In conifers, attacks by bark beetles and associated pathogenic fungi cause an induced wound response, which is characterized by accumulation of antifungal compounds and morphological changes that aid wound healing. In this article the stilbene and terpene concentrations of Norway spruce phloem were monitored as symptoms of induced wound responses in relation to changed nutrient conditions caused by fertilization. Plots of mature Norway spruce were fertilized with N, P or NPK. One year after fertilization the trees were artificially infected with Ceratocystis polonica, a pathogenic fungus associated with the bark beetle Ips typographus. The response of stilbenes to fungal inoculation was mainly qualitative. The concentration of stilbene glycosides in the phloem decreased, and in the immediate vicinity of the site of fungal inoculation, stilbene glycosides were less frequent than in mechanically wounded or unwounded phloem. Corresponding stilbene aglycones were most frequent inside the reaction lesion. The concentration of total stilbene aglycones near the inoculation site was significantly lower in N-fertilized trees than in unfertilized trees. Fungal inoculation caused a strong quantitative response in terpenes. The total terpene concentration of the phloem increased significantly, to almost 100 times greater near the inoculation site compared to the constitutive values. N fertilization significantly reduced the total terpene and total stilbene aglycone concentrations near the inoculation sites. Thus, N fertilization may reduce the ability of Norway spruce to defend itself against fungal pathogens.

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In 1990-1991, Diprion pini extensively defoliated Scots pine (Pinus sylvestris L.) trees in Lauhanvuori National Park in southwestern Finland. Many trees lost all their foliage, while others had ca. 10 % foliage left after the second year of defoliation. Outside the national park, many nearby stands were also heavily defoliated in 1990, but were sprayed with diflubenzuron (Dimilin ® ) in 1991. This protected the current year needles, corresponding to ca 30 % of full foliage.In spring 1992, pine trees with 0, 10, 30 and 100 % foliage remaining (10 small and 10 large trees in each category) were baited with pine bolts to induce stem attacks by pine shoot beetles. All baited trees were attacked by Tomicus piniperda and some by T. minor. The attacks failed in all these trees except those that were totally defoliated and some of the small trees with 10 % foliage left. Many unbaited trees escaped attack entirely, but only totally defoliated trees were successfully colonized (i. e. produced brood). Attack densities and brood production figures peaked in baited, large and totally defoliated trees. None of the measures (cambial electrical resistance, resin flow, induced lesion length by fungal inoculation, amount of hydrocarbons or phenolic compounds) used to describe tree vigour at the time of attack gave better information than the estimated remaining foliage.We conclude that the risk for beetle-induced mortality following defoliation is a function of remaining needle biomass and beetle pressure. Even at high beetle densities (as was simulated by baiting of trees), trees with 10 % of the foliage remaining were able to defend themselves against attacking pine shoot beetles.

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Many mechanisms, functions and structures of life have been unraveled. However, the fundamental driving force that propelled chemical evolution and led to life has remained obscure. The 2nd law of thermodynamics, written as an equation of motion, reveals that elemental abiotic matter evolves from the equilibrium via chemical reactions that couple to external energy toward complex biotic non-equilibrium systems. Each time a new mechanism of energy transduction emerges, e.g., by random variation in syntheses, evolution prompts by punctuation and settles to a stasis when the accessed free energy has been consumed. The evolutionary course toward an increasingly larger energy transduction system accumulates a diversity of energy transduction mechanisms, i.e., species. The rate of entropy increase is identified as the fitness criterion among the diverse mechanisms which places the theory of evolution by natural selection on the fundamental thermodynamic principle with no demarcation line between inanimate and animate.Comment: 17 pages, 1 figur