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Abstract Experiments were conducted at the farm of Faculty of Agriculture, Shebin Elkom , a private farm at Elkom Elakhadar , Shebin Elkom , and laboratory of Economic Entomology and Agricultural Zoology Department to study the population density and population dynamics of the two spotted spider mite, Tetranychus urticae infested four tomato varieties and four varieties of eggplant plantation during 2018/2019 seasons. Ecological studies: 1. Tomato experiments: Ecological studies were performed for two successive plantations (Summer plantation and Nili plantation) on four varieties (Alia- Super strain- Alisa- Sama) as follow: - Incidence studies indicated that all tomato varieties were infested with high number of Tetranychus urticae along two plantations. - Population dynamics of Tetranychus urticae infested tomato plants along two plantations: 1-1 Population dynamics of Tetranychus urticae infested tomato plants along Summer plantations 2018: Population dynamics of Tetranychus urticae cleared that the numbers of the two spotted spider mite, Tetranychus urticae eggs were significantly increased during May month reaching 231.7 , 445.7 , 754.6 , 791.3 , eggs / 20 leaves for Alia , Super strain , Alisa, and Sama varieties, respectively , than that numbers recorded March and April months. Another significant increase was obtained during June month where numbers were 557.0, 838.4, 1114.0 , and 1420.0 eggs / 20 leaves, then significant decrease was observed during July month in all tested varieties. Movable stages of the two spotted spider mite, Tetranychus urticae infested tomato leaves of different varieties were significantly increased from April to May months for all varieties , from 21.7 to 251.3 ; 15.0 to 393.0 ; 19.7 to 435.0 ; and from 30.0 to 558.3 individuals / 20 leaves for Alia , Super Strain , Alisa , and Sama varieties , respectively. In addition , another significant increase was observed during June month for all tested varieties , then the numbers were decreased in July to 300.0 , 738.0, 701.7 , and 1287.1 individuals / 20 leaves. 1-2 Population dynamics of Tetranychus urticae infested tomato plants along Nili plantations 2018: The results cleared that the numbers of the two spotted spider mite, Tetranychus urticae eggs were increased gradually during Nili cultivation from July month where numbers were 13.7, 35.0, 10.0, and 0.0 eggs / 20 leaves for Alia , Super Strain , Alisa, and Sama varieties, respectively . Significantly increases were observed during September , then the highest numbers were recorded during October 790.0, 864.0, 563.3, and 563.3 eggs / 20 leaves, respectively, then numbers decreased again during November . As for movable stages , data showed significant increase from July month to October , then numbers decreased during November . The numbers on all varieties reach its peak during October recording 914.6, 985.3, 403.3, and 676.6 individuals / 20 leaves for Alia , Super Strain , Alisa , and Sama varieties , respectively. 1-3 Susceptibility of four tomato varieties to the infection with Tetranychus urticae. The results cleared that tomato varieties differ in their susceptibility to the infestation with T. urticae specially during summer cultivation . The tested tomato varieties could be arranged in descending order according to their susceptibility to infestation, Sama variety was the most significant susceptible , it recorded 793 individuals as average numbers with 36.71 % infestation, followed by both Super Strain and Alisa varieties with significant differences with other two varieties but no significant differences were recorded between both , recording 566.14 , 530.88 as average numbers and 26.21 , 24.6 % infestation for Super Strain and Alisa , respectively. While , Alia variety was the lowest significant susceptible with 269.94 as average and 12.5 % infestation. Nili cultivation results recorded different trend , where Alia was the most susceptible with average of 567.78 individuals and 35.3 % infestation percentages followed by Super with average of 525.84 individuals and 32.7 %infestation without significant difference with Alia infestation but Ailisa and Sama were less susceptible without significant difference between each other but significantly averages was calculated with Alia and Super , recording 203.6 and 311.34 individuals as average and 12.6 , 19.36 % infestation . from these results , it could be concluded that the four tested varieties were variably infested with Tetranychus urticae during both Summer and Nili cultivation -Effect of multiple fertilization treatments on adult numbers of Tetranychus urticae infested four tomato varieties under field conditions: During Summer cultivation , different fertilizer treatments such as (P2O515% - Sulpher70% - NPK19% - K2O 50% - MgSO4 - K2O 40%, P2O530% - Iron 12% - Zinc 13% - Manganese 13% - Phospho green+ P 40%) were applied before and after planting of tomato seedling. the numbers of Tetranychus urticae were observed in four tomato varieties. During March month the numbers in treated and untreated plants were approximately the same , slightly higher, in the control at some dates, during April the numbers in both treatments and control were gradually increased but more rapid in control , it ranged from 3 to 7 individuals/ leafet during 7 April for different treated varieties , while was from 7 : 12 in control. The numbers increased at the end of April reach 17, 24, 40, and 20 in treated plants , while it were 26, 30, 31,and 35 in control for Alia, Super , Alisa, Sama . During May continuously increase was observed from the beginning of May to the end of the month in both treated and untreated plants , but it was higher in untreated , the numbers were increased from 32 to 250 individuals in Alia treated plants compare with 41 to 280 individuals in untreated ; from 37 to 233 individuals compared with 72 to 451 individuals in Super variety 39 to 200 individuals compare with 79 to 562 individuals in Alisa ; and from 32 to 189 individuals compare with 102 to 677 individuals in Sama variety . Plants in control were dead during June and July months , while treated plants alive and infestation was decreased comparing with May month. from the obtained results it was concluded that Tetranychus urticae numbers were increased from April to May months in both treated and untreated plants. Also, there are significant differences between mite numbers in treated and untreated plants during May month. 3. Eggplant experiment: Ecological studies were performed for one plantation and used four varieties (Patra - Sawad el laeil - Mileda - Distan) as follow: 3-1 Incidence studies indicated that all eggplant varieties were infested with high number of Tetranychus urticae. 3-2 Population dynamics of Tetranychus urticae infested eggplant plants along the plantation. Data cleared the effect of temperature and relative humidity on Tetranychus urticae numbers infested the four eggplant varieties. Egg numbers and movable stages were increased gradually from March to June with increasing temperatures reaching its peak at the beginning of June (32.1 egg / leaf, and 57.5 indiv. / leaf), then numbers decreased in mid of July recorded 8.4 egg / leaf and 18.2 indiv. / leaf) on Patra variety with mean number of 12.2 egg and 22.8 indiv. / leaf. While increasing temperature to 40 ºC at June caused high decrease in mite numbers. Sawad el laeil variety showed the same trend, increasing numbers of eggs reaching its maximum in mid. of June 33.4 egg / leaf, and the numbers of movable stages increased reaching its peak in the first of June (46.5 indiv. / leaf), then numbers began gradually to decreased with mean numbers of (16.12 egg / leaf and 24.83 indiv. / leaf). For Mileda variety results showed that the numbers as for eggs and movable stages of Tetranychus urticae increased gradually reaching its maximum numbers at the beginning of July (24.0 egg / leaf and 34.0 indiv. /leaf), while, the temperature and relative humidity were appropriate to increase the numbers during that period recorded 33 ºC and 78 % RH, then numbers of eggs and movable stages began to decrease again in the mid of July with increasing temperature and relative humidity. The mean numbers were 11.89 and 16.61 for egg and movable stages / leaf respectively. The lowest mean number of eggs and individuals were observed on Distan variety 2.9 and 15.3 / leaf with maximum number at the beginning of July, 22.8 and 28.3 / leaf for eggs and movable stages when temperature ranged from 24 : 33 ºC and relative humidity ranged from 33 : 78 % RH. 4-Susceptibility of four Eggplant varieties to the infection with Tetranychus urticae. The results cleared that eggplant varieties differ in their susceptibility to the infestation with T. urticae The tested eggplant varieties could be arranged in descending order according to their susceptibility to infestation, Sawad el laeil variety was the most significant susceptible , it recorded 450 individuals as average numbers with 31% infestation, followed by Patra variety recording 413.6 as average numbers and 28.49% infestation, but Mileda and Distan varieties were less susceptible without significant difference between each other but significantly differences with other two varieties, recording 299 , 289 as average numbers and 20.60 , 19.91 % infestation for Mileda and Distan , respectively. 5- Control studies: 5-1-Effect of a general control program against tomato pests on the numbers of Tetranychus urticae on four tomato varieties: Different compounds such as( Ridomil Gold® MZ 68 WG _ Pilot 25% WG - Rizolex-T 50% WP- Maxim XL 3.5% - Mospilan 20% SP - Pasha 1.9% EC - Fastac 100 EC - Petaphos 48 % EC - Avaunt 150 EC - Smayel 90 %SP) were used to control tomato pests which attack leaves. The side effect of these compounds was observed on the spider mite , Tetranychus urticae infesting four varieties. Results showed that T. urticae began to appear at the middle of April month in all varieties in both treated and untreated plants , but numbers were lower in treated plants with Pilot Rizolex, Maxim, and Mospilan during March month , these numbers were 3,5,7, and 2 where these numbers were 10, 7, 8, and 11 in untreated plants during 12 April for Alia , Super ,Alisa , and Sama , respectively . After spraying Pasha numbers of mites increased in both treated and untreated plants to 7, 8, 11,and 10 individuals/ 6 leaves for treated and 26, 30, 21,and 35 individuals/ 6 leaves for untreated plants of Alia , Super , Alisa, and Sama varieties . Rapidly increase was observed during May month in untreated plants reach its peak at the end of May month when numbers were 380, 451, 562, and 677 individuals/ 6 leaves , while plants treated with Ridomil , Fastac, and Petaphos had slight infestation calculated at 29 May by 18, 37, 35, and 31 individuals/ 6 leaves for Alia , Super , Alisa, and Sama varieties . Plants in control were dead at the beginning of June, while numbers slightly increased at the middle of June to 23, 31, 29,and 28 individuals/ 6 leaves. 5- 2- Effect of multiple application of chemical pesticides on fruit weights of four tomato varieties: The results showed that spray different chemical treatments which reduced number of pests attacking tomato plants specially Tetranychus urticae , increased the weights of tomato crops in all varieties , in addition to elongate the harvest period of treated plants where untreated plants were dead. results observed that the highest increase percentages in tomato yield was recorded at Alisa variety giving 720.8 %, followed by the Super variety giving 657.1 % , and Sama variety yield increaed by 463.3 % , while Alia variety recorded the least increase in tomato yield estimated as 231.8 % compared with untreated plants. Biological studies: Biological aspects of the two spotted spider mite, Tetranychus urticae under laboratory conditions: The biological aspects of the tetranychid mite when reared on leaves of four tomato varieties were studied under laboratory conditions. The obtained results indicated that the biology of males is slightly faster than the biology of females. Egg incubation period for males were varied and prolonged from 2.3 to 3.7 days according to tomato variety while, this period ranged from 2.7 to 3.7 days for female. Also, larva, protonymph and deutonymph duration were varied for males and females reared on different leaf varieties with shortest periods when reared on Sama and Super strain varieties. Total immature period was significantly prolonged to reach 10.6 days at Alisa variety compared with other variety which recorded 9.25, 9.2 and 9.7 days at Sama, Super strain and Alia varieties, respectively. Also, total immature period was approximately the same for female reared on different leaf varieties with longest periods. The longest longevity periods were significantly recorded on Alia variety 9.75 and 11.8 days for males and females respectively, while the shortest period recorded 8.0 days on super variety as males and 10.6 days on Sama variety as females. The life span of male ranged from 20.65 days for Sama variety to 22.1 days for Alisa with significant difference, also female life span ranged from 24.4 to 26.7 days with significant difference between Sama and Alia only. |