Morphological characters of dauer juveniles of three species of Bursaphelenchus Fuchs, 1937

Abstract

The morphological characteristics of dauer juveniles were examined forBursaphelenchusxylophilus,B. firmaeandB. mucronatus kolymensis. Dauer juveniles ofB. xylophilusandB. firmaewere collected directly from their carrier insects,Monochamus alternatusandM. grandis, respectively.Bursaphelenchs m. kolymensisdauer juveniles were induced experimentally usingM. alternatuspupae. The dauer juveniles of these three species were distinguished according to their respective body shapes.Bursaphelenchus xylophiluswas relatively slender compared to the other species. The position of the excretory pore was anterior to the median bulb inB. firmae, overlapping with the median bulb inB. xylophilus, and posterior to, or overlapping with, the posterior part of the median bulb inB. m. kolymensis. The tail tip ofB. firmaewas conical, that ofB. xylophiluscontained a short projection, while inB. m. kolymensisthe tail tip was blunt with a thick mucron.

PM 7/4 (4) Bursaphelenchus xylophilus

“…The fourth dispersal juvenile stage is the most frequent stage found in the body (thorax and abdomen) of the insect vector. This stage was described by Kanzaki et al (2020) and photos can be seen in EPPO Global Database (https://gd.eppo.int/taxon/ BURSX Y/photos). However, juveniles at other stages, and adults of species belonging to the B. xylophilus group may also be present (Kanzaki et al, 2013).…”

Enzyme-Mediated Amplification (EMA) for Detection of the Pinewood Nematode Bursaphelenchus xylophilus

“…Among Bursaphelenchus species, B. mucronatus is considered to be closely related to B. xylophilus (the PWN), based on their similar taxonomic positions, life cycles, hosts and even vector beetles [29]. The traditional morphological identification technique relies only on the length of the adult female's tail tip to distinguish the PWN from B. mucronatus [15], such that B. mucronatus is sometimes misidentified as the PWN because of morphological overlap between the two species. Furthermore, some studies have reported that the two nematode species can mate and generate viable and reproducible progeny [27], suggesting that they may not be distinct species.…”

“…The PWN has two life forms: propagative and dispersive [13]. When the environment is not suitable for the survival of PWNs (e.g., low temperature, drought or a lack of food), the PWN will change form from the propagative type, with typical morphological characteristics, to the dispersive type, with loss of certain morphological characteristics, including disappearance of the median bulb and the stylet [14,15], such that traditional identification using morphological characters of adult females cannot be adopted to identify the species. In addition, B. xylophilus extracted from wood samples have mucronate tails [16], which are very similar in morphology to those of Bursaphelenchus mucronatus Mamiya & Enda.…”

Artificial induction of third-stage dispersal juveniles of Bursaphelenchus xylophilus using newly established inbred lines

“…Nematodes were then rinsed three times with sterilized water. Fifty surface-sterilized nematodes of each isolate were reared on the hyphae of Cosmospora viridescens , which is frequently used in experiments involving dispersal stage induction [ 50 , 51 ], growing on malt extract agar (2% malt extract, 1.5% agarose) in 4-cm-diameter Petri dishes, and kept at 25°C for 10, 20, and 30 days. Each treatment was repeated eight times.…”