The walnut twig beetle [WTB (Pityophthorus juglandis Blackman)] is the primary insect vector for a pathogen that causes thousand cankers disease (TCD), a disease complex that leads to mortality in species of walnut (Juglans L.). We performed field and laboratory trials to determine if reproduction by WTB varies between two black walnut (Juglans nigra L.) parent trees of a full-sib mapping population of 323 offspring, and between black walnut and butternut (Juglans cinerea L.). These two tree species are native to eastern North America. In field trials, we found no significant differences in colonization density or mean number of adult offspring per female among branch sections from black walnut parent trees or among branch sections from black walnut and butternut, respectively. In laboratory trials with controlled colonization densities of WTB, we found that significantly fewer adult offspring developed in branch sections of the black walnut maternal ‘Sparrow’ parent than the paternal ‘Schessler’ parent over three summer months and one winter month. In the field, high colonization densities likely limited reproduction due to increased intraspecific competition beneath the bark. In the laboratory, where we established a lower colonization density, reproduction was likely influenced by differences in host quality. In laboratory trials, no differences were detected in the number of adult offspring emerging from black walnut and butternut accessions. This finding suggests that butternut is a suitable host for WTB. Future screening of the full-sib mapping population of 323 offspring of black walnut parent trees for WTB resistance is a warranted next step in developing alternative management strategies for TCD in black walnut.
Bibliographical noteFunding Information:
Funding was provided by the NSF-IGERT Norsk Sykepleierforbund Risk Analysis of Introduced Species and Genotypes program at the University of Minnesota (DGE-0653827) and an USDA-Forest Service Special Technology Development Program grant (R2-2012-01) that was administered by Jeffrey Witcosky and Stephanie Stephens, USDA Forest Service, Lakewood, CO. Participation of MVC and SJS in this project was coordinated and supported by USDA National Institute of Food and Agriculture, Specialty Crops Research Initiative Program Project (11684658), ?Development of Disease-resistant Walnut Rootstocks: Integration of Conventional and Genomic Approaches.?
- Domestic invasive species
- Host colonization
- Insect-disease complex
- Pityophthorus juglandis
- Thousand cankers disease