Göran Nordlander

Volatiles of bracket fungi Fomitopsis pinicola and Fomes fomentarius and their functions as insect attractants

Volatiles released from fruiting bodies of the polypores Fomitopsis pinicola and Fomes fomentarius (Polyporaceae) were collected by entrainment and SPME techniques and analyzed by GC-MS. The most significant difference between the two species was found in the terpene fraction. F. fomentarius emitted a more complex blend, with more than 10 sesquiterpenes. During the sporulating phase, the release of (R)- and (S)-oct-1-en-3-ol, octan-3-one, and some sesquiterpene hydrocarbons (mainly β-barbatene) increased in F. pinicola, whereas in F. fomentarius the release of octan-3-one, cis-furanoid linalool oxide, β-phellandrene, β-myrcene, and several sesquiterpene hydrocarbons increased. β-Barbatene was identified for the first time in fungi. Chopping of the fruiting bodies altered the odor composition more in F. fomentarius than in F. pinicola. Five volatiles giving a typical fungal odor (rac-oct-1-en-3-ol, nonan-1-ol, rac-octan-3-ol, octan-1-ol, and octan-3-one) were tested for insect attraction in the field. Females of the three wood-living generalist beetles Malthodes fuscus, Anaspis marginicollis, and A. rufilabris and both sexes of the moth Epinotia tedella were attracted to rac-oct-1-en-3-ol. The generalist predator on fungus-insects Lordithon lunulatus was attracted to rac-oct-1-en-3-ol and octan-3-one in combination. Previous results regarding the host-specific attraction of beetles to the odors emanating from chopped fruiting bodies of F. pinicola and F. fomentarius are discussed in the light of this investigation.

Colonization patterns of insects breeding in wood-decaying fungi

Many insects dependent on dead wood are considered threatened by modern forestry. This may partly be due to substrate patches being too widely scattered to be effectively colonized. We studied how rates of colonization by insect species breeding in polypore fruiting bodies are affected by interpatch distance and habitat matrix characteristics. In field experiments, fruiting bodies of Fomitopsis pinicola and Fomes fomentarius were put out at different distances from natural sources of insects. The anobiid beetles Dorcatoma spp. were the most successful colonizers of distant patches, and they readily flew over open fields. Cis beetles were less successful colonizers, despite their generally higher abundance. We hypothesize that the Dorcatoma spp. are inferior competitors, but superior colonizers of distant resources compared with Cis spp. The flies Leucophenga quinquemaculata (Drosophilidae) and Medetera impigra (Dolichopodidae) appeared to be more affected by distance than the beetles studied in their colonization of fungal fruiting bodies. Lower rates of parasitism were recorded on distant patches, and parasitoids appeared more affected by distance than their hosts. Most of the insect species studied can probably persist in the managed forest landscape if suitable breeding substrate is created continuously on a 1 km2 scale.

A method for trapping hylobius abietis (L.) with a standardized bait and its potential for forecasting seedling damage

A method for trapping walking Hylobius abietis (L.) (Coleoptera: Curculionidae) was developed and evaluated. Synergism between α‐pinene and ethanol in attracting H. abietis was confirmed. The effec...

Insects in polypore fungi as indicator species: a comparison between forest sites differing in amounts and continuity of dead wood

To effectively preserve the threatened fauna of old-growth forest it is important to identify species that are adversely affected by forest management. We focused on insect species living in fruiting bodies of two polypore species and compared their frequency between forests sites differing in terms of the continuity with which their breeding substrate (dead wood) was available (long, short or no continuity). The polypore species studied were Fomitopsis pinicola and Fomes fomentarius, in which the patterns of occurrence were determined for 25 and 27 insect species, respectively. Species showing significantly higher frequency in less managed forests were Oplocephala haemorrhoidalis (Tenebrionidae), Cis quadridens (Cisidae), and Scardia boletella (Tineidae). Some less frequent species showed similar, but non-significant, trends. We suggest that polypore-inhabiting species restricted to sites with a long, continuous supply of dead wood might be used as indicators of sites of high conservation value. Their presence might also be indicative of species of high conservation value in other dead-wood microhabitats with similar temporal and spatial dynamics. The species that we found to be restricted to less managed forests are all included on the Swedish red-list. However, two species not affected by management are also red-listed, showing that numbers of red-listed species must be used with caution as a measure of conservation value.

Orientation of the pine weevil Hylobius abietis to underground sources of host volatiles

Adults of Hylobius abietis (L.) (Coleoptera: Curculionidae) were found to locate conifer roots suitable for oviposition by utilizing host volatiles diffusing through the soil. Underground sources of host volatiles were presented to weevils in a laboratory bioassay. A cold‐trapping condensate of Scots pine, Pinus sylvestris L., and fractions of it were tested. Various fractions containing host terpenes attracted weevils in the bioassay, but the complete pine condensate caused the highest response. Ethanol was also found to be attractive. Weevils caged underground in the absence of host material did not attract weevils on the surface.

Geographical distributions and host associations of larval parasitoids of frugivorous Drosophilidae in Japan

In Japan, dominant parasitoids attacking frugivorous Drosophilidae species were Asobara (Braconidae, Alysiinae), Leptopilina, and Ganaspis species (Figitidae, Eucoilinae). Asobara japonica was found throughout Japan, and its populations in the main islands of Japan were parthenogenetic whereas those in the subtropical islands were sexually reproducing. Other parasitoids showed rather restricted distributions; A.tabida, A. rossica, A. rufescens, and Leptopilina heterotoma occurred mainly in northern to central parts of the main islands, Ganaspis xanthopoda from central to southern parts of the main islands, A. leveri in a southern part of the main islands, and A. pleuralis, L. victoriae, and Ganaspis sp. mainly in the subtropical islands. Their major hosts were species of the D. melanogaster species group in the main islands, and species of the D. melanogaster, immigrans, and polychaeta species groups in the subtropical islands. Host use considerably varied among parasitoid species, especially in the subtropical islands.

Revision of the genus Leptopilina Förster, 1869, with notes on the status of some other genera (Hymenoptera, Cynipoidea: Eucoitidae)

The genus Leptopilina Forster is revised on a world basis. The identity of 31 nominal species, including type species of four other genera, is discussed and 15 lectotypes are designated. Valid species of Leptopilina are L. longipes (Hartig) [type species], L. clavipes (Hartig) n. comb., L. heterotoma (Thomson) n. comb., L. fimbriata (Kieffer) n. comb., L. rufipes (Cameron) n. comb., L. atraticeps (Kieffer) n. comb., L. mahensis (Kieffer) n. comb., L. boulardi (Barbotin et al.) n. comb., and L. cupulifera (Kieffer) n. comb. Leptopilina heterotoma is the valid name for the well-known Drosophila parasitoid currently referred to as Pseudeucoila bochei (Weld). Leptopilina is not synonymous with Ganaspis Forster. Tryhliographa Forster is a senior synonym of Episoclu Forster n. syn. and of Pseudeucoila Ashmead (synonymy confirmed). Leptopilina is described and compared with related genera (Cothonaspis, Rhoptromeris, Odonteucoila) . L. victoriae n. sp. is described from the Seychelles. The five Leptopilina occurring in Europe are redescribed on modern material and a key is given to them.

Host selection patterns in insects breeding in bracket fungi

Abstract.  1. Fungivorous insects are generally viewed as polyphagous, largely because most fungal fruiting bodies constitute an unpredictable resource. To examine the validity of this hypothesis, and degree of phylogenetic relatedness between the preferred hosts of the insects, host selection in the insect fauna of bracket fungi was studied, using data obtained both from the field and the literature.

Limonene inhibits attraction to α-pinene in the pine weevils Hylobius abietis and H. pinastri

The field responses ofHylobius abietis (L.) andH. pinastri (Gyllenhal) (Coleoptera: Curculionidae) to various combinations of two host monoterpenes and ethanol were studied using baited pitfall traps. Both species were attracted to α-pinene, and when ethanol was added the attraction increased by 5–16 times. Limonene completely inhibited the attraction to α-pinene, even when the release rate of limonene was only about 1/50 that of α-pinene. The catches in traps with α-pinene and limonene as well as with limonene alone were similar in size to catches in empty control traps, i.e., no true repellent effect was demonstrated. When limonene was added to the combination of α-pinene and ethanol on old clear-cuttings, the catch ofH. pinastri was completely inhibited while that ofH. abietis was reduced by two thirds. On fresh clear-cuttings the inhibitory effect of limonene on the attraction to the α-pinene-ethanol combination was small or absent. Some aspects of host interactions are discussed as are practical implications regarding the choice of seedling material for planting and prospects of finding deterrents for protecting seedlings from pine weevil damage.

Host finding in the pine weevil Hylobius abietis : effects of conifer volatiles and added limonene

The attraction of Hylobius abietis (L.) (Coleoptera: Curculionidae) to α‐pinene was recently shown to be inhibited by limonene. This study shows that added limonene also affects the response of H. abietis to odours from natural host material. The experiments included both pieces of Scots pine suspended in pitfall traps and planted pine seedlings that had either been manually wounded or left intact. By adding a limonene dispenser, the catch of pine weevils in pine‐baited traps was reduced by about 80–90% in spring and autumn and by about 40–50% in summer. Limonene substantially reduced the rate at which manually wounded seedlings were attacked by weevils in spring and autumn. For intact seedlings, a limonene‐induced reduction in attack rate was found only in autumn. In the absence of limonene, a small wound made on the stem of a seedling increased its probability of being attacked by about fivefold. This figure was estimated by comparing data from all experimental periods with a model assuming a constant ratio of attack rates for the two kinds of seedlings.