[With 1 Table and 2 Figs.]The food consumption and assimilation were determined in the females of the European common vole, Microtus arvalis (Pallas, 1779). The measurements were carried out using 17 pregnant and lactating females as well as 20 non-reproducing females. During the pregnancy the energy requirement of a female with average body weight 28.5 g amounts to the mean value of 13.9 kcal/day and is higher by 32°/o as compared with the control females. The daily food assimilation of the female (25.2 g body weight) during the lactation is equal to 26.6 kcal/day and exceeds by 133°/o the corresponding figure for the non-reproducing female. During the whole period of pregnancy and lactation the female assimilates additionally 304 kcal (including 60.5 kcal for gestation and 243.5 kcal for lactation). Hence the metabolism increases in this period by 82.5°/o on the average. To produce and nurse one young vole the mother requires 75.9 kcal. The losses of energy with feces are equal to 8.95% and with urine to 3.33%, thus the energy present in the food is utilised in the very high degree (87.72%). The efficiency of net production in the breeding period is also high and equal to 13.9% during the pregnancy and 15.4°/o during the lactation.

Two selected examples of PIXE microanalysis in ecophysiology are presented. Studies of heavy metal distributions in mycorrhizal and non-mycorrhizal roots of Plantago lanceolata showed different filtration mechanisms of Zn/Pb and Fe/Mn, both enabling plants to cope with metals present in the environment. Studies of the mechanism used by the beetle Chrysolina pardalina to eliminate excessive amounts of Ni revealed that Malpighian tubules are responsible for the elimination of this metal from the hemolymph.In both examples GeoPIXE software was used for true elemental mapping using the Dynamic Analysis method and analysis of spectra from selected micro-areas. Specimen thickness and matrix composition were obtained from proton backscattering spectra.

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The aim of this study was to determine elemental composition of sap-feeding insects inhabiting various parts of the Ni hyperaccumulating plant Berkheya coddii Roessl., the endemic species of ultramafic outcrops in Mpumalanga, South Africa. Three species were examined: the aphid Protaphis pseudocardui (Aphididae), abundant on young leaves; the mealybug Orthesia sp. (Ortheziidae) colonizing underground parts of this plant, and the bug Norialsus berkheyae (Cixiidae) living on young shoots. Maps of Ni, K, Ca, Zn, and Fe for selected body areas of these species were generated using Dynamic Analysis method on the basis of particle-induced X-ray emission (micro-PIXE) and proton backscattering (BS) measurements. Atomic absorption spectrometry was used to determine Ni, Zn, Cu, Fe contents in the B. coddii organs, in some sapfeeding insect species including these mentioned above, and in the assassin bug hunting on Chrysolina pardalina, a monophagous beetle of B. coddii. Bioaccumulation factor for Ni in the examined species was below 0.05, and much higher for other metals (Zn ‡ 2; Fe £ 5). Ni distribution within body was species-dependent. It was the highest in the antennae of P. pseudocardui, in the head of Orthesia sp. and in the metathorax of N. berkheyae. Distribution patterns of other metals were different among examined species. Ca was recorded mainly in peripheral parts of the body in all species. Zn showed similar distribution to Ni. Fe distribution was similar to Ni only in the mealybugs. Uneven concentrations of metals within selected body regions indicated their relations with specific organs. Analysis of Ni transfer to higher trophic levels was done on the basis of two food nets: B. coddii-C. pardalina-Rhinocoris neavii and B. coddii-P. pseudocardui-Polyrhachis ant and led to the conclusion that the role of sap-feeding insects in Ni transfer was marginal.

This study investigates mechanisms of adaptation to metal toxicity peculiar to the midgut epithelium of Epilachna cf. nylanderi (Mulsant, 1850) (Coccinellidae). This species of beetle has currently been identified in only one locality in South Africa and is known to feed on the nickel hyperaccumulator Berkheya coddii Roessl. (Asteraceae), an endemic plant species of the South African ultramafic ecosystem. Our focus involves an analysis of the morphological features of cells forming the midgut epithelium, which is the first organ exposed to toxic levels of metals ingested by the insect. Through the three key processes of apoptosis, necrosis, and autophagy, excess metals are eliminated from the organism and homeostatic conditions are maintained. Apoptosis and necrosis are both known to be involved in the degradation of midgut epithelial cells, while the role of autophagy is mainly implicated in the disintegration of the organelles of cells. This study reports on the participation of these three key degenerative processes in the removal of excess metals based on targeted observations of the insect midgut epithelium by light and electron microscopies. Additionally, the TUNEL reaction was specifically used to detect apoptosis.

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