Fluctuations of grass pollen content in the atmosphere of East Perugia and meteorological correlations (year 1989)

Summary Gramineae pollination from a pollen monitoring station located in the eastern suburb of Perugia and meteorological correlations are reported. The data refers to the year 1989. Grass pollen peak pollination was from May to July; in this period the influence of relative humidity and of temperature on pollen concentration was very high. Phenological observations, to identify the time of maximum stamen extension in the most common genera in the area, are also reported. During the period of investigation the counts of pollen grains over four-hour periods showed a regular diurnal rhythm with peaks of concentration in the four-hour period 16.00–20.00. Aerosporological data and meteorological data related to four-hour periods were correlated following different criteria.     

Observing the Temperature Dependent Transition of the GP2 Peptide Using Terahertz Spectroscopy

The GP2 peptide is derived from the Human Epidermal growth factor Receptor 2 (HER2/nue), a marker protein for breast cancer present in saliva. In this paper we study the temperature dependent behavior of hydrated GP2 at terahertz frequencies and find that the peptide undergoes a dynamic transition between 200 and 220 K. By fitting suitable molecular models to the frequency response we determine the molecular processes involved above and below the transition temperature (T _D). In particular, we show that below T _D the dynamic transition is dominated by a simple harmonic vibration with a slow and temperature dependent relaxation time constant and that above T _D, the dynamic behavior is governed by two oscillators, one of which has a fast and temperature independent relaxation time constant and the other of which is a heavily damped oscillator with a slow and temperature dependent time constant. Furthermore a red shifting of the characteristic frequency of the damped oscillator was observed, confirming the presence of a non-harmonic vibration potential. Our measurements and modeling of GP2 highlight the unique capabilities of THz spectroscopy for protein characterization.     

A selective differential medium for the isolation of Listeria monocytogenes

A new medium has been developed for the isolation of Listeria monocytogenes from clinical specimens with a mixed flora. Almost complete inhibition of unwanted organisms was achieved and recognition of colonies of Listeria spp. was usually possible after 24 h using the aesculin-ferric ammonium citrate indicator system. Compared to McBride agar the new medium was more inhibitory to representative contaminating species in pure culture and more successful in isolating small numbers of L. monocytogenes from artificially seeded clinical specimens.     

The role of air temperature in determining dormancy release and flowering ofCorylus avellana L.

Summary 7 years of airborne pollen monitoring in Perugia (central Italy) were used to determine the temperature requirements to break dormancy and to resume growth and bloom ofCorylus avellana L.,Corylus needs 1000 chill-units to complete its dormancy and this value, in the Perugian area, is met by the end of December or the first days of January. MoreoverCorylus trees require 220 growth degree hours before they are able to flower. If air temperature is high, this value can be achieved in only 10 days, but if the temperature remains too low, the heat accumulation can require up to 35 days. With these parameters it is possible to build a model to predict the date of the beginning ofCorylus avellana pollen season.     

The population ecology of the Cinnabar Moth,Tyria jacobaeae L. (Lepidoptera,Arctiidae)

Summary This paper describes the results of a study of the factors determining the abundance and distribution of the Cinnabar Moth in Britain. The main part of the study was on a population of the moth at Weeting Heath in Norfolk. This is an area of sandy heath which is heavily overgrazed by rabbits. Here the moth fluctuates violently in number and periodically it completely defoliates its food plant (ragwort, Senecio jacobaea L.) over large areas. This happened in 1960, 1961, 1967, and 1968.Since 1966, the numbers of the moth have been studied in detail and Life Tables are presented for five years.Adult fecundity varies considerably between years. This is due mainly to fluctuations in adult size resulting from changes in larval density. By comparison adult mortality and dispersal have little effect on fecundity; although there is some evidence to suggest that dispersal is density dependent. Because the number of eggs laid in one generation depends on the size of the previous generation, fecundity tends to be acting as a delayed density dependent factor.Mortality is low during the egg stage, but is high amongst young larvae, due mainly to arthropod predation. As the caterpillars grow they become immune from this predation. They are distasteful to vertebrate predators.A larval parasite, Apanteles popularis, kills many of the fully grown larvae. The highest rates of parasitism have coincided with the lowest densities of the moth, however, so that over the five years it has acted as an inverse density dependent factor.In 1967, the population became so large that the ragwort was completely defoliated, and about 20% of the caterpillars died from starvation. In the following year the population was still large and the ragwort plants were small, owing to the effects of defoliation in the previous year. Food ran out early in the season and about 50% of the larvae starved. Because of the overriding effect of starvation, total larval mortality tends to be density dependent.Mortality is high at, or immediately after, pupation and this is thought to be due primarily to predation by moles (Talpa europaea). Pupal mortality does not appear to be density dependent.The upward growth of the population is limited by food supply. Starvation led to a population crash, so that in 1969 only 62 eggs/150 m² were laid compared with 17110 and 16493 in the previous two years. The rate of recovery of the population after this crash was dependent upon the rapid recovery of the ragwort plants. Owing to the wet summer in 1968, plant numbers actually increased after defoliation, due to regeneration from root buds. This was in spite of the fact that no seed was produced in the area in either 1967 or 1968.The only factor which appears to buffer the population against extinction in years when food runs out early in the season, is the heterogeneity within the moth and ragwort populations. The earliest individuals manage to obtain sufficient food in those patches of ragwort which survive longest.Large fluctuations in number only occur in some localities. Other populations of the moth persist at low density and never eat out their food supply. Some data are presented from such a population at Monks Wood. This site is on a heavy clay soil, rabbit grazing is less marked than at Weeting, and ragwort occurs only at a low density. The lusher vegetation supports a very large population of arthropod predators and these take a higher percentage of the young caterpillars than was found at Weeting. Pupal survival is also low due probably to waterlogging of the soil. Pupae can withstand considerable desiccation, but excessive moisture soon leads to their death.The distribution of the moth in Britain and its use for the biological control of ragwort are discussed.     

The feeding habits of the Miridae (Heteroptera) living on broom (Sarothamnus scoparius (L.) Wimm.)

The natural food of five species of Miridae was studied by means of the precipitin test. Besides feeding on broom, all feed to some extent on other small arthropods. None showed any specificity in their attack and the species of prey taken depends on size and availability.

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Zusammenfassung Die natürliche Nahrung von 5 Arten der Miriden (Heterocordylus tibialis, Asciodema obsoletum, Orthotylus adenocarpi, O. virescens, and O. concolor) wurde mit Hilfe des Präzipitintests untersucht. Alle diese Arten fressen an ihrer Wirtspflanze und treten ausserdem auch als Räuber an der auf diesen Pflanzen lebenden Fauna auf. Die Angriffstechnik dieser Arten gab keinerlei Anhaltspunkte für eine Spezialisierung, und es ist wahrscheinlich, dass ihre Beute aus beliebigen kleinen, verhältnismässig trägen Arthropoden besteht. Die älteren Stadien sind besser als die jüngeren befähigt, grössere und lebhaftere Tiere zu erbeuten. O. virescens scheint weniger räuberisch zu sein als die anderen Arten. Auch ist ihre Art und Weise an der Wirtspflanze zu fressen mehr spezialisiert; denn sie ernährt sich hauptsächlich von dem Inhalt der Palisadenzellen und des Schwammparenchyms der Blätter. Die anderen Arten saugen an den jungen Stengeln, indem sie ihre Stechborsten in das Phloëm der Gefässbündel versenken.