Associations of fish with various types of littoral habitats in reservoirs

Fish associations with different types of littoral habitats were studied in four canyon‐shaped reservoirs in the Czech Republic in years 2010 and 2011 by gillnets. Two to three habitats per reservoir–beaches (former meadows), stump fields (former forest) and rubble slopes–were defined and sampled along the longitudinal axis of reservoirs. Effects of reservoir, habitat and locality (position along longitudinal axis) on fish biomass, abundance and species structure were tested for juvenile and adult fish separately. Hierarchical analysis of variance revealed that habitats differed significantly in fish biomass and abundance. Redundancy analysis showed that analysed environmental variables had significant influence on fish community structure. Most variability in community structure was explained by reservoir and then by combination of habitat and slope steepness. Locality position had the smallest influence on community structure. For both adult and juvenile fish total abundance and biomass, the most inhabited habitat was beaches; rubble slopes were the least inhabited. Habitat associations differed among species. Among adults, bream Abramis brama, white bream Blicca bjoerkna and roach Rutilus rutilus were associated with beaches and stump fields, whereas perch Perca fluviatilis, ruffe Gymnocephalus cernuus, asp Aspius aspius and pike Esox lucius were associated with rubble slopes. Bream, white bream, bleak Alburnus alburnus, roach, ruffe and pikeperch Sander lucioperca were associated with beaches among juveniles, whereas the only juvenile associated with rubble slopes was perch. We showed that most common species are associated with distinct habitats and also that utilisation of various littoral habitats differs in general.     

Novel inhibitors of sterol C-14 demethylase and Δ14 Reductase/Δ8 → Δ7 isomerase for cereal disease control

The activity of five experimental fungicides combining structural elements responsible for sterol C-14 demethylase inhibition and sterol nuclear double-bond transformations has been investigated by examining sterol accumulation in Ustilago maydis (DC.) Corda, inhibition of sterol-biosynthesis enzymes in Saccharomyces cerevisiae Meyer using a cell-free system and protective activity in cereals against Erysiphe graminis DC. and Puccinia coronata Corda. Combining the fenpropidin/fenpropimorph basic structure with a pyridine moiety offered no advantage in fungicidal activity. However, the combination of the pyrifenox structure with a morpholine moiety yielded a compound which was a good inhibitor of C-14 demethylase and Δ⁸ → Δ⁷ isomerase in vitro and gave good cereal protection.     

Portal hypertension in a dog due to circumscribed fibrosis of the wall of the extrahepatic portal vein

A two-and-a-half-year-old German shepherd dog with ascites and a high concentration of blood ammonia was investigated. Sonographically, its liver was normal but the portal vein was dilated and the flow of blood within it was slow. A liver biopsy showed that the liver was normal, and did not reveal any possible cause of portal hypertension or ascites. Postmortem, the cranial part of the portal vein was dilated with a cross-striped internal surface, but the caudal part looked normal; there was a stenotic ring between the normal and dilated parts. Histology of the dilated segment revealed marked hypertrophy of both the internal circular and the external longitudinal smooth muscle layers. At the site of the stenosis, the longitudinal muscular layer was replaced by connective tissue. Circumscribed fibrosis in the wall of the portal vein was responsible for the stenosis and the subsequent prehepatic portal hypertension. The cross-striped pattern in the dilated part of the vein was the result of hypertrophy of the inner circular smooth muscle layer.     

On-going expansion of Russian wheat aphid, Diuraphis noxia (Kurdj.) in central Europe (Horn.: Aphididae)

A supplementary research on Russian wheat aphid (= RVA), Diuraphis noxia (Kurdj.) between 1998-99 documented the pest distribution all over the Czech republic already. RVA abundance was proved to be significantly area-dependent within the state. The banker areas are in southern Moravia (district Znojmo, the frontier area near Austria) up to central Moravia. The determined RWA distribution area is much broader than presumed on grounds of climatic characteristics.The abundance of RVA generally decreases from the SE to the NW and N direction, as well as with the increasing altitude within the area.The highest altitude a.s.l. of RWA occurrence in the crop was 762 in. The re-classified main expansion route was determined to follow two directions (sourcing from Hungary and Austria) to southern-central-northem Moravia, and to southern Bohemia and further on to the central Bohemian lowland. The field information indicated the development of preference of RWA for barley.     

Occurrence of anholocylic strains of pest aphids on winter barley and wheat in South Moravia,Czech Republic

Anholocyclic strains ofSitobion avenae (F.),Rhopalosiphum padi (L.) andRhopalosiphum maidis (Fitch) were detected on winter barley and wheat in autumn, 1995 in South Moravia, the Czech Republic. Anholocycly was proved by samples docummenting the species composition and population structure of aphids in 20 localities throughout the area. Natural enemy presence was also determined and the species are listed. Anholocycly established in the cereal aphids in the target area is discussed in relation to a similar evidence known from the north-west Europe and some parts of the Mediterranean.     

LATEX paint as an antifeedant againstHylobius abietis (L.) (Col., Curculionidae) on conifer seedlings

LATEX paint in water solution applied to newly planted conifer seedlings was found to prevent damage byHylobius abietis adult weevils for the whole season. Treatment of the basal third of the trunk was sufficient. Also, utilisation of the results as a model for deerantifeedant treatments and protection againsts the weevils is recommended.With 1 figure     

Comparison of seasonal responses ofHylobius abietis (L.) (Col., Curculionidae) to chemical and natural lures in baited pitfall traps

Differences in catches ofHylobius abietis (L.) adults in baited pitfall traps with chemical (alpha-pinene, ethanol, water) and natural (spruce billets, water) lures were found not in the over-all number of trapped adult weevils, but in the per cent occurrence and number of old and young beetles in individual periods of the season.     

The expansive Russian wheat aphid,Diuraphis noxia (Mordw.) detected in the Czech Republic

The Russian wheat aphid,Diuraphis noxia (Mordw.) has been detected in southern Moravia, the Czech Republic in June, 1995. Its location is related to its incidence in central Hungary. The further predicted area of distribution covers the grain-maize growing districts of southern Moravia (Czeck Republic), neigh-bouring parts of Austria, southern and south-eastern parts of the Slovak Republic. The aphid is classified as a species expanding to the north from its mediaterranean area of distribution, apart of extensive areas (North to South Americas, S. Africa, expected in Australia) which it has covered thorugh accidental introductions and further spread over the world.