A native fungal symbiont facilitates the prevalence and development of an invasive pathogen–native vector symbiosis

Abstract

Abstract. Invasive pathogen-insect symbioses have been extensively studied in many different ecological niches. Whether the damage of symbioses in different introduced regions might be influenced by other microorganisms has, however, received little attention. Eight years of field data showed that the varied levels of the nematode and beetle populations and infested trees of the invasive Bursaphelenchus xylophilus-Monochamus alternatus symbiosis were correlated with patterns in the isolation frequencies of ophiostomatoid fungi at six sites, while the laboratory experiments showed that the nematode produced greater numbers of offspring with a female-biased sex ratio and developed faster in the presence of one native symbiotic ophiostomatoid fungus, Sporothrix sp. 1. Diacetone alcohol (DAA) from xylem inoculated with Sporothrix sp. 1 induced B. xylophilus to produce greater numbers of offspring. Its presence also significantly increased the growth and survival rate of M. alternatus, and possibly explains the prevalence of the nematode-vector symbiosis when Sporothrix sp. 1 was dominant in the fungal communities. Studying the means by which multispecies interactions contributed to biogeographical dynamics allowed us to better understand the varied levels of damage caused by biological invasion across the invaded range.

Gene family expansion of pinewood nematode to detoxify its host defence chemicals

“…The intron number of these potential HGT genes was an average of 2.3 per gene, while for the remainder it was 5 per gene (Table ), consistent with previous studies that fungi usually have about 0.05–3.43 introns and invertebrates usually have 2.92–7.42 introns (Li, Xu, & Ma, ). Interestingly, these candidate HGT genes grouped most closely with fungal species in the genera Sporothrix (Figure ), which are abundant in pine niches (Chu, Wang, Wang, Chen, & Tang, ; Lou et al, ; Péter, Dlauchy, Tornai‐Lehoczki, Gouliamova, & Kurtzman, ; Zhao et al, ). B. xylophilus may feed on these fungi in pine wood and HGT could have occurred from these food sources within the nematode gut.…”

“…[Lou, Lu, & Sun, 2014], Sporothrix spp. [Zhao et al, 2013], Wickerhamomyces spp. [Lou et al, 2014]) ( Figure S18).…”

Are nematodes costly to fig tree–fig wasp mutualists?

“…The best-known aphelenchoidid nematode is the pinewood nematode, Bursaphelenchus xylophilus (Steiner & Buhrer), which is transported by the longhorn pine beetles. The nematode feeds on pine tissues and fungi, and causes pine wilt disease (Futai, 2013;Zhao et al, 2013).…”

Commensal relation between Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) and Monochamus alternatus (Coleoptera: Cerambycidae) within pine trees

“…By contrast, a 7-day rearing experiment by Zhao et al (2013) revealed that adding the Chinese blue-stain fungi of two Sporothrix species and Ophiostoma ips (Rumbold) Nannf. facilitated the growth of M. alternatus larvae of 310 mg in mass when the larvae were reared on an artificial diet comprising finely ground Pinus massoniana Lamb.…”

“…Unlike the study of Zhao et al (2013), our study used pine bolts instead of the artificial diet, which provided M. alternatus larvae two different habitats, the phloem and xylem. Our rearing period of 2.5 months or more was substantially longer than their period of 7 days.…”