Studies on some parasitoids of the Cowpea Aphid aphis craccivora Koch ( homoptera: Aphididae) in Egypt. [electronic resource].

Includes reference.

Survey and population density of the aphid species Aphis craccivora (Koch) infesting broad bean plants and its parasitoids were studied at Zagazig district during the two successive seasons 2006-07 and 2007-08. Two primary parasitoids, Diaeretiella rapae (MIntosh), Ephedrus sp. (Aphidiidae), and a hyperparasitoid, Aphidencyrtus sp. (Encyrtidae) were recorded. Highest rates of parasitism 12.73% were recorded in the 4th week of January 2006-07 and 11.09% in the 2nd week of February 2007-08. Seasonal means of parasitism rates of the primary parasitoids D.rapae and Ephedrus sp. were 8.17 and 6.45% during the two seasons, respectively. Total developmental period of the two parasitoids was investigated at three temperatures (10, 15 and 28 °C). The duration of the two parasitoids was longest at 10 "C. Generally, developmental periods of different stages of the parasitoids shortened as the temperature increased from 10 to 28 °C. Total developmental periods of the two parasitoids ranged between 11.17-27.16 and 12.38-30.48 days for D. rapae and Ephedrus sp., respectively. Sex ratios were 1:l.l and 1:1.07 (m:f) for D. rapae and Ephedrus sp., respectively. Temperature and relative humidity played an important role in the population changes of A. craccivora, D. rapae and Ephedrus sp. Temperature showed a highly significant effect on the population density of Ephedrus sp. in both seasons. The maximum temperature and the minimum relative humidity had a positive significant effects on the population density of D. rapae at both seasons.

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