No abstract

The large-scale cultivation of transgenic crops producing Bacillus thuringiensis (Bt) toxins have already lead to the evolution of Bt resistance in some pest populations targeted by these crops. We used the F2 screening method for further estimating the frequency of resistance alleles of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), to Bt maize, Zea mays L., producing the Cry1Ab toxin. In France, Germany, and Italy, 784, 455, and 80 lines of European corn borer were screened for resistance to Mon810 maize, respectively. In Slovakia, 26 lines were screened for resistance to the Cry1Ab toxin. The cost of F2 screen performed in the four countries varied from U.S. dollars 300 to dollars 1300 per line screened. The major difference in cost was mostly due to a severe loss of univoltine lines during the screen in Germany and Slovakia. In none of the screened lines did we detect alleles conferring resistance to Mon810 maize or to the Cry1Ab toxin. The frequency of resistance alleles were < 1.0 x 10(-3), < 1.6 x 10(-3), < 9.2 x 10(-3), and < 2.6 x 10(-2) in France, Germany, Italy, and Slovakia, with 95% probability, respectively. The average detection probability over all lines was approximately 90%. Making the assumption that European corn borer populations in these countries belong to the same genetic entity, the frequency of alleles conferring resistance to the Cry1Ab produced by the Mon810 maize in western and central Europe was 1.0 x 10(-4), with a 95% confidence interval of 0-3.0 x 10(-4).

Fungi of the order Entomophthorales (Zygomycota, Zygomycetes) constitute a group of mostly insect pathogenic species, which attracts attention of insect pathologists because of their high capacity for use in biological control of pest insects. This work primarily focuses on entomophthoralean species attacking aphids. The Entomophthorales are considered major pathogens of aphids in nature. In fact, the fungi are the only pathogens that regularly and effectively can affect aphid populations in natural ecosystems as well as in agroecosystems. Up to now, 33 entomophthoralean species organized into 9 genera have been recorded in aphid hosts. All fungal species are listed and organised by genus in the work. Descriptions are presented for all the fungal genera and species, including a nomenclature genesis, a geographical distribution, a host specificity/host range, a capability of cultivation in vitro, and possible prospects for their use in biological control strategies. A key to identification of the pathogens is provided as well. A general life cycle outline of the pathogens is followed by fundamental facts on biology and ecology of the fungi and analysis of primary factors that are involved in the study of epizootiology of infectious diseases in insect populations. The abiotic and biotic elements of the environment, which interfere in the pathogen-host interactions, are also underlined. In the last chapter, several examples are reviewed when the Entomophthorales were used against aphids within the four strategies of biological control, namely classical biological control, inoculation biological control, inundation biological control, and conservation biological control. The aim of this review is to cover the present status of knowledge about the natural enemies of aphids and to stimulate an interest of insect pathologists in this group of entomopathogenic fungi.

The phylogenetic structure of 109 soil-borne entomopathogenic Beauveria isolates acquired using the Galleria mellonella bait method from different habitat types in Slovakia was determined by sequence analysis of their ITS and Bloc loci. Three Beauveria species were identified; Beauveria bassiana, B. pseudobassiana and B. brongniartii, represented by 51.4%, 43.1% and 5.5% of acquired isolates, respectively, which were resolved into 15, 1 and 1 distinguishable haplotypes. Correlation analysis with the habitat type and individual habitat characteristics showed strong preferences of the most prevalent haplotypes for agricultural (B. bassiana A1) and forest habitats (B. pseudobassiana) which has possible implications for conservative biocontrol strategies.

The species spectrum of entomophthoralean fungi parasiting aphids was investigated in Slovakia. The surveys focused on aphid fauna occupying both agricultural crops and vegetation at non-crop sites. During the surveys, 15 different entomophthoralean species were identified from 66 aphid species. Of these 15 fungal species, eight had not previously been recorded in Slovakia and one species, Erynia erinacea (Ben-Ze'ev et Kenneth) Remaudie`re et Hennebert, had not been recorded previously in Central Europe. New hosts for some parasitic fungi were also recorded. The occurrence of fungal infection and the fungal species spectrum varied with sampling period and sampling area. In general, the fungi were observed parasiting aphid populations from April until November. Pandora neoaphidis (Remaudie`re et Hennebert) Humber was the predominant fungal pathogen and could effectively reduce aphid populations. Entomophthora planchoniana Cornu and Conidiobolus obscurus (Hall et Dunn) Remaudie`re et Keller were also common pathogens of aphids, but without an epizootic potential. On the other hand, Neozygites fresenii (Nowakowski) Remaudie`re et Keller had a strong tendency to establish epizootics in dense aphid colonies, especially in those of the black bean aphid. Other entomophthoralean species observed in the country were considered to be minor aphid pathogens on account of their low occurrence, lower specificity to aphids, or high specificity to a single aphid species. This is the first detailed report to date on the occurrence of Entomophthorales in Slovakia.