Impact of climatic factors on pod borer complex in Indian bean (Lablab purpureus L.)

Investigations were carried out during winter 2019-20 at the Regional Horticultural Research Station (RHRS) Farm of the Navsari Agricultural University, Navsari, Gujarat, India to study the impact of climatic factors on pod borer complex in Indian bean (Lablab purpureus L.) variety ‘GNIB-22’. The pod borer complex includes Maruca vitrata (Fabricius), Helicoverpa armigera (Hubner) and Etiella zinckenella. Amongst which the larvae of Maruca vitrata (Fabricius) feeds on flower buds and flowers causing premature flower dropping and at the later stage they feed on the seeds of the tender pods resulting in economic loss. The young larva of Helicoverpa armigera (Hubner) feeds on flower buds then attacks pods. Internal tissue are eaten severely and completely hollowed out. Etiella zinckenella is a serious polyphagous pest in India and other countries. The larva feeds on tender parts of the plant and leaves as well as the pods. Studies showed that H. armigera incidence start appeared on plants from the 6^th week after sowing and reached a peak level of 3.74 larvae per plant at 11^th week after sowing it was varied from 0.46 to 3.71 larva per plant. While, incidence of M. vitrata varied from 0.67 to 1.71 larvae per plant and started to appear on plants from the 7^th week after sowing and reached a peak level of 1.71 larvae per plant at 12^th week after sowing; whereas, E. zinckenella incidence appeared on plants from the 7th week after sowing and reached a peak level of 3.75 larvae per plant at 11^th week after sowing which was ranging 0.29 to 3.75 larvae per plant. The result on correlation concluded that the infestation of H. armigera showed significant negative correlation with maximum temperature (r=-0.562) and average temperature (r=-0.516). The infestation of M. vitrata showed significant negative correlation with maximum temperature (r=-0.571) and average temperature (r=-0.525). The infestation of E. zinckenella showed highly significant negative correlation with maximum temperature (r=- 0.590) and average temperature (r=-0.548). Whereas, remaining weather parameters did not show significant effect.