Leptographium wageneri

back stain root disease Dutch disease and multistriatus

DED caused the death of millions of in and from around 1920 through the present epidemics in North America

Originally thought one species of Ophiostoma, O. ulmi with 3 different races

Now two species are recognized, O. ulmi and O. novo-ulmi, and two subspecies of O. novo-ulmi

Two nearly simultaneous introductions in North America and Europe 1920s O. ulmi introduced from Europe, spread throughout NA, but caused little damage to native elm trees either in NA or Europe

1950s, simultaneous introductions of O. novo-ulmi, Great Lakes area of US and Moldova-Ukraine area of Europe. North American and Europe subspecies are considered distinct.

1960 NA race introduced to Europe via Canada.

By 1970s much damage to US/Canada elms killed throughout eastern and central USA

O. novo-ulmi has gradually replaced O. ulmi in both North America and Europe more fit species replacing a less fit species O. novo-ulmi able to capture greater proportion of resource O. novo-ulmi probably more adapted to cooler climate than O. ulmi

During replacement, O. ulmi and O. novo-ulmi occur in close proximity and can hybridize. Hybrids are not competitive, but may allow gene flow from O. ulmi to O. novo-ulmi by introgression:

Backcrossing of hybrids of two plant populations to introduce new genes into a wild population

Vegetative compatibility genes heterogenic incompatibility multiple loci prevents spread of cytoplasmic viruses

O. novo-ulmi arrived as a single vc type, but rapidly acquired both new vc loci AND virus, probably from hybridizing with O. ulmi.

In , only O. novo-ulmi introduced and has remained only a single VC group.

O. ulmi may have earlier hybridized with native O. quercus and obtained virus and vc genes in a similar way.

In Europe, where both subspecies of O. novo-ulmi occur and have overlapping distributions, hybridization is occurring and probably leading to accelerated evolution in the pathogen population Ambrosia , ambrosia fungi

Adult beetles bore into the xylem of recently killed trees, often very soon after tree death, before fungi have colonized the dead wood.

Fungi are carried in a specialized organ, a mycangium, inoculates walls of tunnel as female bores in. When eggs hatch, larvae feed on the fungi lining the tunnels.

Fungi are various species, not as specific as the termite or ant fungi mainly ascomycetous yeasts, Dipodascus, Ambrosiella, Ambrosiozyma Also other anamorphic ascomycetes, some basidiomycetes mycangium with fungi Laboulbeniales about 2000 spp., 140 genera exclusive parasites on the exoskeletons of , some arachnids

Thallus a stroma with perithecial ascomata monoecious species (antheridia and perithecia formed on same thallus) dioecous species (antheridia and perithecia on different thalli)

Perithecia have trichogynes that receive spermatia from antheridia

Very high degree of host specificity Occur on specific insects, specific parts

Some species have been reported to be specific to particular sexes of host insects

Roland Thaxter (Harvard) studied the Laboulbeniales and described 103 genera and 1,250 species 1896-1931

Laboulbeniaceae

Monoecious both ascogonia and antheridia

Dioecious female thallus ascogonia male thallus antheridia

Left. Male Laccophilus copulating with female in a parallel orientation, resulting in positions 1a to 1b and 2a to 2b to be misaligned. Right. Male oriented in a diagonal, as observed in video footage, resulting in the alignment of all positions. 1a. C. uncinatus, 1b. C. simplex. 2a. C. lichanophorus, 2b. C. affinis. 3a. C. hyalinus, 3b. C. marginatus. 4a. C. appendiculatus, 4b. C. dentifer. 5a. C. spiniger, 5b. C. rhyncostoma, 6a. C. unciger, 6b. C. paradoxus. Hosts of Laboulbeniales Laboulbenialean host distribution is more restricted than has been appreciated previously. Not all insects serve as hosts and, although beetles are the most frequent host group, not all groups serve as hosts. Hexapoda (90% of the known species of Laboulbeniales have been found only on adult beetles or flies, mainly the former. Within the major host group, Coleoptera, only 12 of the 24 currently recognized superfamilies of beetles have been reported as hosts for these fungi). Blattoidea (cockroaches and allies) Coleoptera (beetles) Dermaptera (earwigs) Diptera (true flies) Heteroptera (bugs) Hymenoptera Formicidae (ants) Isoptera (termites) Mallophaga (bird lice) Orthoptera (crickets and allies) Thysanoptera (thrips) Acarina () Diplopoda (millipedes) Predaceous Fungi

Fungi that capture microscopic — and rotifers Various hyphal modifications adapted for capturing

Endoparasitic Fungi

Specialized parasites of rotifers, nematodes, amoebae Both are polyphyletic, nutritional/ecological groups

Predaceous fungi include members of , Basidiomycota, Endoparasitic fungi include Ascomycota, Basidiomycota, Chytridiomycota, Zygomycota, and Oomycota

Orbiliomycetes

trapping fungi

Like Nematoctonus (Hymenomycetes) wood inhabiting, nematodes a source of N

Nematode trapping anamorphs only recently connected to teleomorphs based on DNA sequences Nematode capturing fungi mechanisms

Adhesive hyphae – Zygomycetes: Cystopage, Stylopage Adhesive branches – Ascomycota: Dactylella Adhesive nets – Ascomycota: Adhesive knobs – Ascomycota: Arthrobotrys, and Basidiomycota: Nematoctonus Constricting and non-constricting rings – Ascomycota: Arthrobotrys, Dactylella Nematicides – Basidiomycota: Pleurotus

Several genera like Dactylella include species that capture nematodes by different methods

D. copepodii has adhesive branches, D. brochopaga has constricting rings, Arthrobotrys species have adhesive knobs, adhesive nets, non constricting and constricting rings Adhesive branches: Dactylella (Orbiliomycetes) non constricting rings, Arthrobotrys candida and Dactylella arcuata (also adhesive conidia)

non constricting ring species also make adhesiveknobs Adhesive knobs readily break off but function as spores capable of infecting through the nematode cuticle. Predaceous fungi Constricting rings

Arthrobotrys anconia

Traps are formed immediately after germination Rapid expansion of constricting ring

Cells of the unexpanded trap have a preformed equatorial weakness joining a fold of cell wall. Upon mechanical stimulation, the weak portion of the wall breaks causing the cell to expand to 3X cell volume.

The three times increase in volume of the ring cells must result in a three times decrease in osmotic pressure of the ring cells at the time of expansion. So initial pressure in the trap cells not sufficient to crush the tode immediately.

thin portion of wall

preformed wall There is a rapid conversion of reserve materials (glycogen) to glucose in the rings cells to allow the OP of the cell to recover. When the OP of the rings cells exceeds that of the nematode cells then the nematode wall will collapse and the body will be constricted.

In its struggles to escape the nematode will often put its tail into a second ring and be held immobile.

Once captured, the rings cells will germinate and invasive hyphae penetrate into the living body of the nematode, grow throughout the body and digest the contents. This will be accomplished within 12-24 hours. Adhesive nets formed by Arthrobotrys oligospora A nematode trapped in an adhesive net Endoparasitic fungi

Generally do not develop extensive thallus outside the host, spores (conidia) the only form independent of the host

All phyla of fungi except Glomeromycota have endoparasitic forms on nematodes etc.

Chytridiomycota, Zygomycota, Ascomycota, Basidiomycota, Oomycota Adhesive conidia of Drechmeria coniospora (anamorphic Clavicipitaceae) Endoparasites

Harposporium conidia adapted for ingestion, lodge in the buccal cavity