BIOLOGY AND PREDATION EFFICIENCY OF MENOCHILUS SEXMACULATUS (COLEOPTERA: COCCINELLIDAE) ON BEAN APHID

Abstract

A detailed research work was carried out in the laboratory of the Department of Entomology, HSTU, Dinajpur to study the life history and predation efficiency of Menochilus sexmaculatus (Coccinellidae: Coleoptera) on bean aphid, Aphis craccivora Koch. Aphididae: Homoptera during February to April 2014. Mating usually took place within 3 to 4 days after emergence of the beetles. The pre-oviposition and oviposition periods were found to vary from 3 to 6 days and 23 to 35 days respectively. The number of eggs deposited per female ranged from 300 to 400 in their life time. The eggs hatched within 2 to 3 days and the hatchability/viability of eggs varied from 92.98 to 98.78. The 1‘, 2", 3 and 4" larval instars lasted for 2.29, 2.58, 3.29 and 3.05 days respectively. The total duration from egg to adult was completed within 15 to 23 days. The average longevity of male was 34.29 days while female beetle was 37.52 days. The predation efficiency of larvae increased gradually from 1* instar to 3 instar and then sharply peaked in 4" instar. The average predation rate of 1%, 24, 3 and 4" instar larvae were 4.82, 26.88, 64.29 and 93.88 aphids, respectively. They consumed on an average 189.88 aphids during their entire larval period. The female beetle preyed on more aphids than male. The total consumption rate of male and female beetles varied from 1034 to 1097 aphids and 1162 to 1266 aphids, respectively.