SEASONAL ABUNDANCE AND RELATIVE DENSITIES OF COCCINELLID SPECIES AND THEIR INSECT PARASITOIDS ON WHEAT PLANTS AT PILBES DISTRICT, SHARKIA GOVERNORATE, EGYPT

Abstract

Survey and relative densities of coccinellid species and their parasitoids on wheat plants infesting with aphids at Pilbes district, Sharkia Governorate, Egypt was studied during 2015/16-2016/17 seasons. Summarized results show the following: Seven predaceous species belonging to family Coccinellidae viz., Coccinella undecimpunctata L., Coccinella septempunctata L., Coccinella 9-punctata L., Scymnus syriacus Mars, Scymnus interruptus (Goeze), Cydonia vicina isis Cr. and Cydonia vicina nilotica Muls were surveyed on wheat plants infesting with aphids. The general relative densities of the predators were 33.33, 20.29, 19.44, 12.35, 7.41, 4.01 and 2.47% of the total numbers of predators, respectively. C. undecimpunctata activity showed a distinct peak and two peaks of activity in the first and second seasons, respectively. The maximum total monthly counts of 83 and 77 predators were found during March, in the first and second seasons. Five species of hymenopterous parasitoids belong to three families were emerged from collected ladybeetles species, viz., Telenomus sp., Perilitus coccinellae (Schrank), Tetrastichus coccinellae Kurd., Tetrastichus principiae Domenichini and Tetrastichus sp. The egg parasitoid, Telenomus sp. came in the first rank, represented by 59.8%, followed by the larval parasitoid P. coccinellae 14.6%. The correlations between the total number of coccinellid predators and aphids were positive and highly significant in both seasons.