Isoenzymes polymorphism in Metarhizium anisopliae (Deuteromycotina: Hyphomycetes) entomogenous fungi

96 Metarhizium anisopliae strains originating from various insects and countries, have been compared for their conidial size, their virulence towards the european corn borer and the profiles of some of their isoenzymes: glutamate oxalo-acetic transaminases, alcohol dehydrogenases, acid phosphatases.The correspondence factorial analysis has proved the relative homogeneity in M. anisopliae var. major but the M. anisopliae var. anisopliae strains group is very heterogeneous and some sub-populations, more uniform, can be differentiated composed of all the Brazilian strains or of those isolated from Curculionidae.The existence of a group of strains, original and intermediate between the var. major and anisopliae is discussed.     

The effects of white fluorescent light,far-red light,darkness, and moisture on spore germination of Lygodium heterodoxum (Schizaeaceae)

Spores of Lygodium heterodoxum Kunze were stored in dry and fully water-imbibed conditions in darkness at 23–25 C. Spores stored in dry conditions lose viability faster than those stored fully water-imbibed. After 1 year, less than 1% of the spores stored in dry condition germinated, while about 40% of the stored water-imbibed spores still germinated. The spores do not germinate in darkness, but they do germinate under white and far-red light.     

Comparison of four methods for quantification of biofilms in biphasic cultures

Three methods for determining the total biofilm amount in biphasic cultures have been compared: dry weight by filtration after solvent treatment, optical density with a biomass probe and protein content. The activity of the biofilm was estimated through mineral nitrogen consumption. Calculation of the coefficients of variation shows that these parameters could be used to characterise such a biofilm. The optical density by biomass probe was the most reliable one (repeatability <0.5%) to quantify total biofilm and a linear relation was verified against dry weight. © Rapid Science Ltd. 1998     

Sensibilité de la pyrale du mais (Ostrinia nubilalis) [Lep.: Pyralidae] aux hyphomycetes entomopathogenes

Résumé Les œufs de la pyrale du ma?s,Ostrinia nubilalis (Hübner), sont très sensibles àMetarhizium anisopliae (Metsch.)/Sorokin etPaecilomyces fumosoroseus (Wize) (Brown-Smith). Toutes conditions égales par ailleurs, les premiers stades larvaires meurent plus vite mais dans une proportion plus faible que les stades plus agés.Beauveria bassiana (Bals.) (Vuillemin) n^o 147 etM. anisopliae n^o 139 sont particulièrement pathogènes pour ce stade tandis queP. fumoso-roseus attaque facilement les chrysalides. Par adjonction d'une dose faible de chlorpyriphos on sensibilise les larves à la mycose. Les chenilles diapausantes sont très sensibles à la mycose puisque même des doses très faibles (40 sp/cm²) tuent plus de 50% de la population.

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Summary The egges of the European corn borer,Ostrinia nubilalis (Hübner) are very susceptible toMetarhizium anisopliae (Metsch.) Sorokin andPaecilomyces fumoso-roseus (Wize) (Brown-Smith). Whereas all the other conditions are equal, the 1 st larval instars die quicker but in a lower proportion than the later.Beauveria bassiana (Bals.) Vuillemin n^o 147 andM. anisopliae n^o 139 are especially pathogenic to this instar whereasP. fumoso-roseus easily attacks the pupae. By adding a low dose of chlorpyriphos the larvae are more susceptible to mycosis. The diapausing caterpillars are very susceptible to mycosis since doses even very low (40 sp/cm² kill more than 50 % of the population.

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Avec la collaboration technique de Mmes J. Goussard & L. Sénéchal.