A survey of insects attacking seed cones of Pinus cembra in the Alps, the Pyrénées and Massif Central

Abstract

The composition and impact of the entomofauna exploiting seed cones of Swiss stone pine (Pinus cembra L.) was surveyed in native stands and plantations of France, Italy, Switzerland and Austria during 1992–1996. A total of 2785 cones were collected from 25 sites. The cone entomofauna consisted of five species, of which three (Dioryctria abietella, Eupithecia abietaria, Cecidomyia pini) were regularly observed. The two other insects, Polydrusus atomarius and Zeiraphera diniana were observed on first‐year cones, and only in two stands. No spermatophagous insect was detected. None of these insect species could be considered specific to cones of P. cembra. The overall damage never exceeded 40% of the cone crop. The importance of cone damage varied with year, cone abundance, and the position of the tree in the stand. The cone entomofauna of Swiss stone pine largely deviated from that recorded in cones of other high altitude conifers but resembled that of other stone pines growing in Eurasia. The question: why cones of P. cembra were less damaged by insects than those of other alpine conifers is discussed.

Variable Chemistry and Herbivory of Ponderosa Pine Cones

“…Initially, we thought that elevation may be an important determinant of cone insect distribution ( fig. 3), which has been shown in other pine systems (Gworek et al 2007) and in one case specifically for a Dioryctria moth (Dormont and Roques 1999). However, C. ponderosae dominated the cones in a ponderosa population at the same elevation as the Marshall Mesa site and only 9 km away, indicating that this species' distribution may be independent of elevation (K. Keefover-Ring, personal observation).…”

“…3). Dormont and Roques (1999) reported similar amounts of temporal variation in the cone insect fauna of the Swiss stone pine Pinus cembra during a 5-yr period.…”

Impacts of climate change on the establishment, distribution, growth and mortality of Swiss stone pine (Pinus cembra L.)

“…Dormont & Roques (1999) speculate that the limited colonization of Swiss stone pine seeds by in sects may also be due to the behaviour of the European nutcracker. The bird harvests most of the mature cones by the end of the sum mer (Mattes 1982) before the completion of insect larval development within the cone, which may help to limit seed damage by in sects.…”

Why are seed cones of Swiss stone pine (Pinus cembra) not attacked by the specialized pine cone weevil, Pissodes validirostris? A case of host selection vs. host suitability

“…Although it attacks most of the pine species native to Europe, P. validirostris has never been observed on Swiss stone pine (SPP), Pinus cembra L., an alpine conifer (Roques, 1983). Moreover, the cone entomofauna of SPP is limited to only three insect species, none of which is a cone specialist (Roques, 1983;Dormont & Roques, 1999). By comparison, seed cones of sympatric conifers growing at high altitude in the Alps, such as those of European larch (Larix deciduas Mill.)…”

“…The limited insect colonization of SPP cones has led to suggestions that volatiles or oleoresin emitted by these cones may act as a chemical barrier against insect attack (Dormont & Roques, 1999). Preliminary investigations have shown that mountain pine cones sprayed with a solution of cone volatiles from SPP are not attacked by cone weevils (Dormont et al, 1997).…”