1 Morphological characters were elaborated and part of the mitochondrial COI gene was sequenced in order to facilitate the determination of the three European pine bark beetles Tomicus piniperda, T. destruens and T. minor. The sequence information also provided the first information on the phylogenetic and phylogeographical relationships of these species. 2 Three hair rows were found on the antennal club of T. destruens between the second and third suture. Tomicus piniperda had only one row. Three different hair types were detected on the elytra ± two hair types were found on T. piniperda, whereas the third hair type was only detected on the elytra of T. destruens. 3 The COI region (445 bp) revealed high sequence divergence among T. destruens, T. piniperda and T. minor. The three species proved to be monophyletic species with 16.98±19.23% sequence divergence. A phylogenetic approach placed T. minor and T. destruens as sister taxa, which contradicts the morphological findings. 4 European populations of T. piniperda shared two haplotypes, indicating a homogenous distribution of the genotypes. In the American populations only one of these European haplotypes was found. The Greek, Italian and Spanish T. destruens populations revealed three population-specific haplotypes, indicating restricted gene flow. 5 Species-specific primers were designed to allow a rapid and definitive determination of the two sibling Tomicus species by PCR.
Canningia tomici sp. n. (Microsporidia, Unikaryonidae) infects the midgut epithelium, the gut muscules, Malpighian tubules, connective tissues, adipose tissues and the gonads of the pine shoot beetle, Tomicus piniperda (L.) (Coleoptera, Scolytidae). The infection is present in populations of Tomicus piniperda in Europe and in the United States. Uninucleate oval single spores occur in two sizes: 2.8 ± 0.4 · 1.4 ± 0.4 lm and 3.8 ± 0.3 · 2.0 ± 0.2 lm. The polar filament of this microsporidium is fixed subapically in a flat anchoring disc. The thick posterior lamellae of the binary polaroplast are asymmetric due to the lateral fixation of the polar filament.
Background and purpose. The pine shoot beetles Tomicus piniperda and Tomicus minor are secondary tree pests attacking weakened Pinus sylvestris and Pinus nigra. Outbreaks occasionally occur, causing considerable economic damage. The microsporidian pathogen Canningia tomici infects T. piniperda as its principal host. Bioassays were used to study the infectivity, vertical transmission, and effects on survival and fecundity of C. tomici on the two beetle species. Austria (Lower Austria, Burgenland and Styria), Finland (Hyytiälä), Poland (Sękocin) (1, 2). T. piniperda occurs throughout Europe, from the northernmost regions of Norway, Finland, and Sweden, to the south of Central Europe. It has spread to China (3) and was accidentally introduced into the USA (4) and Canada (5, 6). The related species T. minor occurs sympatrically with T. piniperda, but uses different stem regions on pine trees. It is widespread throughout Europe, from Scandinavia to the Mediterranean region (2). Depending on the ambient temperature, overwintering adults of both species initiate flight activity in spring, with T. minor flying later than T. piniperda. Following mating, females tunnel mother galleries into the phloem and lay one clutch of eggs. Re-emergence of adult beetles occurs when breeding and oviposition is completed. Subsequently, they bore into shoots of mature pine trees for regeneration feeding, followed by the initiation of a sister brood in uninfested regions of the same tree or in uninfested logs. Both species may infest the same host tree; T. piniperda prefers the lower parts of trees with thick bark for breeding sites, while T. minor prefers trunk with thin bark. Both species bore/tunnel into one-year-old pine shoots for maturation feeding (7,8). Shoot feeding by young callow adults and older adult beetles causes the primary injuries to pine trees, resulting in twig death and weakening of the infested trees (9, 10). However, both beetle species are known as secondary pests in pine stands during the endemic phase. Nonetheless outbreaks occur occasionally, during which the beetles are able to attack vigorous trees (11). This causes considerable economic damage, particularly by T. minor. In addition to infesting living trees, both beetle species infest wind thrown, felled, and firedamaged trees, as well as fresh logs (7,(12)(13)(14). Moreover, these phloeophagous beetles introduce blue stain fungi (e.g. Leptographium wingfieldii, Ophiostoma minus), which interfere with water conduction, accelerate tree death, (15)(16)(17) and reduce the commercial value of timber when it develops blue stain. Materials and methods. Field collected beetles from several locations inBiological control has never been seriously attempted with bark beetles (18,19) and should be reconsidered in light of the results of a study conducted by Kohlmayr et al. (20), which reports the presence of the microsporidium Canningia tomici in cells of the midgut epithelium, adipose tissue, and ovariols of T. piniperda. Little has been reported about the ...
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