Food consumption and utilisation by larvae of two coccinellid predators, Scymnus levaillanti and Cycloneda sanguinea, on cotton aphid, Aphis gossypii

This study was carried out under laboratory conditions at various temperatures to compare food consumption and efficiency of conversion of food to body mass for larvae of two coccinellid predators, Seymnus levaillanti Mulsant (Coleoptera: Coccinellidae) and Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), which differ in body size and feeding method. The consumption rate of each larval stage of both species increased with increasing temperature. The consumption rate for total development (from egg hatch to pupation) of S. levaillanti was found to be 22.9 aphids per day at 30degreesC. It was much higher for C. sanguinea (975.1 aphids per day at 25degreesC and 1066 aphids per day at 30 degreesC). The larger species, C. sanguinea was more voracious at each temperature than the smaller species, S. levaillanti. The larvae of S. levaillanti, employing pre-oral digestion, were more efficient in converting food to body mass than larvae of C. sanguinea, which used chewing and sucking. The fourth instars of both species were less efficient in converting food to body mass than were their first three instars. It was concluded that body size and feeding method of coccinellid predators play an important role in food consumption and efficiency of conversion of food to body mass.