scholarly journals Preliminary results for the eνaluation of the action of Saissetia oleae parasites in Corfu.

2017 ◽  
Vol 2 ◽  
pp. 3 ◽  
Author(s):  
Ε.Τ. Stratopoulou ◽  
Ε.Τ. Kapatos
Keyword(s):  
Host Population ◽  
Early Summer ◽  
Considerable Proportion ◽  
Population System ◽  
Spring Period ◽  
Internal Parasite ◽  
Saissetia Oleae ◽  
Low Levels ◽  
Ongoing Project ◽  
Of Greece

The action of parasites of Saissetia οleae (OIiv.) (Homoptera-Cοccidae) is studied in Corfu from 1980 in the framework of an ongoing project on the population dynamics of Saissetia οleae. Results obtained during the period 1980-1983 from 17 experimental sites indicate the following: a) the population of S. οleae increased in 1981 but from 1982 it declined to very low levels; following the overall decline of the host population, parasitization rates of third instar larvae (mainly by Μetaphycus helνolus Comp.) were relatively low and ranged from 2.1% to 6.7% for the autumn period and from 14.6% to 29.4% for the spring period; this does not minimize the possibility that Μetaphycus helνolus plays an important role on the regulation οf S. οleae populations; b) a considerable proportion of females of S. οleae is attacked during summer by Μetaphycus lounsburyi How. (an internal parasite on preovipositing females), Μoranila californica How. and Scutellista cyanea Μοtsch. (egg predators), but their significance upon the population system of S. οleae is not expected to be great. The action of Μetaphycus lounsburyi in spring, when the peak of the suitable stage occurs (i.e. fourth instar larvae), appears to be very low, at least for these three years. Its action is delayed and most of the specimens of this parasite emerge from ovipositing females in early summer. Among the species attacking S. οleae females, Μ. californica (recently introduced in Corfu) was the most abundant and it might be worthy to be introduced to other parts of Greece too.

scholarly journals Fungal Decay of First-Crop and Main-Crop Figs

Plant Disease ◽  
2007 ◽  
Vol 91 (12) ◽  
pp. 1657-1662 ◽  
Author(s):  
Mark A. Doster ◽  
Themis J. Michailides
Keyword(s):  
Aspergillus Niger ◽  
Alternaria Alternata ◽  
Late Summer ◽  
Early Summer ◽  
Late Spring ◽  
Fungal Decay ◽  
Main Crop ◽  
Low Levels ◽  
Serious Disease

Fig cultivars grown in California typically have two crops, although the first crop may be unimportant commercially. The first crop, also known as the breba crop, ripens in late spring and early summer, whereas the main or second crop ripens in late summer. For both cultivars studied, Conadria and Calimyrna, the first-crop figs typically are left in the orchard unharvested. First-crop figs had relatively high levels of fungal decay and tended to have more fungal decay than main-crop figs, especially Alternaria rot (caused by Alternaria alternata and Ulocladium atrum). At least 16 different Aspergillus spp. were found decaying first-crop figs. Fig smut, a serious disease caused by Aspergillus niger and related fungi, usually was present at approximately the same level in first-crop and main-crop figs. Aspergillus spp. known to produce the mycotoxins aflatoxin or ochratoxin were found decaying first-crop figs. Aflatoxin was detected in first-crop figs at low levels similar to those detected in the main-crop figs. Because the abundant spores produced on the first-crop figs can infect main-crop figs, the fungal decay of first-crop figs might result in higher levels of decay for main-crop figs.

Parasitism by Aphytis chrysomphali, Mercet and A. melinus Debach of Californian red scale, Aonidiella aurantoo (Maskell), in relation to seasonal availability of suitable stages of the scale

1973 ◽  
Vol 21 (1) ◽  
pp. 111 ◽  
Author(s):  
IW McLaren ◽  
GA Buchanan
Keyword(s):  
Reproductive Potential ◽  
Host Population ◽  
Early Summer ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Western Victoria ◽  
Host Parasite ◽  
Relationship Of ◽  
Scale Control ◽  
North Western

A field study was undertaken to investigate the host-parasite relationship of A. aurantii and two species of Aphytis in north-western Victoria, and to suggest methods for improving and extending the biological control of A. aurantii in Victoria. Monthly samples of scale-infested Valencia oranges from five unsprayed biocontrol properties at Mildura provided information which showed a positive correlation between the percentage of available stages in the host population and the efficiency of parasitism by the Aphytis. This was thought to result from the seemingly inefficient method employed by the Aphytis in selecting a suitable host in which to oviposit; a postulate reinforced by the results of earlier work. The scarcity of suitable hosts at certain times of the year is thought to limit the efficiency of the Aphytis by reducing the chances of the parasite to achieve its reproductive potential. On the basis of this study an improved approach to red scale control is proffered, namely that attempts be made to augment the effectiveness of the established Aphytis by devising methods for increasing the proportion of available stages in red scale populations during late spring and early summer. Field and laboratory evidence indicates that parasitism by Aphytis, rather than variation in weather, is responsible for the considerable seasonal fluctuations in percentage of scales available for parasitism.

Studies of the Lecanium Scale, Eulecanium coryli (L.), and its Parasite, Blastothrix sericea (Dalm.), in British Columbia

1953 ◽  
Vol 85 (5) ◽  
pp. 153-181 ◽  
Author(s):  
K. Graham ◽  
M. L. Prebble
Keyword(s):  
British Columbia ◽  
Population Density ◽  
Chemical Control ◽  
Host Population ◽  
Severe Injury ◽  
Horse Chestnut ◽  
Main Area ◽  
Nursery Stock ◽  
Low Levels

The lecanium scale was introduced into Vancouver with nursery stock from England in 1903, and by 1910 had become firmly established. Severe injury to broad-leaved maple, vine maple and horse chestnut was reported in 1923, and chemical control operations were undertaken from 1924 to 1930, but with very transitory effects (9, 10). The encyrtid wasp, Blastothrix sericea (Dalm.), imported from England in 1928 and 1929, quickly became established at the liberation points in Sorth Vancouver, and by June, 1930 had dispersed over an area of about 20 square miles. In April, 1931, twigs with parasitized scales from North Vancouver were distributed at intervals throughout the main area of lecanium infestation south and east of Vancouver, and by June of that year the parasite was known to be established over an area of about 100 square miles. By 1932, the percentage of parasitism in the mature lecanium females reached 90 to 100 per cent, and host population density was at very low levels (12, 13).

Weather and the Success of Parasites in Population Regulation

1965 ◽  
Vol 97 (8) ◽  
pp. 848-863 ◽  
Author(s):  
Paul DeBach
Keyword(s):  
Population Regulation ◽  
Host Population ◽  
Population Increase ◽  
Population Densities ◽  
Upper Limits ◽  
Desert Areas ◽  
Low Levels ◽  
Favorable Weather ◽  
Host Parasite ◽  
Parasite Complex

AbstractExamples and data based on the host-parasite complex of the California red scale, Aonidiella aurantii (Maskell), and its parasites in untreated test plots in the citrus areas of southern California, not including the San Joaquin Valley and the desert areas, show the following: (1) Weather does not impose upper limits to host population increase. (2) In areas of favorable weather, certain parasites regulate host population densities at very low levels, other factors also being favorable. (3) The parasite Aphytis lingnanensis Compere is affected by weather differentially with respect to the host, and to varying degrees in different localities. The effects of field weather for each 2-week period of the year on all stages of this parasite individually as well as on population growth in held experimental cages are discussed. Adverse effects of weather on the parasite preclude successful population regulation of the host by the parasite at certain times or in particular areas but the range of the parasite is not restricted. (4) Another parasite, Comperiella bifasciata Howard, has its range restricted by weather and not by competition with other parasites to intermediate and interior citrus growing areas. It is never found along the coast. (5) Yet another parasite, Prospaltella perniciosi Tower, has its range restricted by competition and not by weather although it gives the appearance of being restricted by weather because it occurs only in coastal districts. (6) Examples are discussed of interactions between weather and dust, ants, or chemicals with parasites and hosts which result in various modifications of the abundance of the host and parasites. (7) Examples are discussed of the effect of weather on interactions between competing species of parasites and the host which have resulted in striking modifications of the previous distribution of certain parasites.

Competition and Cooperation Among Parasitic Hymenoptera Related to Biological Control

1965 ◽  
Vol 97 (4) ◽  
pp. 409-422 ◽  
Author(s):  
S. E. Flanders
Keyword(s):  
Developmental Stages ◽  
Parasite Fauna ◽  
Host Population ◽  
Parasitic Species ◽  
Competition And Cooperation ◽  
Parasitic Hymenoptera ◽  
Black Scale ◽  
Saissetia Oleae ◽  
Practical Measure ◽  
Host Regulation

Abstract Since the earliest days of this century the interactions of parasitic Hymenoptera that attack the same host species have been reported from time to time in connection with studies on the natural enemy fauna of pest insects. These studies indicate that the synchronous attack by two or more parasitic species on an individual of a host population, multiple parasitism, is of little, if any, importance in the economy of that population, whereas the attack by two or more parasitic species on a sequence of a host’s developmental stages and instars, sequential parasitism, may be highly important, especially from the standpoint of host regulation. Since the host-regulating capacity of a parasite species may vary both seasonally and geographically, sequential parasitism is highly conducive to continuity in the conservation of the host’s food supply, the practical measure of regulative parasitism. The cooperative as well as the competitive aspects of sequential parasitism are discussed. The parasite fauna of the black scale, Saissetia oleae (Bernard), is used to exemplify these aspects of parasitism.

Biochemical Effects of Temperature and Nutritive Stress on Mytilus Edulis L.

1973 ◽  
Vol 53 (2) ◽  
pp. 269-286 ◽  
Author(s):  
P. A. Gabbott ◽  
B. L. Bayne
Keyword(s):  
Mytilus Edulis ◽  
Condition Index ◽  
Early Summer ◽  
The Body ◽  
Ostrea Edulis ◽  
Rapid Loss ◽  
Biochemical Effects ◽  
Spring Period ◽  
Body Tissues ◽  
Effects Of Temperature

In a previous paper Bayne & Thompson (1970) showed that temperature and nutritive stress resulted in a decline in body condition of mussels, Mytilus edulis, when kept in the laboratory. Both carbohydrate and protein were lost from the body tissues but the losses (as a percentage of the initial values) were greater from the germinal (mantle) than from the somatic (non-mantle) tissues. In spite of the loss of body reserves, M. edulis was able to continue maturation of the gonad during the autumn to spring period. In the early summer, however, when the gametes were fully ripe, stress resulted in a recession of the gonad and a rapid loss of protein from the mantle tissues. A similar decline in condition index and loss of glycogen and protein has been reported for adult oysters, Ostrea edulis, when maintained under hatchery conditions (Gabbott & Walker, 1971).

scholarly journals First Record of Cheiloneurus clαviger (Thomson) (Hymenoptera: Encyrtidae) on Corfu Island

2017 ◽  
Vol 12 ◽  
pp. 85
Author(s):  
M.V. Macropodi ◽  
G. Viggiani
Keyword(s):  
Larval Instar ◽  
Research Programme ◽  
First Record ◽  
Limiting Factor ◽  
Ongoing Research ◽  
Internal Parasite ◽  
Fourth Larval Instar ◽  
Saissetia Oleae ◽  
Ongoing Research Programme ◽  
First Time

During an ongoing research programme on Saissetia oleae (Oliv.) (Homoptera: Coccidae) and its parasites on the island of Corfu, the presence of the hyperparasite Cheiloneurus clαviger (Thomson) (Hymenoptera: Encyrtidae) was recorded, for the first time, in samples of parasitized Saissetia oleae in 1991. The identification of C. clagiver was made by the junior author. The adults of Cheiloneurus clαviger emerged from S. oleae females parasitized by Metaphycus lounsburyi (How.) (Hymenoptera: Encytridae), after they were placed in plastic capsules. Tables 1 and 2 give the number of adults of S. oleae, C. claviger and M. lounsburyi that emerged from S. oleae at two experimental fields. M. lounsburyi is one of the main parasitoids of S. oleae acting as an internal parasite of the fourth larval instar. The numbers of C. claviger emerged were very low compared with the numbers of M. lounsburyi, indicating that at present C. claviger is not a serious limiting factor for the population of M. lounsburyi. The presence of a group of coarse bristles at the apex of the scutellum and the long marginal vein of fore wings are the peculiarities of the genus Cheiloneurus. The incomplete infuscation of the fore wings and the colour of the antennae with only the 5th funicular segment blackish can easily allow the discrimination of C. claviger females from those of congeneric species. Cheiloneurus clαviger is reported as a hyperparasitoid of several coccids of economic impor tance mainly via other encyrtid parasitoids. In Italy, C. claviger has been found to act as a hyperparasite of Kermesidi (genus Kermes) which infest Pinoideae. Previous reports on the entomophagous fauna of S. oleae on Corfu do not include C. claviger and it is assumed that the hyperparasitoid has been introduced rather recently. The actual role oil the parasitic complex of S. oleae and the distribution of this hyperparasite on the island should be further investigated.

Jōyō kanji as core building blocks of the Japanese writing system

2014 ◽  
Vol 17 (2) ◽  
pp. 173-194 ◽  
Author(s):  
Terry Joyce ◽  
Hisashi Masuda ◽  
Taeko Ogawa
Keyword(s):  
Large Scale ◽  
Building Blocks ◽  
Considerable Proportion ◽  
Writing System ◽  
Writing Systems ◽  
Lexical Database ◽  
Structural Nature ◽  
Structural Levels ◽  
Special Relevance ◽  
Ongoing Project

The architecture of writing systems metaphor has special relevance for understanding the structural nature of the Japanese writing system, and, more specifically, for appreciating how the 2,136 kanji of the 常用漢字表 /jō-yō-kan-ji-hyō/* ‘List of characters for general use’ function as the core building blocks in the orthographic representation of a considerable proportion of the Japanese lexicon. In seeking to illuminate the multiple layers of internal structure within Japanese kanji, the Japanese lexicon, and the Japanese writing system, the paper draws on insights and observations gained from an ongoing project to construct a large-scale Japanese lexical database system. Reflecting structural distinctions within the database, the paper consists of three main sections addressing the different structural levels of kanji components, jōyō kanji, and the lexicon. Keywords: Japanese writing system; building blocks; jōyō kanji; components; orthographic structure; database

Many Migraineurs Have Low Levels of Vitamin D

2008 ◽  
Vol 41 (18) ◽  
pp. 16
Author(s):  
DIANA MAHONEY
Keyword(s):  
Vitamin D ◽  
Low Levels
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