Influence of Cultivar on Aphids (Hemiptera: Aphididae) and Associated Natural Enemies in Pakistani Wheat Ecosystems

The objective of this study was to determine the influence of cultivar on aphids and their natural enemies in wheat (Triticum aestivum L.). Thus, twenty Pakistani wheat cultivars were grown at the Agricultural Research Institute in Tarnab-Peshawar, Pakistan during the winter ('rabi' in local language) season. Plots were arranged in a randomized complete block design with three replicates per treatment/cultivar. Population of aphids, and numbers of parasitoids and predators were recorded at weekly intervals. Rhopalosiphum padi Linnaeus, Schizaphis graminum Rondani, and Sitobion avenae Fabricius were the predominant aphid species (Homoptera: Aphididae). Two species of parasitoids Aphidius ervi L. and Aphidius colemani Viereck were recorded. Coccinella septempunctata L. (Coleoptera: Coccinellidae), Chryoperla carnea Stephens (Neuroptera: Chrysomelidae), and several species of Hover flies (Diptera: Syrphidae) were the most common predators. In general, aphids were reported in all wheat cultivars. Cultivar Saleem-2000 presented the highest number of aphids per tiller (9.1), while Gomal-2008 presented the lowest (1.9). Based on aphid presence per tiller, no cultivar was found to be Susceptible or Highly Susceptible, but 1 cultivar was found to be Moderate Susceptible, 8 Moderate Resistant, 9 Resistant, and 2 Immune. Rate of parasitism and predation increased when aphid density increased. In general, wheat cultivar influenced aphid population pressure, and indirectly influenced the natural population of parasitoids and predators.