**2.1.3 Yeasts associated with the gut of some pests**

In the gut of some maize' pests (*Diabrotica virgifera*, *Helicoverpa armigera* and *Ostrina nubialalis*), Molnar et al. (2008) isolated 97 yeast strains; furthermore they detected yeasts as well as other fungi of the genera: *Acremonium*, *Aspergillus*, *Cladosporium* and *Fusarium* by means of cloning and denaturing gradient gel electrophoresis (DGGE). The occurence of clones was given in percents. All methods reveald that *Metschnikowia* spp., closely related to *Metschnikowia pulcherrima*, *Cryptococcus* spp. (*Cr. luteolus, Cr. zeae* and *Cr. flavescens*) as well as *Candida* spp., bearing close similarity to *C. xestobii* or *C. sake,* and *Pseudozyma* spp. were the most frequently identified yeasts. *Pichia guiliermondii* and *Rhodotorula* species were less common. Some of occassionaly found yeasts e.g. *Aureobasidium pullulans, Candida quercitrusa, Hanseniaspora uvarum, Sprobolomyces coprosmae, Tilletiopsis washingtonensis* were detected however only via culturing. There are some publications reporting presence of the yeasts in the gut of mosquitos (*Diptera*: *Culicidae*), which are known to be vectors of many diseases in humans. Gusmão et al. (2007; 2010) identified *Pichia caribbica, Pichia guilliermondii, Pichia* (syn. *Kodamaea*) *ohmeri, Candida fermentati* and *Candida nodaensis* in the diverticulum of *Aedes aegypti*. Ricci et al. (2011a) investigated yeasts in the gut of *Anopheles stephensi* using molecular and cultivation-dependent methods. Forty six clones that expressed fragments of the 18S rRNA gene retrieved from the gut samples of 6 adults were sequenced. Eleven clones were identified as *Wickerhamomyces anomalus*, known also as *Pichia anomala*, while others could be assigned either to genus *Candida* or *Pichia* or to unidentified fungus. Moreover, 100 colonies were cultured from 10 insect speciemens, classified based on their morphology and identified as *Candida intermedia*, *Hanseniaspora uvarum* and *W. anomalus* (77%, 15% and 8% respectively) by sequencing analysis of 18S and 26S rRNA genes and ITS fragments. *W. anomalus* was detectable using both approaches. Furthermore, Ricci et al. (2011a; 2011b) observed the presence of *W. anomalus* in the midgut of different mosquitos species *Anopheles stephensi, Anopheles gambiae, Aedes albopictus* and *Aedes aegypti*  of both sexes as well as on larvae, pupae and gonads, thereby supposed close relationship between this yeast species and mosquitos.

Biodiversity of Yeasts in the Gastrointestinal

huge variety of yeasts (Suh et al., 2005a).

*Arxula Candida Cryptococcus Debaryomyces Dipodascus Endomyces Galactomyces Geotrichum Hanseniaspora Kluyveromyces Lodderomyces Metschnikowia Pichia Saccharomyces Saturnispora Stephanoascus Williopsis Zygoascusa*

insects during the study of Suh et al. (2005a).

midgut.

Ecosystem with Emphasis on Its Importance for the Host 287

*ernobii* and the strains related to the one *Candida* sp. were prevalent in all parts of gut and frass and *P. guilliermondii* and *C. ernobii* were cultured most frequently from the posterior

In relation to high number of the yeast isolates (richness) described above, comparatively low yeast diversity was found in the assemblage of *Dendroctonus* beetles. It thereby underlined the impact of the host and/or environmental factors on the yeasts diversity. Nevertheless, examination of yeasts harbouring the GIT of beetles from 27 families reviled a

Fungi

Dikarya

Ascomycota Basidiomycota

Fig. 1. Schematic representation of the different yeast taxa belonging to the two phyla *Ascomycota* and *Basidiomycota* of the Dikarya subkingdom isolated from the intestinal tract of

yeasts isolated from the gut of insects corroborates this supposition.

During three-years-period, Suh et al. (2005a) isolated about 650 yeasts from the gut of diverse beetles collected from the south-eastern USA and Panama. Sequence analyses of the D1&D2 domains of LSU rRNA gene revealed 290 single species belonging to at least 27 taxa (Fig. 1.); the great majority of which were ascomycetous and some basidiomycetous yeasts. It is noteworthy that nearly 200 yeasts determined throughout the study were considered by the authors to represent new, not yet described species. In the meantime, some of them (table 1) were characterized by Suh, Nguyen, Blackwell and their co-workers. Based on their observation Suh et al. (2005a) suggested that almost each beetle species may be a host for at least one unknown yeast species. In the last decades, describing of many novel species of

*Fellomyces Filobasidiella Leucosporidium Rhodosporidium Sporidiobolus Tilletia Tremella Trichosporon Ustilago*
