Seasonal incidence of major insect pest of soybean and their natural enemies in Marathwada region of Maharashtra

AbstractThe field experiment revealed that incidence of the chickpea pod borer Helicoverpa armigera. Larval population of Helicoverpa armigera was 0.80 larvae/mrl during 32nd SMW, the incidence increased in next few weeks, during 35th SMW population recorded highest population (4.60 larvae /mrl) during 35th SMW. Population of Spodoptera litura (was recorded highest population (3.41 larvae/mrl). Population was suddenly declined to 1.40 larvae/mrl after 37th SMW. Larval population of semilooper was 2.61 larvae/mrl during 31st SMW, the incidence increased in next few weeks, during 35th SMW recorded highest population (5.16 larvae/ mrl). The girdle beetle infestation crossed the economic threshold level (15% infested plants) during 36th SMW by recording 21.22% infestation. At harvest the infestation reached to 31.52% during 40th SMW. The infestation of stemfly was notice in 31st SMW with 1.20% infested plants. Thereafter, the infestation increased rapidly and within next week it recorded highest per cent infested plants during 39th SMW. In Helicoverpa armigera and Spodoptera litura a weak negative correlation was observed with the rainfall, morning and evening relative humidity (r = -102), (r = -0.223) and (r = 0.011), respectively and positives correlation was non-significant with maximum temperature (r = 0.005) and minimum temperature (r = 0.301). The correlation of girdle beetle with weather parameters like rainfall (r = -0.466), morning relative humidity (r = 0.149) and evening relative humidity (r = -0.465), was non-significant while with maximum temperature (r = 0.594*) significant and positive correlation and minimum temperature (r = -0.636*) and stemfly correlation of rainfall (r = -0.163), morning relative humidity (r = 0.078) and evening relative humidity (r = 0.192), was non-significant while with maximum temperature (r = -0.040).