A.M.A. IBRAIHM
Biological Control Laboratory, Fac. Agric.Cairo University , Cairo , Egypt

ABSTRACT

The relationship between aphid species, Myzus persicae (Sulz.), Aphis gossypii (Glov.) and Aphis pomi De Geer infesting apple trees in Giza and their parasitoids; Ephedrus persicae Frogatt, Aphidius matricariae Hal., Diaeretiella rapae McIntosh and Praon volucre Hal. had been studied during 1993. The aphids first appeared on these trees on the first week of March by 0.8 individuals? leaf. Three aphid peaks of 9.6, 12.6 and 12.2 aphids/leaf were noticed on April 15th, May 27th and July 8th, respectively. Consequently, 12.5, 24.6 and 28.7% parasitism were reported for the parasitoids mentioned above. Both E. persicae and A. matricariae were the dominate and highly effective species against the aphids M. persicae and A. gossypii. 35.9% and 34.1% of the total percentage of parasitism were found to be resulted from them. The other two parasitoids namely D. rapae (15.6%) and P. volucre (14.4%) are less important. During the last week of May and second week of July, the highest density of the aphid parasitoids occurred and this was enough to suppress the population of aphids beyond the economic level. Statistical analysis showed significant correlation between aphid and associating parasitoids.

Key Words: Aphids, Parasitoids, Apple trees.