Seasonal Incidence of Spotted Pod Borer (Maruca vitrata F.) in Indian bean and Correlation with Meteorological Aspects

Aim: To study the population dynamics of spotted pod borer infesting Indian bean in relation to weather parameters

Study Design: Field trail; Randomized Block Design.

Place and Duration of Study: The study was conducted at College farm at Navsari Agricultural University during Rabi of 2022-23 and 2023-24.

Methodology: 50 plants were randomly selected from the net plot area. The observations on the number of larvae per plant and per cent pod damage were counted.

Results: The larval population, in year 2022-23 started from 51st SMW. The peak activity was observed in 4th SMW when 6.46 larvae/plant population was recorded which coincided with the peak flowering stage. During the second season (year 2023-24) also, the pest population started from 51st SMW with pest population of 0.8 larvae/plant. The peak pest population was observed on 4th SMW with 6.84 larvae/plant. The pod damage started from 2nd SMW with 10.05 per cent and gradually increased. The peak was recorded in 12th SMW, highest pod damage was observed with 55.89 per cent. Similar to previous year, the pod damage was recorded from 2nd SMW with 11.67 per cent and peak was seen in 8th SMW with 56.63 per cent damage. The correlation of number of larvae per plant with maximum (r=-0.63), minimum (r=-0.62), average temperature (r=-0.74) and average vapour pressure (r=-0.59) showed significantly negative correlation. During year 2023-24, minimum (r=-0.637) and average temperature (r=-0.610) showed significant negative correlation. In case of pod damage, it was revealed that maximum temperature (r=0.58) and bright sunshine hours (BSSH) (r=0.59) exhibited significant positive correlation with pod damage per cent, in year 2022-23. A similar trend was seen in year 2023-24 where, maximum temperature (r=0.692) and BSSH (r=0.787) showed significant positive correlation.

Conclusion: Temperature and to some extent vapour pressure plays a significant role in the population fluctuation of spotted pod borer in Indian bean.