Life cycle and population dynamics of Bursaphelenchus willibaldi (Nematoda: Rhabditida: Aphelenchoididae) in vitro

Abstract

Summary To develop models of forest ecosystem functioning, it is necessary to estimate parameters of the population dynamics of nematode species. Parameters of ontogenesis of Bursaphelenchus willibaldi from oak in culture of the fungus Botrytis cinerea were determined in vitro: oviposition began 2.7 (1-3) days after inoculation with adult nematodes; timelines of juvenile formation were: second-stage juveniles: 3.2 (3-4) days, third-stage juveniles: 3.6 (3-5) days, fourth-stage juveniles: 4.8 (3-6) days, first generation (1G) ended with a J4 moulting to adult after 5.8 (4-6) days. One day after the formation of the first generation, nematodes left the 2% potato-sugar agar (PSA) medium with the feed fungus and moved upwards, forming a migratory group (MG). In PSA the total nematode abundance reached peaks on day 11 (2G) and in the MG on day 27 (4.5G). The fecundity of females during population growth was determined as 3.4 (2.1-5.9) eggs day−1 and a model of exponential population growth was developed for total nematodes , ; and for females , . Under conditions of unrestricted reproduction and temperature of 21-23°C, the nematode and fungus can colonise 1 m3 of PSA-like medium in 36.8 days. The survival stage in the propagative generation was presumably J4. The female lifespan consists of a feeding and reproductive phase in the PSA (6 days) and a survival phase in the MG (1 month to 1 year). In MG, nematodes formed swarming groups of 20-200 individuals.