The use of chlorophyll fluorescence and leaf gas exchange as methods for studying the different responses to ozone of two bean cultivars

After exposure to 80 ppb of ozone for a single 4 h period, asignificant reduction in photosynthetic activity was rapidlyinduced in two cultivars of Phaseolus vulgaris, cv. Pinto, O₃-sensitiveand cv. Groffy, O₃-resistant. Pinto displayed a strong and irreversiblereduction in A_max accompanied by stomatal closure and an increasein intercellular CO₂ concentration. The fluorescence parametersindicated that the electron transport around PSII had been altered.The increase in non-photochemical quenching was related to anenergy dissipation through non-radiative mechanisms. Photosynthesiswas also reduced in the cv. Groffy, but the effect was reversiblewith time. Groffy showed alteration in the photochemical functioningof the thylakoids and specific disturbances of the water-splittingenzyme system of PSII, but these alterations disappeared only20 h after the end of fumigation. Recovery of photosyntheticability was more delayed with time and needed 7 d to show valuessimilar to the controls. Physiological tools, such as gas exchangeand chlorophyll fluorescence, play a major role in the earlydetection of environmental stress such as O₃ pollution, andin distinguishing the responses between cultivars with differentO₃-sensitivity. Key words: Gas exchange measurements, nonphotochemical quenching, Phaseolus vulgaris, photochemical quenching, stomatal conductance     

Effect of long-term feeding history on functional and numerical response of Neoseiulus californicus (Acari: Phytoseiidae)

The functional and numerical responses of the predatory mite Neoseiulus californicus to eggs and protonymphs of Tetranychus urticae were studied on excised strawberry leaflet discs under laboratory conditions (25 ± 1°C, 75–85% RH and 16L : 8D). Four strains of the phytoseiid were compared: three originated from a long-term mass-rearing with different food (T. urticae, Dermatophagoides farinae and Quercus spp. pollen) and under controlled conditions, while the fourth was directly collected from a natural environment and therefore considered a wild strain. The different nutritional histories affected the responses of N. californicus on tetranychids. On the whole, the wild strain gave better performance. When egg prey was administered this strain and the one mass-reared on two-spotted spider mites showed similar functional as well as numerical responses; on the contrary, when protonymphs were furnished, the wild strain did not differ from that mass-reared on pollen. The strain previously fed on house dust mites gave the worst performance and also showed the lowest percentages of females in the progeny. The functional responses obtained were predominantly type II curves. In all cases considered, no stored energy was allocated for reproduction and, with the exception of the wild strain on eggs, the prey was exploited less efficiently as the consumption increased. In spite of the differences evidenced in this experiment all strains were characterized by high predation and oviposition rates. Thus the results obtained suggest no drawbacks in the use of mass-reared N. californicus as biocontrol agents. © Rapid Science Ltd. 1998     

Studies on the isolation,growth and maintenance of Malassezia pachydermatis

Results related to the isolation, cultivation, culture and maintenance of the opportunistic pathogen Malassezia pachydermatis are reported. A dextrose nutrient medium with 1.5% yeast extract turned out to be the most favourable medium for its development. It permitted identification in 24 hours and maintenance of isolates for three months without subculturing. Addition of Tween 80 (1%) significantly enhanced the isolation of this yeast from clinical materials.     

Etiology and Epidemiological Observations of Elaeagnus Leaf Spot Caused by Septoria elaeagni

A foliar disease, causing necrotic spots and severe defoliation of Elaeagnus angustifolia, was detected in Tuscany, Italy, in 1979. The causal agent was identified as Septoria elaeagni. It was not pathogen to E. umbellata, E. pungens, E. multiflorum, and Hippophae rhamnoides. Ultrafiltrates from liquid cultures showed toxicity against E. angustifolia and some herbaceous species, non hosts of the pathogen. Disease was significantly more severe in an overhead irrigation system than when water was delivered to the soil alone.     

Distribution of echinococcosis/hydatidosis in Italy

Results of an epidemiological survey carried out in 88 slaughterhouses in Italy from 1979 to 1983 are reported. Data have been compared to national surveys previously conducted in 1955 and from 1968 to 1978. Analysis of various factors affecting the incidence of the disease in different areas of the country are reported.     

Antemortem diagnosis of an apparent case of feline candidiasis

Candidiasis in cats has always been linked with such predisposing factors as parvovirus infections and antibiotic and chemotherapeutic treatments. Moreover these cases were all diagnosed post-mortem.The clinical observations and the diagnostic procedures used in an antemortem case of probable idiopathic intestinal candidiasis in a cat are reported. The therapeutic measures used and the method of evaluating the efficacy of antimycotic treatment are also described.     

Essential‐Oil Polymorphism in the ‘Resurrection Plant’ Myrothamnus moschatus and Associated Ethnobotanical Knowledge

Gas chromatography/mass spectroscopy analysis (GC/MS) of essential oils obtained from populations of the resurrection plant Myrothamnus moschatus, growing in different areas of Madagascar, allowed identification of three main chemotypes in the species. The first one was provided by plants with a high content of trans‐pinocarveol and pinocarvone; the second one involved plants with high percentages of limonene, cis‐ and trans‐p‐mentha‐1(7),8‐dien‐2‐ol, and β‐selinene; and the third chemotype was characterized by plants with high levels of oxygenated sesquiterpenes such as caryophyllene oxide and α‐ and β‐isomers of caryophylla‐4(12),8(13)‐dien‐5‐ol. Chemical data were supported by chemometric technique as the principal component analysis. Furthermore, the relationship between the dioecy and phytochemistry within one population was also considered. Finally, correlations between chemical variations and ethnobotanical data were assessed.