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Species of the genus Schizaphis (Aphidinae: Aphidini) are highly restrictive in host plant selection. Out of 40 species, sixteen (40%) showed monophagy, twelve (30%) oligophagy and another twelve (30%) polyphagy. S. chaenometicola hosted only on Rosaceae (Chaenomeles speciosa) in dicotyldons and fifteen species were monophagous in monocotyledons – one on Typhaceae (Typha capensis) in corolliferae and rest fourteen in glumiflorae (Cyperaceae and Poaceae). The GAI values in most of the cases were close to 1.000. In all polyphagous species of Schizaphis host plants from glumiflorae were part of the host range and their GAI values ranged 0.667-1.682. Generalized view of host affinity to taxonomic groups revealed that Schizaphis spp. selected host plants from all the divisions of dicotyledons (5.23%) and monocotyledons (94.77%). However, host species from glumiflorae (Cyperaceae and Poaceae) in monocotyledons alone demonstrated their distinct affinity (87.11%). The most important species was S. graminum which feed on 109 host species belonging to 54 genera and six families. Evolutionary pattern manifested that all the host families in monocotyledons of S. graminum evolved from Liliales stock. No host species was found representing primitive orders like Butomales, Alismatales and Commelinales and their advanced orders.
Keywords: Aphids, Schizaphis spp., Dicotyledons, Monocotyledons, General Affiliation Index (GAI).