Direct Positive Effects Of Basidiomycota On Invertebrates Fruit Bodies And Mycelia As Food And Habitat

Mycelia are highly nutritious (Swift and Boddy, 1984; see below). Not surprisingly, therefore, many invertebrates use fungi as a food source, either grazing directly on mycelia or fruit bodies, or indirectly by ingesting mycelium within decomposing litter (Maraun et al., 2003). Mycophagy is most prevalent amongst members of the phylum Arthropoda, although there are also many examples within the Mollusca, Enchytraeidae, Annelida, Collembola and Nematoda. For example, nematodes in the genus Filenchus fed and reproduced on Coprinus cinereus, Flammulina velutipes, Rhizoctonia solani mycelium and even on the

Table 1 Illustrative examples of symbiotic relationships between saprotrophic Basidiomycota and invertebrates

Fungus

Invertebrate

Nature of symbiosis Effect on fungus

Effect on invertebrate

References

Lepiota,

Attine ants

Mutualism: ants

Provision of plant

Leucoagaricus

cultivate the fungus

resources; maintenance of favourable abiotic and biotic environment; carriage of spores to new nests

Termitomyces

Macrotermitinae

Mutualism: ants cultivate the fungus

Provision of plant resources; maintenance of favourable abiotic and biotic environment; carriage of sexual and, in some species, asexual spores to new nests

Amylostereum

Siricid wood

Mutualism:

Inoculation into a

areolatum, A.

wasps: Sirex,

females carry

suitable

chailletii and

Urocerus and

asexual spores to

environment;

Cerrena

Tremex spp.

trees; larvae

widespread

( = Daedalea)

develop in

clonal

unicolor

colonized wood

populations

Nutrition; ingested enzymes

Nutrition; ingested enzymes

Softening of wood; improved nutrition; ingested enzymes

Nutrition; ingested enzymes

Nutrition; ingested enzymes

Softening of wood; improved nutrition; ingested enzymes

Martin (1992), Baas and Cherrett (1996), Hernandez et al. (1999), Ortius-Lechner et al. (2000), Mueller (2002)

Wood and Thomas (1989), Martin (1992), Aanen et al. (2002), Mueller and Gerardo (2002)

Martin (1992), Thomson and Koch (1999)

(Continued)

Table 1 (Continued)

Fungus Invertebrate Nature of symbiosis

Septobasidium

Scale insects

Mutualism and parasitism: scales live within a mycelial mat on the surface of plants

Wood-rotting species, e.g.

Laetiporus sulphureus, Fistulina hepatica, Phellinus cryptarum, Bjerkandera fumosa, Trametes versicolor and Coniophora putearía Phallaceae Polypores

Death watch beetle

Xestobium rufovilosum

Diptera Gamasid mites

Larvae burrow in wood colonized by the fungus

Mutualism Feeding within fruit bodies

Agarics and polypores

Insecta

Feeding within fruit bodies

Effect on fungus Effect on invertebrate

References

Obligate; nutrition and dispersal

May benefit from nutrient input in faeces; harm may accrue from comminution

Some scales are parasitized, others benefit from a buffered microclimatic environment and protection from predators Softening of wood; improved nutrition

Fisher (1940, 1941)

Spore dispersal Decreased reproductive output; spore destruction; spore dispersal Decreased reproductive output; spore destruction; spore dispersal

Nutrition Nutrition and breeding ground

Nutrition and breeding ground

Tuno (1998) Makarova (2004)

Hammond and Lawrence (1989), Hanski (1989)

Polypores

Coleóptera

Feeding within fruit bodies

Agaricus bisporus mycelium

Mycelial systems of cord-forming wood decomposers on soil

Inter- and intra-specifically interacting non-compatible mycelia Coprinus cinereus and Flammulina velutipes mycelium Coprinus comatus, Hohenbuehelia, Hyphoderma and Pleurotus mycelium Fibularhizoctonia sp.

Fungus gnats Mycophagy

(Phoridae and Sciaridae) Collembola Mycophagy

Fungus gnats (Sciaridae); Collembola

Mycophagy

Nematoda

Mycophagy

Nematoda

Invertebrate killing

Reticulitermes (Isoptera: Rhinotermitidae)

Sclerotia mimic eggs and are tended by the termites

Decreased reproductive output; spore destruction; spore dispersal

Negative

Morphological changes, increases and decreases in hyphal coverage Outcome of interactions sometimes modified

Nutrition and breeding ground

Nutrition and breeding ground

Nutrition and breeding ground

Guevara et nl (2000a, 2000b, 2000c), Thunes et ni (2000), Schigel et nl (2004), Orledge and Reynolds (2005) Sheepmaker et nl (1996)

Harold et nl (2005), Bretherton et nl (2006), Tordoff et nl (2006), Wood et nl. (2006) Boddy et nl (1983); Fig. 1

Nutritional

Protection; transport to a competitor free environment

Death

Enhanced e survival

Thorn and Barron (1984), Barron and Thorn (1987), Tzeam and Liou (1993), Luo et nl (2004) Matsuura et nl (2000), Matsuura (2005)

nematophagous (see below) Pleurotus ostreatus in agar culture and soil (Okada et al., 2005). In another example, the enchytraeid Enchytraeus crypticus destroyed colonies of the nematophagous fungus Hirsutella rhossiliensis, and reduced biological control of the root-knot nematode Meloidogyne javanica (Jaffee, 2004). Mycelia of some species are more palatable than others, and there is sometimes considerable variation between closely related species and strains (Smith et al., 2006a, 2006b), and in different mycelial regions (see below).

Both perennial (e.g. polypore brackets) and ephemeral (e.g. Agaricales) fruit bodies provide food sources and breeding grounds for a diversity of invertebrates, including nematodes (Jaffee, 2006; Li et al., 2006), enchytraeids (Nowak et al., 2005), mites (Makarova, 2004), Collembola (Greenslade et al., 2002; Naka-mori and Suzuki, 2005a, 2005b), Coleoptera (beetles; Thunes et al., 2000; Schigel et al., 2004; Orledge and Reynolds, 2005) and Diptera (flies; Jonsell and Nordlander, 2002; Yamashita and Hijii, 2003). Insects that feed on agarics are mostly polyp-hagic, selective pressures promoting use of a wide variety of species, because the fruit bodies are unpredictable and ephemeral resources, whereas over half of the insects feeding in brackets in Sweden were monophagous (Jonsell and Nordlander, 2002). Ciid beetles can be divided into host-use groups, each ciid taxon only belonging to a single host-use group, but often utilizing several members of that group (Orledge and Reynolds, 2005). The high degree of monophagy in insects in general and the host-use groups of ciids is probably ultimately defined by chemical defences of the host bracket.

Though some invertebrates are able to use living fruit bodies, others are only able to use those that are decaying, and different invertebrate species are found at different stages of decay. Those fungivores that are polyphagous on brackets mainly colonize them after they have been decaying for some time, defence chemicals having presumably decreased by then (Jonsell and Nordlander, 2002). Early colonizers, that tend to be monophagous, have the advantage over later colonizers in that they have so-called priority effects and a more nutritious environment, but they have a narrower choice of fungal resources.

In some cases, the advantage is other than food or habitat resource. Basidiomycete species in the genus Septobasidium, for example, form complex relationships with scale insects. These insects are plant parasites and suck plant sap using their long stylet mouthparts. The scale insects are found in the middle layer of the fungus, in chambers that are only slightly larger than the insects themselves and are inter-connected by numerous tunnels. Some of the scale insects are parasitized by the fungus (Dykstra, 1974; Evans, 1989). These parasitized individuals are immobile and usually occupy a chamber where they are attached to the plant via their suctorial tube. The scale insect nourishes itself with the plant sap, and the fungus, attached to the insect by haustoria, is subsequently indirectly nourished by the plant. At first glance, it may appear that this is simply a case of parasitism with the fungus getting all the benefits, but there are benefits to the scale insects. Only some are parasitized, but they are all sheltered from the environment and protected from predators, allowing them to live longer than their free-living brethren. It has been shown that, in at least some cases, the fungal covering over the scale insects is deeper than the reach of the ovipositors of parasitic wasps that seek out scale insects (Morse and Normak, 2006).

Fruit bodies also form an important part of the diet of some vertebrates. Many non-domesticated mammals and birds are opportunistic mycophagists, others, for example, squirrels and several marsupials, are classed as preferential my-cophagists concentrating on fruit bodies when they are available, and a few are obligately mycophagous (e.g. two marsupial rat kangaroos—Potorous longipes and P. gilbertii; Claridge and Trappe, 2005).

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Responses

  • berilac
    Is septobasidium spp a decomposer parasite or mutualist?
    6 years ago

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