scholarly journals Seasonal Dynamics of Taphrina deformans Inoculum in Peach Orchards

2007 ◽  
Vol 97 (3) ◽  
pp. 352-358 ◽  
Author(s):  
V. Rossi ◽  
M. Bolognesi ◽  
S. Giosuè
Keyword(s):  
Life Cycle ◽  
Relative Humidity ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Parasitic Stage ◽  
Tree Canopies ◽  
Trap Plants ◽  
Second Period ◽  
Curled Leaves

The dynamics of the inoculum of Taphrina deformans were studied during a 4-year period by (i) inspecting curled leaves for the presence of asci, (ii) placing deposition spore samplers within the tree canopies, and (iii) exposing potted peach plants (trap plants). These three approaches produced consistent results. Four main periods characterized the dynamics of the inoculum: the first period coincides with the parasitic stage of the pathogen's life cycle and the other periods with the saprophytic stage. Mid- to late spring (first period) was characterized by the presence of asci on infected leaves which produced and ejected large quantities of ascospores in 96% of the samplings. Rainfall was not necessary for ascospore dispersal, which was favored by air temperature <20°C and relative humidity ≥80% or wetness duration >8 h. In summer and autumn (second period), blastospores were trapped in 54 and 24% of samplings, respectively, with low spore numbers. In the winter (third period), blasto-spores were trapped in the lowest numbers and in only 6% of samplings. In late winter to early spring (fourth period), blastospores were found in 56% of samples, with increasing numbers. Rainfall significantly influenced blastospore dispersal and temperature was correlated with the seasonality found during the saprophytic stage.

Ecological observations on the cattle tick, Boophilus microplus (Canestrini)

1957 ◽  
Vol 8 (4) ◽  
pp. 394 ◽  
Author(s):  
GJ Snowball
Keyword(s):  
Dairy Herd ◽  
Early Spring ◽  
Boophilus Microplus ◽  
Cattle Tick ◽  
Late Winter ◽  
Tick Population ◽  
Parasitic Stage ◽  
Free Living ◽  
Larval Population ◽  
Low Levels

Studies were undertaken during 1948-1950 on Boophilus microplus under field conditions in southern Queensland to determine the duration of the non-parasitic stages, and to relate this information to tick incidence on cattle. In the area where the observations were made, the population of ticks on cattle is high in summer and autumn and low in minter and spring. Each week throughout the investigation engorged female ticks, freshly fallen from cattle, were placed in a pasture plot and their subsequent history recorded. Concurrently, observations were made on the changes in tick population on a dairy herd on an adjacent farm. Female ticks exposed on the plot between April and July produced virtually no progeny, and it is probable that the ticks in the pasture traversed by the dairy cattle exhibited a similar, though less severe, inhibition of reproduction. This failure to reproduce, combined with the dying out of larvae and protracted developmental periods of eggs, reduced to very low levels the larval population available to infest cattle during the months of August–October. Ticks exposed from late July to the following autumn produced progeny. There was a tendency for the progeny of ticks exposed in the late winter and early spring to hatch a t about the same time in the late spring, and this synchronous hatching was probably responsible for the 'spring rise' in tick population on cattle. It appears likely that the engorged female adults dropped in the early autumn represent the most important stage in the overwintering of the species in this area. Some of their larvae survive the adverse winter conditions, either in the free-living or the parasitic stage, and give rise to adults, which fall in the late winter and spring, and which in turn produce the larvae of the spring rise.

Reproduction in the Macropod Marsupial Potorous tridactylus (Kerr).

1962 ◽  
Vol 10 (2) ◽  
pp. 193 ◽  
Author(s):  
RL Hughes
Keyword(s):  
Post Partum ◽  
Cell Types ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Polymorphonuclear Leucocytes ◽  
Marsupial Species ◽  
Heat Period ◽  
Breeding Seasons ◽  
Made In

Thirty-five female Tasmanian rat-kangaroos, Potorous tridmtylus (Kerr), were studied. This marsupial is both polyoestrous and monovular. The length of the oestrous cycle is approximately 42 days (range 39-44 days). Study of vaginal smears over intervals that included 14 oestrous periods revealed that the proportions of cornified cells reached a maximum of over 80% at oestrus, and conversely the other cell types (i.e. nucleated epithelial cells and polymorphonuclear leucocytes) were at minimal concentrations. In four females copulation was apparently permitted at any time during the period of rapid increase in the proportion of cornified cells. One female repeatedly received a male over a 12-day heat period. Copulations were brief and were observed only between 4.00 p.m. and 1.45 a.m. In two females coitus was found to precede ovulation. The gestation period (defined as the interval between copulation and parturition) varied between 30 and 43 days in four animals. In one instance parturition was witnessed 37.5 days after copulations that were restricted to a 12-hr period. A marked increase in pouch vascularity occurred a few hours prior to parturition. Parturition was witnessed on one occasion and is described. The time taken to reach the pouch was 10 min; attachment was made in a further 12 min. On another occasion a neonatus removed from a teat shortly after parturition took 5 min to locate the teat and a further 15 min to complete reattachment. Permanent attachment of the offspring to a teat occupied 64 days in one instanc; in another it lasted 46 days but as the offspring died 6 days later it may be that the teat was vacated prematurely. The manner in which permanent nipple attachment is achieved is discussed and a description of the development of external features of pouch young is given. Nipples increased in both length and diameter during the first 115 days of suckling, after which regresslon began. The regresslon was correlated wlth the process of weanlng. An indication of three successive lactations was obtained from nipple dimensions. Pregnancy (occupying about 38 days) did not prevent oestrus from appearing at the normal time (i.e. approximately 42 days after the preceding oestrus). Mating occurred at the post-partum oestrus but lactation inhibited further oestrous cycles as well as delaying the development of the resultant uterine embryo. The period of delayed pregnancy can be as long as 4+ months. During most of this period the embryo remained free in the uterus as a dormant blastocyst, diameter 0.25-0.28 mm. Embryonic development was resumed during the weaning period when suckling was intermittent and diminishing or when the offspring was prematurely lost. Observations on both captive and wild populations suggested the existence of two breeding seasons, one in late winter and early spring, the other in summer. However, the evidence on which these breeding seasons are based is extremely limited. Reproduction in Potorous is compared with that in other marsupial species.

Observations on Rate of Growth, Coloration, and the abnormal Six-instar Life-cycle in Locusta migratoria migratorioides, R. &. F.

1936 ◽  
Vol 27 (1) ◽  
pp. 77-85 ◽  
Author(s):  
K. H. L. Key
Keyword(s):  
Life Cycle ◽  
Relative Humidity ◽  
Light Intensity ◽  
Locusta Migratoria ◽  
Fourth Instar ◽  
The Other ◽  
Locusta Migratoria Migratorioides ◽  
The Third ◽  
Rate Of Growth ◽  
Progression Factor

1. All material was reared under constant conditions of temperature, light intensity and relative humidity. Two relative humidities were used—very wet and very dry. In some cases various coloured backgrounds were used. All material was solitaria, and was kept isolated.2. Average weights were calculated from weighings made at all periods within the stadia, and thus represent the weights at the mid-points of the stadia.3. The figures could not be fitted to the theory of a progression factor of 2.4. Females are on the average 50 per cent, heavier than males even in the third instar; the sexes can probably be distinguished in this way much earlier.5. The first three stadia are of about the same length; the fourth is longer, the fifth much longer.6. The percentage rate of growth between the mid-points of successive stadia is of the same order for all pairs, though somewhat lower for the first and last pairs.7. Hoppers kept in a very dry atmosphere are much lighter than those kept wet —proportionally more so in the later than in the earlier instars; on the other hand each stadium is lengthened—proportionally more so in the earlier than in the later stadia; the percentage rate of growth is just half that of hoppers kept wet.8. The findings of Faure in regard to the causes of differences in coloration were fully confirmed.9. The occurrence of a sixth instar in the females is due to an inherited factor.10. This “ extra ” instar may represent an extra morphological third instar or an extra morphological fourth instar.

scholarly journals Seasonal variation in the vertical distribution of zone over Oakshin Gangotri, Antarctica

MAUSAM ◽  
2021 ◽  
Vol 42 (3) ◽  
pp. 275-278
Author(s):  
A.L. KOPPAR ◽  
S.C. NAGRATH
Keyword(s):  
Seasonal Variation ◽  
Vertical Distribution ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Double Peak ◽  
The Vertical Distribution

Ozone soundings made from Dakshin Gangotri, Antarctica during 1987 are presented. The vertical distribution of ozone over Antarctica is characterised by a double peak profile, one around 200-150 hPa and the other around 50 hPa. During late winter-early spring the upper peak is considerably depleted. Tropospheric ozoe remains low and nearly constant throughout the year.  

Reproductive Development of Female Plum Curculio (Coleoptera: Curculionidae) in the Mid-Atlantic: Presence of Multivoltine Populations

2008 ◽  
Vol 43 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Tracy C. Leskey
Keyword(s):  
Ovarian Development ◽  
Reproductive Development ◽  
Early Spring ◽  
Conotrachelus Nenuphar ◽  
Atlantic Region ◽  
Plum Curculio ◽  
Tree Canopies ◽  
Tree Fruit ◽  
Developmental Rates ◽  
Second Period

The plum curculio, Conotrachelus nenuphar (Herbst), is a key pest of pome and stone fruit throughout eastern and central North America. There are two strains of plum curculio, the univoltine ‘northern’ strain and the multivoltine ‘southern’ strain. Voltinism associated with populations located in the mid-Atlantic region has been unclear from historic records, with recent studies suggesting multivoltine populations. In studies conducted in West Virginia, female plum curculios obtained from emergence and screen traps and from samples of host tree canopies strongly indicate the presence of at least some multivoltine populations, based on an ovarian development bioassay. Two periods of active oogenesis were detected. The first occurred in early spring between late April and early May and represented overwintered females reaching sexual maturity. A second period of oogenesis was detected beginning in late June and continuing through early August. Based on degree day accumulations and known developmental rates of plum curculio, the mid-Atlantic is comprised, at least in part, of multivoltine populations. Fruit growers, therefore, must consider that plum curculio can pose a threat to tree fruit throughout the active growing season.

Coping with darkness and low temperatures: foraging strategies in Steller's eiders, Polysticta stelleri, wintering at high latitudes

2001 ◽  
Vol 79 (3) ◽  
pp. 402-406 ◽  
Author(s):  
Geir Helge Systad ◽  
Jan Ove Bustnes
Keyword(s):  
Low Temperatures ◽  
Early Spring ◽  
The Other ◽  
Foraging Strategies ◽  
Winter Period ◽  
Late Winter ◽  
Feeding Time ◽  
High Latitudes ◽  
Late Autumn ◽  
Polysticta Stelleri

To examine how Steller's eiders, Polysticta stelleri, wintering at 70°N cope with adverse winter conditions in terms of darkness and low temperatures, we studied their feeding behaviour during four periods between late autumn and early spring. Steller's eiders were most likely to feed during daylight and twilight, but they also fed during darkness. The incidence of feeding was highest at low tide, and there was a significant interaction between tidal cycle and winter period. Hence, the birds fed more intensively at low tide in midwinter (January) than during the other periods. Air temperatures were between 8 and 10°C lower in midwinter than during the other periods, and during this period the eiders also fed more by means of nondiving techniques (up-ending, surface feeding). The total estimated feeding time was highest in late autumn and midwinter (5.9 and 6.3 h were spent actively feeding, respectively) and lower in late winter and spring (5.1 and 4.6 h, respectively). Thus, as energy requirements increased as a result of low temperatures, Steller's eiders increased their feeding effort, but also reduced feeding costs by reducing diving depth. The results of this study suggest that the Steller's eider is behaviourally well adapted to survive winter at high latitudes at relatively low stress.

The biology of a landlocked form of the normally catadromous salmoniform fish Galaxias maculatus (Jenyns). I. Life cycle and origin

1971 ◽  
Vol 22 (2) ◽  
pp. 91 ◽  
Author(s):  
DA Pollard
Keyword(s):  
Life Cycle ◽  
New Zealand ◽  
River System ◽  
Heavy Rain ◽  
Early Spring ◽  
Ancestral Population ◽  
Late Winter ◽  
Eastern Australia ◽  
Galaxias Maculatus ◽  
Western Victoria

In contrast to most other members of the family Galaxiidae which live and reproduce in fresh water, Galaxias maculatus, the common jollytail of Australia and "whitebait" of New Zealand, is normaIly catadromous throughout its range (south-eastern Australia, New Zealand, and southern South America). In some athalassic inland lakes on the volcanic plains of south-western Victoria, however, a number of populations apparently descended from this species have becomelandlocked. The life cycle of the forminhabiting one of these lakes (the "landlocked jollytail" of Lake Modewarre) may be briefly summarized as follows: Gonadal maturation in the adult fish, which live in the slightly saline landlocked lake, begins around March and is almost completed by about June. The final stage of maturation is not reached, however, until these fish migrate short distances up intermittent inflowing creeks when the latter begin to flow in late winter and spring (July-October). Spawning takes place when the creeks are swollen after heavy rain, the eggs being deposited amongst flooded vegetation in shallow areas of slow-flowing water along the creek banks. Many of the spent fish die after spawning. The eggs, which are stranded when the flood-waters subside, develop amongst the vegetation on the banks above the normal water level. After development is complete reimmersion by the first flood to cover them stimulates hatching. The normal developmental period is probably about 2 weeks, but in the absence of flooding hatching can be delayed up to at least a month after fertilization. The newly hatched larvae are washed downstream into the lake where they feed and grow to maturity. They migrate upstream to spawn in the following late winter-early spring season at an age of approximately 1 year. The fish grow to about 9 cm in their first year, 14 cm in their second, and 17 cm in their third year. The average size of the females is greater than that of the males. The general features of the life history of this landlocked form are compared and contrasted with those of the stream-dwelling species G. maculatus and a number of other salmoniform fishes. The geological origin of the complex of lakes in south-western Victoria inhabited by landlocked galaxiid populations is discussed, and an hypothesis concerning the origin of the Lake Modewarre form from an ancestral population of G. maculatus in the Barwon-Leigh River system is advanced.

scholarly journals Episódios e gênese dos eventos climáticos extremos em Goiânia-GO / Episodes and genesis of extreme climate events in Goiânia-GO

2019 ◽  
Vol 29 (57) ◽  
pp. 583-608
Author(s):  
Diego Nascimento ◽  
Luan Victor Lima ◽  
Vitor Cruz
Keyword(s):  
Relative Humidity ◽  
Extreme Events ◽  
Minimum Temperature ◽  
Summer Precipitation ◽  
South Atlantic Convergence Zone ◽  
Early Spring ◽  
Maximum Temperature ◽  
Late Winter ◽  
Air Masses ◽  
Autumn And Winter

Sob a abordagem da climatologia geográfica, que leva em consideração a dinâmica das massas de ar na análise do ritmo e da gênese do clima, o presente trabalho busca apresentar os episódios de eventos climáticos extremos ocorridos em Goiânia-GO e abordar os mecanismos atmosféricos responsáveis pela gênese dos mesmos. Os eventos extremos foram levantados a partir de dados diários precipitação, temperatura máxima e mínima e umidade relativa do ar, registrados pela estação meteorológica do Instituto Nacional de Meteorologia (INMET), compreendendo a série temporal de 1961 a 2018 (58 anos). A identificação dos mecanismos atmosféricos atuantes nos dias dos episódios extremos foi realizada a partir da leitura e interpretação de cartas sinóticas da Marinha do Brasil, tendo como base o recorte temporal de 2012 a 2018. Foi possível apontar a ocorrência de eventos extremos em períodos específicos do ano, como no caso de eventos de precipitação no verão, sob influência da Massa equatorial continental e da Zona de Convergência do Atlântico Sul; de temperatura máxima no final do inverno e início da primavera, quando predomina a Massa equatorial continental e a Massa tropical Atlântica; de temperatura mínima no outono e inverno, condicionados pela incursão da Massa polar; de umidade relativa do ar no inverno, ocorrendo devido a atuação dos sistemas atmosféricos que habitualmente definem a condição sinótica em Goiânia.Palavras–chave: eventos extremos, massas de ar, fatores, mecanismos, impactos.Abstract Under the approach of Geographical Climatology, which takes into account the dynamics of the air masses in the analysis of the rhythm and the genesis of the climate, the present work seeks to present the episodes of extreme climatic events occurring in Goiânia-GO and to indicate the atmospheric mechanisms responsible for the genesis of this events. The extreme events were listed from daily precipitation, maximum and minimum temperature and relative humidity data, recorded by the meteorological station of the National Institute of Meteorology, comprising the time series from 1961 to 2018 (58 years). The identification of the atmospheric mechanisms acting on the days of the extreme episodes was performed from the reading and interpretation of Brazilian Navy's synoptic charts, based on the temporal cut from 2012 to 2018. It was possible to indicate the occurrence of extreme events in specific periods of the year, as in the case of summer precipitation events, under the influence of Continental equatorial mass and South Atlantic Convergence Zone; of maximum temperature in late winter and early spring, when Continental equatorial mass and Atlantic tropical mass predominate; of minimum temperature in autumn and winter, conditioned by the incursion of Polar mass; of relative humidity of the air in the winter, occurring due to the performance of the atmospheric systems that habitually define the synoptic condition in Goiânia.Keywords: extreme events, air masses, factors, mechanisms, impacts

scholarly journals Annual variations of the presence of Nereididae (Annelida: Polychaeta) from intertidal rocky shores along the east coast of Algeria

Check List ◽  
2015 ◽  
Vol 11 (6) ◽  
pp. 1808
Author(s):  
Zoubeida Meghlaoui ◽  
Tarek Daas ◽  
Meriem Snani ◽  
Ouided Daas-Maamcha ◽  
Patrick Scaps
Keyword(s):  
Rocky Shore ◽  
East Coast ◽  
Seawater Temperature ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Rocky Shores ◽  
Surface Seawater ◽  
Sea Temperature ◽  
Annual Variations

Four species of nereidid polychaetes, Peri­ner­eis cultrifera, P. macropus, Nereis falsa, and Platy­ner­eis dumerilii, were identified during three years in four intertidal rocky shore sites (El-Kala, Annaba, Skikda and Collo) along the east coast of Algeria during the years 2011–2013. Species’ distribution fluctuated according to sites and season. Perinereis cultrifera was observed during most of the year, except in summer. Perinereis macropus was observed at El-Kala, Skikda and Collo mainly in late winter and early spring. Nereis falsa was observed during most of the year in El-Kala and Annaba; this species was also observed in Skikda in 2011 but then disappeared in the last two years of this study. Finally, the presence of P. dumerilii was noticed only in El-Kala for a few months (mainly in March and April). Perinereis cultrifera, P. macropus and P. dumerilii reproduce after acquiring the epitokous form between April and May, when surface seawater temperature starts rising. The largest mature oocytes were about the same for P. cultrifera (279 µm) and P. macropus (278 µm), while this value was smaller for P. dumerilii (166 µm). In contrast to the other three species of nereidid polychaetes, N. falsa reproduces without epitokal modification between July and August when sea temperature was highest. The largest mature oocytes (168 µm) are about the same as P. dumerilii but is much small than those of P. cultrifera and P. macropus. 

Factors affecting the productivity of irrigated annual pastures. 1. Time of first irrigation in late summer-early autumn

1986 ◽  
Vol 26 (3) ◽  
pp. 297 ◽  
Author(s):  
CR Stockdale
Keyword(s):  
Nitrogen Content ◽  
Irrigation Treatment ◽  
Subterranean Clover ◽  
Late Summer ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Factors Affecting ◽  
Autumn And Winter ◽  
Clover Content

The influence of time of first irrigation (mid-February, early March, or late March) on the productivity of an annual pasture was studied for 3 years in northern Victoria. Beginning the irrigation of annual pastures in late summer instead of at the normal time of late March- April provided additional herbage in autumn and winter and did not adversely affect herbage production in late winter-early spring; up to 2.3 t/ha DM of additional herbage was obtained by mid June and 4.3 t/ha DM over the whole season. Earlier irrigation also increased the subterranean clover content of the pasture, resulting in herbage that was lower in digestibility and higher in nitrogen content than that in the other treatments. The benefit of early irrigation in increasing clover content may be offset by invasion by weeds. In this experiment, a potential weed problem in the earliest irrigation treatment appeared at the beginning of year 3.

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