الفهرس 
Taxonomy and nomenclature
MATERIALS AND METHODSOnly 14 pages are availabe for public view
 |  | from | 194 |  |  |
| | | from | 194 | | |
Abstract
6.1. Survey studies The survey was conducted during summer and winter plantation in two successive seasons, 2016 and 2017 to determine the occurrence of tomato leaf miner (TLM), Tuta absoluta (Meyrick) on the potential host plants at Gharbeya Governorate, Egypt. The study included the inspection of six plant species (tomato, potato, black nightshade, eggplant, sweet pepper and common bean). The survey occurred in four regions at Gharbeya governorate including Sammanoud, El-Mahla El-Kobra, Tanta, and Zefta. TLM were recorded on four species (tomato, potato, black nightshade and eggplant), while the other two species (sweet pepper and common bean) were not infested with TLM. Result indicates that tomato species is the most preferred host plant by TLM then other cultivated Solanum species. TLM infestation level on potato plants were significantly higher than the other two species. Although, tomato is the preferred host plant and had a better nutritional quality than other hosts, TLM can develop on other cultivated plants in Egypt such as potato and eggplant. Generally, results of both plantation and both seasons indicated that the highest infestation of tomato plants was found at Sammanoud, El-Mahla El-Kobra and Zefta regions. 6.2. Population dynamics The population dynamics of TLM stages were studied on tomato plants (Alisa and Xaman varieties). Male populations were observed weekly using delta sticky pheromone traps baited with synthetic sex pheromone. Egg and larval stages were counted weekly by direct examination for all parts of 6 plants with the aid of lenses and stereomicroscopes. The study was carried out in summer and winter growth plantation during 2016 and 2017 at Sammanoud, Gharbeya governorate, Egypt. Counting of males in traps and sampling of plants began from the second week of planting (March 4th and February 5th, during seasons 2016 and 2017, respectively) and continued until harvesting. 6.2.1. Population fluctuations of TLM males: TLM males were found in traps from the beginning of the season with considerable numbers then increased gradually with the development of plants. In both plantations and seasons, 2-3 peaks were recorded. Generally, the population density level during the first season was higher than the second one where the general averages of caught males were 172.5±23.2 and 106.5±12.7 m/t/w in summer plantation, and it were 105.5±5.7 and 81±5.1 m/t/w during winter plantation, respectively. In the summer plantation, the highest rate of increase in TLM male populations occurred directly before the period of the highest peaks and almost during April to the mid of May. During 2016 season, peaks were observed after 7, 11, and 13 weeks with means of 226.7±17.7, 283±9.6, 233±9.8 m/t/w, respectively. During 2017 season, the first peak was 66±6.4 m/t/w in week 5 while the second and the highest one was occurred in week 12 with 196±4.4 m/t/w. During winter plantations, three main peaks were recorded in both seasons. They were observed after 7, 10, and 12 weeks with means of 123.7±4.8, 151±8.5, and 122.3±6.4 m/t/w in season 2016 and in weeks 4, 8, and 12 with means of 86±12.9, 111.7±3.5 and 83±4.2 m/t/w during 2017 season, respectively. 6.2.2. Population fluctuations of immature stages (Eggs and larvae). Eggs of TLM appeared on plants with relative low number then recorded 2-3 peaks during both seasons. In summer plantations, the maximum number of eggs were found in weeks 10 and 9 during the 2016 and 2017 season, respectively. Peaks were recorded in weeks 4, 8, and 10 during the first season and weeks 6, 9, and 12 during the second one. General averages of egg counts were 39.9±7.1 and 30.3±6.5 E/6P during the two seasons, respectively. In winter planation, the maximum numbers were recorded in weeks 9 and 7 during the two successive seasons. After the last peak, eggs counts steadily decreased until the end of the seasons. The general averages of egg counts in winter plantations were 28.2±7.2 and 17.4±6.3 E/6P respectively Larval stage counts started with very low number then two outbreaks were observed in during both plantations and seasons. In summer plantations 2016, peaks were recorded on weeks 10 and 12 (128 and 105 L/6P, respectively). In summer 2017, peaks were perceived on weeks 11 and 14 (79 and 89 L/6P). General averages of count larvae were 52.0±12.1 and 37.9±8.0 L/6P during both season, respectively. In winter 2016 season, peaks were recorded on week 5 and 9 (26 and 41 L/6P respectively). In the second season, peaks were perceived on weeks 7 and 13 (27 and 5 L/6P, respectively). The general seasonal averages of larvae during the two winter seasons were 16.8±3.3 and 9.1±2.6 L/6P, respectively. 6.2.3. The effect of weather factors TLM population dynamics. Statistical analysis of regression coefficient between weather factors and the population size of TLM males, eggs and larvae, during summer and winter plantations were calculated. Generally, in most biological systems, the relationship between the temperature and organism’s activity is nonlinear. While it could be linear within a specific rage of temperature. Subsequently we examined both linear and quadratic regression models to find out which one fits our data. In addition, multiple regression model was calculated to account for the interaction between both factors (Temp. and RH). 6.2.3.1. Male populations of TLM: During summer plantation, the regression coefficient in the linear model between temperature and population size was positive and highly significant (b=11.55, P < 0.01). During this period, the linear model fits our data more than the quadratic model indicating that temperature was almost lower than the maximum threshold. The highest recorded average of temperature during the first and the second season was 26.4 and 24.9 oC recorded in weeks 13 and 15, respectively. RH % has negative significant linear regression coefficient (b=-17.0 and P < 0.05). RH decreased from March toward the end of the season (May). During winter plantations, the coefficient (b) was lower than during the summer. In addition, the relationship was significant with quadratic model (P = 0.068 and 0.036 respectively). It indicates that the temperature possessive greater positive influence on summer plantation than on winter plantation. The highest average of temperature during the first and the second season was 31.1 and 26.7 C recorded in the second week. Statistical analysis showed meaningful differences between linear and multiple linear regression coefficients. In multiple linear regression, the regression coefficient (b) of temperature decreased while b of RH increased (negatively decreased). Which indicates that interaction between temperature and RH decreases the positive effect of temperature and the negative effect of RH. During the winter, the regression coefficient (b) of temperature increased while b of RH decreased. In the same time, RH did not have any significant effects on the population size. Which indicates that although RH is not significant but it has additive positive effect on the role of temperature.