Developmental biology and feeding efficiency of Menochilus sexmaculatus (Coleoptera: Coccinellidae) (Fabricius) reared on Aphis craccivora (Hemiptera:Aphididae) (Koch)

Abstract

Menochilus sexmaculatus(Fabricius) predates on soft bodied, plants sap feeding insect pests. This species is a potential biocontrol agent to use in augmentative release programmes and requires more biological and ecological data. The objective of this study was to examine the development biology of M. sexmaculatus and to assess its suitability as a biocontrol agent. The study was conducted in the. All the experiments were conducted under laboratory conditions at 27ºC and 80 % RH. Mean incubation period of eggs was 3.0 ± 0.4 days. The total larval duration was 7.1 ± 0.5 days; L1, L2, L3 and L4 durations were 2.1 ± 0.3, 1.1 ± 0.4, 1.9 ± 0.3 and 1.9 ± 0.3 days, respectively. The pre-pupal and pupal periods were 1.1 ± 0.3 and 3.1 ± 0.3 days, respectively. Mean longevity of male and female beetles were 38.0 ± 0.6 and 47.3 ± 1.0 days, respectively. Mean pre-oviposition period was 3.0 ± 0.1 days and the oviposition period was 43.3 ± 1.0 days. The mean body length of L1, L2, L3 and L4 instars were 1.9 ± 0.1, 2.7 ± 0.3, 6.0 ± 0.1 and 7.8 ± 0.5 mm while, the mean width were 0.4± 0.1, 0.9 ± 0.0, 1.2 ± 0.1 and 3.3 ± 0.1 mm. Mean length and width of adult females were 6.2 ± 0.2 and 4.5 ± 0.3 mm respectively, and those of the males were 4.3 ± 0.5 mm and 3.2 ± 0.3 mm, respectively. L1, L2, L3 and L4 larvae consumed aphid nymphs at the rate of 10.3 ± 1.9, 7.5 ± 1.3, 38.1 ± 3.5 and 69.1 ± 3.1per day, respectively. L1, L2, L3 and L4 consumed adult aphids at the rates of 3.3 ± 0.6, 3.3 ± 0.6, 12.1 ± 0.9 and 25.1 ± 1.7per day, respectively. Female beetles consumed 1624.1 ± 0.2 nymphs and 1204.3 ± 1.3 adult aphids during their entire adult life span. Males consumed 1302.0 ± 1.5 nymphs and 1006.4 ± 0.4 adult aphids during their entire life span. The feeding efficacy increased with the larval instars. Feeding Efficacy of M. sexmaculatus adults was higher than larvae.