الفهرس 
Introduction
Survey of onion pestsOnly 14 pages are availabe for public view
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Abstract
Survey of the onion pests:- Survey of pests fauna associated with onion at both open field and store, ware carried out at Experimental Research Station, Faculty of Agriculture Masoura University, El-Mansoura region throughout two successive seasons [2007/08 and 2008/09]. Onion variety namely Giza 6 was direct seed in nursery bed on 15th November2007 and 10th November 2008. Plants were transplanted, 6th January 2008 and 5th January 2009. The main insect pests infesting onion plants during the two seasons in Mansoura region were Thrips tabaci Lind. (36.3 and 36.9%), Aphis gossypii Glov. (28.7 and 28.5%), Eumerus amoenus Loew. (19.3 and 18.0%), Empoasca lybica de Berg. (11.1 and 11.8%) and Liriomyza trifolii Burgess (2.4 and 2.1%) in 2007/08 and 2008/09 seasons, respectively. On the other hand, the main insect pests attacking onion plants with low occurrence were Nezara viridula (0.4 and 0.4%), Bemisia tabaci (0.4 and 0.6%), Spodoptera littoralis (0.2 and 0.4%) and Cryptoblabes gnidiella (0.3 and 0.5%) during the two successive seasons, respectively. The main predators inhabiting onion plants and associated with the insect pests infesting this crop during the two successive seasons were the coccinellid Coccinella undecimpunctata (31.7 and 17.0%) , Coccinella septempunctata (32.3 and 38.7%), Cydonia vicina nilotica (19.2 and 28.7%) and the chrysopid, Chrysoperla carnea (16.8 and 15.6%) during 2007/08 and 2008/09 seasons, respectively. Population abundance of the main insect pests:- The onion thrips T. tabaci :- The maximum number of Thrips tabaci nymphs by using direct count method were 785 and 675 nymphs/ 10 plants in the second week of April 2008 and in the first week of April 2009 in the two successive seasons, respectively. On the other hand, the maximum number of T. tabaci adults by using direct count method were 100 and 68 individuals/ 10 plants in the fourth week of March 2008 and in the second week of March 2009 in the two seasons, respectively. The average number of T. tabaci nymphs were 297.2 ± 82.2 nymphs/ 10 plants during the first season 2007/08 and 249.9 ± 80.9 nymphs/ 10 plants during the second season 2008/09, while the average number of T. tabaci adults were 41.1± 9.8 and 30.2± 8.9 individuals / 10 plants during two seasons, respectively. Moreover, by using sticky trap method, the maximum number of T. tabaci adults were 218 and 200 individuals/trap in the first week of March 2008 and in the second week of April 2009 in the two seasons, respectively. The average number of T. tabaci adults were 112.0 ± 14.6 and 92.7 ± 21.2 individuals/ trap during the two seasons, respectively. The maximum number of T. tabaci nymphs by using direct count method were 675 nymphs/ 10 plants in the second week of April 2008 and in the first week of April 2009 in the two successive seasons, respectively. On the other hand, the maximum number of T. tabaci adults by using direct count method were 100 and 68 individuals/ 10 plants in the fourth week of March 2008 and in the second week of March 2009 in the two seasons, respectively. The average number of T. tabaci nymphs were 297.2 ± 82.2 nymphs/ 10 plants during the first season 2007/2008 and 249.9 ± 80.9 nymphs/ 10 plants during the second season 2008/2009, while the average number of T. tabaci adults were 41.1± 9.8 individuals / 10 plants during two seasons, respectively. Moreover, by using sticky trap method, the maximum number of T. tabaci adults were 218 and 200 individuals/trap in the first week of March and in the second week of April 2009 in the two seasons, respectively. The average number of T. tabaci adults were 112.0 ± 14.6 and 92.7 ± 21.2 individuals/ trap during the two seasons, respectively. The onion aphid, A. gossypii: The maximum number of A. gossypii nymphs were 585 and 475 nymphs/10 plants in the second week of April 2008 and in the first week of April 2009, respectively. On the hand, the maximum number of A. gossypii adults were 188 and 100 individuals/ 10 plants in the first week of April 2008 and in the beginning of April 2009 during two seasons, respectively. Moreover, the average number of A. gossypii nymphs were 204.4 ± 59.0 and 188.5 ± 52.6 nymphs/ 10 plants, while the average number of A. gossypii adults were 54.0 ± 20.8 and 50.3 ± 14.8 individuals/ 10 plants during the two successive seasons, respectively. The cotton leaf hopper E. lybica:- The average number of E. lybica nymphs by using direct count method were 64.8 ± 18.9 and 55.4± 15.7 nymphs/ 10 plants while, the average number of E. lybica adults were 28.9 ± 22.2 and 35.0 ± 6.0 individuals/ 10 plants during the two successive seasons 2007/2008 and 2008/2009, respectively. Moreover, by using sticky trap method, the average number of E. lybica adults were 31.8 ± 9.0 and 34.3 ± 9.2 individuals/ trap during the two successive seasons, respectively. The onion bulb fly E. amoenus :- The highest peak of E. amoenus maggots were 356 and 286 maggots/100 bulbs in the third week of August 2008 and in the second week of August 2009 in the two seasons, respectively. On the other hand, the average number of E. amoenus maggots were 146.0 ±47.1 and 129.6 ±27.3 maggots/100 bulbs in the two successive seasons 2008 and 2009, respectively. Influence of the daily mean temperature (DMT) and the daily mean relative humidity (DRH) on the activity of the main insect pests. The effect of DMT or DRH on the activity of T. tabaci or E. lybica by using sticky trap methods were positive and significant during the two seasons of the study. On the other hand, the relationship between the daily mean temperature and the daily mean relative humidity and the activity of the all main insect pests infesting onion plants were positive and insignificant during the two successive seasons 2007/08 and 2008/09.Susceptibility of two onion varieties to infestation by onion thrips T. tabaci:- During the first season 2007/08. The highest peak of T. tabaci nymphs were 758 and 809 nymphs/10 plants in the second week of April 2008 and the highest adults activity with 101 and 122 individuals/10 plants in the fourth week of March 2008 on the two onion varieties Giza 6 and Giza 20, respectively. The highest monthly average number of T. tabaci nymphs 536.3 and 533.0 nymphs/10 plants in April 2008 and the highest monthly average for adult activity were 72.4 and 76.0 individuals/10 plants on Giza 6 and Giza 20, respectively. During the first season, there is no significant differences between the two varieties and Giza 20 more susceptible to nymphs or adults of T. tabaci. Infestation. During the second season 2008/09:- The highest peak of nymphs were 675 and 703 nymphs/10 plants in the first week of April 2009 and for adults activity 87 and 99 individuals/10 plants in the fourth week of March 2009 on Giza 6 and Giza 20, respectively. The highest monthly average number of T. tabaci nymphs and adults were (412.4 and 420.8 nymphs/10 plants) and (59.8 and 58.6 individuals/10 plants) during March 2009 on two onion varieties Giza 6 and Giza 20, respectively