundersen-Rindal, Dawn E.; Kuhar, Thomas P.; Tholl, Dorothea (2018-08-23)
    Insects use a diverse array of specialized terpene metabolites as pheromones in intraspecific interactions. In contrast to plants and microbes, which employ enzymes called terpene synthases (TPSs) to synthesize terpene metabolites, limited information from few species is available about the enzymatic mechanisms underlying terpene pheromone biosynthesis in insects. Several stink bugs (Hemiptera: Pentatomidae), among them severe agricultural pests, release 15-carbon sesquiterpenes with a bisabolene skeleton as sex or aggregation pheromones. The harlequin bug, Murgantia histrionica, a specialist pest of crucifers, uses two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol as a male-released aggregation pheromone called murgantiol. We show that MhTPS (MhIDS-1), an enzyme unrelated to plant and microbial TPSs but with similarity to trans-isoprenyl diphosphate synthases (IDS) of the core terpene biosynthetic pathway, catalyzes the formation of (1S,6S,7R)- 1,10-bisaboladien-1-ol (sesquipiperitol) as a terpene intermediate in murgantiol biosynthesis. Sesquipiperitol, a so-far-unknown compound in animals, also occurs in plants, indicating convergent evolution in the biosynthesis of this sesquiterpene. RNAi-mediated knockdown of MhTPS mRNA confirmed the role of MhTPS in murgantiol biosynthesis. MhTPS expression is highly specific to tissues lining the cuticle of the abdominal sternites of mature males. Phylogenetic analysis suggests that MhTPS is derived from a trans-IDS progenitor and diverged from bona fide trans-IDS proteins including MhIDS-2, which functions as an (E,E)-farnesyl diphosphate (FPP) synthase. Structure-guided mutagenesis revealed several residues critical to MhTPS and MhFPPS activity. The emergence of an IDS-like protein with TPS activity in M. histrionica demonstrates that de novo terpene biosynthesis evolved in the Hemiptera in an adaptation for intraspecific communication.
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    Supercooling Points of Murgantia histrionica (Hemiptera: Pentatomidae) and Field Mortality in the Mid-Atlantic United States Following Lethal Low Temperatures
    DiMeglio, Anthony S.; Wallingford, Anna K.; Weber, Donald C.; Kuhar, Thomas P.; Mullins, Donald E. (2016-10)
    The harlequin bug, Murgantia histrionica (Hahn), is a serious pest of brassicaceous vegetables in southern North America. While this insect is limited in its northern range of North America, presumably by severe cold winter temperatures, specific information on its cold hardiness remains unknown. We determined the supercooling points (SCPs) for Maryland and Virginia adult populations and found no significant difference among these populations. SCPs were similar for adults ( = -10.35 A degrees C; 2.54) and early and late instar 11.00 C; rX 4.92) and between adult males and females. However, SCPs for first instars 21.56 C; rX 1.47) and eggs (X 23.24 C; rX1.00) were significantly lower. We also evaluated field survival of overwintering harlequin bug adults during extreme cold episodes of January 2014 and January 2015, which produced widespread air temperatures lower than -15 A degrees C and subfreezing soil temperatures in the Mid-Atlantic Region. After the 48-h episode in 2014, bug mortality in exposed field sites averaged 88%, compared to < 5% mortality of bugs sheltered in an unheated greenhouse (recorded minimum temperature 4.4 A degrees C). After the 2015 episode, 80% of adults that were established in the field the previous November and then sheltered in an unheated garage during the episode, died, in contrast to 96% mortality in exposed field sites. Our results provide new information on M. histrionica overwintering biology, and thermal limitations to its distribution, which leads to improved predictive capabilities to forecast pest severity.
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    Toxicity and field efficacy of four neonicotinoids on harlequin bug (Hemiptera: Pentatomidae)
    Wallingford, Anna K.; Kuhar, Thomas P.; Schultz, Peter B. (Florida Entomological Society, 2012-12)
    Harlequin bug, Murgantia histrionica (Hahn), is a pest of cole crops in the USA. Laboratory toxicity assays revealed that the neonicotinoid insecticides imidacloprid, thiamethoxam, dinotefuran, and clothianidin are toxic to harlequin bug nymphs; LC50 = 0.57, 0.52, 0.39, and 0.39 ppm, respectively. Field experiments were conducted to evaluate the efficacy of these insecticides over time when applied as a one-time soil drench. Each of the 4 neonicotinoids provided significant control of harlequin bug for at least 14 d after application.
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    Trapping of Crucifer-Feeding Flea Beetles (Phyllotreta spp.) (Coleoptera: Chrysomelidae) With Pheromones and Plant Kairomones
    Weber, Donald C.; Konstantinov, Alexander S.; Khrimian, Ashot; Bier, Alexander D.; Lubenow, Lesley A.; Knodel, Janet J.; Haber, Ariela; Wallingford, Anna K.; Mason, James A. C.; Kuhar, Thomas P. (Oxford University Press, 2022-04-13)
    Flea beetles (Coleoptera: Chrysomelidae) of the genus Phyllotreta are major pests of cole crops, canola, and related crops in the mustard family (Brassicaceae). Adults may damage seedlings or larger crop plants, impairing crop growth, rendering crops unmarketable, or killing seedlings outright. The two major North American crucifer pest species, Phyllotreta striolata (F.) and Phyllotreta cruciferae (Goeze), have male-produced pheromones attractive to both female and male adults. We tested the racemic synthetic pheromones, himachaladiene and hydroxyhimachalanone, as well as the host-plant-produced allyl isothiocyanate, alone and in combination, with experimental trapping in Maryland, Virginia, and North Dakota, using clear and yellow sticky traps and the ground-based 'rocket' trap (modified from boll weevil trap). Phyllotreta striolata was consistently attracted to the hydroxyketone, and captures were often enhanced by allyl isothiocyanate (AITC), but its response to pheromones, AITC, and trap color were variable from state to state. Phyllotreta cruciferae was strongly attracted to AITC, but its response to pheromone components varied by state, and this species was found rarely at the Maryland site. Phyllotreta bipustulata (F.) was attracted to the diene component, a new finding for this species. Several other genera of flea beetles were captured, some showing response to the semiochemicals and/or color. Results will be helpful in monitoring and possibly population suppression; however, further research is necessary to develop more efficient syntheses, optimal lure loadings, combinations, and controlled release methods.