03917nam a2200181Ia 4500 26167 26167 OSt 20220826135238.0 140128s9999 xx 000 0 und d 632.6 DEV/PA Devanesan S Pathogenesity of Thai Sacbrood Virus to the Ecotypes of Apis Cerana Indica Fab. in Kerala Vellayani Department of Agricultural Entomology, College of Agriculture 1998 PhD Identification of ecotypes of the Indian bee A. cerana indica Fab. in different ecological niche in Kerala adopting statistical analysis of the morphometric data was attempted in the investigation. Sixty worker bees each were collected from 18 locations distributed throughout Kerala and data on 50 selected characters were collected. Univariate analysis showed significant variations in the data with reference to all the fifty characters indicating the desirability of a multivariate analysis for identifying sub groups of A. cerana indica available in the state. A comparison of the honeybee population of the three topographic divisions of the state viz., highrange, highland and midland, with reference to each morphometric character revealed that the bees from highrange were distinct from those of highland and midland. There was less distinction between the bees of the latter two divisions. It also indicated that the highrange bees possessed longer proboscis, antennae, wings and legs. The abdominal size also showed an increasing trend in highland and highrange bees. Eleven morphometric characters were positively correlated with altitude while seven characters showed negative correlation. Multivariate(discriminant) analysis of the morphometric data revealed the existence of four different clusters / ecotypes in A. cerana indica populations of Kerala. Cluster I included all the six locations of midland and four locations of highland. Two locations of highland at higher altitude formed cluster 11. Pampadumpara of the highest altitude in highrange came in cluster IV and remaining locations of the highrange constituted cluster Ill. Contribution of each morphometric character towards divergence of the clusters was also assessed. Seventeen characters contributing 2.5 to 6.4 per cent of divergence were thus identified. Bees from all the four clusters / ecotypes showed susceptibility to Thai Sacbrood Virus (TSBV) infection. Studies on the pathogenicity of TSBV showed that all four larval instars of A. cerana indica were susceptible to TSBV. One day old larvae were highly susceptible recording 100 per cent mortality closely followed by 2 and 3 day old larvae showing 84 to 92 and 82 to 96 per cent mortality respectively, with an incubation period of 3-4 days. Four day old larvae were comparatively less susceptible recording 72 to 74 per cent mortality with an incubation period of 3 to 5 days. The infected larvae were seen lying on the floor of the brood cells on their back with the head directed outwards and turned upwards like the prow of a boat. In later stages they became plumbier than healthy larvae. After death each larva showed a sac like appearance when lifted up and it was filled with a milky fluid formed probably by the histolysis of the tissues. In 10 to 15 days the sac got shrunk into a small browinish black scale \ " loosely lying at the floor of the' cell. The presence of diseased larvae was found to upset the behaviour of workers and queen. These resulted in the fast dwindling of the population and cessation of cleaning activities in the hive. The hive lost the desired qualities of a bee abode and hence the surviving bees deserted the same causing total loss to apiary. Abraham Jacob (Guide) http://krishikosh.egranth.ac.in/handle/1/5810084391 ddc TH 0 0 ddc 0 0 KAUCLV KAUCLV THESES 2014-03-18 0 632.6 DEV/PA 171215 2014-03-18 00:00:00 2014-03-18 TH