Transformed "Floating Leaf Disk" Lab

2021 ◽  
pp. 44-48
Author(s):  
Lenore Teevan
Keyword(s):  
Leaf Disk ◽  
Floating Leaf

Sensitivity of Australian isolates of Plasmopara viticola to acylanaline fungicides

1987 ◽  
Vol 27 (4) ◽  
pp. 601
Author(s):  
T Wicks ◽  
TC Lee ◽  
J Overton
Keyword(s):  
Phosphorous Acid ◽  
Plasmopara Viticola ◽  
Leaf Disk ◽  
Sensitivity Testing ◽  
Fungicide Sensitivity ◽  
Floating Leaf

A floating leaf disk technique was used to test the sensitivity of Australian isolates of Plasmopara viticola to 4 acylanaline fungicides, phosethyl-A1 and phosphorous acid. Sporulation of all 15 isolates was completely inhibited by 1 mg/L of metalaxyl. Benalaxyl, oxadixyl and ofurace at 10 mg/L and phosethyl-A1 and phosphorous acid at 100 mg/L also completely inhibited sporulation of each of the isolates tested for each fungicide. These results indicate that acylanaline insensitive isolates of P. viticola are either not present or are not widely distributed in grape growing areas of Australia. Cultures of selected P. viticola isolates have been established on tissue-cultured grapevines. Sporangia from these cultures can be used as standards for future fungicide sensitivity testing.

scholarly journals High-Throughput Feeding Bioassay for Lepidoptera Larvae

2021 ◽  
Author(s):  
Inoussa Sanané ◽  
Judith Legrand ◽  
Christine Dillmann ◽  
Frédéric Marion-Poll
Keyword(s):  
High Throughput ◽  
European Corn Borer ◽  
Time Course ◽  
Leaf Disk ◽  
Source Image ◽  
Test Case ◽  
Analysis Program ◽  
Corn Borer ◽  
Feeding Activities ◽  
Camera Holder

AbstractFinding plant cultivars that are resistant or tolerant against lepidopteran pests, takes time, effort and is costly. We present here a high throughput leaf-disk consumption assay system, to screen plants for resistance or chemicals for their deterrence. A webcam capturing images at regular intervals can follow the feeding activities of 150 larvae placed into individual cages. We developed a computer program running under an open source image analysis program to analyze and measure the surface of each leaf disk over time. We further developed new statistical procedures to analyze the time course of the feeding activities of the larvae and to compare them between treatments. As a test case, we compared how European corn borer larvae respond to a commercial antifeedant containing azadirachtin, and to quinine, which is a bitter alkaloid for many organisms. As expected, increasing doses of azadirachtin reduced and delayed feeding. However, quinine was poorly effective at the range of concentrations tested (10–5 M to 10–2 M). The model cage, the camera holder, the plugins, and the R scripts are freely available, and can be modified according to the users’ needs.

Studies on rates of development and reproduction of California red scale, Aonidiella aurantii (Mask.) (Homoptera : Diaspididae) on citrus

1972 ◽  
Vol 20 (1) ◽  
pp. 37 ◽  
Author(s):  
JR Willard
Keyword(s):  
Leaf Disk ◽  
Distilled Water ◽  
Aonidiella Aurantii ◽  
Innate Capacity ◽  
Disk Method ◽  
Capacity For Increase

Red scale were reared in the laboratory on disks cut from lemon leaves floated on distilled water in plastic vials. Scales could be reared to maturity on the disks and females would produce crawlers. Rates of development measured at four temperatures using the leaf disk method were similar to data reported by earlier authors. Unfertilized females were found to remain alive and could be fertilized up to 16 weeks after the second moult. On the average, the longevity of unfertilized females was shown to be 3.5 weeks longer than that of fertilized females. The fecundity of females collected from the field was measured at a series of constant temperatures. Estimates of the capacity for increase (rc) and the innate capacity for increase (rm were obtained at four temperatures. Both these statistics were shown to be greatly influenced by temperature; rc was found to be an underestimate of rm at higher temperatures.

scholarly journals Plant traits and environment: floating leaf blade production and turnover of waterlilies

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3212 ◽  
Author(s):  
Peter F. Klok ◽  
Gerard van der Velde
Keyword(s):  
Plant Traits ◽  
Vegetation Period ◽  
Leaf Biomass ◽  
Leaf Life Span ◽  
Turnover Rates ◽  
Leaf Production ◽  
Nuphar Lutea ◽  
Nymphaea Alba ◽  
Floating Leaves ◽  
Floating Leaf

Floating leaf blades of waterlilies fulfill several functions in wetland ecosystems by production, decomposition and turnover as well as exchange processes. Production and turnover rates of floating leaf blades of three waterlily species, Nuphar lutea (L.) Sm., Nymphaea alba L. and Nymphaea candida Presl, were studied in three freshwater bodies, differing in trophic status, pH and alkalinity. Length and percentages of leaf loss of marked leaf blades were measured weekly during the growing season. Area and biomass were calculated based on leaf length and were used to calculate the turnover rate of floating leaf blades. Seasonal changes in floating leaf production showed that values decreased in the order: Nymphaea alba, Nuphar lutea, Nymphaea candida. The highest production was reached for Nuphar lutea and Nymphaea alba in alkaline, eutrophic water bodies. The production per leaf was relatively high for both species in the acid water body. Nymphaea candida showed a very short vegetation period and low turnover rates. The ratio Total potential leaf biomass/Maximum potential leaf biomass (P/Bmax) of the three species ranged from 1.35–2.25. The ratio Vegetation period (Period with floating leaves)/Mean leaf life span ranged from 2.94–4.63, the ratio Growth period (Period with appearance of new floating leaves)/Vegetation period from 0.53–0.73. The clear differences between Nymphaea candida versus Nuphar lutea and Nymphaea alba, may be due to adaptations of Nymphaea candida to an Euro-Siberic climate with short-lasting summer conditions.

scholarly journals Transmission Efficiency of Papaya ringspot virus by Three Aphid Species

2008 ◽  
Vol 98 (5) ◽  
pp. 541-546 ◽  
Author(s):  
C. M. Kalleshwaraswamy ◽  
N. K. Krishna Kumar
Keyword(s):  
Aphis Gossypii ◽  
Transmission Efficiency ◽  
Leaf Disk ◽  
Ringspot Virus ◽  
Test Plant ◽  
Infected Leaf ◽  
Papaya Ringspot Virus ◽  
Access Period ◽  
Virus Retention ◽  
Aphid Inoculation

The transmission efficiency of Papaya ringspot virus (PRSV) by three aphid vectors (i.e., Aphis gossypii, A. craccivora, and Myzus persicae) was studied. Efficiency was measured by single-aphid inoculation, group inoculation (using five aphids), duration of virus retention, and the number of plants following a single acquisition access period (AAP) to which the aphids could successfully transmit the virus. Single-aphid inoculation studies indicated that M. persicae (56%) and A. gossypii (53%) were significantly more efficient in transmitting PRSV than A. craccivora (38%). Further, in the former two species, the time required for initiation of the first probe on the inoculation test plant was significantly shorter compared to A. craccivora. PRSV transmission efficiency was 100% in all three species when a group of five aphids were used per plant. There was a perceptible decline in transmission efficiency as the sequestration period increased, although M. persicae successfully transmitted PRSV after 30 min of sequestration. A simple leaf-disk assay technique was employed for evaluating the transmission efficiency of three species of aphids. The results of leaf-disk assays also indicated that A. gossypii (48%) and M. persicae (56%) were more efficient PRSV vectors than A. craccivora. Using leaf-disk assays, the ability of individual aphids to inoculate PRSV serially to a number of plants was studied. Following a single AAP on an infected leaf, M. persicae was more efficient than the other two species with 52.5% transmission after the first inoculation access period (IAP). However, its inoculation efficiency significantly decreased with the second and subsequent IAPs. A. gossypii was able to transmit PRSV sequentially up to four successive leaf disks, but with significantly declining efficiency. Since A. gossypii is reported to be the numerically dominant vector in south India in addition to being a more efficient vector capable of inoculating PRSV to multiple plants, it should be the target vector for control strategies.

Skin-related enzyme inhibitory activity by hydrolyzable polyphenols in water chestnut (Trapa natans) husk

2021 ◽  
Vol 85 (3) ◽  
pp. 666-674
Author(s):  
Midori Yasuda ◽  
Masaki Ikeoka ◽  
Shin-ichi Kondo
Keyword(s):  
Suppressive Effect ◽  
Postprandial Blood Glucose ◽  
Water Chestnut ◽  
Trapa Natans ◽  
Related Enzyme ◽  
Inhibitory Activities ◽  
Blood Glucose Elevation ◽  
Lifestyle Related Diseases ◽  
The Devil ◽  
Floating Leaf

ABSTRACT Water chestnut is a floating leaf plant native to Asia and Europe. Its fruit has long been used as an edible and herbal medicine. Water chestnut contains many polyphenols and its consumption can prevent lifestyle-related diseases because it has a suppressive effect on postprandial blood glucose elevation; however, its suitability as a cosmetic material is unknown. Therefore, this study aimed at investigating the antiaging effect of polyphenols contained in the husk of the devil water chestnut (Trapa natans). Six hydrolyzable polyphenols—1,6-di-O-galloyl-β-d-glucopyranose, 1,2,6-tri-O-galloyl-β-d-glucopyranose, 1,6-di-O-galloyl-2,3-O-(S)-hexahydroxydiphenoyl-β-d-glucopyranose (nobotanin D), eugeniin, 1,2,3,6-tetra-O-galloyl-β-d-glucopyranose, and trapain—were collected and isolated from the water chestnut husk. These polyphenols showed high antioxidant and antiglycation activities. In addition, inhibitory activities against hyaluronidase, elastase, and collagenase were observed. Especially, eugeniin and trapain, which have many gallic acids and a hexahydroxy-biphenyl group, showed high inhibitory activities. Thus, the polyphenols in water chestnut are beneficial for antiaging effects.

scholarly journals Development of a Miniaturized 24-well Strawberry Leaf Disk Bioassay for Evaluating Natural Fungicides

2008 ◽  
Vol 3 (7) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Xiaoning Wang ◽  
David E. Wedge ◽  
Nurhayat Tabanca ◽  
Robert D. Johnson ◽  
Stephen J. Cutler ◽  
...  
Keyword(s):  
Leaf Surface ◽  
Higher Plants ◽  
Polar Compounds ◽  
Leaf Disk ◽  
Biologically Active ◽  
Department Of Agriculture ◽  
Lead Compounds ◽  
The Us ◽  
Pure Compounds ◽  
Environmentally Safe

There is great incentive to discover biologically active natural products from higher plants that are more effective than synthetic agrochemicals and are environmentally safe. Research emphasis at the US Department of Agriculture has therefore been on the development of alternative approaches to utilizing natural plant products in pest management. Discovery and evaluation of natural product fungicides is largely dependent upon the availability of miniaturized antifungal bioassays. We report on the development of a miniaturized 24-well leaf disk assay for evaluating plant extracts and pure compounds. Compounds applied directly to the leaf surface can be evaluated in a dose-response for fungicidal activity and phytotoxicity. The assay is sensitive to microgram quantities, can determine chemical sensitivity between fungal isolates, and adaptable to complex mixtures, lipophilic extracts, and non-polar compounds. The use of digital imaging and analytical software provided quantitative data and the ability to fine tune the data analysis. Identification of new potential lead compounds can be repeated quickly in time and real on-the-leaf-surface activity can be evaluated in high throughput formats and published in a reasonable time.

scholarly journals Food availability and larval density affect ovarian development in Plutella xylostella (L.) (Lepidoptera: Yponomeutidae)

1999 ◽  
Vol 28 (4) ◽  
pp. 611-616 ◽  
Author(s):  
Marina Castelo Branco ◽  
Alexander G. Gatehouse
Keyword(s):  
Population Density ◽  
Food Availability ◽  
Plutella Xylostella ◽  
Ovarian Development ◽  
Diamondback Moth ◽  
Larval Density ◽  
Leaf Disk ◽  
Plant Age ◽  
Insect Migration ◽  
Petri Dishes

The effect of Diamondback Moth (Plutella xylostella L.) population density and plant age on the rate of ovarian development was investigated. In tests carried out in Petri dishes, the density of larvae/leaf disk affected the rate of ovarian development. A high proportion of moths from larvae reared on leak disks from two or four-month-old spring cabbage at a density of seven or 14 larvae/leaf disk were mature at emergence. But moths reared at the same type of plant at a density of 28 larvae/leaf disk were largely immature at emergence. When the larvae were reared at a density of 30 larvae/plant on two or four-month-old spring cabbage plants, a high proportion of females were mature at emergence. Crowding has an important effect on the rate of ovarian development in Diamondback Moth with possible consequences for the migratory potential of moths, as insect migration generally occurs when the ovaries of the females are immature. The density of moths necessary to increase the proportion of immature females in the field is probably higher than 30 larvae/plant.

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