The invertebrate-pathogenic fungus flora of Thailand |
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Before 1989 less than ten “insect fungi” were reported from Thailand, Most of these were species that could be
commonly found around the World as pathogens of insects in agricultural ecosystems. Species such as the ubiquitous
Beauveria bassisna and Metarhizium anisopliae which infect a wide range of invertebrate hosts. The first reliably recorded species of ‘insect fungus’ from Thailand was reported by Petch (1932). This was Cordyceps gentilis on a hornet which was collected in July 1929 from ‘northern Siam’. Coredyceps gentilis is a close relative of Cordyceps sphecocephala (which was the first species of Cordyceps to be recognized and illustrated by Father Torrubia from Cuba in 1754 ) and was considered a synonym by Hywel-Jones (1995a). It was a further sixty years before a systematic survey of the insect fungi of Thailand was started. Cordyceps khaoyaiensis and Cordyceps pseudomilitaris became the first new species of “insect fungi” described from Thailand (Hywel-Jones 1994). After more than fifteen years of forest survey and other country in the World. Description of these fungi is a continuing process with many new species having been reported (Hywel-Jnes & Sivichai 1995; Hywel-Jones, Evans & Jun 1997; Hywel-Jones & Goos 1998). More recently the powerful tool of molecular phylogenetics has been applied to increasing our understanding of the taxonomy of these fungi as well as their relatedness and evolution. Mojor papers have involved research from the study of insect fungi in Thailand (Artjariyasripong et al. 2001; Luangasa-ard et al. 2004 ,2005; Stensrud et al. 2005’ Spatafora et al. 2007; Sung et al. 2007a; Sung et al. 2007b). “Insect fungi” are known from several taxonomic regions of the King dom Fungi. However, the majority of species reported from Thailand are members of the families Clavicipitaceae, Cordycipitaceae and Ophiocordycipitaceae (Order Hypocreales). This bias is reflected in this work. Most of the ‘insect fungi’ we will describe in this series will also be members of these three families. |
THE MYCOFLORA OF THAILAND |
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Before reviewing a specialized group such as invertebrate-pathogenic fungi it is opportune to consider what is known
of in Thailand. A starting point is the 1990 Presiderntial Address to the British Mycolofical Society by Professor
David Hawksworth (Hawksworth 1991). In that address Hawkswroth noted that about 69,000 species of fungi are known.
He presented several figures to predict what the undescribed pool of species might be. These estimated went from an almost
revolutionary 13.5 million fungi(based interestingly on extrapolation from insect species number estimates) to a more conservative
1.5 million. For the purpose of consequent number predictions the conservative 1.5 million fungi is presumed. A feature of many mycological studies in the tropics is that these were made by colonial scientists stationed in colonies of European powers. Thailand is unique in being the only tropical Asian country never to be controlled from Europe. A consequence of this, however, is that now little is known of the biological diversity of any fungi in Thailand. With a land area half that of Thailand’s, temperate and insular the British lsles has 12,000 species of fungi recorded. When the Norwegian scientist Trond Schumacher surveyed the ascomycetes from northern Thailand , he noted “The mycoflora of Thailand is badly known’ (Schumacher 1982), Schumacher reviewed the published literature for staring that ‘about 250 species have previously been reported”. There are now records for about 3000 species (Hywel-Jones, unpubl. data). David Hawksworth noted that the British fungal flora has increased 62% in the last 47 years and has a rate of increase of 13% per decade. In the index of Fungi from 1981-90 there were 459 new species described from Britain (2.9% of the World total of 16013 species for this period). In contrast, Thailand had 31 new species described (0.2% of the world total). This demonstrated what little is known of fungi in general from Thailand. Biodiversity is a huge issue! |
BIOLOGICAL CLASSFICATION |
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Systematics and classification are often viewed by biologists as something permanent . this is probably only true in plants and animals, where almost every species has already been discovered and named, In the fungal kingdom revisions are constantly made due to discovery of new taxa. The classification of fungi has changed even more in the last decade not only because of new discoveries but also due to the advancement of molecular techniques. In the fungal world classification is a very dynamic process For classification purposes related genera are grouped into families, families are grouped into orders, orders into classes, classes into phyla, and phyla into Kingdoms. For fungi it has been arranged into a fixed hierarchy and characterized by these set of endings:
Phylum (Division): -mycota
Subphylum (Subdivision): -mycotina
Class: -mycetes
Subclass: -mycetidae
Order: -ales
Family: -aceae
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Species and genus concepts. |
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The species is the smallest unit of taxonomy and is central to biology. Although this topic has been much debated, and still is, it has targeted mostly plants and animals and less the fungi. Despite the complexity of the fungal life cycle, we believe that species exits in fungi. There are several species concepts and definitions (theoretical and practical) and it will be difficult to stick to one particular species concept. Here are some of the commonly used concepts that provide some recognition criteria: Morphological species concept. This concept is based on differences and similarities in morphological characters However, in the fungi, morphological featured prove to be highly variable and are strongly affected by environment/culture conditions. A character’s degree of importance is often a mycologist’s personal choice. Biological species concept. May (1940) recognized species as “groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups”. In fungi, this concept has been used to identify compatibility among individuals. However, mating test are impossible for those that lack the production of meiospores. Significantly, many fungi are homothallic and produce meiospores readily without a ‘partner’. Also, other heterothallic fungi will just not mate in vitro. Phylogenetic species concept. In the molecular age where DNA sequencing is routine, phylogenetic analysis of variable nucleic acid characters clusters organisms into groups within which patterns of ancestry and descent can be recognized. Changes in the gene sequences of the offspring from the parent/ancestor can be recognized be recognized before changes have occurred in morphology or mating behaviour. |
THE SERIES |
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The species is the smallest unit of taxonomy and is central to biology. Although this topic has been much debated, and still is, it has targeted mostly plants and animals and less the fungi. Despite the complexity of the fungal life cycle, we believe that species exits in fungi. There are several species concepts and definitions (theoretical and practical) and it will be difficult to stick to one particular species concept. Here are some of the commonly used concepts that provide some recognition criteria: This is the first volume in a continuing series which will illustrate ca. 30 taxa a year of invertebrate-pathogenic fungi of Thailand. This is not an authoritative taxonomic treatment of these fungi. However, we hope that for each taxon enough information is brought together to give the interested reader some insight into the diversity and distribution of these fungi in Thailand. Please enjoy. |