Title: Voracity and conversion efficiency by larvae of Coccinella septempunctata L. (Coleoptera: Coccinellidae) on Aphis fabae Scop. (Homoptera: Aphididae) reared on two faba bean cultivars with different levels of resistance
Abstract: This study was conducted under laboratory conditions to determine the consumption rate and food utilization of predator Coccinella septempunctata larvae. Predator larvae were fed on black bean aphids, Aphis fabae, maintained separately either on partially resistant, 79S4, or on the aphid-susceptible, Vicia faba major, cultivars. There were no significant differences in the consumption rate of each instar of the predators between the two cultivar treatments, except for the first instar. When predator larvae were supplied with aphids being kept on partially resistant 79S4 plants as a source of food, 14.49 aphids were consumed per day by each larva during larval development, which was significantly greater than the consumption by predator larvae fed the diet of aphids from susceptible plants (on average 13.72 aphids/d). Also, total consumption by predator larvae was higher when the consumed aphids were obtained from partially resistant host plants, where approximately 648.9 aphids were needed during development. In contrast, only 569 aphids from susceptible faba bean plants were devoured by each predator larva during larval growth. The predator larvae using aphids from susceptible faba bean plants as a source of food were considerably more efficient in converting food to body mass.