scholarly journals Transmission of Pantoea ananatis and P. agglomerans, Causal Agents of Center Rot of Onion (Allium cepa), by Onion Thrips (Thrips tabaci) Through Feces

2014 ◽  
Vol 104 (8) ◽  
pp. 812-819 ◽  
Author(s):  
B. Dutta ◽  
A. K. Barman ◽  
R. Srinivasan ◽  
U. Avci ◽  
D. E. Ullman ◽  
...  
Keyword(s):  
Immunofluorescence Microscopy ◽  
Thrips Tabaci ◽  
Mechanical Inoculation ◽  
Onion Thrips ◽  
Pantoea Ananatis ◽  
Exponential Relationship ◽  
Frankliniella Fusca ◽  
Tobacco Thrips ◽  
Relationship Of ◽  
The Relationship

Frankliniella fusca, the tobacco thrips, has been shown to acquire and transmit Pantoea ananatis, one of the causal agents of the center rot of onion. Although Thrips tabaci, the onion thrips, is a common pest of onions, its role as a vector of P. ananatis has been unknown. The bacterium, P. agglomerans, is also associated with the center rot of onion, but its transmission by thrips has not been previously investigated. In this study, we investigated the relationship of T. tabaci with P. ananatis and P. agglomerans. Surface-sterilized T. tabaci were provided with various acquisition access periods (AAP) on onion leaves inoculated with either P. ananatis or P. agglomerans. A positive exponential relationship was observed between thrips AAP duration and P. ananatis (R2 = 0.967; P = 0.023) or P. agglomerans acquisition (R2 = 0.958; P = 0.017). Transmission experiments conducted with T. tabaci adults indicated that 70% of the seedlings developed center rot symptoms 15 days after inoculation. Immunofluorescence microscopy with antibodies specific to P. ananatis revealed that the bacterium was localized only in the gut of T. tabaci adults. Mechanical inoculation of onion seedlings with fecal rinsates alone produced center rot but not with salivary secretions. Together these results suggested that T. tabaci could efficiently transmit P. ananatis and P. agglomerans.

scholarly journals Interactions Between Frankliniella fusca and Pantoea ananatis in the Center Rot Epidemic of Onion (Allium cepa)

2016 ◽  
Vol 106 (9) ◽  
pp. 956-962 ◽  
Author(s):  
Bhabesh Dutta ◽  
Ronald Gitaitis ◽  
Apurba Barman ◽  
Utku Avci ◽  
Kathleen Marasigan ◽  
...  
Keyword(s):  
Positive Relationship ◽  
Immunofluorescence Microscopy ◽  
Life Stages ◽  
Mechanical Inoculation ◽  
Pantoea Ananatis ◽  
Transmission Mechanisms ◽  
Frankliniella Fusca ◽  
Contaminated Food ◽  
Fitness Parameters ◽  
Important Disease

An Enterobacteriaceae bacterium, Pantoea ananatis (Serrano) Mergaert, is the causal agent of an economically important disease of onion, center rot. P. ananatis is transmitted by an onion-infesting thrips, Frankliniella fusca (Hinds). However, interactions between F. fusca and P. ananatis as well as transmission mechanisms largely remain uncharacterized. This study investigated P. ananatis acquisition by thrips and transstadial persistence. Furthermore, the effects of bacterial acquisition on thrips fitness were also evaluated. When thrips larvae and adults were provided with acquisition access periods (AAP) on peanut leaflets contaminated with the bacterium, an exponentially positive relationship was observed between AAP and P. ananatis acquisition (R2 ≥ 0.77, P = 0.01). P. ananatis persisted in thrips through several life stages (larvae, pupae, and adult). Despite the bacterial persistence, no significant effects on thrips fitness parameters such as fecundity and development were observed. Immunofluorescence microscopy of adult thrips with P. ananatis-specific antibody after 48 h AAP on contaminated food revealed that the bacterium was localized only in the gut. These results suggested that the pathogen is not circulative and could be transmitted through feces. Mechanical inoculation of onion seedlings with fecal rinsates produced center rot symptoms, whereas inoculation with rinsates potentially containing salivary secretions did not. These results provide evidence for stercorarian transmission (transmission through feces) of P. ananatis by F. fusca.

Relationship of fluid filtration to lung vascular pressure during edema

1991 ◽  
Vol 70 (1) ◽  
pp. 202-209 ◽  
Author(s):  
I. C. Ehrhart ◽  
W. F. Hofman
Keyword(s):  
Weight Gain ◽  
Fluid Flux ◽  
Exponential Relationship ◽  
Lung Weight ◽  
Tissue Pressure ◽  
Fluid Filtration ◽  
Constant Rate ◽  
Relationship Of ◽  
The Relationship ◽  
Lung Lobes

Effect of edema on the relationship between rate of fluid filtration and vascular pressure was studied in ventilated isolated dog lung lobes blood-perfused at constant flow. Constant rate of lobe weight gain (S), representing transvascular fluid flux, was obtained at different venous pressures (Pv) as Pv was increased stepwise from 2 to 40 and then similarly decreased from 40 to 2 Torr (n = 6). In another group (n = 6), edema was maximized by reversing the sequence of Pv change; S was obtained during similar Pv steps as Pv was decreased from 40 to 2 and then returned to 40 Torr. In both groups, delta S was disproportionately greater for delta Pv at higher Pv's, with S vs. Pv fit by an exponential curve (P less than 0.001). The exponential relationship was independent of lung hydration inasmuch as greater edema on the second limb of Pv change did not alter the curve (P greater than 0.05). At 144% weight gain, interstitial compliance was 55.5 +/- 26.8 ml.100 g-1.Torr-1 (n = 10). Interstitial pressure reportedly remains constant, i.e., fails to increase to further buffer fluid filtration, after transition of the lung interstitium from low to high compliance at approximately 40% lung weight gain. If so, then the exponential S vs. Pv relationship observed in the present study at elevated interstitial compliance does not appear related to tissue pressure-buffering effects.

scholarly journals Thrips (Thysanoptera) associated with onion (Allium cepa L.) and Welsh onion (Allium fistulosum L.)

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Marta Olczyk ◽  
Maria Pobożniak
Keyword(s):  
Allium Cepa ◽  
Growing Season ◽  
Thrips Tabaci ◽  
Allium Fistulosum ◽  
Onion Thrips ◽  
Welsh Onion ◽  
Allium Cepa L ◽  
Onion Cultivar ◽  
The Relationship ◽  
Thrips Population

AbstractWe determined the abundance, species composition, sex ratio and seasonal dynamics of thrips on one cultivar of Welsh onion (Allium fistulosum) and eight cultivars of onion (Allium cepa) in South Poland within three vegetation seasons (2014–2016). Nine species of Thysanoptera were identified on A. cepa and A. fistulosum. Irrespective of the onion cultivar, Thrips tabaci was the dominant species (64.4% of all collected thrips specimens), while Frankliniella intonsa also occurred in high numbers (28.3%). Conversely, Welsh onion was most often inhabited by F. intonsa (62.7%), although T. tabaci was also numerous (28.3%). The predatory Aeolothrips intermedius accounted for 4.5% on A. cepa and 2.9% on A. fistulosum. In the most numerous species, T. tabaci, F. intonsa and A. intermedius populations were formed mainly by females. The cultivar most colonised by thrips was Kroll of A. fistulosum. The tested cultivars of A. cepa demonstrated varying degrees of attractiveness to thrips in the subsequent years. The relationship between populations of T. tabaci, F. intonsa and A. intermedius changed in the subsequent months of the growing season. In June, mainly T. tabaci and F. intonsa occurred on onion plants, while from July, the percentage shares of F. intonsa and the predatory A. intermedius in the thrips population on many onion cultivars increased. The level of attractiveness of A. cepa related to onion thrips, which is reported as a main pest of onion, varies depending on the year and cultivar.

Some characteristics of the thrip vector relationship of tomato spotted wilt virus in Canada

1976 ◽  
Vol 54 (5-6) ◽  
pp. 402-405 ◽  
Author(s):  
Y. C. Paliwal
Keyword(s):  
British Columbia ◽  
Tomato Spotted Wilt Virus ◽  
Frankliniella Occidentalis ◽  
First Generation ◽  
Thrips Tabaci ◽  
Eastern Canada ◽  
Tomato Spotted Wilt ◽  
Frankliniella Fusca ◽  
Wilt Virus ◽  
Relationship Of

Two isolates of tomato spotted wilt virus (TSWV) from British Columbia were transmitted by Frankliniella occidentalis, which is common in British Columbia but does not occur in eastern Canada. Frankliniella occidentalis from B.C. transmitted the virus to a smaller proportion of Emilia plants as compared with Frankliniella fusca, a known vector that occurs in eastern Canada, after a 48-h acquisition feeding as nymphs on infected Emilia leaves. Neither isolate of the virus was transmitted by Thrips tabaci, which is a vector of TSWV in some other countries. Males and females and macropterous and brachypterous forms of F. fusca did not differ significantly in their vector ability. TSWV was detected serologically in homogenates of 50 ‘exposed' F. fusca (first-generation adults reared on newly infected plants) but was difficult to detect in homogenates prepared from these thrips 2 weeks later. Thrip transmissibility of the virus declined considerably when propagated for long periods without passage through the thrip vector.

scholarly journals Foliar chemical protection against Pantoea ananatis in onion is negated by thrips feeding

2020 ◽  
Author(s):  
Spencer Stumpf ◽  
Leanna Leach ◽  
Rajagopalbab Srinivasan ◽  
Tim Coolong ◽  
Ron Gitaitis ◽  
...  
Keyword(s):  
Growth Stage ◽  
Cost Effective ◽  
The United States ◽  
Thrips Tabaci ◽  
Growth Stages ◽  
Pantoea Ananatis ◽  
Chemical Treatments ◽  
Frankliniella Fusca ◽  
Cupric Hydroxide ◽  
Bulb Rot

Center rot of onion, caused by Pantoea ananatis, is an economically important disease in onion production in Georgia and elsewhere in the United States. Growers rely on frequent foliar applications of bactericides, and in some cases, plant defense inducers to manage this disease. However, regular prophylactic applications of these chemicals is not cost-effective and may not be environmentally friendly. Thrips (Thrips tabaci and Frankliniella fusca) are vectors of P. ananatis, and their feeding may compromise the effectiveness of foliar applications against P. ananatis. In this study, foliar treatments of acibenzolar-S-methyl (Actigard 50WG), cupric hydroxide (Kocide 3000), and Actigard + Kocide were evaluated for their effectiveness in the presence and absence of thrips infestation at two critical onion-growth stages; bulb initiation and bulb swelling. Onion growth stage had no impact on effectiveness of either Kocide or Actigard. In the absence of thrips, Kocide application resulted in reduced center rot incidence compared with Actigard, regardless of the growth stage. However, when thrips were present, the efficacy of both Kocide and Actigard was reduced with bulb incidence not significantly different from the non-treated control. In independent greenhouse studies in the presence or absence of thrips, it was observed that use of protective chemicals (Kocide or Actigard and their combinations) at different rates also affected the pathogen progression into the internal neck tissue and incidence of bulb rot. These results suggest that thrips infestation can reduce the efficacy of protective chemical treatments against P. ananatis.

Establishing the relationship of ascospore loads with blackleg (Leptosphaeria maculans) severity on canola (Brassica napus)

2004 ◽  
Vol 55 (8) ◽  
pp. 849 ◽  
Author(s):  
A. D. Wherrett ◽  
K. Sivasithamparam ◽  
M. J. Barbetti
Keyword(s):  
Brassica Napus ◽  
Crop Residues ◽  
Leptosphaeria Maculans ◽  
Disease Index ◽  
Adult Plant ◽  
Exponential Relationship ◽  
Glufosinate Ammonium ◽  
Highly Correlated ◽  
Relationship Of ◽  
The Relationship

A study was carried out to determine the relationship of blackleg (Leptosphaeria maculans) to ascospore loads from infested canola residue, and also to determine whether effects of chemicals on L. maculans development and ascospore discharge from residues would be reflected in subsequent disease on a freshly sown crop. Residues were dipped in a water-only control or solutions of flutriafol or glufosinate-ammonium and placed in the field prior to early winter rains where they remained through the growing season. Canola (Brassica napus cv. Dunkeld) was seeded adjacent to residues. Early seedling lesion and adult plant crown canker development were monitored. A significant exponential relationship between numbers of ascospores discharged from residues and seedling percentage disease index (SPDI; range 0–100%) and adult plant percentage disease index (APDI; range 0–100%) was evident. In particular, large variations in SPDI and APDI were evident in relation to changes in level of inoculum where less than 25 × 105 ascospores/stem (approx.) were discharged. A reduction in ascospore numbers discharged from 25 × 105 ascospores/stem to 5 × 105 ascospores/stem resulted in a significant reduction of SPDI and APDI. Above this ascospore/stem threshold, responses to inoculum increases were minimal, with relatively little further increase in SPDI or APDI. Our study established, for the first time, a clear response of disease severity to numbers of ascospores discharged. SPDI was lower in plots containing flutriafol- or glufosinate-ammonium-treated residues compared with water-only control plots. Nearly all seedlings remained symptom-free in flutriafol-treated plots compared with only 20% in the water-only control plots. Crown canker measurement on adult plants indicated significantly lower APDI in plots containing flutriafol- or glufosinate-ammonium-treated residues compared with the untreated control plots. SPDI was highly correlated to APDI.

scholarly journals Transmission of Pantoea ananatis, Causal Agent of Center Rot of Onion, by Tobacco Thrips, Frankliniella fusca

Plant Disease ◽  
2003 ◽  
Vol 87 (6) ◽  
pp. 675-678 ◽  
Author(s):  
R. D. Gitaitis ◽  
R. R. Walcott ◽  
M. L. Wells ◽  
J. C. Diaz Perez ◽  
F. H. Sanders
Keyword(s):  
Disease Transmission ◽  
Causal Agent ◽  
Pantoea Ananatis ◽  
Postharvest Losses ◽  
Nondestructive Assay ◽  
Frankliniella Fusca ◽  
Incubation Periods ◽  
Tobacco Thrips

Center rot of onion, caused by Pantoea ananatis, was first reported on onion in Georgia in 1997 and has continued to reduce yields and cause postharvest losses. In a previous study, we developed a nondestructive assay that demonstrated an association between P. ananatis and approximately 10% of the tobacco thrips, Frankliniella fusca, surveyed. In this study, we report that all strains of P. ananatis, isolated from surface-sterilized, crushed thrips, were pathogenic when inoculated onto greenhouse-grown onion plants. Furthermore, when 6 to 12 thrips harboring populations of P. ananatis of 1 × 103 CFU ml-1 or greater were placed on healthy onion seedlings to feed, disease transmission occurred in 52% of the plants challenged. Incubation periods ranged from 4 to 9 days. Bacteria isolated from symptoms typical of those associated with center rot were characterized and identified as P. ananatis. In contrast, an equal number of plants remained healthy for up to 28 days after being exposed to the same number of tobacco thrips that were identified as being free of P. ananatis.

scholarly journals The thermal decomposition of crystals of barium azide

1939 ◽  
Vol 172 (950) ◽  
pp. 314-325 ◽  
Keyword(s):  
Simple Expression ◽  
Microscopical Examination ◽  
Solid Product ◽  
Exponential Relationship ◽  
Silver Oxalate ◽  
Potassium Azide ◽  
Relationship Of ◽  
The Relationship ◽  
Lead Styphnate

In solid reactions of the type A solld = B solld + C gas the reactions are sometimes autocatalytic, being accelerated by the solid product. The solid product may be disseminated throughout the crystal in a diffuse manner, as has been shown by the microscopical examination of partially decomposed crystals of mercury fulminate (Garner and Hailes 1933) or potassium azide (Garner and Marke 1936), or may be aggregated into visible nuclei as in the case of alkaline earth (Harvey 1933 ; Marke 1937; Maggs 1939) or lead azides (Garner and Gomm 1931). In previous investigations an induction period has been found during which the evolution of gas is negligible, which is followed by an accelerating rate of development of pressure. For a certain period of the reaction the relationship of pressure and time is that of an exponential type which in a number of cases takes the simple form, log p = kt + const. This expression is obeyed over the early part of the reaction for single crystals of mercury fulminate (Garner and Hailes 1933), barium azide (Harvey 1933), and lead styphnate (Hailes 1933). It also holds for silver oxalate (Macdonald 1936 a , b ) in a finely crystalline form and for ground mercury fulminate. Attempts have been made to account for the exponential relationship in terms of the spread of reaction chains throughout the crystal, but there are certain difficulties in the way of the application of the chain theory, especially when nuclei are formed. There are, besides, cases where this simple expression does not fit the experimental results, notably that of ground calcium (Marke 1937) and barium (Harvey 1933) azides.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

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