Tomato yellow leaf curl begomovirus (TYLCV) severely invaded tomato plantations in Egypt (Lower and Middle Egypt) in 1989. This study aimed to discover the relationship between TYLCV and other epidemic-associated factors in the Fayium area. The rate of TYLCV infection was inspected visually for three successive years (1994/1996) in the Fayium area. During the same period, whiteflies were collected for virus detection using bait-plant and DNA hybridization techniques. DAS-ELISA was used to detect mixed virus infections in tomato plants. TYLCV infection was prevalent (60-68%) and severe (2.1-3.0) in the Fayium fields. Cucumber mosaic cucumovirus (CMV) was found in some fields (5-28%) with moderate severity (1.0-20). Potato Y potyvirus (PVY) and potato leaf roll polerovhs (PLRV) were found in few fields (5-19% and 5% respectively) at very low seventy. There was a negative correlation between TYLCV Occurrence and distance from the source of infection, and a positive correlation (98%) between TYLCV intensity and percentage of viruliferous whiteflies in 1994 and 1995. There was no positive correlation between TYLCV and the total population of whiteflies caught during the same period. Five percent of viruliferous whiteflies, as proved by cDNA hybridization, led to 46% TYLCV infection. The same percentage of whiteflies, as shown by bioassay, led to 68% TYLCV infection. Monitoring of viruliferous whiteflies could be used for early prediction of TYLCV infection.

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The present study includes three points, i.e., wheat cultivar susceptibility, seasonal fluctuation of mite species, associated predators and evaluation of certain control materials against mites on wheat plants. The susceptibility of the three wheat cultivars (Sakha 93, Giza 168 and Gemiza 9) to investigation of mite species Petrobia tritici Kandeel, El-Naggar and Mohamed and two spotted spider mite, Tetranychus urtica) was inspected during the two successive seasons of 05/06 and 06/07 at Zagazig district. The obtained results revealed that the Sakha 93 cultivar was more susceptible to P. tritici infestation. The relatively higher numbers ranging 9.37-11.26 and 2.142-8.18 mite/leaf were recorded for the two mite species during the two seasons, respectively. The relatively lower mean numbers ranged 4.47-5.37 and 1.76-4.47 mite/leaf were recorded on Giza 168, while the moderate numbers of 6.36-8.47 and 2.08-4.7 mite/leaf were recorded on Gemiza 9 cultivar for the two mite species during the two study seasons. The yield of test cultivar was found in contrast with infestation levels, where the relatively lower yield ranging 3.68-4.0 g/plant was recorded for the more susceptible cultivar, Sakha 93; while the highest yield ranging 6.0-6.02 g/plant was recorded for the more tolerant cultivar, Gemiza 9 which infested by moderate number of mites. The result of seasonal fluctuation of the mite species infested the three tested cultivars revealed that the population of P. tritici recorded 1-2 peaks during the two seasons with the highest mean numbers of 28.0 and 34.33 mite/leaf on Sakha 93 at the first weak of April during the two seasons, respectively. The two spotted spider mite recorded 3-4 peaks on the tested cultivars during the two seasons with highest peak of 26.0 mite/leaf on Sakha 93 at early-April during the first season. During the second season, the highest peak of 7.0 mite/leaf was recorded at the end of March on Gemiza 9. The relatively higher total predators number ranging 7.33-11.67 and 3.0-6.33 individuals/plant were recorded in timing with the high number of phytophagous mites on tested cultivars during the first and second seasons, respectively. As evaluation of toxicant materials results, the all tested materials reduced the numbers of mites significantly compared with control with highest reduction percentages recorded for the convention pesticides followed by plant extracts and other materials. Regarding to reduction percentages, three groups were conducted, the first ranging 78.84-96.55 % (pesticides), 70.94-88.23 % (plant extracts) and 45.24-69.93 % (bio-products) during the two study seasons. Therefore, it could be concluded that the plant extracts and bio-products can be used as control agents for mites IPM programs in wheat fields.

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