Biological Studies on 7-spot Ladybird Beetle, Coccinella septempunctata L. with Cereal Aphid, Sitobion avenae (F.) as Prey

Abstract

The studies on the biology of seven spot ladybird beetle, Coccinella septempunctata L. were conducted in laboratory with cereal aphid, Sitobion avenae (F.) as prey at a temperature range of 20–23 degree Celsius. The incubation period was recorded to be 4.2 days with a range of 3.5–4.5 days. The average hatchability was 81.89 per cent with a range 70–90 per cent. The predator passed through four larval instars completing the average duration in 2.27, 1.81, 2.25, and 3.06 days, respectively. The total larval period was observed to be 9.39 days with a range of 8.2–10.5 days. The pupal period lasted for 4.7 days with a range 4.0–4.9 days. On an average male longevity was observed to be 36.91 days with a range of 33 to 37 days. However, the female survived for 39.9 days with a range of 33–47 days. The beetles started mating 4–11 days after emergence with an average pre-mating period of 6.4 days. The mating duration was recorded as 54 minutes with a range of 41 to 62 minutes. The average pre-oviposition, oviposition and post-oviposition periods were 8.3, 22.4 and 9.2 days, respectively. The average fecundity was 476.4 eggs per female. The female outnumbered the males in a female biased sex ratio in nature and their sex ratio was observed to be 1: 1.6.