THE EFFECT OF LIGHT ON THE RESISTANCE OF HARD RED SPRING WHEATS TO THE WHEAT STEM SAWFLY, CEPHUS CINCTUS (HYMENOPTERA: CEPHIDAE)

1984 ◽  
Vol 116 (5) ◽  
pp. 677-684 ◽  
Author(s):  
N. D. Holmes
Keyword(s):  
Experimental Evidence ◽  
Weather Variables ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Annual Variations ◽  
Light Filters ◽  
The Hours ◽  
Sufficient Reduction ◽  
Effect Of Light

AbstractSawfly-resistant bread wheats varied widely among years in resistance to the wheat stem sawfly, Cephus cinctus Nort. Experimental evidence showed that the major factor involved was a reduction in the intensity of sunlight. A reduction in the intensity of sunlight by up to 50%, which was produced by shading the growing plants with cotton sheeting, caused minor decreases in sawfly resistance. More intensive shading with solid-sided cages and with combined light filters of red and yellow caused the plants to become hollow-stemmed and very susceptible to sawfly damage.Annual variations in sawfly resistance in plants grown in the field from 1949 to 1978 were significantly related to variations in the number of days with measurable precipitation, to the amounts of precipitation, and to the hours of bright sunshine in the period between 25 May and 5 July. These weather variables were significantly interrelated and were important primarily because they indicated the amounts of light received by the plants. A sufficient reduction in the amount of light (particularly during mid-June) significantly reduced sawfly resistance.

THE EFFECT OF THE WHEAT STEM SAWFLY, CEPHUS CINCTUS (HYMENOPTERA: CEPHIDAE), ON THE YIELD AND QUALITY OF WHEAT

1977 ◽  
Vol 109 (12) ◽  
pp. 1591-1598 ◽  
Author(s):  
N. D. Holmes
Keyword(s):  
Protein Content ◽  
Significant Loss ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Annual Variations ◽  
Moisture Contents ◽  
Yield And Quality

AbstractLarvae of the wheat stem sawfly, Cephas cinctus Nort, reduced the weight of grain per head by an average of 17.3% in the two spring wheats Red Bobs and Thatcher with annual reductions varying from 10.8% to 22.3%. They also lowered the protein content in Thatcher by an average of 0.6% and a maximum of 1.2%. However, because a significant loss in protein content occurred in only 1 of 6 years in Red Bobs, the effects of the larvae on protein content cannot be generalized for all varieties.The losses in weight per head resulted from a mean reduction of 11.9% in the weight of the kernels combined with a mean reduction of 1.9 in the number of kernels per head. The larvae caused the losses by feeding in the stems and by cutting them when the moisture contents of the kernels were relatively high. Annual variations in losses were attributed to the dates of the infestation, to the amount of precipitation in July and August, and to differences in dates of cutting by the larvae.

Effect of Time of Seeding Apex Wheat on Infestation and Sex Ratio of the Wheat Stem Sawfly, Cephus cinctus Nort. (Hymenoptera: Cephidae)

1952 ◽  
Vol 84 (3) ◽  
pp. 90-92 ◽  
Author(s):  
L. A. Jacobson ◽  
C. W. Farstad
Keyword(s):  
Sex Ratio ◽  
Field Experiment ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus

In 1945 a field experiment was designed at the Lethbridge laboratory to augment data on the effect of the time of seeding on infestation by the wheat stem sawfly, Cephus cinctus Nort. At that time one of the recommendations for the control of this insect was to delay seeding wheat until after May 15. The resulting crop escaped infestation because of the retarded plant during the period of the sawfly flight.

Using matrix population models to inform biological control management of the wheat stem sawfly, Cephus cinctus

2017 ◽  
Vol 109 ◽  
pp. 27-36 ◽  
Author(s):  
Tatyana A. Rand ◽  
Courtney E. Richmond ◽  
Edward T. Dougherty
Keyword(s):  
Biological Control ◽  
Population Models ◽  
Matrix Population Models ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Control Management

Survey of Wheat Stem Sawfly (Hymenoptera: Cephidae) Infesting Wheat in Eastern Colorado

2021 ◽  
Author(s):  
Darren M Cockrell ◽  
Terri Randolph ◽  
Erika Peirce ◽  
Frank B Peairs
Keyword(s):  
Triticum Aestivum ◽  
Wheat Variety ◽  
Triticum Aestivum L ◽  
The State ◽  
Economic Effects ◽  
Management Decisions ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Growing Region

Abstract From 2012 through 2020, a survey of wheat stem sawfly, Cephus cinctus Norton, was conducted in wheat (Triticum aestivum L.) fields in Eastern Colorado. In 2013, results showed sawfly infestations concentrated in the northern part of the state with only a few highly infested sites, with 38 of the 94 sampled sites having any infestation (five of which had >50% infestation levels). By 2020 sawfly had been found in all eastern counties sampled, and 72 of the 106 sites sampled were found to contain sawfly (11 of which had >50% infestation levels). The spread of this pest across the Colorado wheat-growing region will have lasting economic effects. The information gathered from this and future surveys will inform wheat variety development and aid in management decisions made by growers across the state.

SAWFLY RESISTANCE IN WHEAT: III. CHANGES IN RESISTANCE DURING THE DEVELOPMENT OF THE WHEAT PLANT

1960 ◽  
Vol 40 (1) ◽  
pp. 7-20 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Quantitative Data ◽  
Field Experiments ◽  
Wheat Plant ◽  
Flowering Stage ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Stage Of Development ◽  
First Instar ◽  
Golden Ball

Quantitative data obtained in field experiments showed that the resistance of wheat to attack by the wheat stem sawfly (Cephus cinctus Nort.) depended on the stage of development of the plants at the time of oviposition. Wheat plants were usually most heavily infested for a part or all of the period from 1 week before shot blade to 1 week after the flowering stage. Rescue, H46146, H4191, Golden Ball, and Melanopus lost their resistance to the development of the eggs and first-instar larvae some time between shot blade and flowering. Thatcher and Red Bobs did not show this type of resistance. The mortality of the older larvae increased in plants infested toward maturity. The time at which this increase began depended on the variety involved and ranged from just before shot blade to just after flowering.

A COMPARISON OF INJURY AND SURVIVAL OF LARVAE OF CEPHUS CINCTUS NORT. AFTER INTRACELLULAR AND EXTRACELLULAR FREEZING

1961 ◽  
Vol 39 (3) ◽  
pp. 349-357 ◽  
Author(s):  
R. W. Salt
Keyword(s):  
Strong Evidence ◽  
Crystal Size ◽  
Activity Level ◽  
New Method ◽  
Freezing Injury ◽  
Ice Crystal ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Level Of Activity ◽  
Ice Crystal Size

Extracellular freezing of larvae of the wheat stem sawfly, Cephus cinctus Nort., was produced at −2.5 °C by a new method. Slow further cooling to −10, −15, or −20 °C added to extracellular ice with no intracellular freezing. Other larvae that were supercooled to and frozen at −10, −15, or −20 °C froze intracellularly. Comparisons of the effects of these two types of freezing were therefore possible at equivalent temperatures. Level of activity after freezing was used as the criterion of injury.Intracellular freezing was more injurious than extracellular freezing at −15 and −20 °C, but not at −10 °C. Injuries, as well as differences in injury due to type of freezing, decreased gradually to insignificance above −10 °C. Although larvae frozen extracellularly held an initial advantage over those frozen intracellularly, survivors of the latter group retained their vitality better, probably because they lost weight more slowly.Differences in injury and in activity level after freezing at −15 and −20 °C were insufficient to justify the use of freezing site (intracellular or extracellular) as a principal basis for explaining freezing injury. The same conclusion applies to ice crystal size and configuration, which differed vastly in the two types of freezing.These conclusions depend on whether freezing was actually intracellular or extracellular as represented. Strong evidence is presented that freezing was in fact as specified.

Host plant interactions between wheat germplasm source and wheat stem sawfly Cephus cinctus Norton (Hymenoptera: Cephidae) I. Commercial cultivars

2013 ◽  
Vol 93 (4) ◽  
pp. 607-617 ◽  
Author(s):  
B. L. Beres ◽  
H. A. Cárcamo ◽  
J. R. Byers ◽  
F. R. Clarke ◽  
C. J. Pozniak ◽  
...  
Keyword(s):  
Host Plant ◽  
Insect Pest ◽  
Economic Losses ◽  
Plant Interactions ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Wheat Germplasm ◽  
Commercial Cultivars ◽  
Solid Stem ◽  
The Impact

Beres, B. L., Cárcamo, H. A., Byers, J. R., Clarke, F. R., Pozniak, C. J., Basu, S. K. and DePauw, R. M. 2013. Host plant interactions between wheat germplasm source and wheat stem sawfly Cephus cinctus Norton (Hymenoptera: Cephidae) I. Commercial cultivars. Can. J. Plant Sci. 93: 607–617. The wheat stem sawfly (WSS) Cephus cinctus Norton (Hymenoptera: Cephidae) is an economically destructive insect pest of wheat in the northern Great Plains. A significant resurgence of the insect pest in the southern prairies of Canada caused substantial economic losses from 1999 through 2007. Solid-stem cultivar selection is critical to the management of WSS but adoption of the use of these cultivars was low, which compounded losses at harvest. A study was conducted from 2001 to 2003 in southern Alberta and Saskatchewan, Canada (1) to establish the range of susceptibility of hollow- and solid-stem varieties representing the major spring wheat classes and (2) to determine the impact of host plant on WSS population dynamics. The solid-stem varieties were generally superior at reducing damage and fitness response of WSS. However, in addition to the durum cultivars AC Navigator and AC Avonlea, the variety McKenzie, which was considered hollow, provided improved efficacy over other hollow-stem cultivars. Our study suggests solid-stem cultivars are highly effective but prone to inconsistent performance and should therefore be integrated into a holistic strategy for WSS that includes agronomics and biocontrol. A companion paper will report on the response of cultivars with novel sources of germplasm.

scholarly journals On the annual variation of the magnetic declination, at different periods of the day

1854 ◽  
Vol 6 ◽  
pp. 73-74
Keyword(s):  
Annual Variation ◽  
Graphical Representation ◽  
Horizontal Line ◽  
Annual Variations ◽  
Cape Of Good Hope ◽  
Magnetic Declination ◽  
Annual Range ◽  
The Hours ◽  
The Mean ◽  
St Helena

In this communication the author has arranged and presented together the Annual variations which the magnetic declination undergoes at every hour of the day at the four Colonial Observatories established by the British government, at Toronto, Hobarton, the Cape of Good Hope and St. Helena. This has been done by means of a graphical representation, in which the annual variations at every hour are shown by vertical lines varying in length according to the amount of the range of the annual variation at each hour; each line having also small cross lines marking the mean positions of the several months in the annual range. The mean declination in the year at the respective hours is marked by a horizontal line which crosses all the verticals at each station. The hours are those of mean solar time at each station, the day commencing at noon.

CYTOLOGY AND PARTHENOGENESIS OF THE WHEAT STEM SAWFLY, CEPHUS CINCTUS NORT. (HYMENOPTERA: CEPHIDAE)

1955 ◽  
Vol 33 (3) ◽  
pp. 161-174 ◽  
Author(s):  
Margaret Rowlatt Mackay
Keyword(s):  
Chromosome Complement ◽  
Chromosome Morphology ◽  
Diploid Males ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Bisexual Population ◽  
Monopolar Spindle ◽  
Spermatogonial Metaphase ◽  
Male Karyotype ◽  
Relationship Of

A chromosome complement of 18 was established for the female of Cephus cinctus Nort. by counts of 18 elements at oogonial metaphase and nine bivalents at pachytene. The male has a haploid set of nine chromosomes on the basis of counts at spermatogonial metaphase and at meiotic metaphases I and II. Male haploidy was confirmed by the fact that the male karyotype comprises one member of each morphologically identifiable pair present in the female. Spermatogenesis is characterized by lack of synapsis and complete abortion of the first meiotic division. Formation of a monopolar spindle at first meiotic metaphase is discussed. A cytological comparison of thelyotokous and arrhenotokous strains of C. cinctus failed to reveal any difference in chromosome number or in chromosome morphology. Cephus cinctus reproduces largely by arrhenotoky, the population normally being bisexual; the males develop from unfertilized eggs, most of the females arising from fertilized eggs; azygous, or impaternate, females occur sporadically. From the bisexual population a thelyotokous strain has arisen that is not distinguishable by cytological comparison; the females of both arrhenotokous and thelyotokous races are diploid; no diploid males were found. The haplo-diploid relationship of male to female was confirmed; male haploidy has become established by adaptive modifications in meiosis, as indicated in the cytological details given.

Factors affecting colony attendance by Ancient Murrelets (Synthliboramphus antiquus)

1990 ◽  
Vol 68 (3) ◽  
pp. 433-441 ◽  
Author(s):  
Ian L. Jones ◽  
Anthony J. Gaston ◽  
J. Bruce Falls
Keyword(s):  
Weather Conditions ◽  
Weather Variables ◽  
Short Term ◽  
Weather Effects ◽  
Factors Affecting ◽  
Cyclical Pattern ◽  
The Hours ◽  
Nesting Season ◽  
Colony Attendance

We studied factors influencing variation in nightly levels of activity (birds arriving and vocalizing) and numbers of birds staging offshore at a colony of Ancient Murrelets at Reef Island, British Columbia, during 1984, 1985, and 1986. Activity was restricted to the hours of darkness and extremely variable in magnitude from night to night. The rate of entry into burrows tended to decrease, and the amount of vocalization and numbers of birds at the staging area increased during the nesting season. We detected an underlying 4-day cyclical pattern of attendance. Nightly variability of activity at the colony was affected by moonlight and weather conditions. Since activity, particularly vocalization, was reduced on moonlit nights, we suggest that nocturnal colony attendance is a strategy to avoid diurnal predators in this species. The largest numbers of birds were present and vocalizing at the colony on calm moonless nights. Weather conditions explained a substantial proportion of the night to night variability in murrelet activity. Among weather variables, wind speed had the most consistent effect and was particularly important in 1985. Both short-term, i.e., of a particular night, and long-term, i.e., over the previous 3 days, conditions influenced activity. Our observations suggest that direct weather effects at the colony may be more important than weather effects related to foraging conditions. Interyear differences in activity may have resulted from the interaction of weather and general foraging conditions.

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