Population dynamics of aphid, Myzus persicae (Sulzer)(Hemiptera: Aphididae) on different Brassica species
Present studies deal with continuous observation of aphid population on different brassica species at every fourteen days interval. Five plants were selected randomly from each plot. The top 10cm terminal portion was used for counting of aphid population. The first appearance of aphid population was found at end of December in Brassica rapa var toria, B. rapa var yellow sarson and Brassica juncea. The correlation coefficients between aphid population and abiotic factors revealed contradictory results. Except for a few instances the abiotic parameters show a low order of association with aphid population. A significant negative correlation of aphid population was found with maximum temperature in B. rapa var toria (r= -0.963**), B. rapa var yellow sarson (r= -0.877*) and B. juncea (r= -0.913*). The population dynamics study of coccinellid beetles revealed that its population increased gradually with the increase of aphid population and vice-versa. In our experiment none of the weather parameters alone was responsible for the multiplication and growth of the aphid but it is assumed that during major part of rabi season, the meteorological parameters remained conducive for the rapid multiplication of aphid.