Genetically based resistance to the white pine weevil in jack pine and eastern white pine

Abstract

White pine weevil (Pissodes strobi Peck) damage was evaluated in one white pine (Pinus strobus L.) and four jack pine (Pinus banksiana Lamb) half-sib family test sites to determine the role of tree genotype in resistance to the weevil. Halfsib family explained a significant proportion of the variation in weevil attack at all sites. Estimates of family (0.16-0.54) and individual (0.09-0.24) heritabilities of jack pine resistance to white pine weevil were moderate. Estimates of family (0.37) and individual (0.22) heritability of resistance of white pine to the weevil were also moderate when the percentage of test trees damaged by the weevil was relatively low, but were insignificant four years later when more than three-quarters of trees were damaged. Significant positive correlations between mean tree height and mean incidence of trees damaged by the weevil were observed for four of seven site-years but relationships were weak, suggesting that any cost, with respect to height growth, to breeding weevil resistant trees may be small. Key words:Pinus, Pissodes strobi, trade-offs, tree improvement, tree resistance, white pine weevil. RÉSUMÉLes dommages du charançon du pin blanc (Pissodes strobi Peck) ont été évalués dans un site de test de familles de descendance uniparentale de pin blanc (Pinus strobus L.) et dans quatre sites contenant des familles de descendance uniparentale de pin gris (Pinus banksiana Lamb), afin de déterminer le rôle du génotype de l'arbre dans sa résistance au charançon. La famille a expliqué une proportion significative de la variation dans les attaques du charançon à tous les sites. Les estimations des héritabilités familiales (0.16-0.54) et individuelle (0.09-0.24) de la résistance du pin gris aux attaques du charançon du pin blanc étaient modérées. Les estimations des héritabilités familiale (0.37) et individuelle (0.22) de la résis-tance du pin blanc au charançon étaient également modérées lorsque le pourcentage d'arbres endommagés par le charançon était relativement bas, mais devenaient non significatives quatre ans plus tard, lorsque plus des trois-quarts des arbres étaient endommagés. Des corrélations positives significatives entre la hauteur moyenne des arbres et la moyenne de l'incidence des arbres endommagés par le charançon ont été observées pour quatre des sept sites-années, mais les relations étaient faibles, ce qui suggère que tout coût de la reproduction d'arbres résistants au charançon, par rapport à la croissance en hauteur, pourrait être moindre.

High genetic variation and moderate to high values for genetic parameters of Picea abies resistance to Pissodes strobi

“…When this method is used with our study data, the heritability estimates also increase ( b h f am 2 =0.75±0.05 and b h ind 2 =0.35± 0.06), as compared with values reported in Table 2. In half-sib family tests in New Brunswick, Canada, Verrez et al (2010) reported family heritability estimates for weevil attack rates ranging from 0.16 to 0.54 for jack pine and of 0.37 for eastern white pine.…”

“…To ensure accuracy, operational forest tree breeding programs require that estimates be obtained from at least 75 open-pollinated families (e.g., Perron et al 2013). Heritability estimates of resistance to the white pine weevil have been conducted on interior spruce (Kiss and Yanchuk 1991;King et al 1997), Sitka spruce (Moreira et al 2012), jack pine (Pinus banksiana Lamb), and eastern white pine (Verrez et al 2010). The rare studies on Norway spruce that have reported white pine weevil resistance heritability estimates or a strong genetic control for this trait were conducted on a small number of families from the Hudson's Place provenance and a few European provenances (Nieman and Boyle 1989;Coleman et al 1987).…”

Genetic parameters of growth and stem quality traits for jack pine second-generation progeny tested in New Brunswick

“…The large fluctuation of genetic parameter estimates among test series in SF in this study seemed to mimic patterns found with the infection of shoot insects. For instances, Verrez et al (2010) found that jack pine families differed in suffering white pine weevil damage, but that the differences varied among four field trials and between years.…”

“…Second, stem forking in jack pine is likely associated with shoot insect attack (Thomas 1958). Although appreciable genetic resistance to shoot insects has been reported in other conifers species such as genetic resistance to white pine weevil in Sitka spruce (King et al 2011), the observed genetic resistance in jack pine to white pine weevil seemed to vary among trials and years (Verrez et al 2010). No confirmed genetic resistance mechanisms to other insects have been reported in jack pine.…”

“…Therefore, it is reasonable to assume that genetic variation in stem forking could partly reflect genetic resistance of jack pine to shoot infecting insects, although further study is needed to confirm such a causal relationship. Verrez et al (2010) indicated that genetic resistance to white pine weevil may exist in jack pine, while studies on loblolly pine (Xiong et al 2010;Cumbie et al 2012) and white pine (Pinus chiapensis (Martínez) Andresen) (Dvorak et al 1996) indicated that genetic variation in stem forking exists among clones, families, or provenances.…”