Department of Entomology, Punjab Agricultural University, Ludhiana
Studies on the physical basis of resistance of Callosobruchus maculatus (Fabricius) in soybean were made on three varieties of soybean (PK 416, SL 295 and Punjab Soybean No. 1) and compared with two varieties of cowpea (cowpea 74 and cowpea 88). Seed size was found to be positively correlated with oviposition preference. Cowpea 88 having large seed size and darker seed coat was most preferred for oviposition. Whereas soybean varieties received less number of eggs because of its shinny and convex seed surface and creamy seedcoat. Hardness of seed was maximum in Punjab Soybean No. 1, followed by cowpea 74, SL 295, PK 416 and cowpea 88. Seed hardness was found to be negatively but non-significantly correlated with per cent adult emergence. Thickness of seedcoat was maximum in Punjab Soybean No. 1 followed by SL 295, cowpea 88, PK 416 and cowpea 74. Cowpea 74 which had less thickness of seedcoat as compared to cowpea 88 was found to be the most preferred host of C. maculatus.
C.maculatus, development, physical characters, soybean
