Antixenosis, Anatomical and Biochemical Studies on some Egyptian Wheat Cultivars Infested with Bird Cherry-Oat Aphid (Rhopalosiphum padi L.) (Hemiptera: Aphididae)

Abstract

The bird cherry-oat aphid, (Rhopalosiphum padi L.) (Hemiptera: Aphididae), is one of the most important and serious polyphagous pest infesting cereals. Antixenosis test for twenty Egyptian wheat cultivars (Giza 148, Giza 152, Giza 156, Giza 168, Giza 171, Gimmeiza 7, Gimmiza 9, Gimmiza 10, Gimmiza 11, Gimmeiza 12, Misr 1, Misr 2, Sakha 8, Sakha 93, Sakha 94, Shandwel 1, Sids 1, Sids 12, Sids 13 and Sids 14) were evaluated against R. padi infestation after 24 hrs and 48 hrs of aphids release and when the plants aged 7 and 15 days. Giza 156 recorded highly preference for aphids after 24 and 48 hrs when the plants aged 7 days, while Sids 13 showed that the least preference to aphids. Giza 148 revealed that highly preference to aphids after 24 and 48 hrs when the plants aged 15 days, plus Giza 152 and Giza 156 had similar results after 48 hrs. Otherwise, Sakha 93 and Sakha 94 cleared that the least preference. Then ten of those cultivars were chosen (Giza 148, Giza 152, Giza 156, Gimmiza 11, Misr 1, Misr 2, Shandwel 1, Sids 1, Sids 12 and sids 13) to study their leaf morphological characters, anatomical structure and some biochemical studies were assayed. Giza 152 had the lowest chlorophyll a and total chlorophyll compared to other cultivars. Also, Giza 152 had the least thick for mesophyll thickness, lower epiderms thickness, blade thickness and the shortest main vascular bundle dimension length and midrib thickness length too. Moreover, Sids 13 showed that the highest number of trichomes density, the thickest thickness for mesophyll tissue, the thickest thickness for blade and the longest main vascular bundle dimension length. It could be concluded that existence of high level of antixenosis in Egyptian wheat cultivars may decrease the population density and preference of R. padi and also cause a suppression of cereal viruses (e.g. BYDV) and reduce the pesticides application to wheat fields.