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.

Causes of Variations in Effectiveness of Bracon cephi (Gahan) (Hymenoptera: Braconidae) as a Parasite of the Wheat Stem Sawfly

1963 ◽  
Vol 95 (2) ◽  
pp. 113-126 ◽  
Author(s):  
N. D. Holmes ◽  
W. A. Nelson ◽  
L. K. Peterson ◽  
C. W. Farstad
Keyword(s):  
Host Plants ◽  
First Generation ◽  
Second Generation ◽  
Wheat Stem Sawfly ◽  
Sawfly Larvae ◽  
Early Ripening ◽  
Low Levels ◽  
One Year ◽  
High Level

AbstractAdults of B. cephi emerged at the same time as the adults of their host, the wheat stem sawfly, and started to oviposit about mid-July. The second generation started to emerge between August 5 and 15. This generation, which was complete in some years, was apparently only partial in years in which adults of the first generation continued to oviposit late in the season. In most cases the larvae of Bracon that were present at harvest time were from eggs laid after August 1.Most of the overwintering B. cephi were located in the lower internodes of the sawfly-infested wheat stems. Although B. cephi attacked some sawfly larvae in their stubs most sawflies escaped parasitism once they had cut their host stems.High host densities per stem in hollow-stemmed wheats were detrimental to Bracon during the early part of the season as the unparasitized sawfly larvae in stems containing B. cephi destroyed the parasite larvae.The sawfly-susceptible wheats were more suitable than the resistant for parasitism. Generally, differences in parasitism between wheats and between barleys were caused by differences in length of survival of the sawfly larvae in the different host plants; longer survival led to higher parasitism.The fluctuations in amounts of parasitism mainly depended on the synchronization of development between B. cephi and the sawfly. Parasitism increased when the sawfly larvae cut their host stems sufficiently late to allow establishment by the second generation of B. cephi and decreased when the sawfly cut too early for parasitism by the second generation. The date of ripening of the host plant governs the date of cutting by the sawfly; hence, the amount of parasitism is influenced by the levels of soil moisture and temperature during the growing season, by differences in rate of development of various plant hosts, and by the date of seeding. Low levels of parasitism resulted from early ripening of the sawfly host plants in two consecutive years, whereas a moderately high level occurred even though the weather of the current year was conducive to early ripening, provided that the wheat in the preceding year had ripened late. It appears that moderate to high levels of parasitism required that the crop ripen late in at least one year out of two.

Differences in population dynamics of Bradybaena fruticum (O.F. Müller, 1774) (Gastropoda: Pulmonata: Bradybaenidae) in a submontane and lowland area of Poland

2012 ◽  
Vol 62 (4) ◽  
pp. 451-462 ◽  
Author(s):  
Małgorzata Proćków ◽  
Elżbieta Kuźnik-Kowalska ◽  
Małgorzata Lewandowska
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Weather Conditions ◽  
Growing Season ◽  
Climatic Conditions ◽  
Slow Phase ◽  
Average Growth Rate ◽  
Average Growth ◽  
Fast Phase ◽  
Growing Seasons

Population dynamics of a meso-hygrophilous helicoid Bradybaena fruticum was studied in SW Poland at two localities with similar habitat but different climatic conditions. Unexpectedly, at the submontane site in Szczytna the growth appeared to be significantly faster than in the lowland site (Wrocław), where the weather conditions varied widely during the whole growing season. In Szczytna the average growth rate was 0.26 whorl/month; 0.36 whorl/month in the fast phase (juveniles from hatching till 5.0 whorls), and 0.07 whorl/month in the slow phase (snails with 5.1 whorls till lip formation). During the whole growing season, the average increment was 4.5 whorls, whereas the maximum was 5.45 whorls. In Wrocław the average growth rate was 0.05 whorl/month; 0.1 whorl/month in the fast phase, and only 0.01 whorl/month in the slow phase. The average growth of juveniles, estimated during two growing seasons, equalled 3.8 whorls; the maximum recorded value was 4.75 whorls. In the winter there was hardly any growth. In earlier studies it was found that at higher altitude the growth rate seems to decrease and therefore appears to be correlated with the thermal regime of the locality. In this study it was established that the weather patterns, like months with drought or occasional flooding, are likely to influence the population dynamics in the lowland population.

scholarly journals Effect of Precipitation and Temperature on Larval Survival of Cephus cinctus (Hymenoptera: Cephidae) in Barley Cultivars

2020 ◽  
Vol 113 (4) ◽  
pp. 1982-1989
Author(s):  
Buddhi B Achhami ◽  
Gadi V P Reddy ◽  
Jamie D Sherman ◽  
Robert K D Peterson ◽  
David K Weaver
Keyword(s):  
Host Plant ◽  
Larval Growth ◽  
Growing Season ◽  
Larval Survival ◽  
Economic Losses ◽  
Site Specific ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Barley Cultivars ◽  
Precipitation And Temperature

Abstract Host plant traits strongly affect survivorship of insect herbivores, and host suitability is especially important for the wheat stem sawfly, Cephus cinctus Norton, which spends its entire egg, larval, and pupal periods in a single stem. Measuring larval survival inside stems from egg hatch through diapause-mediated dormancy is a potential measure of population size for the next year but is also useful in assessing effects of growing season precipitation and temperature. Larval growth is synchronized with host plant growth, and the larva cannot switch hosts. Thus, incorporating plant physiological time, as growing degree days (GDD), may yield a better prediction of larval survival. Therefore, we assessed wheat stem sawfly survival from early larval growth to the beginning of autumnal diapause in barley cultivars selected from across feed, forage, and two- or six-row malt groups. Field experiments were conducted in Gallatin and Chouteau counties, Montana, in 2016 and 2017. We used Kaplan-Meier estimation to assess larval survival among cultivars. We found that the survival of pre-diapause larvae was greatest in ‘Hockett’ (36.5%) and lowest in ‘Celebration’ (15.4%). Precipitation and temperature during the growing season affected temporal patterns for larval survival across study sites. Adjusting survivorship curves using site-specific GDD accumulation allowed cultivar-specific survivorship to be estimated more precisely for each site, despite differing environmental influences. Our findings suggest that measuring wheat stem sawfly survival across barley cultivars and standardizing by site-specific GDDs may provide better recommendations on barley cultivars that impede wheat stem sawfly population growth and reduce economic losses.

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.

Cephus cinctus. [Distribution map].

1979 ◽  
Author(s):  
Keyword(s):  
North America ◽  
Geographical Distribution ◽  
Host Plants ◽  
Distribution Map ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
New Distribution

Abstract A new distribution map is provided for Cephus cinctus Nort. (Hymenopt., Cephidae) (Western Wheat-stem Sawfly). Host Plants: Wheat, barley, rye and various grasses. Information is given on the geographical distribution in NORTH AMERICA, Canada, USA.

Parasites of the Wheat-stem Sawfly, Cephus pygmaeus, Linnaeus, in England

1931 ◽  
Vol 22 (4) ◽  
pp. 479-545 ◽  
Author(s):  
George Salt
Keyword(s):  
Host Plants ◽  
Insect Pests ◽  
Wide Distribution ◽  
Western Canada ◽  
Native Grasses ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus ◽  
Principal Factors

For a number of years the western grass-stem sawfly, Cephus cinctus, Norton, has been accounted one of the major insect pests of wheat in Western Canada. Originally a grass-feeder, it began to attack wheat about the beginning of the present century, at first only occasionally and at the edges of fields in Manitoba, later much more commonly and with a very wide distribution throughout the wheat-growing areas of Manitoba, Saskatchewan, and Alberta. While this sawfly was confined to native grasses it was held in check by two principal factors (Criddle, 1922) : shortage of grass stalks suitable for oviposition, and parasites. When, however, it began to attack wheat, both of these restraints were evaded. In the first place the wheat fields provided an abundance of host-plants. In the second place, the natural parasites of the sawfly did not move with it into the grain fields—whether they are unaware of the presence of their host in wheat plants or are unable to attack it in that situation is unknown.

scholarly journals Impact of extreme weather conditions on the population dynamics of bark beetles in the forests of Eastern Serbia

2015 ◽  
pp. 27-37
Author(s):  
Mara Tabaković-Tošić ◽  
Marija Milosavljević
Keyword(s):  
Population Dynamics ◽  
Bark Beetle ◽  
Bark Beetles ◽  
Weather Conditions ◽  
State Enterprise ◽  
Aggregation Pheromones ◽  
Pheromone Traps ◽  
Ice Storm ◽  
One Year ◽  
Pheromone Dispensers

The paper presents the results of a one-year study of population dynamics of bark beetles by the method of bark beetle trapping using pheromone traps with the following pheromone dispensers-aggregation pheromones: IAC Ecolure (for Ips acuminatus and I. sexdentatus), IT Ecolure (for I. typographus) and PC Ecolure (for Pityogenes chalcographus), after the ice storm that hit the region of Eastern Serbia, especially the forest estate Timočke šume Boljevac (State enterprise Srbijašume) in November 2014. The population levels of the monitored bark beetle species in the controlled area in 2015 were generally within the limits of normal conditions.

Irrigation regime and water consumption of potatoes in the Republic of Bashkortostan, depending on the reclamation condition of lands

2020 ◽  
Vol 0 (6) ◽  
pp. 13-19
Author(s):  
Guzel Gumerova ◽  
Georgiy Gulyuk ◽  
Dmitry Kucher ◽  
Anatoly Shuravilin ◽  
Elena Piven
Keyword(s):  
Water Consumption ◽  
Weather Conditions ◽  
Growing Season ◽  
Vegetation Period ◽  
Forest Steppe ◽  
Total Water ◽  
Total Water Consumption ◽  
Republic Of Bashkortostan ◽  
Irrigated Lands ◽  
The Republic

Data of long-term researches (2015–2018) in southern forest-steppe zone of the Republic of Bashkortostan, is justified theoretically and experimentally the mode of irrigation of potatoes on leached chernozems of unsatisfactory, satisfactory and good ameliorative condition of irrigated lands. For the growing periods of potatoes with different heat and moisture supply, the number of watering, the timing of their implementation, irrigation and irrigation norms are established. On lands with unsatisfactory meliorative state the number of irrigation depending on weather conditions of potato vegetation period varied from 0 to 3 (1.5 on average) with average irrigation norm – 990 m3/ha. With satisfactory meliorative state of lands the number of irrigation on average increased from 0 to 4 (2.3 on average) with irrigation norm – 1305 m3/ha. On lands with good meliorative state the number of irrigation was the highest – from 1 to 5 (3 on average) with average irrigation irrigation norm is 1653 m3/ha. It was noted that in the dry periods of potato vegetation the greatest number of watering was carried out (3–5 watering), and in the wet periods (2017) watering was not carried out except for the area with a good reclamation state, where only one irrigation was carried out by the norm of 550 m3/ha. Water consumption of potato was studied in dynamics as a whole during the growing season and the months of the growing season depending on weather conditions of vegetation period and land reclamation condition of irrigated lands, as well as in the control (without irrigation). The lowest total water consumption was in the area without irrigation and averaged 226.8 mm. In irrigated areas, its values increased to 319-353.4 mm. The average daily water consumption varied from 2.12 to 3.3 mm. The highest rates of potato water consumption were observed in June and July, and the lowest – in May and August. In the total water consumption of potatoes on the site without irrigation, the largest share was occupied by atmospheric precipitation and in addition to them the arrival of moisture from the soil. Irrigation water was used in irrigated areas along with precipitation, the share of which was 30.2–46.1 %.

scholarly journals Effect of different soil and weather conditions on efficacy, selectivity and dissipation of herbicides in sunflower

2020 ◽  
Vol 66 (No. 9) ◽  
pp. 468-476
Author(s):  
Miroslav Jursík ◽  
Martin Kočárek ◽  
Michaela Kolářová ◽  
Lukáš Tichý
Keyword(s):  
Cation Exchange Capacity ◽  
Chenopodium Album ◽  
Soil Layer ◽  
Weather Conditions ◽  
Growing Season ◽  
Application Rate ◽  
Exchange Capacity ◽  
Vertical Transport ◽  
Application Rates ◽  
High Precipitation

Six sunflower herbicides were tested at two application rates (1N and 2N) on three locations (with different soil types) within three years (2015–2017). Efficacy of the tested herbicides on Chenopodium album increased with an increasing cation exchange capacity (CEC) of the soil. Efficacy of pendimethalin was 95%, flurochloridone and aclonifen 94%, dimethenamid-P 72%, pethoxamid 49% and S-metolachlor 47%. All tested herbicides injured sunflower on sandy soil (Regosol) which had the lowest CEC, especially in wet conditions (phytotoxicity 27% after 1N application rate). The highest phytotoxicity was recorded after the application of dimethenamid-P (19% at 1N and 45% at 2N application rate). Main symptoms of phytotoxicity were leaf deformations and necroses and the damage of growing tips, which led to destruction of some plants. Aclonifen, pethoxamid and S-metolachlor at 1N did not injure sunflower on the soil with the highest CEC (Chernozem) in any of the experimental years. Persistence of tested herbicides was significantly longer in Fluvisol (medium CEC) compared to Regosol and Chernozem. Dimethenamid-P showed the shortest persistence in Regosol and Chernozem. The majority of herbicides was detected in the soil layer 0–5 cm in all tested soils. Vertical transport of herbicides in soil was affected by the herbicide used, soil type and weather conditions. The highest vertical transport was recorded for dimethenamid-P and pethoxamid (4, resp. 6% of applied rate) in Regosol in the growing season with high precipitation.  

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