Geography of larval dormancy in the tree-hole mosquito, Aedes triseriatus (Say)

1981 ◽  
Vol 59 (6) ◽  
pp. 1014-1021 ◽  
Author(s):  
Christina M. Holzapfel ◽  
William E. Bradshaw
Keyword(s):  
Photoperiodic Response ◽  
Late Winter ◽  
Aedes Triseriatus ◽  
Embryonic Diapause ◽  
Rate Of Development ◽  
Larval Diapause ◽  
Tree Hole ◽  
Critical Photoperiod ◽  
Response To Temperature ◽  
Fail Safe

Among Aedes triseriatus from 30–40° N latitude, photoperiod and temperature mediate the onset and maintenance of larval diapause. Photoperiod has a significant effect not only on the initiation and maintenance of diapause but also on the rate of postdiapause development, both directly and by modifying response to temperature. The critical photoperiod for larval diapause is shorter than that for controlling rate of development. Over most of the range considered, both the critical photoperiod for the induction and maintenance of larval diapause and that for rate of development are shorter than the critical photoperiod governing embryonic diapause. Based on relative photoperiodic response and censuses of overwintering populations, we conclude that larval diapause in A. triseriatus is mainly a backup or fail-safe system for embryonic diapause and that the major adaptive significance of larval diapause relates to the modulation of late winter and spring development rather than to overwintering, per se.

Towards the Reliable Prediction of Time to Flowering in Six Annual Crops. V. Chickpea (Cicer arietinum)

1994 ◽  
Vol 30 (3) ◽  
pp. 271-282 ◽  
Author(s):  
R. H. Ellis ◽  
R. J. Lawn ◽  
R. J. Summerfield ◽  
A. Qi ◽  
E. H. Roberts ◽  
...  
Keyword(s):  
Cicer Arietinum ◽  
Sowing Date ◽  
Coefficient Of Determination ◽  
Predictive Tool ◽  
Reliable Prediction ◽  
General Application ◽  
Additive Rate Model ◽  
Significant Difference ◽  
Critical Photoperiod ◽  
Response To Temperature

SUMMARYFour genotypes of ‘desi’ and two of ‘kabuli’ chickpea (Cicer arietinum) were sown at six locations in Australia on various dates between 1986 and 1988, giving 22 combinations of site and sowing date with diverse photothermal environments. Times from sowing to first flowering (f) varied from 30 to 162 d, mean pre-flowering temperatures from 10.8° to 29.3°C and mean photoperiods from 11.3 to 15.6 h d−1. There was no evidence that any observation had been obtained in photoperiods shorter than the ceiling photoperiod (Pcc) or longer than the critical photoperiod (Pc). This suggests that, in typical agricultural environments, chickpea crops experience photoperiods (P) which should satisfy the condition Pcce < P < Pc. In one ‘kabuli’ and two ‘desi’ genotypes, 1/f was influenced by both temperature and photoperiod. The coefficient of determination (R2) for a linear, additive rate of development model ranged from 0.74 to 0.80, with no significant difference in either temperature sensitivity or photoperiod sensitivity among these three genotypes. In the remaining three genotypes, no significant response to temperature was detected between 10.8° and 29.2°C, so rate of progress to flowering was influenced solely by photoperiod. There was no significant difference in the sensitivity of 1/f to P among these three genotypes. The linear, additive rate model found here to be so satisfactory as a predictive tool for phenology, is also shown to have much wider general application.Predicción del liempo de floración

scholarly journals (74) Winter Greenhouse Performance and Photoperiod Responses of 51 Cultivars of Seed-grown Trailing Petunias

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1065B-1065 ◽  
Author(s):  
H. Brent Pemberton ◽  
William R. Roberson
Keyword(s):  
Petunia Hybrida ◽  
Plant Architecture ◽  
Photoperiodic Response ◽  
Early Spring ◽  
Tidal Wave ◽  
Late Winter ◽  
Night Temperature ◽  
Standard Type ◽  
Incandescent Light ◽  
Modern Standard

Long days are known to hasten flowering of Petunia hybrida. However, breeding of modern standard-type petunia cultivars has reduced this response. With the introduction of new genetics involved in the creation of trailing-type petunias, many cultivars have been observed to have a strong photoperiodic response to the point that it is an issue for late winter or early spring flowering cropping cycles. In order to characterize this photoperiodic response in modern seed-grown trailing-type petunia cultivars, seed of 51 cultivars of trailing petunias (Petunia hybrida) were sown in November in 288 plug trays. When established about 4 weeks later, uniform plants were selected and transplanted individually to 15-cm pots. Plants were exposed to either natural days or a 4-hour night interruption using incandescent light from 2200 to 0200 HR each day until flowering. A minimum night temperature of 17 °C was maintained. Days to first flower from sowing ranged from 72 to 117 days. Generally, the night interruption treatment hastened flowering. However, the degree of hastening ranged from 4 and 5 days for `Ramblin' Burgundy Chrome' and `Ramblin' Lilac Glo', respectively, to 27 and 32 days for `Tidal Wave Cherry' and `Tidal Wave Hot Pink', respectively. Effects of night interruption treatment on plant architecture will also be presented.

AUTECOLOGY OF TWO AESHNA SPECIES (ODONATA) IN WESTERN VIRGINIA

1984 ◽  
Vol 116 (4) ◽  
pp. 567-578 ◽  
Author(s):  
Timothy G. Halverson
Keyword(s):  
Life Cycles ◽  
Growth Patterns ◽  
Juncus Effusus ◽  
Embryonic Diapause ◽  
Maturation Period ◽  
Larval Diapause ◽  
Early Evening ◽  
High Dispersal ◽  
Males And Females ◽  
Dead Plant

AbstractAeshna tuberculifera Walker and A. umbrosa Walker were studied in the Shenandoah Mountains, Rockingham County, Virginia for 5 years. Both species had 2-year life cycles. They passed the first winter in an embryonic diapause and the second in a larval diapause. Although A. umbrosa was slightly smaller and developed earlier in the year, growth patterns of the two species were similar. Adults emerged from mid-summer to mid-fall with a slight protandry. Sex ratio at emergence was equal in A. tuberculifera but slightly biased toward males in A. umbrosa. Individuals emerging later in the season tended to be smaller than those emerging earlier, and the decline in size was linear over time. The maturation period lasted 4–6 weeks. Poor recovery of marked teneral and breeding adults indicates either high mortality or high dispersal, but observed movement among ponds by marked breeding adults suggests high dispersal. Breeding males of both species defended entire ponds for short periods. Both males and females were present more frequently in the afternoon than during the morning or at mid-day. Females often oviposited in the late afternoon or early evening when males were usually absent from the ponds. A. tuberculifera used stems of Juncus effusus L. almost exclusively for oviposition, while A. umbrosa used a variety of dead plant or other material and rarely used J. effusus stems.

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.

Photoperiodic control of the maintenance and termination of larval diapause in Wyeomyia smithii (Coq.) (Diptera: Culicidae) with notes on oogenesis in the adult female

1971 ◽  
Vol 49 (8) ◽  
pp. 1065-1073 ◽  
Author(s):  
Stephen M. Smith ◽  
Reinhart A. Brust
Keyword(s):  
Ice Cores ◽  
Instar Larva ◽  
Wyeomyia Smithii ◽  
Larval Diapause ◽  
Short Day ◽  
Northwestern Ontario ◽  
Long Day ◽  
Two Generations ◽  
Critical Photoperiod ◽  
Third Instar Larva

Some aspects of overwintering and oogenesis in the pitcher-plant mosquito, Wyeomyia smithii (Coq.), were examined. The species was shown to overwinter in a diapause state as a third-instar larva. The diapausing larvae overwinter within the frozen ice cores of the host plant but they were nevertheless shown to be intolerant of prolonged periods of freezing at temperatures only a few degrees below 0 °C. The winter survival of the species probably depends almost entirely on the insulating benefits of a snow cover. Larval diapause was stable under short-day conditions but was very rapidly broken when the larvae were exposed to long-day photoperiods. The critical photoperiod required to break larval diapause in a population from the Kenora region of Ontario was between [Formula: see text] and 15 h of light per diem. This critical photoperiod did not change during a prolonged period of overwintering. Larvae which experienced 5 or fewer long-day cycles remained in diapause when they were returned to short-day conditions but diapause was irreversibly broken in larvae exposed to 8 or more long-day cycles in succession. Data on growth rates of larvae as a function of temperature and photoperiod were used to predict the seasonal cycle of W. smithii in northwestern Ontario where the species is probably restricted to a maximum of two generations per year. All females of W. smithii were autogenous for the first ovarian cycle and adult diets of carbohydrate did not affect fecundity. Unlike other mosquitoes, the female of W. smithii was found to be precocious, emerging with the ovarian follicles already initiated with development of the follicles up to stage IIIa of Christophers.

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