Variation in the suitability of Pinus sylvestris to feeding by two defoliators, Diprion pini (Hym., Diprionidae) and Graellsia isabellae galliaegloria (Lep., Attacidae)

Abstract

Feeding bioassays were conducted on several Pinus sylvestris clones to establish if there were any differences in suitability for two pine defoliators: the sawfly Diprion pini L. (Hym., Diprionidae), which causes considerable damage in Europe, and the rare and protected moth Graellsia isabellae galliaegloria Oberthür (Lep., Attacidae). There were significant differences in survival, weight, sex‐ratio and female fecundity of D. pini on Scots pine clones. However, sawfly survival appeared to be the most stable variable in time and three clone categories were revealed by conducting feeding bioassays on 16 clones. The survival of G. isabellae galliaegloria until the formation of the chrysalis was significantly different among clones. It varied from 35 to 75% but no clear clone category was distinguished. The two clone classifications according to insect survival showed differences. In particular, one unsuitable clone for D. pini development appeared to be favourable to moth development. The 3‐carene richness of foliage was significantly linked with sawfly survival and the monoterpene composition of foliage was not linked with G. isabellae galliaegloria survival.

Influence of soil and topography on defoliation intensity during an extended outbreak of the common pine sawfly (Diprion pini L.)

“…C-based defensive compounds, such as resin acids (Larsson et al 1986), phenolics (Giertych et al 2007) and 3-carene monoterpene (Barre et al 2003) have been found to have negative effects on pine sawfly performance. Bryant et al (1983) suggested that plants growing on nutrientpoor sites have a surplus of C from which they can allocate a part to C-based defense compounds.…”

“…Changes in climate have already been shown to affect the outbreak severity (Haynes et al 2014) and shift in the range of defoliating insects (Battisti et al 2006), and thereby alter the functioning of forest ecosystems. In addition to climate, defoliator populations are regulated by a range of biotic and abiotic factors, including natural enemies (Kollberg et al 2014), topography (Kharuk et al 2007) and soil (Mayfield et al 2007).…”

“…However, other fertilization experiments have shown a negative effect (Larsson & Tenow 1984) or no effect (Björkman et al 1991) on defoliator performance. Tree foliage nitrogen (N) and car-bon (C) contents relate to both their nutritional value (Lyytikäinen 1994, Giertych et al 2007, which can benefit insect performance, and to the production of defense compounds such as C-based monoterpenes (Barre et al 2003) and phenolics (Giertych et al 2007) and N-based alkaloids (Barbosa & Krischik 1987), which can repel insects. For example, Scots pine (Pinus sylvestris L.) needle N contents increase with soil N contents (Björkman et al 1991, Raitio 1999, which have also been shown to affect the contents of secondary defense compounds (Björkman et al 1991, Kainulainen et al 1996.…”

Is the expansion of the pine processionary moth, due to global warming, impacting the endangered Spanish moon moth through an induced change in food quality?

“…The experiment was carried out in a clonal plantation of Scots pines established in 1989 at INRA Orléans (01°54′43.2′′E; 47°49′57.1′′N) using grafts originating from Haguenau Forest, Eastern France. The clonal effect on larval development of both T. pityocampa and A. isabellae had already been assessed, revealing that clone 872 was most suitable for the development of A. isabellae (Auger-Rozenberg et al 1996;Barre et al 2003). To minimize a possible confounding effect of tree genotype, we decided to use only ramets from this clone.…”

Feeding behavior and performance of Neodiprion sertifer larvae reared on Pinus sylvestris needles

“…Growth and survival of pine sawfly was also positively influenced by high concentration of needle nitrogen, phosphorus and soluble carbohydrates (Björkman et al, 1991;Lyytikäinen, 1994) and adversely by higher water content (Christiansen and Austarå, 1996), monoterpenes (Barre et al, 2003) and resin acid concentration (Björkman et al, 1991;Géri et al, 1993;Larsson et al, 2000). Chemical composition of food also influences mortality, fecundity and ability to produce repellents or sex pheromones (Eisner et al, 1974;Géri et al, 1993).…”