Biology and bean aphid predation efficiency of lady bird beetle Micraspis discolor (Fabricius) (Coleoptera : Coccinellidae)

Abstract

The experiment was conducted at the Department of Entomology, Hajee Mohammad Danesh Science and Technology University, Dinajpur. The mean preoviposition period of the beetle Micraspis discolor was 5.1+0.48 days and the oviposition period was 40.10 +0.46 days. The female beetles laid on an average 235.50£7.96 eggs and the hatching % was 83.93 +2.11. The average incubation period was 3.1+ 0.22 days and the duration of total the larval period from egg to adult was 10.76 +1.35 days. The pre-pupal and pupal periods were 1.50 +0.20and 2.60+ 0.21days, respectively. The mean longevity of the male and the female beetles were 40.20 +1.0 and 47.50 +0.82 days, respectively. The length of the egg was 1.2 +0.02 and the breadth was 0.5 +0.01mm. The 1°‘, 2™ , 3 and the 4" instar larvae were 1.6 +0.05 , 3.13 +0.08 , 4.10 +0.16 and 5.1 +0.08 mm in length, while their breadths were 0.62 +0.02 , 0.70 40.06, 1.1 +0.10 and 1.3 +0.09 mm respectively. The average lengths of the male and female pupae were 3.1+0.08 and 3.3+0.09 mm and the breadths were 2.10.05 and 2.5+0.08 mm, respectively. The length and the breadth of the adult male and the female beetles were 4.1+0.06, 3.3 +0.08 3.7+0.05, 3.1 +0.06mm and mm respectively. Predation efficiency of 1°, 2", 3" and 4" instar larvae were 1.9+0.20, 3.6+0.19, 4.4340.24 and 6.08+0.24 aphids, respectively, while the predation efficiency of male and female adults were 1003.27+104.35 and 1216.40+ 22.89aphids. The data of the aphid predation of the beetles reveal that the larvae of the 4" instar showed significantly the highest predation performances and the 1° instar showed the lowest one. The female beetles were more effective in aphid predation in compared to male beetles.