scholarly journals Seeking Alfalfa Resistance to a Rhizophagous Pest, the Clover Root Curculio (Sitona hispidulus F.)

Insects ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 906
Author(s):  
Kaitlin Rim ◽  
Jamie Crawford ◽  
Steven J. Price ◽  
Donald R. Viands ◽  
Ricardo A. Ramirez
Keyword(s):  
Management Practices ◽  
Screening Method ◽  
Head Capsule ◽  
Larval Feeding ◽  
Susceptible Population ◽  
Sitona Hispidulus ◽  
Adult Feeding ◽  
Resistant Population ◽  
Clover Root ◽  
Crc Management

Since the cancellation of broad-spectrum soil-active insecticides in alfalfa (Medicago sativa L.) production, clover root curculio (Sitona hispidulus F.) (CRC) larval root damage has increased. Current CRC management practices are limited in their ability to suppress larval feeding belowground. First, we field screened developmental alfalfa populations for CRC damage. Subsequently, we developed a soil-less arena to observe nodule feeding and development (head capsule width) of larvae in the lab. This method was used to evaluate five alfalfa populations (two CRC-susceptible (control) and three CRC-resistant populations) against larvae. Further, one CRC-resistant population paired with its genetically similar susceptible population were tested against adult leaf consumption and oviposition in the greenhouse. Field screening revealed that the alfalfa populations selected for little or no larval root feeding damage were more resistant to CRC larval feeding than their corresponding unselected cultivars and significantly more resistant than populations selected for susceptibility. The development of a soil-less arena provided a useful method for evaluation of root-larva interactions. Although larval development was similar across susceptible and resistant alfalfa populations, one CRC-resistant population (NY1713) displayed overall increased nodulation and, thus, had a significantly lower proportion of nodules consumed by larvae. Adult feeding and oviposition aboveground were similar across all populations tested. These results provide possible candidates and screening method for the development and evaluation of alfalfa cultivars that may reduce the impacts of larval feeding and that offer an additional option for CRC management.

Wild Mustard (Brassica kaber) Resistance to Ethametsulfuron But Not to Other Herbicides

1996 ◽  
Vol 10 (4) ◽  
pp. 847-850 ◽  
Author(s):  
G. Mark Jeffers ◽  
John T. O'Donovan ◽  
Linda M. Hall
Keyword(s):  
Dry Weight ◽  
The Other ◽  
Controlled Environment ◽  
Susceptible Population ◽  
Initial Frequency ◽  
Wild Mustard ◽  
Resistant Population ◽  
Imidazolinone Herbicides ◽  
Brassica Kaber ◽  
Very High

In 1993, a wild mustard population growing in a canola crop near Wetaskiwin, AB was poorly controlled by ethametsulfuron after only one previous use of the herbicide. Controlled environment experiments were conducted to compare the response of this suspected resistant population (R) with that of a known susceptible population (S) collected near Vegreville, AB to increasing rates of ethametsulfuron, metsulfuron, chlorsulfuron, thifensulfuron, HOE 075032, imazamethabenz, imazethapyr, metribuzin, and 2,4-D. The R wild mustard population was highly resistant to ethametsulfuron, slightly resistant to low rates of metsulfuron but not resistant to any of the other herbicides tested. This suggests that the mechanism of resistance may differ from that reported for other sulfonylurea and imidazolinone herbicides. Since resistance was documented after only 2 yr of ethametsulfuron use, the initial frequency of resistance to this herbicide in wild mustard populations may be very high. Dry weight of untreated plants did not differ significantly between the S and R populations suggesting little or no differences in competitiveness between them.

Improving Dryland Crop Simulation by Assimilating Soil Moisture and Vegetation Data

2020 ◽  
Author(s):  
Yang Lu ◽  
Justin Sheffield
Keyword(s):  
Soil Moisture ◽  
Crop Production ◽  
Management Practices ◽  
Water Productivity ◽  
Vegetation Indices ◽  
Screening Method ◽  
Model Performance ◽  
State Parameter ◽  
Aquacrop Model

<p>Global population is projected to keep increasing rapidly in the next 3 decades, particularly in dryland regions of the developing world, making it a global imperative to enhance crop production. However, improving current crop production in these regions is hampered by yield gaps due to poor soils, lack of irrigation and other management practices. Here we develop a crop modelling capability to help understand gaps, and apply to dryland regions where data for parametrizing and testing models is generally lacking. We present a data assimilation framework to improve simulation capability by assimilating in-situ soil moisture and vegetation data into the FAO AquaCrop model. AquaCrop is a water-driven model that simulates canopy growth, biomass and crop yield as a function of water productivity. The key strength of AquaCrop lies in the low requirement for input data thanks to its simple structure. A global sensitivity analysis is first performed using the Morris screening method and the variance-based Extended Fourier Amplitude Sensitivity Test (EFAST) method to identify the key influential parameters on the model outputs. We begin with state-only updates by assimilating different combinations of soil moisture and vegetation data (vegetation indices, biomass, etc.), and different filtering/smoothing assimilation strategies are tested. Based on the state-only assimilation results, we further evaluate the utility of joint state-parameter (augmented-states) assimilation in improving the model performance. The framework will eventually be extended to assimilate remote sensing estimates of soil moisture and vegetation data to overcome the lack of in-situ data more generally in dryland regions.</p>

scholarly journals Differences between Macrolide-Resistant and -Susceptible Streptococcus pyogenes: Importance of Clonal Properties in Addition to Antibiotic Consumption

2012 ◽  
Vol 56 (11) ◽  
pp. 5661-5666 ◽  
Author(s):  
C. Silva-Costa ◽  
A. Friães ◽  
M. Ramirez ◽  
J. Melo-Cristino ◽  
Keyword(s):  
Streptococcus Pyogenes ◽  
Antibiotic Consumption ◽  
Macrolide Resistance ◽  
Typing Method ◽  
Susceptible Population ◽  
Content Type ◽  
Resistant Population ◽  
Changing Patterns ◽  
Group A ◽  
Two Populations

ABSTRACTA steady decline in macrolide resistance amongStreptococcus pyogenes(group A streptococci [GAS]) in Portugal was reported during 1999 to 2006. This was accompanied by alterations in the prevalence of macrolide resistance phenotypes and in the clonal composition of the population. In order to test whether changes in the macrolide-resistant population reflected the same changing patterns of the overall population, we characterized both macrolide-susceptible and -resistant GAS associated with a diagnosis of tonsillo-pharyngitis recovered in the period from 2000 to 2005 in Portugal. Pulsed-field gel electrophoresis (PFGE) profiling was the best predictor ofemmtype and the only typing method that could discriminate clones associated with macrolide resistance and susceptibility within eachemmtype. Six PFGE clusters were significantly associated with macrolide susceptibility: T3-emm3-ST406, T4-emm4-ST39, T1-emm1-ST28, T6-emm6-ST382, B3264-emm89-ST101/ST408, and T2-emm2-ST55. Four PFGE clusters were associated with macrolide resistance: T4-emm4-ST39, T28-emm28-ST52, T12-emm22-ST46, and T1-emm1-ST28. We found no evidence for frequent ongoing horizontal transfer of macrolide resistance determinants. The diversity of the macrolide-resistant population was lower than that of susceptible isolates. The differences found between the two populations suggest that the macrolide-resistant population of GAS has its own dynamics, independent of the behavior of the susceptible population.

A Waterhemp (Amaranthus tuberculatus) Population Resistant to 2,4-D

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 379-384 ◽  
Author(s):  
Mark L. Bernards ◽  
Roberto J. Crespo ◽  
Greg R. Kruger ◽  
Roch Gaussoin ◽  
Patrick J. Tranel
Keyword(s):  
Dose Response ◽  
Dry Weight ◽  
Population Based ◽  
Susceptible Population ◽  
Herbicide Resistant ◽  
Synthetic Auxins ◽  
Resistant Population ◽  
Amaranthus Tuberculatus ◽  
Susceptible Populations ◽  
Dose Response Study

A waterhemp population from a native-grass seed production field in Nebraska was no longer effectively controlled by 2,4-D. Seed was collected from the site, and dose-response studies were conducted to determine if this population was herbicide resistant. In the greenhouse, plants from the putative resistant and a susceptible waterhemp population were treated with 0, 18, 35, 70, 140, 280, 560, 1,120, or 2,240 g ae ha−12,4-D. Visual injury estimates (I) were made 28 d after treatment (DAT), and plants were harvested and dry weights (GR) measured. The putative resistant population was approximately 10-fold more resistant to 2,4-D (R:S ratio) than the susceptible population based on both I50(50% visual injury) and GR50(50% reduction in dry weight) values. The R:S ratio increased to 19 and 111 as the data were extrapolated to I90and GR90estimates, respectively. GR50doses of 995 g ha−1for the resistant and 109 g ha−1for the susceptible populations were estimated. A field dose-response study was conducted at the suspected resistant site with 2,4-D doses of 0, 140, 280, 560, 1,120, 2,240, 4,480, 8,960, 17,920, and 35,840 g ha−1. At 28 DAT, visual injury estimates were 44% in plots treated with 35,840 g ha−1. Some plants treated with the highest rate recovered and produced seed. Plants from the resistant and susceptible populations were also treated with 0, 9, 18, 35, 70, 140, 280, 560, or 1,120 g ae ha−1dicamba in greenhouse bioassays. The 2,4-D resistant population was threefold less sensitive to dicamba based on I50estimates but less than twofold less sensitive based on GR50estimates. The synthetic auxins are the sixth mechanism-of-action herbicide group to which waterhemp has evolved resistance.

The relative competitiveness of atrazine susceptible and resistant populations of Chenopodium album and C. strictum

1981 ◽  
Vol 59 (5) ◽  
pp. 689-693 ◽  
Author(s):  
S. I. Warwick ◽  
L. Black
Keyword(s):  
Biomass Production ◽  
Aboveground Biomass ◽  
Competitive Ability ◽  
Chenopodium Album ◽  
Dry Weight ◽  
Replacement Series ◽  
Susceptible Population ◽  
Resistant Population ◽  
Reproductive Biomass ◽  
Susceptible Populations

The total aboveground biomass and reproductive dry weight of one atrazine resistant and one susceptible population from southern Ontario of each of two species of Chenopodium, C. album and C. strictum, were compared. The comparison was made between plants grown under both noncompetitive and competitive conditions. Results from a spaced noncompetitive trial provided evidence for: (1) greater total and reproductive biomass production and earlier flowering of resistant and susceptible populations of C. album as compared with both populations of C. strictum, (2) greater aboveground total and reproductive biomass production of the susceptible population of C. album as compared with the resistant population, and (3) greater total aboveground biomass production (but similar reproductive biomass) of the susceptible population of C. strictum as compared with the resistant population. Results from the competition trials (i.e., plants grown in a de Wit replacement series), provided evidence for inter- and intra-specific differences in competitive ability: (1) the susceptible population of C. album was found to be more competitive than the susceptible population of C. strictum, (2) the susceptible population of C. album was a superior competitor to the resistant population, and (3) the resistant and susceptible populations of C. strictum appeared to be equally competitive.

COMPARISON OF MALE AND FEMALE RESPONSES TO DICOFOL IN EUROPEAN RED MITE, PANONYCHUS ULMI (KOCH), USING A RAPID ASSAY TECHNIQUE

1991 ◽  
Vol 123 (6) ◽  
pp. 1157-1161
Author(s):  
B.K. Mable ◽  
D.J. Pree ◽  
T.A. Denbesten
Keyword(s):  
Panonychus Ulmi ◽  
Susceptible Population ◽  
Male And Female ◽  
Rapid Assay ◽  
Resistant Population ◽  
Laboratory Colonies ◽  
Males And Females ◽  
Petri Dishes ◽  
Female Responses ◽  
Assay Technique

AbstractConcentration:response regressions were established for male and female Panonychus ulmi from dicofol resistant and susceptible laboratory colonies using a rapid assay technique which utilizes pesticide residues in enclosed Petri dishes. Modification of the technique, which was developed for females, allowed reproducible results with males. Males and females from the resistant population showed similar levels of resistance compared with the susceptible population (ca. 4-fold). Within populations, males were approximately 3-fold more sensitive than females. Implications of these differences for field populations and the usefulness of males in inheritance studies are discussed.

scholarly journals Storage and Utilization of Reserves by the Garden Chafer, Phyllopertha Horticola L

1956 ◽  
Vol 33 (3) ◽  
pp. 566-575
Author(s):  
ROGER LAUGHLIN
Keyword(s):  
Total Nitrogen ◽  
Instar Larva ◽  
The Other ◽  
Activity Period ◽  
Larval Feeding ◽  
The Third ◽  
Winter Half ◽  
Adult Feeding ◽  
Phyllopertha Horticola ◽  
Third Instar Larva

1. Samples of all stages of Phyllopertha horticola L. have been analysed for fat, total nitrogen and glycogen. 2. Total nitrogen increases throughout the larval feeding period, while fat and glycogen are laid down mainly in the latter half. 3. From November, when the third-instar larva goes into hibernation, until June, when the eggs have been matured and laid, no food is taken. 4. Of the store of fat and glycogen in the hibernating larva at the beginning of the winter, half is used up by the time the adult emerges. The other half is used in the formation of eggs. 5. Adult feeding provides energy for the post-oviposition activity period.

scholarly journals Interaction between clover root weevil and clover root type

2000 ◽  
Vol 53 ◽  
pp. 420-424 ◽  
Author(s):  
D.A. Care ◽  
J.R. Crush ◽  
S. Hardwick ◽  
S.N. Nichols ◽  
L. Ouyang
Keyword(s):  
Image Analysis ◽  
Fine Roots ◽  
Larval Feeding ◽  
Root Damage ◽  
Larval Weight ◽  
Sitona Lepidus ◽  
Clover Root ◽  
Trifolium Repens L ◽  
Root Feeding ◽  
Root Types

A slant board experiment investigated the effect of four white clover (Trifolium repens L) root types on tolerance of root feeding by larvae of clover root weevil (Sitona lepidus Gyllenhål) Root damage was determined by image analysis and larval weight gains were measured Differences in root type did not have a major impact on initial damage by clover root weevil However different root types were affected differently by the clover root weevil A clover genotype with long fine roots had more functional root length after larval feeding than genotypes with different root types

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