Seasonal Incidence of Insect-pests of Soybean and their Correlation with Abiotic Factors

A field experiment was conducted during kharif crop season 2015-16 at college of agriculture, Indore (M.P.) on cultivar RVS 2001-4 to assess the effect of weather factors on the trend of blue beetle and tobacco caterpillar activities. The crop was sown in second week of June, 2015-16 in an area of 200 (20x10m) square meters following the recommended agronomical practices with the spacing of 40 x10 cm rows and plants, respectively. The observations on the appearance of major insect pests were recorded from germination to harvest of the crop at weekly intervals at 10 different sites in 1 meter row length from each site once in a week and correlation was worked out. For blue beetle per cent infestation and for tobacco caterpillar, larval population was counted. Blue beetle infestation started in 26th MSW with 1.3% damage. The infestation increased and reached its peak as 7.5 % in 32th SMW ending 31th August. After that the infestation decreased slowly in next two weeks and noted least as 3.1% in 33th SMW ending 7th September. The occurrence of tobacco caterpillar started with 2.5% insects in 29th SMW ending 10th august. The population fluctuated and reached its peak as 14.5% in 35th SMW ending 21st September. Both the insects significant negative correlation with maximum temperature (blue beetle, r = -0.667 and tobacco caterpillar, r = -0.528). Blue beetle significant positive correlation with rain fall and rainy day (Rainfall r = 0.572 and Rainy day, r= 0.572) and tobacco caterpillar significant positive correlation with morning humidity was recorded. Rest of the abiotic factors exhibited non significant positive or negative correlation for both insects.