Field Evaluation of Different Insecticides against Aphids (Homoptera: Aphidae) on Different Wheat, Triticum aestivum Varieties at Khairpur, Sindh

Wheat, Triticum aestivum (L) is the main staple food of the world population, feeding more than one billion people of the world. It is rich in protein and calories than any other cereal crop (Abd-ElHaleem et al., 2009). In Pakistan wheat contributes 14.4% to agriculture and 3.1% to GDP with production increased to 24.231 thousand tons in 2012-13 as compared to 23.471 thousand tons in previous years that showing an increase of 3.2% (MINFA, 2013). It is a staple food in Pakistan that grown on 8414 million hectares producing 21749 million tons of grain with a yield of 2585 kg per hectare (MINFAL, 2008). The main cash crop cultivated with the largest area under cultivation in Pakistan (Anwar et al., 2009). The wheat crop is encountered by both biotic and abiotic stresses comprising of drought temperature, diseases and insect pests (Akhtar et al., 2010). Mostly, it is attached by sucking pest aphid which is known as a dangerous problem for wheat and cereal crops (Dixon, 1987). Aphid populations stay on wheat for a short period during which they multiply rapidly. Besides, there are so many insect pests that damage to this crop in this country; among of them the severe infestation is caused by aphids that loss directly and indirectly up to 35-40% through sap sucking from plants and by transmitting 20-80% viral and fungal diseases (Aslam et al., 2005). The reduction in crop yield reached up to 10-50 % (Trdan and Milevoj, 1999). Thus, the population density also depends upon abiotic factors (Aheer et al., 2007 and 2008; Wains et al., 2008).