Study of Population Dynamics of Insect-pests in Different Growing Environments and their Relationship with Microclimate of Pigeonpea Cultivars

Background: Pigeonpea is a low input, rainfed crop that provides economic returns every part of the plant. Insect-pests are the major biotic constraints limiting the productivity of this crop. Keeping all these factors in mind, the present experiment was conducted to study the population dynamics of insect-pests in different growing environments and their relationship with microclimate of pigeonpea cultivars. Methods: A field experiment was conducted at research farm of Department of Agricultural Meteorology, Chaudhary Charan Singh Haryana Agricultural University, Hisar, during Kharif season 2017. Insect-pests population was recorded from the five tagged plants at weekly interval starting from 38th standard meteorological week (SMW) till harvesting of the crop. Ground sheet method was used to record the population of larvae of M. vitrata and H. armigera. Larvae of M. vitrata and H. armigera falling on cloth sheet of size 60 cm × 60 cm laid near plant stem were counted. Web formed by M. vitrata larvae were visually counted and then removed to count larvae feeding inside the webs. Result: In our experiment, it was found that H. armigera infestation started from 38th SMW in all the varieties and D1 and D2 sown crop while in D3 sown crop it started in 40th SMW. On the other hand the larval population of M. vitrata started from 38th SMW, 39th SMW and 40th SMW in all varieties and D1, D2 and D3 sown crops, respectively where as the formation of webs in all the varieties and D1 sown crop started from 38th SMW while in D2 and D3 sown crops started from 39th SMW and continued till 45th SMW. Mean larval population of H. armigera, M. vitrata and number of webs per plant was found highest in D1 sown crop on variety Manak.