Insect induced resistance in Lodgepole pine: effects on two pine feeding insects

Abstract

A series of experiments was performed in order to establish if the insect defoliators Panolis,fklmnzea (D&S) (Lept., Noctuidae) and Neodiprion sertifer (Geoff.) (Hym., Dripionidae) cause an induced response in lodgepole pine, Pinus contortci, and if so, what affect this response is likely to have on the two insects.Surviva1 and growth of P.framrneu was significantly affected by defoliation of seedling Skeena River lodgepole pine (KLP). On mature foliage from one forest site P. flammea larvae showed no significant difference in feeding preference between heavily defoliated trees and trees with less than 10% defoliation. On foliage from another forest site P. frurnrnea larvae preferred trees with no previous defoliation. N . sertifer larvae significantly preferred foliage from previously defoliated trees. Insect defoliation of mature trees resulted in significant changes in the terpenoid compounds in leaf and stem resins. It is possible that both P. flamrnea and N . sertifer are affected by the carbon-nutrient balance of their host. It seems that P. flarnrnea however, unlike N . sertifer, is also affected by induced defences in lodgepole pine, particularly in younger trees. These differences are probably related to the feeding strategies of the two insects: P . frammea feeds on both current and previous year foliage, while N . sertifer feeds only on previous year foliage. The outbreak dynamics of P. framrnea and N . sertifer in commercial lodgepole pine plantations are discussed in light of the results obtained.

Delayed induced changes in the biochemical composition of host plant leaves during an insect outbreak

“…One important response is the occurrence of herbivore-induced changes in the biochemical composition of leaves which can render the plant less palatable to potential future herbivores. Although certain types of herbivory may also predispose plants for more herbivory (Danell and Huss-Danell 1985;Roland and Myers 1987;Danell et al 1997), most research has concentrated on induced resistance, which may result from changes which either increase the toxicity or decrease the nutritive quality of leaves, or both (Scriber and Slansky 1981;Karban and Myers 1989;Haukioja 1990;Tallamy and Raupp 1991;Herms and Mattson 1992;Trewhella et al 1997; Wold and Marquis 1997). Many studies have emphasized the possible role of secondary compounds as the chemical basis of resistance.…”

Tree Defenses Against Insects

“…Since plants are modular organisms, any damage to hormonally active plant meristems is bound to rearrange resource flows within the plant Dyer et al, 1991), and this may lead to drastic changes in the suitability of adjacent plant parts for insects. Consistent with the multiple ways whereby induced resistance against insects can emerge is the pronounced variance between the results of individual experiments; for birch see Ruohomäki et al (1992), for pines Watt (1990), Lyytikäinen (1994), Trewhella et al (1997), Raffa et al (1998) and Smits et al (2001). Unlike many of the mechanisms activated by defense pathways, such as the octadecanoid cascade, responses based on mechanical damage via altered sink-source relations seem to be local (Tuomi et al, 1988, Långström et al, 1990Henriksson, 2001, Henriksson et al, 2003.…”

“…After mammalian browsing, plants may become better for insects (Danell and Huss-Danell, 1985); insect feeding can lead to a similar outcome (Bryant et al, 1991). Since responses to the breaking of apical dominance are of a very general nature, it is not surprising that induced susceptibility has been found in many types of woody plants, including eucalypts (Landsberg, 1990), birch , oak (Hunter and West, 1990), alder (Williams and Myers, 1984), willows (Hjälten and Price, 1996), and pines (Trewhella et al, 1997;Raffa et al, 1998).…”

The ecological interaction of the mountain pine beetle and jack pine budworm in the boreal forest

“…In lodgepole pine, defence induction of feeding by the pine beauty moth (Panolis flammea D&S) and the European sawfly (Neodiprion sertifer Geoff.) were tested on the other species' fitness (Trewhella et al 1997). Feeding by both insects led to significant changes in needle chemistry, which reduced P. flammea fitness but not that of N. sertifer, suggesting that plant defences have different impacts on herbivores.…”