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ŠUMARSKI LIST 3-4/2014 str. 72     <-- 72 -->        PDF

Isaria fumosorosea Wize is a well-known entomopathogenic fungus with a worldwide distribution and a relatively wide host range which makes it an interesting agent for the development of biocontrol methods (Zimmermann 2008; Hunter et al. 2011). For more than 30 years, it was named Paecilomyces fumosoroseus and recently transferred to the genus Isaria (Samson 1974; Luangsa-ard et al. 2004, 2005; Gams et al. 2005; Hodge et al. 2005; Sung et al. 2007). Isaria fumosorosea has been isolated from many arthropods, mainly Lepidoptera, from air, water, plants, and often from soil samples (Meyer et al. 2008; Zimmermann 2008; Tkaczuk et al. 2011). In the catalogue of the USDA-ARS Collection of Entomopathogenic Fungal Cultures (ARSEF) (Humber and Hansen 2005) strains of Isaria fumosorosea are listed from 27 different countries, comprising North America, Central America, South America, Europe, Africa, Australia, and Asia. Isaria fumosorosea is regarded as a species complex, and various strains are successfully used for biocontrol of several pest insect species, for example whiteflies, thrips, aphids, and spider mites. It´s application for whitefly control, for example, started in 1990 with an isolate from Apopka, Florida (later named PFR 97, Apopka strain). This strain was also highly virulent to sweet potato whitefly and other pests (Osborne and Landa 1992, 1994; Landa et al. 1994; Stauderman et al. 2012). De Faria and Wraight (2007) assembled information about mycopesticides and disclosed that the most common among the presented 171 products were mycoinsecticides and mycoacaricids based on Beau­veria bassiana (33.9 %), Metarhizium anisopliae (33.9 %), Isaria fumosorosea (5.8 %), and B. brongniartii (4.1 %).
Because of the high interest for Isaria fumosorosea, it´s biology, ecology, natural occurrence and geographical distribution, host range, production of metabolites and effects of abiotic and biotic factors on the fungus are well studied (Avery et al. 2010). Furthermore, the use of this species in biocontrol in laboratory and field experiments (Feng et al. 2004; Pineda et al. 2007; Daniel and Wyss 2009), including their effects on non-target organisms (Tounou et al. 2003), were investigated by different authors and discussed by Zimmermann (2008).
The aim of our study was to determine the efficacy of an isolate of Isaria fumosorosea, isolated from pupae of Hyphantria cunea Drury in Georgia and re-isolates from Dendrolimus pini L., Lymantria monacha L. and L. dispar L. and to evaluate their potential as biological control agents of the forest pest insects L. monacha and L. dispar under laboratory conditions.
Materials and Methods
Materijali i metode
Lymantria monacha and L. dispar larvae were used for the experiments. First instar L. monacha larvae were collected in May 2013 from pine trees in the vicinity of Biebersdorf (region of Forest District Lieberose, Southern Brandenburg) and second and third instar larvae were collected in June in the vicinity of Staakow (region of Forest District Lieberose, Southern Brandenburg). Material was transferred to the laboratory of the University for Sustainable Development at Eb­erswalde. L. dispar larvae originated from a laboratory strain of the insect (New Jersey standard-strain from USA).
Four isolates of Isaria fumosorosea were used in the bio­assays: One original isolate of Isaria fumosorosea from Hyphantria cunea found in Georgia (ARSEF access no. 10244), and three re-isolates from D. pini, L. monacha and L. dispar. Re-isolates were obtained after contamination of D. pini, L. monacha and L. dispar larvae with conidia of the original isolate of Isaria fumosorosea in the laboratory and isolation of new fungal isolates from dead hosts into pure cultures