White pine weevil performances in relation to budburst phenology and traumatic resin duct formation in Norway spruce

Abstract

1 As the phenological window hypothesis was reported to be significant in influencing the fitness of many herbivores feeding on tree foliage, could it also explain the performance of an insect such as the white pine weevil Pissodes strobi mainly attacking the bark phloem of conifers? 2 Under field conditions, adult weevils were caged on Norway spruce trees presenting a natural variation in their shoot growth phenology. 3 We evaluated white pine weevil biological performances, including oviposition, the number of emerged insects, survival, adult mean weight and tree defense responses as reflected by the production of induced resin canals. 4 None of the white pine weevil biological parameters was significantly affected by Norway spruce phenology. 5 The number of eggs per hole, the number of oviposition holes per leader, the number of emerged adults and their mean weight were not affected by host phenology. 6 The intensity of the traumatic response observed was variable and not correlated with budburst phenology. 7 Trees with higher traumatic responses, forming two or more layers of traumatic ducts, had lower adult emergence and estimated survival. 8 The distance between the first layer of traumatic resin ducts and the start of the annual ring was not correlated with the number of emerged weevils. 9 Norway spruce, which is an exotic tree in North America and a relatively recent host for the white pine weevil, might not possess the defense mechanisms necessary to fight off the white pine weevil.

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

“…For Sitka spruce, white spruce, and interior spruce, several white pine weevil resistance mechanisms were identified, related to density of resin canals and sclereids for example Tomlin and Borden 1994;Alfaro et al 2004;King et al 2011;Moreira et al 2012). Some of these could play a similar role for Norway spruce (Nagy et al 2000;Boucher et al 2001b;Poulin et al 2006), even if it is an exotic species in Eastern Canada and did not coevolve with white pine weevil as did the indigenous white spruce. Resin canal traits of Norway spruce stem were found to be under strong genetic control (Rosner and Hannrup 2004).…”

Interactions virus-fungus- insect in pine pitch canker disease

“…In addition, T. piniperda has been proposed as a predominant species in the study area according to some distribution models Horn et al, 2012). Nevertheless, its coexistence with T. destruens was observed in plot A, and it has been previously reported in Pinus pinaster Aiton stands in other locations of the Iberian Peninsula Vasconcelos et al, 2006).…”

“…In Atlantic habitats, T. piniperda sometimes co-occurs with Mediterranean shoot beetle (Tomicus destruens Wollaston) Vasconcelos et al, 2006). Mediterranean shoot beetle causes intense damages in thermophilic woodlands throughout its range, circumscribed to the Mediterranean Basin (Gallego & Galián, 2008;Horn et al, 2006Horn et al, , 2012.…”

“…Then, they were sonicated (J. P. Selecta Ultrasons 2.6l; J. P. Selecta, Barcelona, Spain) for 5 s at 40 kHz to obtain spore suspensions (Ambourn et al, 2006). The sampling plots showed favorable characteristics for sympatry of T. piniperda and T. destruens (Vasconcelos et al, 2006); therefore, the body of each insect was reserved for molecular identification.…”

“…In the Iberian Peninsula, T. piniperda mainly inhabits pine woodlands in central and northern areas and is sometimes found in sympatry with the species Tomicus destruens Wollaston. Unlike the pine shoot beetle, T. destruens predominantly occurs in the Mediterranean Basin where it can cause severe damage in thermophilic forests Vasconcelos et al, 2006). T. piniperda can co-occur with Tomicus minor Hartig which also has a Palearctic range and mainly colonizes damaged trees .…”