SEASONAL OCCURRENCE AND CHEMICAL CONTROL OF THE BROMEGRASS SEED MIDGE, CONTARINIA BROMICOLA (DIPTERA: CECIDOMYHDAE), IN SASKATCHEWAN

1983 ◽  
Vol 115 (1) ◽  
pp. 75-79 ◽  
Author(s):  
P. S. Curry ◽  
R. P. Knowles ◽  
J. Waddington
Keyword(s):  
Flowering Time ◽  
Treatment Effect ◽  
Chemical Control ◽  
Second Generation ◽  
Field Tests ◽  
Seasonal Occurrence ◽  
Heading Time ◽  
Two Peaks

AbstractPopulations of the bromegrass seed midge, Contarinia bromicola Marikovskiy and Agafonova, were sampled in bromegrass plots in Saskatchewan in the years 1974 to 1980 inclusive. Two peaks of midge adult numbers were observed, the first at bromegrass heading time in early June and the second about 20–25 days later at bromegrass flowering. Parasitism by a species of Tetrastichus (Eulophidae) varied from 30% to 75%. Carbofuran (0.14 kg A.I./ha) or dimethoate (0.56 kg A.I./ha) spray, applied just before emergence of adult midges at flowering time, significantly reduced numbers of midges and parasites resident in the plants in both of two field tests; a second generation of midge larvae, following invasion by midge adults, was significantly reduced by residual treatment effect in only 1 of the 2 years.

scholarly journals THE EFFECT OF LEVEL OF HETEROZYGOSITY ON THE PERFORMANCE OF HYBRIDS BETWEEN ISOGENIC LINES OF BARLEY

Genetics ◽  
1976 ◽  
Vol 84 (4) ◽  
pp. 765-775
Author(s):  
A A Zali ◽  
R W Allard
Keyword(s):  
Complex Structure ◽  
Field Tests ◽  
Kernel Weight ◽  
Heading Time ◽  
Male Sterile ◽  
Planting Dates ◽  
Isogenic Lines ◽  
Marked Chromosome ◽  
Allelic State ◽  
Chromosome Segments

ABSTRACT Sixteen "isogenic" lines of Atlas 46 barley differing in one to four short chromosome segments, and 16 heterozygotes obtained by crossing these lines to male-sterile Atlas, were used to study the effect of level of heterozygosity on performance. In field tests conducted in four environments (two planting dates in two years) significant differences were found among the homozygous isogenic lines for the traits seed yield, kernel weight, tiller number, plant height, and heading time; thus each of the marked chromosome segments carries genes which, when homozygous, affect these quantitative characters. It was also found that heterozygotes produced more and heavier kernels and were taller and earlier than homozygotes but there was no clear indication that the degree of heterosis increased as the number of heterozygous segments increased from one to five. Degree of heterosis was, however, strongly affected by the environment, by allelic state at each segment (especially the segment marked by the two-row, six-row spike locus), and also by genotype for other marked segments. These results indicate that heterosis in barley has a more complex structure than can be adequately represented by simple models, such as the multiplicative model in which fitnesses are the product of fitnesses at individual loci, or threshold models in which optimum fitness is approached asymptotically as the number of heterozygous loci increases.

scholarly journals The role of epistasis and its interaction with environment in fine-tuning heading time in barley

2020 ◽  
Vol 71 (3) ◽  
pp. 743-746
Author(s):  
Nikolai K Christov
Keyword(s):  
Flowering Time ◽  
Fine Tuning ◽  
Heading Time ◽  
Experimental Botany

This article comments on: Afsharyan NP, Sannemann W, Léon J, Ballvora A. 2020. Effect of epistasis and environment on flowering time of barley reveals novel flowering-delaying QTL allele. Journal of Experimental Botany 71, 893–906.

scholarly journals Chemical control of flowering time

2016 ◽  
pp. erw427 ◽  
Author(s):  
Irina Alexandra Ionescu ◽  
Birger Lindberg Møller ◽  
Raquel Sánchez-Pérez
Keyword(s):  
Flowering Time ◽  
Chemical Control

Laboratory and field tests in 1966-67 on chemical control of wireworms (Agriotes spp.)

1969 ◽  
Vol 64 (1) ◽  
pp. 21-29 ◽  
Author(s):  
D. C. GRIFFITHS ◽  
G. C. SCOTT ◽  
J. R. LOFTY ◽  
P. F. ROBERTS
Keyword(s):  
Chemical Control ◽  
Field Tests

SEASONAL OCCURRENCE AND NUMBER OF GENERATIONS OF LYGUS LINEOLARIS AND L. BOREALIS (HETEROPTERA: MIRIDAE) IN SOUTHERN MANITOBA

1995 ◽  
Vol 127 (4) ◽  
pp. 543-559 ◽  
Author(s):  
G.H. Gerber ◽  
I.L. Wise
Keyword(s):  
Oilseed Rape ◽  
Overlapping Generations ◽  
First Generation ◽  
Second Generation ◽  
Seasonal Occurrence ◽  
Lygus Lineolaris ◽  
Thlaspi Arvense ◽  
Two Generations ◽  
Agricultural Areas ◽  
Field Plots

AbstractThe seasonal occurrence and number of generations of Lygus lineolaris (Palisot de Beauvois) were studied on alfalfa (Medicago sativa L.), everbearing strawberries (Fragaria × ananassa Duchesne), oilseed rape (Brassica napus L.), and stinkweed (Thlaspi arvense L.) in field plots at Winnipeg, Manitoba, and in commercial alfalfa and oilseed rape fields throughout the agricultural areas of Manitoba in 1990–1993. Lygus borealis (Kelton) was studied only during 1993. Lygus lineolaris had two non-overlapping generations in southern Manitoba. Overwintered adults migrated onto host plants during die first 3 weeks of May, and females containing chorionated eggs were found in relatively small numbers for 5–6 weeks until the last 3 weeks of June. First-generation nymphs were present from the last half of May until the last half of July. During the last 2 weeks of June, the overwintered adults disappeared suddenly and were replaced completely by first-generation adults. First-generation adults eclosed during the last 2 weeks of June and in July, and first-generation females containing chorionated eggs were present for about 6–7 weeks until mid-August. Second-generation nymphs first appeared in late July or early August and most completed development by the end of September. Second-generation adults were found from the first half of August until they hibernated in October and November. Most second-generation females contained previtellogenic eggs and. therefore, were in reproductive diapause. In 3 of the 4 years, the overwintered adults appeared to include all second-generation adults plus 0–20% of the first-generation adults. The data from commercial alfalfa and oilseed rape fields indicated that the seasonal occurrence of L. lineolaris was relatively uniform in most or all agricultural areas of Manitoba. Lygus lineolaris has one generation (the second generation) on oilseed rape, and the eclosion and dispersal of reproductively active first-generation adults were well synchronized with the bud and flower stages of this host plant in southern Manitoba. In 1993, L. borealis had two generations and its seasonal occurrence was similar to that of L. lineolaris.

Seasonal succession and spatial–temporal distribution patterns of six larval cytospecies of the Simulium venustum/verecundum complex (Diptera: Simuliidae)

1993 ◽  
Vol 71 (1) ◽  
pp. 116-124 ◽  
Author(s):  
John W. McCreadie ◽  
Murray H. Colbo
Keyword(s):  
Spatial Distribution ◽  
Second Generation ◽  
Seasonal Succession ◽  
Temporal Distribution ◽  
Distribution Patterns ◽  
Seasonal Occurrence ◽  
Generation Number ◽  
Avalon Peninsula ◽  
Ecological Profiles

The seasonal succession of S. venustum/verecundum cytospecies found in both sublacustrine and downstream habitats on the Avalon Peninsula, Newfoundland, was investigated. EFG/C venustum (= Simulium truncatum Lundström) appeared 1–5 weeks earlier than other cytospecies. ACD verecundum (= S. rostratum Lundström) and AA verecundum usually appeared later and remained in streams longer than EFG/C, AC(gb) venustum, CC2 venustum, or CC3 venustum. Seasonal occurrence of sympatric cytospecies often overlapped, though development was typically staggered and population peaks were asynchronous. EFG/C, and probably CC3, are univoltine in Newfoundland. AC(gb) may have a second generation at a few sites. CC2 has two or more generations per year in Newfoundland, though generation number varied among sites. ACD and AA are multivoltine. Proportionally more ACD and AA were found on vegetation than on rocks, whereas the reverse was true for EFG/C. As well, the density of a mixed ACD–AA population was usually higher on vegetation than on rocks. Cytospecies composition at sublacustrine sites was different from sites farther downstream. The results of the present investigation were also combined with those of a previous study on spatial distribution to construct spatial–temporal ecological profiles for four cytospecies (EFG/C, AC(gb), ACD, AA). Each cytospecies showed a distinct profile.

Insect Enemies of Lecanium coryli L. (Homoptera: Coccoidea) in Saskatchewan

1962 ◽  
Vol 94 (7) ◽  
pp. 739-742 ◽  
Author(s):  
L. O. T. Peterson
Keyword(s):  
Chemical Control ◽  
Adult Stage ◽  
Seasonal Occurrence ◽  
Natural Mortality ◽  
Ulmus Americana ◽  
Nymphal Stage ◽  
Female Host ◽  
Eleven Species

Local outbreaks of Lecanium coryli L. on white elm, Ulmus americana L., at Indian Head and Regina, Saskatchewan, were investigated from 1957 to 1960. Information on the seasonal occurrence, habits of the females, natural mortality, and chemical control of the scale has been reported (Peterson, 1960). During this investigation, data on insects attacking the scale were collected and are presented in this paper. Eleven species of hymenopterous parasites and one dipterous predator were collected. All were associated with the late nymphal stage and/or the adult stage of the female host. Table I lists the hymenopterous species and shows the numbers of adults and their emergence periods, recorded from 1958 to 1960.

Retardation of Hydrilla (Hydrilla verticillata) Regrowth through Chemical Control of Vegetative Reproduction

Weed Science ◽  
1980 ◽  
Vol 28 (3) ◽  
pp. 245-251 ◽  
Author(s):  
K. K. Steward
Keyword(s):  
Acetic Acid ◽  
Chemical Control ◽  
Vegetative Reproduction ◽  
Field Tests ◽  
Hydrilla Verticillata

Several chemicals were evaluated in the laboratory for their ability to inhibit growth of hydrilla [Hydrilla verticillata(L.f.) Royle] from tubers. Fenac [(2,3,6-trichlorophenyl)acetic acid] and dichlobenil (2,6-dichlorobenzonitrile) were effective in controlling regrowth in outdoor aquaria. In field tests, hydrilla regrowth was controlled for over 13 months by single applications of 34 kg/ha rates of fenac and over 48 months in one of three replicates treated with 11 kg/ha dichlobenil. Regrowth occurred in controls within 2 to 6 months. There were no differences in the number of viable propagules found in hydrosoil before and 13 months after treatments. Regrowth occurred from root-stocks and from tubers. Regrowth was associated with disappearance of the herbicides from water.

POSTEMBRYONIC GROWTH AND DEVELOPMENT OF F1 AND F2 TOBACCO BUDWORMS (LEPIDOPTERA: NOCTUIDAE) FROM PARTIALLY STERILE MALES

1972 ◽  
Vol 104 (2) ◽  
pp. 165-172 ◽  
Author(s):  
F. I. Proshold ◽  
J. A. Bartell
Keyword(s):  
Heliothis Virescens ◽  
Growth And Development ◽  
Second Generation ◽  
Field Tests ◽  
Tobacco Budworm ◽  
Larval Instars ◽  
Continuous Release ◽  
Delayed Development ◽  
Lepidoptera Noctuidae ◽  
Inherited Sterility

AbstractTobacco budworms, Heliothis virescens (F.), with inherited sterility caused by irradiation of the male parent were smaller than progeny from normal parents and developed more slowly throughout the larval and pupal periods. In the second generation the population segregated into two groups, those with normal and those with delayed development. Also, when the P1 male received 15.0 krad, 8% of the F1 larvae had more than the normal five instars. Moreover, when those F1 progeny that had only five larval instars were outcrossed to normal moths, this tendency for supernumerary molts increased nearly 3-fold. The slower development of progeny of treated moths would have to be considered in field tests made to evaluate the effect of inherited sterility on the tobacco budworm. However, with continuous release of irradiated males, the delayed development or smaller size of the progeny should not lessen the possibility that this method could successfully suppress field populations.

Sign in / Sign up

Export Citation Format

Share Document