Biology and predatory potential of Coccinella septempunctata Linn. on green bug Schizaphis graminum R. under controlled conditions

The purpose of study was to determine the redatory potential and biology of Coccinella septempunctata Linn. on green bug Schizaphis graminum (Rondani) under controlled conditions at Insectary-Bio Control Labs. National Agricultural Research Centre (NARC), Islamabad. The results revealed that egg incubation period of C. septempunctata reared on S. graminum was 5.12, 3.62 and 3.20 days at 20 plus minus 1 degree C, 25 plus minus 1 degree C, and 30 plus minus 1 degree C, respectively. Fecundity and egg hatchability percentage was considerably effected by temperature regimes. The total larval and pupal duration of predator was significantly reduced with the increase in temperature. The pre-oviposition, oviposition and post-oviposition periods ranged between 17.33 to 28.23, 10.20 to 22.2 and 9.93 to 21.93 days, respectively. Male longevity was lesser than female at three temperatures. Though instars were found voracious feeders of S. graminum, the fourth instar consumed the highest number of aphids. Mean predatory potential of all larval instars progressed with the increase in temperature. Mean predatory potential of adult female was significantly higher than males on all tested temperatures. The developmental stages of C. septempunctata attained lower apparent mortality, indispensible mortality, "survival ratio" and maximum survival at 25 plus minus 1 degree C. The "total generation mortality" (K) was recorded (0.2518) at 20 plus minus 1 degree C, followed by (0.1674) at 25 plus minus 1 degree C. The present study revealed that 25 plus minus 1 degree C has been proved as the most suitable for development and predatory potential of C. Septempunctata. In the present study the importance of improving our understanding in mass rearing and utilization of predators in biological control program is discussed.