Laboratory Approach: Alternate Dietary Sources for Coccinellid Ladybird Beetles
Laboratory Approach: Alternate Dietary Sources for Coccinellid Ladybird Beetles
Nazia Suleman* and Asia Riaz
ABSTRACT
Coccinellid beetles are effective predators of soft bodied insect pests. They can be mass reared in laboratories for applied biological control against sucking insect pests. Laboratory rearing of ladybirds often need live host, preferably aphids. Artificial diets prepared from different sources do not prove very successful due to complexity of preparation for coccinellid beetles. Short seasonal availability of aphids hinders the rearing procedures. Therefore, some alternate natural dietary sources are essential to continue the mass rearing of ladybirds. In present study, we compared the longevity and egg laying of two species of ladybirds on alternate natural dietary sources other than natural dietary sources i.e., live aphids. The longevity of seven spotted ladybird Coccinella septempunctata was significantly higher on control (live aphids, Mean= 171.5 days) than other treatments including frozen aphids, frozen eggs of Angoumois grain moth and soaked raisins. Among all treatments, longevity was minimum on frozen aphids (Mean= 66.4 days) for seven spotted beetles. Similarly for zigzag beetle, Menochilus sexmaculatus, the number of days the beetles survived was significantly higher on live aphids (Mean= 106.54 days) and was minimum on soaked raisins (Mean= 67.21 days). Among different diets, the fecundity of both beetle species was maximum on live aphids (M. sexmaculatus, mean = 32.4; C. septempunctata, Mean = 42.4). The females of zigzag ladybird produced least number of eggs when given either frozen aphids or frozen eggs and seven spotted did not lay eggs on any other treatment. As an outcome, beetles survived for substantial period on alternate dietary sources (up to six months) and such alternatives can be used until provision of natural host i.e., aphids is made available.
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