THELYOTOKOUS PARTHENOGENESIS IN CEPHUS CINCTUS NORT. (HYMENOPTERA: CEPHIDAE)

1938 ◽  
Vol 70 (10) ◽  
pp. 206-207 ◽  
Author(s):  
C. W. Farstad
Keyword(s):  
Crop Losses ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Southern Alberta

The wheat stem sawfly (Cephus cinctus Nort.) has recently become established as a serious pest of wheat in the Nobleford—Lethbridge area of southern Alberta, the first appreciable damage to wheat occurring in 1934. Each succeeding year the insect has increased and spread rapidly throughout the area, and in many cases crop losses have run as high as 75 to 80 per cent.

POPULATION DYNAMICS OF THE WHEAT STEM SAWFLY, CEPHUS CINCTUS (HYMENOPTERA: CEPHIDAE), IN WHEAT

1982 ◽  
Vol 114 (9) ◽  
pp. 775-788 ◽  
Author(s):  
N. D. Holmes
Keyword(s):  
Population Dynamics ◽  
Host Plants ◽  
Weather Conditions ◽  
Growing Season ◽  
Field Margins ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Southern Alberta ◽  
One Year ◽  
Major Factors

AbstractThe effects of the major factors on populations of the wheat stem sawfly, Cephus cinctus Norton, were studied in the field at Lethbridge, Alberta between 1970 and 1977. Fecundity of the females, which contain an average of 32.7 eggs, is influenced by the condition and variety of host plants in which they develop as larvae. Populations of the adults that emerge from infested crops cut 7–9% by the larvae in one year may infest 70–80% of the stems of adjacent crops in the following year. Increased adult densities, however, fail to increase markedly the percentage of stems infested because the adults concentrate at field margins when they reinfest the most preferred stems. Because only one larva can mature in each stem, competition within stems that receive more than one egg causes a major drop in the population but not in the percentage of infested stems cut. Another major drop is caused by host plant resistance, which is influenced in both susceptible and resistant wheats by the weather during the growing season. On an average, all of the larvae die in 28% of the infested stems of two susceptible wheats and in 67% of those of a resistant wheat. The mortality in resistant wheats, however, is generally not sufficient to prevent economic infestations in subsequent years. Parasitism, which was a major factor in only 7 of 36 years in southern Alberta, is increased by weather conditions that cause delayed ripening of the wheat crops. The mortality of mature larvae and pupae averaged 21.3%. It is affected by extremes of moisture and temperature and can be increased slightly by shallow tillage of infested stubble.

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.

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.

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.

Preharvest sampling plan for larvae of the wheat stem sawfly, Cephus cinctus (Hymenoptera: Cephidae), in winter wheat fields

2005 ◽  
Vol 137 (5) ◽  
pp. 602-614 ◽  
Author(s):  
Christian Nansen ◽  
Mark E. Payton ◽  
Justin B. Runyon ◽  
David K. Weaver ◽  
Wendell L. Morrill ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Insect Pest ◽  
Sampling Plan ◽  
Sampling Effort ◽  
Infestation Level ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Explanatory Variables ◽  
Increased Risk ◽  
Harvest Efficiency

AbstractThe wheat stem sawfly, Cephus cinctus Norton, is the most important insect pest of dryland wheat, reducing both harvest efficiency and head weight. When wheat lodged (flattened) by C. cinctus is straight-cut, harvest efficiency is affected in three ways: (1) lodged stems are difficult to collect with the combine, so mature wheat is lost; (2) the combine has to operate more slowly to collect as many of the lodged stems as possible; and (3) there is increased risk of damage to the combine due to lowering of the combine header to recover lodged stems. An alternative harvest method is to swath the wheat before lodging occurs and place it in windrows prior to combining. When swathing is used, harvest efficiency is not affected by the C. cinctus infestation level; however, this type of harvesting is more expensive and labor-intensive than straight- cutting. Thus, swathing should be used only when the crop is heavily infested by C. cinctus, while straight-cutting should be used when the level of C. cinctus infestation is lower. Adapting harvesting practices to the C. cinctus infestation level requires a sampling plan that can reliably and cost-effectively predict the infestation level in a given field. In this study, we (i) evaluate the relationship between sampling effort along field edges and precision of the estimated average infestation level in 6 wheat fields, and (ii) generate a Gaussian regression analysis of the infestation level up to 200 m into 18 wheat fields using two variables, distance from the edge and average infestation level at the edge, as explanatory variables. We conclude that little additional precision for estimates of infestation level is gained by collecting more than 10 samples along field edges. We also conclude that the average C. cinctus infestation level along field edges can be used successfully to predict infestation levels up to 200 m into winter wheat fields. The proposed sampling should be implemented about one month before harvest to provide growers with enough time to make logistical preparations for harvest.

Observations on Hyperparasitism of the Wheat Stem Sawfly Cephus cinctus Nort. (Hymenoptera: Cephidae)

1953 ◽  
Vol 85 (7) ◽  
pp. 249-251 ◽  
Author(s):  
W. A. Nelson
Keyword(s):  
Hessian Fly ◽  
Field Crop ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus

The biology of Bracon cephi (Gah.) (Hymenoptera: Braconidae) was described recently (Nelson and Farstad, 1953). During studies from the Field Crop Insect Laboratory, Lethbridge, on the biology of this important parasit, observations were made on various other hymenopterous parasites associated with the wheat stem sawfly, Cephus cinctus Nort. The parasites discussed herein are Eupelmella vesicularis (Retz.) (Eupelmidae), Eurytoma atripes Gah. (Eurytomidae), and Merisus febriculosus Gir. (Pteromalidae). These three parasites have been noted by Gahan (1933) as parasites of the hessian fly, Phytophaga destructor (Say).

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