A Case Study: Walnut Twig Beetle, Pityophthorus juglandis Blackman (Coleoptera: Curculionidae: Scolytinae) in Bucks County, Pennsylvania

Turcotte, Richard M.; Martin, Danielle K.H.; Smith, Paul; Kasson, Matthew T.; Rhodes, Dana

doi:10.3157/021.123.0404

Cited by 4 publications

(2 citation statements)

References 3 publications

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“…The demand for claro walnut among woodworkers, again makes California a likely source of introduced WTB. Indeed, the area of WTB infestation in Pennsylvania for instance, is centered around the property of a woodworker who is known to have imported and stored raw, barked walnut wood from California (and nowhere else) in both 2001 and 2008 [ 67 ]. Our analyses suggested that the invasive populations in Ohio, Pennsylvania, and Tennessee were very similar to each other ( Table 3 ).…”

Section: Discussionmentioning

confidence: 99%

Phylogeography of the Walnut Twig Beetle, Pityophthorus juglandis, the Vector of Thousand Cankers Disease in North American Walnut Trees

et al. 2015

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Thousand cankers disease (TCD) of walnut trees (Juglans spp.) results from aggressive feeding in the phloem by the walnut twig beetle (WTB), Pityophthorus juglandis, accompanied by inoculation of its galleries with a pathogenic fungus, Geosmithia morbida. In 1960, WTB was only known from four U.S. counties (in Arizona, California, and New Mexico), but the species has now (2014) invaded over 115 counties, representing much of the western USA, and at least six states in the eastern USA. The eastern expansion places TCD in direct proximity to highly valuable (> $500 billion) native timber stands of eastern black walnut, Juglans nigra. Using mitochondrial DNA sequences, from nearly 1100 individuals, we examined variation among 77 samples of WTB populations across its extended range in the USA, revealing high levels of polymorphism and evidence of two divergent lineages. The highest level of genetic diversity for the different lineages was found in the neighboring Madrean Sky Island and Western New Mexico regions, respectively. Despite their proximity, there was little evidence of mixing between these regions, with only a single migrant detected among 179 beetles tested. Indeed, geographic overlap of the two lineages was only common in parts of Colorado and Utah. Just two haplotypes, from the same lineage, predominated over the vast majority of the recently expanded range. Tests for Wolbachia proved negative suggesting it plays no role in "driving" the spread of particular haplotypes, or in maintaining deep levels of intraspecific divergence in WTB. Genotyping of ribosomal RNA corroborated the mitochondrial lineages, but also revealed evidence of hybridization between them. Hybridization was particularly prevalent in the sympatric areas, also apparent in all invaded areas, but absent from the most haplotype-rich area of each mitochondrial lineage. Hypotheses about the specific status of WTB, its recent expansion, and potential evolutionary origins of TCD are discussed.

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Section: Discussionmentioning

confidence: 99%

Phylogeography of the Walnut Twig Beetle, Pityophthorus juglandis, the Vector of Thousand Cankers Disease in North American Walnut Trees

et al. 2015

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“…Both the beetle and pathogen have also been recovered from a walnut grove in Italy ( Montecchio et al 2014 ). Given the tremendous distance between and disjunct nature of these detections, human transport of infested walnut wood is strongly suspected as a pathway contributing to the range expansion of these organisms ( Newton and Fowler 2009 , Turcotte et al 2013 ).…”

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confidence: 99%

Walnut Twig Beetle (Coleoptera: Curculionidae: Scolytinae) Colonization of Eastern Black Walnut Nursery Trees

Audley

Klingeman

Mayfield

et al. 2017

Journal of Insect Science

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Thousand cankers disease, caused by the invasive bark beetle Pityophthorus juglandis Blackman and an associated fungal pathogen Geosmithia morbida M.Kolařík, E. Freeland, C. Utley, N. Tisserat, currently threatens the health of eastern black walnut (Juglans nigra L.) in North America. Both the beetle and pathogen have expanded beyond their native range via transport of infested walnut wood. Geosmithia morbida can develop in seedlings following inoculation, but the ability of P. juglandis to colonize young, small diameter trees has not been investigated. This study assessed the beetle’s colonization behavior on J. nigra nursery trees. Beetles were caged directly onto the stems of walnut seedlings from five nursery sources representing a range of basal stem diameter classes. Seedlings were also exposed to P. juglandis in a limited choice, field-based experiment comparing pheromone-baited and unbaited stems. When beetles were caged directly onto stems, they probed and attempted to colonize seedlings across the range of diameters and across sources tested, including stems as small as 0.5 cm in diameter. In the field experiment, beetles only attempted to colonize seedlings that were baited with a pheromone lure and appeared to prefer (though not statistically significant) the larger diameter trees. Despite several successful penetrations into the phloem, there was no evidence of successful progeny development within the young trees in either experiment. Further investigation is recommended to better elucidate the risk nursery stock poses as a pathway for thousand cankers disease causal organisms.

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Status and Impact of Walnut Twig Beetle in Urban Forest, Orchard, and Native Forest Ecosystems

Seybold

Klingeman²,

Hishinuma

et al. 2019

Journal of Forestry

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A Case Study: Walnut Twig Beetle, Pityophthorus juglandis Blackman (Coleoptera: Curculionidae: Scolytinae) in Bucks County, Pennsylvania

Cited by 4 publications

References 3 publications

Phylogeography of the Walnut Twig Beetle, Pityophthorus juglandis, the Vector of Thousand Cankers Disease in North American Walnut Trees

Phylogeography of the Walnut Twig Beetle, Pityophthorus juglandis, the Vector of Thousand Cankers Disease in North American Walnut Trees

Walnut Twig Beetle (Coleoptera: Curculionidae: Scolytinae) Colonization of Eastern Black Walnut Nursery Trees

Status and Impact of Walnut Twig Beetle in Urban Forest, Orchard, and Native Forest Ecosystems

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