Role of various biophysical factors on distribution and abundance of spotted pod borer, Maruca vitrata (Geyer) on mung bean*

Nine plant parameters, viz., pod wall thickness, number of pods/cluster, angle between the pods, trichomes of leaves, pods and stems, trichome length, pod length and pod width were studied in relation to the expression of varietal reaction towards spotted pod borer Maruca vitrata in ten varieties of mung bean. It was observed that highly susceptible cultivar LGG-450 had least number of trichomes on stems (8.9), pods (3.0) and leaves (13.0) as compared to highly tolerant cultivar LGG-497 which had 12.3, 7.2 and 22.8 trichomes/mm², respectively. Similarly, trichome length was also least (0.46 mm) in susceptible cultivar, LGG-450 compared to resistant cultivar, LGG-497 (0.62mm). Pod wall thickness, angle between the pods and pod width showed a negative correlation with pod damage. Highly susceptible cultivar LGG-450 possessed lowest pod wall thickness (0.50 mm), least pod width (4.03 mm) and minimum pod angle (38°) as compared to most tolerant cultivar LGG-497 (0.55 mm, 4.90 mm and 85° respectively).