Abstract
Multiple regression analysis of the data described in a previous paper identified alate Myzus persicae of the spring and summer migrations as the most important factor affecting spread of beet yellows virus in the sugar‐beet root crop in England. Apterae of M. persicae spread little virus, and the contribution of alatae and apterae of Aphis fabae was negligible. A simple mathematical model of the spread of infection was developed. Assuming that the crop is visited by N aphids at a time when the proportion of plants infected is k 0 , the predicted proportion of infection for a time 3–4 weeks later ( k 1 ) is k 1 = k 0 + 100(1‐ k 0 ) (1‐ e ‐N1 ), where I = p [( 1‐k 0 ) t + k 0 t ‐1]/ k 0 . This formula adequately accounts for the observed spread of infection when N = 1 /10 sticky trap count for the 3–4 weeks preceding the time when k 0 infection is observed; p = probability of infection by a single aphid =½; t = number of movements per aphid effective for spreading beet yellows virus = 5. The good fit of this formula to the observed data supports the results of the regression analyses in showing that alate M. persicae were mainly responsible for spreading beet yellows virus. Once infection had been introduced into the root crops in the spring spread was mainly within fields, or between fields in the same neighbourhood. In areas where beet and mangold seed crops were grown intensively some infection was spread to the root crops by summer migrants from infected seed crops. Apart from this, the greater prevalence of yellows in seed crop areas was caused by the greater development of M. persicae infestation of the root crops which occurs in these areas. The proportion of plants infected by spring migrants entering the root crops before the end of June was small and variable. It did not vary significantly between seed and non‐seed areas. This implies either that initial infection came equally from sources other than seed crops, or that, if the seed crops were the main sources of infection, winged aphids acquired infectivity by visiting them during migration, and later became very widely dispersed. In contrast to yellows, mosaic virus spread mainly in the neighbourhood of seed crops within the seed‐crop areas. No significant relation between aphid numbers and increase of infection was established, but there is a strong suggestion that alatae of M. persicae and A. fabae spread the virus, and that the contributions of both species are equal. This suggests that mosaic virus is not spread by movement of aphids within the root crops, but only by infective migrants coming from outside sources. As the virus is non‐persistent the sources must be near to the root crops, and as there is little internal spread many infective migrants are needed to cause a high level of infection. The seed crops fulfil these conditions as they are often severely infected with mosaic, and both vector species breed on them. The irregularity of the data relating aphid numbers to mosaic incidence is probably caused mainly by individual variation in the intensity of infection of seed crops, and in the proportion of migrants caught on the traps which actually derive from them.
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Claims 14
Claim · model-written summary
Spring and summer alate Myzus persicae were the strongest predictor of beet yellows spread.
- Taxon
- sugar‐beet
Beta vulgaris subsp. vulgarise0 - Interactor
- Myzus persicae
Myzus persicaee0pestt1 - Outcome
- spread of beet yellows viruse0
- Setting
- Englande0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“alate Myzus persicae of the spring and summer migrations as the most important factor affecting spread of beet yellows virus in the sugar‐beet root crop in England.”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Apterous M. persicae spread little beet yellows virus.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Interactor
- M. persicaeMyzus persicaee0pestt1
- Outcome
- spread little viruse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Apterae of M. persicae spread little virus”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Alate and apterous Aphis fabae contributed negligibly to beet yellows spread.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Interactor
- Aphis fabae
Aphis fabaee0pestt1 - Outcome
- contribution of alatae and apterae of Aphis fabae was negligiblee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the contribution of alatae and apterae of Aphis fabae was negligible”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
A spread model adequately fit observed beet yellows infection using trap counts and assumed aphid parameters.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- observed spread of infectione0
- Value
- 5e0
- Comparator
- sticky trap counte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This formula adequately accounts for the observed spread of infection when N = 1 /10 sticky trap count for the 3–4 weeks preceding the time when k 0 infection is observed; p = probability of infection by a single aphid =½; t = number of movements per aphid effective for spreading beet yellows virus = 5.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Yellows spread mainly within or among nearby fields after spring introduction.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- spread was mainly within fields, or between fields in the same neighbourhoode0
- Setting
- fieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Once infection had been introduced into the root crops in the spring spread was mainly within fields, or between fields in the same neighbourhood.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Summer migrants from infected seed crops spread some infection to root crops in intensive seed crop areas.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- infection was spread to the root crops by summer migrantse0
- Setting
- areas where beet and mangold seed crops were grown intensivelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In areas where beet and mangold seed crops were grown intensively some infection was spread to the root crops by summer migrants from infected seed crops.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Greater yellows prevalence in seed crop areas was attributed to greater M. persicae infestation.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Interactor
- M. persicaeMyzus persicaee0pestt1
- Outcome
- greater prevalence of yellowse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the greater prevalence of yellows in seed crop areas was caused by the greater development of M. persicae infestation of the root crops”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
The proportion infected by spring migrants before June end was small and variable.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- proportion of plants infectede0
- Qualifier
- before the end of Junee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The proportion of plants infected by spring migrants entering the root crops before the end of June was small and variable.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Initial infection did not differ significantly between seed and nonseed areas.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- proportion of plants infected by spring migrantse1
- Setting
- seed and non‐seed arease0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It did not vary significantly between seed and non‐seed areas.”
e1“The proportion of plants infected by spring migrants entering the root crops before the end of June was small and variable.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Mosaic spread mainly near seed crops within seed crop areas.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- mosaic virus spreade0
- Setting
- neighbourhood of seed crops within the seed‐crop arease0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mosaic virus spread mainly in the neighbourhood of seed crops within the seed‐crop areas.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
No significant aphid number relation with mosaic infection increase was established.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- increase of infectione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No significant relation between aphid numbers and increase of infection was established”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
The authors suggested both aphid species spread mosaic equally.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Interactor
- M. persicaeMyzus persicaee0pestt1
- Second interactor
- A. fabaeAphis fabaee0pestt1
- Outcome
- spread the viruse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there is a strong suggestion that alatae of M. persicae and A. fabae spread the virus, and that the contributions of both species are equal.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
The authors inferred mosaic spread from outside migrants instead of movement inside root crops.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Interactor
- aphidsAphidomorphae0pestt1
- Outcome
- mosaic virus is not spread by movement of aphids within the root cropse0
- Qualifier
- infective migrants coming from outside sourcese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mosaic virus is not spread by movement of aphids within the root crops, but only by infective migrants coming from outside sources.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
t1“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”
Claim · model-written summary
Variation in seed crop infection and migrant origin was proposed to explain irregular mosaic incidence data.
- Taxon
- sugar‐beetBeta vulgaris subsp. vulgarist0
- Outcome
- irregularity of the data relating aphid numbers to mosaic incidencee0
- Qualifier
- individual variation in the intensity of infection of seed cropse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The irregularity of the data relating aphid numbers to mosaic incidence is probably caused mainly by individual variation in the intensity of infection of seed crops, and in the proportion of migrants caught on the traps which actually derive from them.”
t0“THE SPREAD OF BEET YELLOWS AND BEET MOSAIC VIRUSES IN THE SUGAR‐BEET ROOT CROP”