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E . L ON C , M .-M . L EC A DE T, T .M . L A CH OW I CZ AN D E. PA N EK . 1997. Twenty-four Bacillus thuringiensis (Bt) strains were isolated and examined in respect of serotype, plasmid content crystal-composing proteins and insecticidal activity. Strains PO1-PO11 and PO14-PO15 were recognized as B. thuringiensis kurstaki H3a3b3c. The strains PO12 and PO13 were found to share a common novel antigen determining the new serotype H-47, and were designated as serovar wratislaviensis. Further investigations showed that all strains carried multiple plasmids (for example six different large plasmids in PO12 strain) and formed crystals composed of either two proteins, 135·8 kDa and 66·2 kDa (strains PO1-PO11 and PO14-PO24), or one protein, 66·2 kDa (strains PO12 and PO13). Preliminary toxicity tests with crude suspensions of spores and crystals showed rather low activity (³50% mortality) against fruitfly larvae and nymphs of cockroaches and high toxic effects (up to 90% mortality) against house fly larvae.

The paper presents changes that occured in the myxomycete flora of the nalure reserve Łężczok during the last 30 years. The ecological analysis of slime moulds is also given. During thc first periode of investigations (1967-1968) only 34 myxomycete species were found. During the second one, i.e. in the years 1996-2001 (except for 2000) - 47 species. In total, the myxomycete flora of the reserve includes 59 taxa. Among them 22, mostly cosmopolitic species were stated during both sampling periods. Twelve species were stated during earlier investigations only, while during recent studies 25 new species were found.

Results confirm domination of the occurrence of slime moulds on decaying wood of <i>Fagus</i> (33 taxa), as well as on <i>Tilia</i> (31). The list of species found on wood of <i>Acer pseudoplatanus</i> was extended up to 18. In such a specific microhabitat as litter 33 taxa were found, and among them abundant occurrence of <i>Diachea leucopodia</i> and <i>Diderma testaceum</i> was conspicuous. Dependence of the occurrence of myxomycetes on climatic conditions is manifeted by various periods of "fructification" of particular species. August and September were the most favourable months (49 taxa each) while July was the worst one (30 taxa). Slime moulds inhabiting litter had their maximum from June to August.

In the paper the results of two years mycological studies carried out in the "Łężczok" reserve are presented. Due to specific habitat diversity an interesting distribution model of some fungal taxa was observed. The data on each taxon include: abundance, type of substrate, type of habitats and information on fruit-bodies occurrence.