Search

Symbiosis with microbes is crucial for survival and development of wood-inhabiting longhorn beetles (Coleoptera: Cerambycidae). Thus, knowledge of the endemic fungal associates of insects would facilitate risk assessment in cases where a new invasive pest occupies the same ecological niche. However, the diversity of fungi associated with insects remains poorly understood. The aim of this study was to investigate fungi associated with the native large poplar longhorn beetle (Saperda carcharias) and the recently introduced Asian longhorn beetle (Anoplophora glabripennis) infesting hardwood trees in Finland. We studied the cultivable fungal associates obtained from Populus tremula colonised by S. carcharias, and Betula pendula and Salix caprea infested by A. glabripennis, and compared these to the samples collected from intact wood material. This study detected a number of plant pathogenic and saprotrophic fungi, and species with known potential for enzymatic degradation of wood components. Phylogenetic analyses of the most commonly encountered fungi isolated from the longhorn beetles revealed an association with fungi residing in the Cadophora-Mollisia species complex. A commonly encountered fungus was Cadophora spadicis, a recently described fungus associated with wood-decay. In addition, a novel species of Cadophora, for which the name Cadophora margaritata sp. nov. is provided, was isolated from the colonised wood.

An industrially valuable tree, aspen, suffers from several fungal diseases and insect pests such as the large poplar borer (Saperda carcharias). The role of the beetle as a pest of aspen and hybrid aspen was investigated in five aspen and three hybrid aspen stands in Finland. Approximately 50% of the trees in the study had signs of the large poplar borer. Of these trees, 5% had insect exit holes. Approximately 70% of the trees with larval galleries had only one or two larval galleries. The trees with larval galleries were on average 2 m shorter than those without larval galleries. No significant difference could be detected in the diameter growth between these two groups. The proportion of decay was greater in hybrid aspen (27%) than in aspen (14%). These results show that the large poplar borer is an important pest of both aspen and hybrid aspen in Finland. No significant difference was observed between the aspen and hybrid aspen stands in the number of trees with larval galleries. Hybrid aspen therefore does not appear to be more sensitive to damage caused by the large poplar borer. Thus, a change from hybrid aspen to regular aspen in aspen cultivation is unnecessary, presuming that healthy saplings and an optimal rotation time are used.

The total forest area of Spain amounts to 26.5 Mill. hect. but only 12 Mill. hect. are stocked; 7 Mill. hect. by broad-leaved forest and 5 Mill. hect. by coniferous forest. The effective percentage of wooded land amounts, for the time being, to only 24.2 per cent. Between 1940 and 1945 1.8 Mill. hect. were forested with mainly 6 species of pine. About 80 per cent of the most important forest pests of Spain which belong to the most destructive enemies of the forest, are also to be found in central Europe. The most serious pests in stands of pine species are:Thaumetopoea pityocampa Schiff.,Lymantria monacha L. (onP. silvestris only),Diprion pini L., andNeodiprion sertifer Geoffr. The area attacked byTh. pityocampa, after the most recent evaluation, amounts to 1,750,000 hect., 600,000 of which exhibit serious damage of frass. The yearly loss of increment caused byTh. pityocampa is estimated upon 175,000 cubic metres volume and represents a value of 1.7 Mill. dollars. In reforestations of pine,Pissodes notatus F.,Blastophagus piniperda L., andRhyacionia buoliana Schiff., become harmful. As seed pests,Pissodes validirostris Gyll. andDioryctria mendacella Stgr. are economocally important, destroying the desired fruits ofPinus pinea L. or preventing their ripening. In contrast to the large number of pine pests that of other coniferous tree species play a little role. For silver fir, however, a serious pest arose by the regrettable introduction ofAdelges (Dreyfusia) nusslini C. B. into the Pyrenees;Pristiphoia erichsonii Htg., too, has to be considered a potential pest for the extended young crops of larch. It is remarkable that the possible Adelgids of larch withSacchiphantes viridis Ratz.,Adelges laricis Vall., andCholodkovskya viridana Chol. are complete although their host is not autochthonous in the Pyrenees.S. abietis L. was also recorded. Among the pests of broad-leaved trees, these of the oaks, especially ofQuercus ilex L. andQ. suber L, have the greatest importance, led on byTortrix viridana L.,Lymantria dispar L.,Malacosoma neustria L.,Catocala nymphagoga Esp., andC. (Ephesia) nymphaea Esp.T. viridana and its accompanying species formerly prevented the development on a large area, the “mast” ofQ. ilex which forms in many provinces the basic nutrition in comprehensive swine-breeding. Before an intensive chemical control was set up, yearly losses in swine mast amounted to 17 Mill. dollars. In poplar plantations serious damages are caused byCryptorrhynchus lapathi L.,Paranthrene tabaniformis Rott,Saperda carcharias L., andMelanophila picta Pall. The total yearly damage caused by forest pests in Spain amounts to approximately, 33 Mill. dollars. In Spain all duties of forest protection are managed by a central Institute the “Servicio de Plagas Forestales, Madrid”. The strong point of activities in forest protection lies so far in chemical control of forest pests. Between 1953 and 1965, 2,972,919 hect. of forests endangered by forest insects, were treated; 2,338,613 hect. of which were treated againstT. viridana. The control ofTh. pityocampa is well organised, methodically original and effective. Basic research in biological and integrated control is practised.

In a locality in Southern Finland where the white-backed woodpecker, (Bechst.), was previously breeding was found many conical borings excavated during the winter in young aspens ( L.) on average 8.1 cm in diameter. Full-grown larvae of (L.) (Coleoptera, Cerambycidae) hibernated in pupal chambers constructed about 0.5 m above ground level. Below this chamber the larva has usually prepared an exit hole. After the larva has blocked itself in the pupating chamber it is easy to prey for the woodpecker during the whole winter.Dendrocopos leucotosPopulus tremulaSaperda carchariasS. sarcharias

Records of diseases of Cerambycidae have appeared very infrequently in the literature. Crawshay (1907) described an unidentified disease of larvae of Tetropium gabrieli Weise. Garman (1921) and MacLeod (1954a) reported a fungus, Beauveria globulifera, a strain of Beauveria bassiana (Bals.) Vuill., from adults of Cyllene robiniae (Forst.) and a larva of Acanthocinus aedilis (L.) respectively. Duffy (1953) recorded the fungi lsaria sp. on adults of Phryneta spinator (Fab.), and Entomophthora grylli on larvae of Saperda carcharias (L.). A wilt disease, suspected of being caused by a virus, was reported by Beeson (1931) in larvae of Celosterna scabrator Fab.) reared in glass tubes.