| Titles |
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English :
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Studies on legumes Aphid Aphis craccivora Koch and its relation to the Yellow Mosaic virus disease in Bean plant
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| Abstract |
The present study investigated the main insect pest infesting bean under field conditions including the population dynamics and some factors affecting their configurations on viral infection relationship on bean crop and different environmental and cultural conditions. The study also covered the efficiency of different control agents of field treatments on population dynamics. The investigations also regarded the bean yellow mosaic virus disease. They included isolation and identification by using different techniques.
1- Population density of Aphis craccivora Koch on bean plants under different conditions.
Population dynamics encompass all variations in population number in time, space or both and the processes responsible for these variations. It is essential and important for pest control programs.
1.1- Seasonal abundance:
The fluctuations of population densities of A. craccivora on bean plant were achieved in winter and summer plantation seasons for two successive years.
In general, the results indicated that the numbers of winged aphids were less than wingless aphids during the two successive years. However, the population density of the winged and wingless insects reached their maximum during February and the first of March in the two winter plantation seasons. While the number of the collected insects reached its maximum during April in the summer plantation season of the two successive years.
In general, the population density in the two summer seasons was lower level than in the two winter seasons.
1.2- Environmental conditions:
The effects of maximum and minimum temperatures, relative humidity and their interaction on the population density of the aphids infesting bean plants were studied and the obtained results showed that:
• During the winter plantation seasons the maximum and minimum temperatures proved to have a highly significant negative effect on the population density of the aphid in 1997 and insignificant effect on the population density of the aphid in 1998. Likewise the relative humidity had a negative effect in 1997 and positive effect in 1998 although this effect being insignificant on the population density of aphids.
• During summer plantation seasons, the maximum and minimum temperatures proved to have a significant negative effect on the population density of aphids. While the relative humidity had slight insignificant positive effect in 1997 and slight insignificant negative effect on the population density of aphids in 1998.
1.3- Plantation time:
The rate of aphid infestation was found of low level during the early plantation date (February 1st). This infestation rate was increased in the late plantation dates (February16th and March 3rd). Aphid infestation rate was also increased during the late plantation date (March18th).
In general, significant differences occurred between the four planting dates as a factor affecting the population densities of aphid on bean.
1.4- Viral infection:
The relationship between the viral infection (BYMV) and the population density of winged and wingless aphids are always
significantly positive during winter plantation season;, but highly significantly negative during summer plantation seasons.
2- Toxicological studies:
2.1- Laboratory tests:
The efficiency of certain toxicants on Aphis craccivora was tested. All the tested agents were found efficient on the aphid A. craccivora. The insecticide malathion recorded the most efficient toxicant against aphids_ It gave the lowest LC50 value followed by the biological agent biofly, zanzalakht, mineral oil and finally M-pede.
2.2- Field studies:
2.2.1- Evaluation of some control agents against the aphid population on bean plant (single spray):
The present investigation dealt with the comparative studies on the effect of the biological agent biofly, the mineral oil (Super masrona), M-pede (soap), plant extract zanzalakht and a chemical insecticide malathion on the population density of Aphis craccivora on bean plant.
In general, malathion and the mineral oil had the longest persistent action which showed the highest reduction in aphid population during seven-day relaxing period, while the aqueous solution of Zanzalakht showed a moderate toxicity during this period. Biofly and M-pede on the other hand, gave the least effect against aphid population.
2.2.2- Seasonal evaluation of some control agents against the aphid population on bean plant:
The mineral oil and the aqueous solution of zanzalakht treatments gave satisfactory results against aphids in winter and summer plantation seasons comparing with malathion treatment, where the
population densities were significantly reduced. On the other hand, biofly and M-pede gave the lowest effect on aphid population in winter and summer plantation seasons.
3- The bean yellow mosaic virus (BYMV):
3.1- Symptomatology:
Bean yellow mosaic virus was isolated and identified from naturally infected bean plants. The infected plants had mosaic symptoms of yellow colour leaves. The infection by BYMV was confirmed by using biological, serological and molecular assays.
3.2- Biological assays:
3.2.1- Host range:
The symptoms of BYMV resembled those of common mosaic. The host range of BYMV isolate was almost identical and confined to leguminous hosts. From the different non-leguminous plant species tested only Chenopodium amaranticolor Costel & Reyn gave reaction as local lesion.
3.2.2- Physical properties:
The BYMV isolate was characterized by inactivation at 55ºC for ten minutes, the dilution-end point was 1:2000 and the longevity in vitro was only one day at room temperature.
3.2.3- Vector competence:
Aphis craccivora Koch is an active vector in transmitting the BYMV isolate. The percentage of transmission reached 50%.
3.3- Serological test:
Positive results were obtained on plants having a mosaic symptoms induced by virus infection. No positive reaction was detected in healthy samples.
3.4- Detection of BYMV using reverse transcription- polymerase chain reaction (molecular assay):
A single product of 820≈bp presumably was detected. No fragments were amplified from the RNA extracted from uninfected bean plants.
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| Publication year |
2002
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| Availability location |
معهد بحوث وقاية النباتات
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| Availability number |
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| Organization Name |
Plant Protection Research Institute (PPRI)
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| Country |
Egypt
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| Publisher |
Name:
كلية العلوم - جامعة عين شمس
Place:
جامعة عين شمس
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| Author(s) from ARC |
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| Agris Categories |
Pests of plants
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AGROVOC
TERMS |
Aphis craccivora.
Bean yellow mosaic potyvirus.
Legumes.
Plant viruses.
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| Publication Type |
PhD Thesis
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