الفهرس 
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Abstract
S6.1. Field studies. Population abundance of the immature stages and adult stages:- Field experiments were conducted at the Experimental Research station, Faculty of Agriculture, Mansoura University, ¼ feddan were cultivated with cucurbit cultivars Squash, Cucumber, Snake cucumber and Watermelon. Each cultivar was planted in five replicates (each one was 50 m2) during two planting dates, the summer plantation (June plantation) on the beginning of June and the second late summer plantation (August plantation) during beginning of August in the two successive seasons 2009 and 2010 6.1.1.1. On squash plants:- During summer (June) plantation in both seasons 2009 and 2010 the highest peak of abundance for eggs (62.4 and 70.0 eggs /m2) in the second weak of July, for larvae (41.0 and 53.0 larvae / m2) in the fourth weak of July, for pupae (31.6 and 37.5 pupae / m2) in the first weak of August and for adult stage (20.8 and 33.2 adults / m2) in the second weak of August during the two successive seasons on squash plants, respectively. On the other hand, in late summer (September) plantation during the two seasons, the highest peak of abundance for eggs (70.0 and 86.0 eggs /m2 ) in the end of September , for larvae (43.5 and 59.0 larvae / m2 ) in the fourth weak of October 2009 and the second weak of October 2010 , for pupae (30.5 and 41.4 pupae / m2 ) in the fourth weak of October 2009 and the third weak of October 2010 and for adults (19.0 and 29.3 adults / m2 ) in the end of October, during the two successive season on squash plants, respectively. Moreover, the highest average numbers of immature stages were recorded in July and for adult stage in August in summer plantation, while in late summer plantation, the highest average number of immature stages as well as adult stage recorded in October in both seasons of the study. 6.1.1.2. On cucumber plants:- During summer (June) plantation in both seasons 2009 and 2010 the highest peak of abundance for eggs (33.2 and 40.0 eggs /m2) in the second weak of July, for larvae (23.0 and 31.0 larvae / m2) in the fourth weak of July, for pupae (18.5 and 22.6 pupae / m2) in the first weak of August and for adult stage (13.0 and 15.0 adults / m2) in the second weak of August during the two successive seasons 2009 and 2010 on cucumber plants, respectively. On the other hand, during late summer (September) plantation during the two seasons, the highest peak of abundance for eggs (38.0 and 43.5 eggs /m2 ) in the end weak of September , respectively , for larvae (24.8 and 27.5 larvae / m2 ) in the second weak of October 2009 and 2010 , for pupae (15 and 21.0 pupae / m2 ) in the third weak of October 2009 and , for adults (11.0 and 15.0 adults / m2 ) in the end of October, during the two successive season on cucumber plants, respectively. Moreover, the highest average numbers of immature stages were recorded in July and for adult stage in August in summer plantation, while in late summer plantation, the highest average number of immature stages as well as adult stage recorded in October in both seasons of the study. 6.1.1.3. On snake cucumber plants:- During summer (June) plantation in both seasons 2009 and 2010 the highest peak of abundance for eggs (80.0 and 86.0 eggs /m2) in the second weak of July, for larvae (45.0 and 69.8 larvae / m2) in the fourth weak of July, for pupae (25.0 and 54.0 pupae / m2) in the first weak of August and for adult stage (20.0 and 38.2 adults / m2) in the second weak of August during the two successive seasons on snake cucumber plants, respectively. On the other hand, during late summer (September) plantation during the two seasons, the highest peak of abundance for eggs (93.0 and 98.6 eggs /m2 ) in the fourth weak of September, for larvae (67.0 and 72.4 larvae / m2 ) in the second weak of October 2009 and 2010 , for pupae (41.2 and 54.4 pupae / m2 ) in the third weak of October 2009 and , for adults (25.0 and 43.8 adults / m2 ) in the end of October, during the two successive season on snake cucumber plants, respectively. Moreover, the highest average numbers of immature stages were recorded in July and for adult stage in August in summer plantation, while in late summer plantation, the highest average number of immature stages as well as adult stage recorded in October in both seasons of the study. 6.1.1.4 . On watermelon plants:- During summer (June) plantation in both seasons 2009 and 2010 the highest peak of abundance for eggs (50.0 and 54.1 eggs /m2) in the second weak of July, for larvae (35.7 and 40.8 larvae / m2) in the fourth weak of July, for pupae (24.7 and 33.0 pupae / m2) in the first weak of August and for adult stage (20.3 and 25.6 adults / m2) in the second weak of August during the two successive seasons on watermelon plants, respectively. On the other hand, during late summer (September) plantation during the two seasons, the highest peak of abundance for eggs (43.5 and 53.4 eggs /m2) in the end weak of September, for larvae (30.5and 35.0 larvae / m2) in the second weak of October 2009 and 2010 , for pupae (20.0 and 26.3 pupae / m2 ) in the third weak of October 2009 and , for adults (15.0 and 17.5 adults / m2) in the end of October, during the two successive season on watermelon plants, respectively. Moreover, the highest average numbers of immature stages were recorded in July and for adult stage in August in summer plantation, while in late summer plantation, the highest average number of immature stages as well as adult stage recorded in October in both seasons of the study. 6.1.2.Host plant preference of E.chrysomelina on different cucurbit plants:- 6.1.2.1. For female egg-laying Results revealed that, snake cucumber plant harboured the highest average number of eggs (59.1 ± 4.9 and 63.3 ± 5.2 eggs / m2) in late summer plantation during the two study seasons, respectively. On the other hand, cucumber plants harboured the lowest average number of eggs (18.2 ± 3.0 and 23.4 ± 3.5 eggs / m2) in summer plantation 2009 season and late summer plantation in 2010 season, respectively. Moreover, there were a highly significant differences between the number of egg - laying on different cucurbit plants during the two seasons in the two plantations. Meanwhile, it can noticed that, the melon ladybird beetle females preferred snake cucumber to egg-laying followed by squash, watermelon and cucumber revealed the lowest cucurbit plant to the insect female to egg-laying preference. The total duration of the immature stages were the shortest (37.4± 2.6 days) when the insect pest reared on snake cucumber followed by (39.0 ± 3.5 days) on squash, (39.5± 2.7 days) and watermelon and the longest periods were recorded on cucumber and represented by (40.9 ± 2.4 days) .Highly significant differences were recorded between the total duration of the immature stages reared at different host plants. The highest percentages of hatchability, the survival of larval stage , pupal stage as well as the total immature stages were recorded when the insect reread on snake cucumber and represented by 95.0 , 88.4 , 97,6 and 82% , respectively. On the other hand, the lowest percentages were 89.0, 72.1, 93.7 and 60% for hatching, the survival of larval stage, pupal stage and the total immature stages on cucumber, respectively The ovipositional periods ( pre – oviposition period , oviposition period and inter - oviposition period ) as well as the female and male longevity were the shortest when the melon ladybird beetle reared on snake cucumber followed by squash ,watermelon, and cucumber .