Bursaphelenchus trypophloei sp. n. (Nematoda: Parasitaphelenchinae) – an associate of the bark beetle, Trypophloeus asperatus (Gyll.) (Coleoptera: Curculionidae, Scolytinae), in aspen, Populus tremula L.

Abstract

Bursaphelenchus trypophloei sp. n. is described from weakened and dead twigs of living or recently fallen aspen trees, Populus tremula, in Poland. All propagative stages of the nematode were present in larval galleries of a bark beetle, Trypophloeus asperatus, and its dauer juveniles could be found in the haemocoel of older larvae, pupae and adult beetles. Characteristic morphology of the male spicules with distinct cucullus, extended anterior vulval lip, lateral fields with four incisures, and number and arrangement of male caudal papillae indicate that B. trypophloei sp. n. is closely related to the xylophilus group. This relation has been further confirmed by DNA sequencing and phylogenetic analysis of the 28S and ITS-1 rDNA region. Bursaphelenchus trypophloei sp. n. can be separated from other species in the xylophilus group by the morphology of spicules which have a shorter capitulum and unique rostrum which is pointed somewhat anteriorly, relatively thick vulval flap, which is straight, parallel to the body long axis or bent towards the body wall at its distal end, and other morphological and morphometric characters, i.e., shape of female tail, position of excretory pore at or posterior to nerve ring, spicule length of 25.7 (23.1-28.0) μm (as measured along arc) and shape, moderate length, i.e., L = 702 (603-946) μm in females and L = 679 (543-828) μm in males, and slender body (a = 39.2 (33.0-45.2) and 40.9 (32.0-46.4) in female and male, respectively). The taxonomic separation of the new species is also confirmed by the unique molecular profile of the ITS region (ITS-RFLP). Full reproductive incompatibility of B. trypophloei sp. n. with B. xylophilus, B. mucronatus, B. fraudulentus, B. populi and B. doui has been demonstrated in in vitro diallelic cross-breeding. The newly described nematode revealed limited ability to develop and reproduce on Botrytis cinerea cultures although it produced large populations on laboratory cultures of Cytospora chrysosperma -a fungus naturally associated with galleries of the nematode vector, T. asperatus.

Bursaphelenchus crenati Rühm, 1956 (Tylenchina: Aphelenchoididae), a nematode associated with the Greater ash bark beetle, Hylesinus crenatus Fabricius, in dying ash, Fraxinus excelsior L., in Europe

“…It is probable that the difference in fungal composition introduced to the bark by each ash beetle species could be responsible for making this association so specific. Our earlier studies have revealed that B. trypophloei and B. masseyi developed specifically on fungi introduced to the bark of poplar by bark beetles which also served as exclusive vectors of these nematodes (Tomalak & Filipiak, 2011;Tomalak et al, 2013). However, further research is needed to elucidate the basis of the observed specificity.…”

Overview of the Genus Boleodorus and First Reports of Boleodorus thylactus and B. volutus from Southern Alberta, Canada

“…The tree contained a highly supported major clade (PP = 1.0) comprising all the species of the genus Boleodorus, including the B. thylactus and B. volutus from Alberta, Canada (Figure 5). The D2-D3 domains of the 28S rRNA gene alignment (699 bp long) included 98 sequences of Tylenchidae species (four of them new, belonging to B. thylactus, and three others from B. volutus) and three outgroup species, Bursaphelenchus trypophloei Tomalak [73] (FJ998283), Bursaphelenchus mucronatus Mamiya and Enda [74] (AB932857), and Aphelenchoides fragariae (MK077677). The Bayesian 50% majority rule consensus tree inferred from the D2-D3 alignment shows one highly supported major clade (PP = 1.0) comprising species of Boleodorus, including B. thylactus and B. volutus from Alberta, Canada (Figure 6).…”

Preliminary survey of nematodes associated with broadleaved trees in İzmit Forest Management Directorate, Turkey

“…Bursaphelenchus species have been examined mostly for conifers. However, so far, many species have been also found from broadleaved trees in numerous places in the Northern Hemisphere (Braasch & Burgermeister, 2007; Kanzaki & Giblin‐Davis, 2018; Kurashvili et al., 1980; Ryss et al., 2015; Ryss & Subbotin, 2017; Tomalak & Filipiak, 2010, 2011; Tomalak et al., 2013). Further studies are necessary to determine the distribution of B. mucronatus and other Bursaphelenchus species on broadleaf forests and possible insect vectors in Turkey.…”

“…In addition to coniferous trees, some broadleaved tree species are also known to be the hosts of Bursaphelenchus species (Braasch & Burgermeister, 2007; Kanzaki & Giblin‐Davis, 2018; Ryss et al., 2005, 2015; Ryss & Subbotin, 2017; Tomalak & Filipiak, 2010, 2011; Tomalak et al., 2013). The presence of Bursaphelenchus species in broadleaved forest trees is not known in Turkey.…”