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العنوان
BIOLOGICAL INTERACTIONS BETWEEN PATHOGENS
AND LEAFHOPPERS INFESTING SUGAR BEET
PLANTS IN EGYPT /
المؤلف
ABD-EL-AZIZ, HEBA ESSAM IBRAHIM.
هيئة الاعداد
باحث / هبة عصام إبراهيم عبد العزيز
مشرف / عزة كمال عبد الرحمن إمام
مناقش / محمود مصطفى حسن البلك
مناقش / خالد عبد الفتاح الدجدج
تاريخ النشر
2022.
عدد الصفحات
138 P. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
علوم النبات
تاريخ الإجازة
1/1/2022
مكان الإجازة
جامعة عين شمس - كلية الزراعة - قسم وقاية النبات
الفهرس
Only 14 pages are availabe for public view

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from 138

Abstract

SUMMARY
The present work aimed to survey and identify different leafhopper species infesting sugar beet plant also detection and molecular identification of pathogens associated with sugar beet plants that transmitted by leafhoppers in Egypt
1. Surveying of leafhopper species infesting sugar beet plants in
Egypt:
Leafhoppers adults and nymphs were collected from sugar beet plants at different localities in Egypt using both sweeping net and aspirator throughout 2017 to 2020.
Nine leafhopper species belonging to two subfamilies and five genera were surveyed.
Synonyms, diagnostic morphological characters, host plants and geographical distribution of each species were done. Results showed that Hebata (Alboneurasca) decipiens was the most widespread among different species at Sharqyia, Fayoum, Qalyubyia, Kafr El-sheikh and Giza Governorates in Egypt.
The surveyed nine leafhopper species:
1.1. Hebata (Alboneurasca) decipiens
This species was the most widespread among these species and collected from four Governorates, Kafer El-Sheikh, Fayoum, Qalyubyia and Giza during 2017 to 2020. This species was identified according to Prof. Dr. christopher H. Dietrich of the Illinois Natural History Survey, USA.
1.2. Hebata (Signatasca) distinguenda
This species was found on sugar beet plant during this work in Fayoum Governorate during 2017 to 2020.
1.3. Jacobiasca lybica
This species was found on sugar beet plant during this work in Kafr El-sheikh during 2017 to 2020.
1.4. Eupteryx cypria Ribaut
As far as the available literature of leafhoppers, this genus is considered as a new record on sugar beet plants in Egypt. This species was found on sugar beet plant during this work in Giza and Qalyubyia Governorates during 2017 to 2020.
1.5. Balclutha frontalis (Ferrari)
This species was found on sugar beet plants during this work in Kafr El-sheikh Governorate during 2017 to 2020.
1.6. Balclutha incisa ( Matsumura )
This species was found on sugar beet plants during this work in Kafr El-sheikh Governorate during 2017 to 2020. This species was identified according to Prof. Dr. christopher H. Dietrich of the Illinois Natural History Survey, USA.
.
1.7. Aconurella prolixa (Lethierry)
This species was found on sugar beet plants during this work in Kafr El-sheikh and Qalyubyia Governorate during 2017 to 2020.
1.8. Exitianus pondus Ross
This species was found on sugar beet plants during this work in Kafr El-sheikh and Qalyubyia Governorate during 2017 to 2020
1.9.Psammotettix striatus (Linnaeus)
This species was found on sugar beet plants during this work in Kafr El-sheikh Governorate during 2017 to 2020. This species was identified according to Prof. Dr. christopher H. Dietrich of the Illinois Natural History Survey, USA.
2- Taxonomical revision of some leafhoppers infesting sugar beet
plants in Egypt.
Historical review in Egypt of each leafhopper species were provided. Also, data of distribution at different localities in different governorates were recorded. The samples were described and identified to genus or species.
3- Population fluctuations of the most common species of leafhoppers.
H. decipiens on sugar beet plant
Results revealed that H. decipiens was the most abundant leafhopper species on sugar beet plants. Population of H. decipiens were monitored using sweeping net during season 2018/2019 and 2019-2020 at Giza and Qalyubyia Governorate at weekly counts with corresponding main climatic factors. Sampling started after 45 days of planting sugar beet in the field from the first of December 2019 until the first of June 2020
3.1 at Giza Governorate
The data showed that H. decipiens had two peaks of activity during season 2019/2020 on sugar beet plants. The first one occurred at 4th week of April with total number of 1048 insect / 100 double strokes. The second peak was occurred at 1st week of June with total number of 1129 insect / 100 double strokes.
The number of H. decipiens individuals were negatively correlated with relative humidity (r= -0.72) while they were positively correlated with maximum temperature(r= 0.75). The explained variance was 62%. This means that all the tested factors affected on the populations by 62%
3.2. at Qalyubyia Governorate
During season 2018/2019 the data showed that H. decipiens recorded also two peaks of activity during the season of sugar beet plants at Kaha region. The first one was occurred at 3rd week of January with total number of 921 insect / 100 double strokes. The second peak occurred at 1st week of February with total number of 1015 insect / 100 double strokes.
Both maximum and minimum temperature (r values= -0.69 and -0.77, respectively) correlated negatively with the populations of H. decipiens. The explained variance values was 69%. This means that the four tested factors affected the population of this insect by 69%.
During season 2019/2020, the data showed that H. decipiens again recorded two peaks of activity during this season on sugar beet plants. The first one occurred at 2nd week of January with total number of 2643 insect / 100 double strokes. The second peak was occurred at 1st week of February with total number of 2981 insect / 100 double strokes.
The maximum and minimum temperatures correlated negatively with the population of this insect (r= -0.82 and -0.79, respectively) while the relative humidity correlated positively (r= 0.68) with all the population of this insect. The explained varience of all these factors affected the population of this insect by 76%.
4. Relationship study between the leafhopper and plant pathogens.
4.1. Survey of phytopathogens that transmitted by leafhoppers
Survey of phytopathogens in both leafhoppers and sugar beet plant swas conducted at different sugar beet fields at five Governorate and eight localities of Egypt; Giza, Qalyubyia, Sharqia, Fayoum and Kafr El-sheikh throughout the period from 2017 until 2020.
4.1.1. Survey of Geminivirus in both leafhoppers and sugar beet plant
Results for Geminivirus detection for both beet curly top virus (BCTV) and tomato yellow leaf curl virus (TYLCV) in leafhoppers Hebata (alboneurasca) decipiens collected from five governorates gave 22 positive leafhopper samples to TYLCV from 34 samples in year 2018-2019. While 14 sample from 34 sample collected in year 2019-2020 gave positive results for TYLCV. No leafhopper samples gave a positive results for BCTV. On the other hand, 50 positive leaf samples to TYLCV from 230 samples found in year 2018-2019 while 34 samples from 154 samples collected in year 2019-2020 gave positive results for TYLCV. No sugar beet leaves samples gave a positive result for BCTV.
4.1.2.Survey of Phytoplasma in both leafhoppers and sugar beet plant
Results for Phytoplasma detection in leafhoppers H. decipiens collected from five governorates gave 34 positive leafhopper samples to phytoplasma from 34 samples in year 2018-2019 while 23 samples from 34 samples collected in year 2019-2020 gave positive results. On the other hand, 37 positive leaf samples to phytoplasma and 193 negative from 230 samples were recorded in year 2018-2019 while 27 positive samples to phytoplasma and 127 negative from 154 samples collected in year 2019-2020 gave positive results.
4.2. Transmission of Phytoplasma by leafhopper
The collected infected leafhopper H. decipiens individuals with phytoplasma from sugar beet fields could successfully transmit the same symptoms of disease when fed on new sugar beet plants. Several symptoms appeared on sugar beet plants such as stunting, leaf curling, little leaf symptoms, increased spacing between branches and loss of apical dominance of the shoots after 30-60 day from feeding on healthy plants.
5.Detection and identification of some pathogenic isolates transmitted
by.leafhopper
Nested PCR was used successfully to distinguish phytoplasma in both sugar beet leaves and leafhoppers. The PCR products were visualized using agarose gel electrophoresis at 50bp Gene Ruler DNA ladder as a DNA size marker. DNA fragment of 1200bp was observed from both the positive and infected sugar beet symptomatic samples. Genetic sequencing analysis has revealed and confirmed the presence of phytoplasma in different detected sugar beet samples. The partial 16S rDNA gene region of one positive sample was bidirectionally sequenced at Macrogen Korean company by automated DNA sequencing using the same primers as used in PCR reaction.
Results confirmed the presence of Candidatus phytoplasma in different detected sugar beet samples. The similarity percentage and the phylogenetic tree for the kept 16S rDNA nucleotide sequences of the phytoplasma ascertained in sugar beet. The first statement of the existence was symptomatology, and partial genetic characterization of a 16SrXIV phytoplasma infected sugar beet in Egypt. The Egyptian isolate was submitted to the gene bank under accession no. of OP032749.
5.2. PCR for detection of Geminivirus
Genetic sequencing analysis has revealed and confirmed the presence of Geminivirus Tomato yellow leaf curl virus (TYLCV) in different detected sugar beet samples. Phylogenetic and molecular evolutionary analyses by neighbor-joining and 1,000 bootstrap replicates were performed on chosen GenBank data to visually assess the genetic relationships of sugar beet plant matter. Results confirm the presence of TYLCV in different detected sugar beet samples. The similarity percentage and the phylogenetic tree for the kept nucleotide sequences of TYLCV ascertained in sugar beet. The Egyptian isolate was submitted to the gene bank under accession no. of OP032749.
6.The efficacy of Sivanto prime insecticide in H. decipiens molting:
The potency of the tested insecticide, was evaluated against H.
decipiens. Nymphs were left to feed on treated leaves for 24, 48 and 72 hours then the mortality percentage was determined as LC50 value was 4.64, 0.854, 0.369 and LC90 value was 53.703, 2.919 and 2.005 respectively.