Photoperiodism in Orthopodomyia signifera

1973 ◽  
Vol 51 (3) ◽  
pp. 355-357 ◽  
Author(s):  
William E. Bradshaw
Keyword(s):  
North Carolina ◽  
Rapid Development ◽  
Larval Instar ◽  
Developmental Rate ◽  
Photoperiodic Response ◽  
The Third ◽  
Tree Hole ◽  
Fourth Larval Instar ◽  
Lower Temperature ◽  
Short Days

Larvae of the tree-hole mosquito, Orthopodomyia signifera, were collected from North Carolina and subjected to long- and short-day photoperiods. Long days at 25 °C permit rapid molting of fourth instar larvae to pupae. Lower temperature (15 °C) modifies developmental rate but does not appear to block photoperiodic response to long days. Short days at 25 °C may halt development, may retard development, or may permit rapid development in either the third or fourth larval instar. O. signifera is probably polymorphic for both the stage at which diapause may occur and for the depth or firmness with which it is established.

Photoperiodic control of development in the pitcher-plant mosquito, Wyeomyia smithii

1972 ◽  
Vol 50 (6) ◽  
pp. 713-719 ◽  
Author(s):  
William E. Bradshaw ◽  
L. Philip Lounibos
Keyword(s):  
Larval Instar ◽  
Pitcher Plant ◽  
Photoperiodic Control ◽  
Wyeomyia Smithii ◽  
Diapause Termination ◽  
Environmental Consequences ◽  
The Third ◽  
Short Day ◽  
Critical Daylength ◽  
Short Days

Wyeomyia smithii diapause in the third larval instar. Long days avert or terminate and short days promote or maintain diapause. Diapause occurs early in the third instar and may be terminated by photoperiodic stimuli without the intervention of chilling or other factors. Fifty percent termination of diapause requires about 3 long days and another [Formula: see text] days are consumed in the third instar for postdiapause development. The critical daylength is identical for both the initiation and termination of diapause, 14.75 h of light per day. But, the photoperiodic clock monitoring diapause decisions is several times as accurate during initiation as in termination, reflecting the more drastic environmental consequences of development misdirection in the fall than in the spring. This accuracy is further enhanced by a prolongation of the second instar under short-day conditions. The doubling in the duration of the second instar exhibits the same critical daylength properties as diapause determination.The third instar is divisible into four distinct developmental periods: prediapause, diapause, termination of diapause, and postdiapause. Methods for quantifying these periods are presented. Similar manipulations could be employed for other diapausing arthropods, regardless of the stage at which dormancy occurs or the cues used in its regulation.

scholarly journals Photoperiodic Response of Peanut Species1

1983 ◽  
Vol 10 (2) ◽  
pp. 59-62 ◽  
Author(s):  
H. T. Stalker ◽  
J. C. Wynne
Keyword(s):  
North Carolina ◽  
Day Treatment ◽  
Photoperiodic Response ◽  
Reproductive Capacity ◽  
Arachis Species ◽  
Short Day ◽  
The North ◽  
Long Day ◽  
Wild Peanut ◽  
Short Days

Abstract Many Arachis species collections do not produce pegs in North Carolina even though they flower profusely. To investigate reasons for the failure of fruiting, nine wild peanut species of section Arachis and three A. hypogaea cultivars representing spanish, valencia and virginia types were evaluated for response to short and long-day treatments in the North Carolina State Phytotron Unit of the Southeastern Environmental Laboratories. The objective of this investigation was to determine the flowering and fruiting responses of Arachis species to short and long-day photoperiods. Plant collections grown under a 9-hour short-day treatment were generally less vigorous, but produced more pegs than corresponding plants grown in long-day treatments which were produced by 9 hours of light plus a 3-hour interruption of the dark period. Annual species produced significantly more flowers and pegs than perennial species during both long and short days. The total number of flowers produced ranged from 0 during short days for A. correntina to more than 300 for A. cardenasii in long-day treatments. Only one plant of each species A. chacoense and A. villosa, and no plants of A. correntina, flowered in short days. Total numbers of pegs produced in short-day treatments were generally greater than in long-day treatments and the ratio of total number of pegs/total number of flowers was consistently greater during short-day treatments. A general trend was observed for more flowers produced in long-day treatments, but more pegs produced in short days. This study indicated that photoperiod can be manipulated to increase the seed set of some species and the success rate of obtaining certain interspecific hybrids. Furthermore, introgression from wild to cultivated species may possibly alter the reproductive capacity of A. hypogaea to photoperiod.

Biology of tree-hole mosquitoes: photoperiodic control of development in northern Toxorhynchites rutilus (Coq.)

1975 ◽  
Vol 53 (7) ◽  
pp. 889-893 ◽  
Author(s):  
William E. Bradshaw ◽  
Christina M. Holzapfel
Keyword(s):  
Rapid Growth ◽  
Fourth Instar ◽  
Photoperiodic Control ◽  
The Third ◽  
Winter Conditions ◽  
Tree Hole ◽  
Critical Photoperiod ◽  
Northern Portion ◽  
Toxorhynchites Rutilus ◽  
Short Days

Carnivorous larvae of the tree-hole mosquito, Toxorhynchites rutilus, were collected from the northern portion of their range. Long days were found to promote rapid growth and metamorphosis from egg to adult; short days retard development during the second and third instars and evoke diapause in the fourth. All larvae exposed continuously to long days from embryos to the third or fourth instar developed without entering diapause. Diapause-averting long days experienced earlier in development could be reversed in at least some individuals by subsequent short days. Among laboratory-reared larvae or those caught early in the fall, the critical photoperiod for the maintenance of diapause is around 13 h of light per day. Among larvae caught in midwinter, diapause is not maintained in all larvae at any photoperiod and in 50% or less of the larvae at photophases shorter than 12.5 h. Winter conditions in the northern part of the range of T. rutilus appear to play a prominent role in the maintenance and termination of diapause.

scholarly journals Biological Effect of Different Concentrations of Bacillus Thurngensis Isolated From The Soils of Sawa Lake, Al Muthanna Governorate on The of Hypera postica at Different Time Periods

2021 ◽  
Vol 923 (1) ◽  
pp. 012007
Author(s):  
Meeri Kadhim Al-Fatlawi ◽  
Iktifaa Naeem Jasim ◽  
Nidaa Saud AlShammary ◽  
Khudheyer A. A. Alnomani
Keyword(s):  
Biological Effect ◽  
Larval Instar ◽  
Bacterial Isolates ◽  
Hypera Postica ◽  
Killing Rate ◽  
The Third ◽  
The North ◽  
Fourth Larval Instar ◽  
Time Periods

Abstract This study conduct in Al-Muthanna governorate to assess five concentrations of Bacillus thurngensisagonist Hyperapostica. The results showed the presence of Bacillus thurngensisin all the studied sites of Lake Sawa in Muthanna Governorate, and the rates of its presence were close to the same sites, and the rate of its presence in those sites was 35%, and its highest rate was recorded in the north and east of the lake, as it reached 40% and the lowest amounted to 30% in the two sites south and west site. The results of the study showed that five concentrations were taken from bacterial isolates of B. thuringiensisdiffered in the rates of killing larvae, pupae and adults of the insect Hyperapostica in vitro, Where the concentrate 1.7 × 103 spore/ml was characterized by a higher killing ratecompared to the four studied concentrations, the killing rates were (75.750, 71.080, 69.79, 64,361, 49.117 and 42,060)% for the first larval instar, the second larval instar, the third larval instar, the fourth larval instar, and the pupae, respectively, and the lowest killing rate recorded 6.873% at concentration 0.64 × 107after 24 hours of treatment.

A second diapause in Wyeomyia smithii: seasonal incidence and maintenance by photoperiod

1975 ◽  
Vol 53 (2) ◽  
pp. 215-221 ◽  
Author(s):  
L. P. Lounibos ◽  
W. E. Bradshaw
Keyword(s):  
Larval Instar ◽  
Fourth Instar ◽  
Continuous Exposure ◽  
Seasonal Incidence ◽  
Wyeomyia Smithii ◽  
The Third ◽  
Critical Photoperiod ◽  
Plant Habitat ◽  
Short Days

Wyeomyia smithii ordinarily diapauses in the third larval instar, but a second, photoperiodically maintained developmental arrest may occur in the fourth instar. Two years of sampling from a Massachusetts bog revealed that the fourth-instar diapause phenotype is most abundant in the spring after the termination of third-instar diapause, and in the fall when a new overwintering generation of third instars accumulates in the pitcher-plant habitat. Fourth-instar larvae from this population cannot, however, survive the winter. This mortality during winter is apparently balanced by advantages that a second diapause confers upon the mosquito population in the spring.Fourth-instar diapause may be induced from diapausing third-instar larvae in the laboratory by a brief exposure to long days followed by short days, or by a long-term exposure to short days at 25 °C. Continuous exposure to long days readily terminates fourth-instar diapause. The critical photoperiod and number of long days required for the termination of diapause is similar for larvae which diapause in either the third or fourth instar.

Responses of Some Turkish Wheat Cultivars to Vernalization and Photoperiod

1988 ◽  
Vol 24 (2) ◽  
pp. 237-245
Author(s):  
Serpil Terzioğlu
Keyword(s):  
Bread Wheat ◽  
Normal Development ◽  
Photoperiodic Response ◽  
Reliable Information ◽  
Floral Initiation ◽  
Wheat Cultivars ◽  
Primary Shoot ◽  
Time Of Year ◽  
Short Days

SUMMARYThe vernalization and photoperiodic response of six locally adapted bread wheat cultivars grown under natural daylength conditions during the summer or winter months was examined in glasshouse experiments. The wheat was vernalized by chilling imbibed grains at 2 ± 1°C for 0, 15 or 45 days. Vernalization for 45 days followed by long summer days led to floral initiation in all cultivars within 28 days but vernalization for 0 or 15 days only led to floral initiation in one cultivar. Vernalization followed by long days reduced the time from transplanting to anthesis, resulting in early ear emergence. Vernalization followed by short days accelerated the development of all the cultivars, but normal development could also occur without vernalization at this time of year. Apical differentiation of the primary shoot and its length and development gave the most reliable information on the period of vernalization required.

Microstructure Development in Copper Welded by the FSW-Process

2003 ◽  
Vol 807 ◽  
Author(s):  
Therese Källgren ◽  
Rolf Sandström
Keyword(s):  
Welding Process ◽  
Mechanical Deformation ◽  
Microstructure Development ◽  
Friction Stir ◽  
Friction Heat ◽  
The Third ◽  
Lower Temperature ◽  
Weld Root ◽  
Nuclear Fuel Waste ◽  
Joining Process

ABSTRACTTo ensure safe storage of nuclear fuel waste, copper canisters are proposed as corrosion barrier. One alternative for sealing the copper canisters is Friction Stir Welding (FSW). During the joining process friction heat and mechanical deformation appear between the rotating tool and the material being welded. Liquid metal will not form, since this is a solid state welding process. Three distinct microstructural zones are developed namely the nugget, the thermo-mechanically affected zone (TMAZ) and heat-affected zone (HAZ). The nugget is in the centre of the weld, where the pin is located and where severe plastic deformation occurs that leads to recrystallisation. Surrounding the nugget, the TMAZ is only partially recrystallised, due to lower temperature increase and deformation compared to the nugget. The third zone, HAZ, surrounds the TMAZ. The initial nugget can have a classic round aluminium nugget image, when the welding conditions are cold, but the steady state nugget, is wider near the shoulder and shorter in the weld root.

The Post-embryonic Development of the Tracheal System in Drosophila melanogaster

1957 ◽  
Vol s3-98 (41) ◽  
pp. 123-150
Author(s):  
JOAN M. WHITTEN
Keyword(s):  
Drosophila Melanogaster ◽  
Adult Stage ◽  
Larval Instar ◽  
Pupal Stage ◽  
Tracheal System ◽  
True Nature ◽  
The Third ◽  
Air Sacs ◽  
Abdominal Region ◽  
Pupal Cuticle

The fate of the tracheal system is traced from the first larval instar to the adult stage. The basic larval pattern conforms to that shown for other Diptera Cyclorrhapha (Whitten, 1955), and is identical in all three instars. According to previous accounts the adult system directly replaces the larval: the larval system is partly shed, partly histolysed, and the adult system arises from imaginal cell clusters independently of the preceding larval system. In contrast, it is shown here that in the cephalic, thoracic, and anterior abdominal region there is a definite continuity in the tracheal system, from larval, through pupal to the adult stage, whereas in the posterior abdominal region the larval system is histolysed, and the adult system is independent of it in origin. Moreover, in the pupal stage this region is tracheated by tracheae arising from the anterior abdominal region and belonging to a distinct pupal system. Moulting of the tracheal linings is complete at the first and second larval ecdyses, but incomplete at the third larval-pupal and pupal-adult ecdyses. In consequence, in both pupal and adult systems there are tracheae which are secreted around preexisting tracheae, others formed as new ‘branch’ tracheae, and those which have been carried over from the previous instar. In the adult the newly formed tracheae of the posterior abdominal region fall into a fourth category. Most of the adult thoracic air sacs correspond to new ‘branch’ tracheae of other instars. The pre-pupal moult and instar are discussed with reference to the tracheal system and tentative suggestions are made concerning the true nature of the pre-pupal cuticle. There is no pre-pupal tracheal system. Events traced for Drosophila would seem to be general for Cyclorrhapha, both Acalypterae and Calypterae. The separate fates of the anterior and posterior abdom inal systems, in contrast with the straightforward development in Dipterc Nematocera, would appear to mark a distinct step in the evolution of the system in Diptera.

scholarly journals DEPARTMENT OF GEOMORPHOLOGY AND PALEOGEOGRAPHY OF THE IVAN FRANKO NATIONAL UNIVERSITY OF LVIV: STAGES OF DEVELOPMENT, ACHIEVEMENTS AND CHALLENGES

2020 ◽  
pp. 3-29
Author(s):  
Yaroslav Kravchuk ◽  
Ivan Kovalchuk ◽  
Lidiya Dubis
Keyword(s):  
Rapid Development ◽  
Research Direction ◽  
Environmental Research ◽  
Scientific School ◽  
Stages Of Development ◽  
Gis And Remote Sensing ◽  
Geomorphological Mapping ◽  
The Third ◽  
School Research ◽  
National University

This year we celebrate the 70th anniversary of the Department of Geomorphology (since 2000 – Geomorphology and Paleogeography) of the Faculty of Geography, Ivan Franko National University of Lviv, formed on the basis of the existing Lviv school of geography, which possessed old traditions and scientific achievements in the research of relief, in particular, of its development and formation. On the occasion of the anniversary, the article attempts to analyze the main achievements of the Department over the 70-year period, to highlight the main stages of its development and to outline the new challenges facing the Department today. There is the “Engineering, ecological and regional geomorphology” scientific school successfully functioning at the Department. Within its borders, the “Paleogeography of the Pleistocene” research direction is rapidly developing with significant achievements recognized at the international level. Anthropogenic and dynamic geomorphology, historical and geographical research, and geomorphological mapping with the use of GIS and remote sensing have been intensively developed. Over the last decade, research on the environmental issues, including spatial planning and design of nature reserves and ecological networks, as well as the study of geoheritage, geotourism and geoeducation have been singled out into independent areas. Overall, there are four development stages of the Department: the first ‒ from its foundation (1950) till 1970, the second ‒ during 1971-1990, the third ‒ during 1990-2010, and the fourth ‒ from 2010 till present. For each of them, the main scientific and practical achievements of the Department are briefly analyzed. The most important event in the first stage was the launching of fundamental comprehensive regional research, including the Ukrainian Carpathians, under the supervision of P. Tsys; in the second one ‒ the development of regional and engineering-geomorphological research and the introduction of stationary and semi-stationary research of modern relief-forming processes for the first time in Ukraine; in the third one ‒ the formation of a research school of engineering, ecological and regional geomorphology and the rapid development of Pleistocene paleogeography, as well as of environmental research; in the fourth one ‒ active development of the “Engineering, Ecological and Regional Geomorphology” scientific school and of the “Pleistocene Paleogeography” research direction, as well as of the investigations related to geoheritage, geotourism and geoeducation. The main current challenges are outlined at the end of the article. Key words: geomorphology; paleogeography; stages of development; scientific school; research directions; research; achievements; challenges.

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