Measurement of antibiosis in maize (Zea mays) genotypes against pink stem borer (Sesamia inferens)

Study of antibiosis is used to identify the sources of resistance in plant germplasm. The quantitative determination of six parameters of antibiosis was carried out in 20 genotypes of maize (Zea mays L.) against Sesamia inferens (Walker). The number of larvae recovered from 30 plants of each genotype at three sampling intervals (7, 14 and 21 days after artificial infestation with neonates) was maximum (39) from WNZPBTL6 and minimum (13) from HKI 1040-11-7 and Basi local. The larval developmental period was found to range from 26-32 days. The expression of antibiosis in terms of prolonged larval period was observed in AEB(Y) C5 55-1 (32 days), PFSR S3 (31 days), CM 202 (31 days), and HKI PC4B (31 days), whereas shortest development period of 26.5 days was recorded in Basi local. Maximum and minimum pupal development period was recorded for AEB(Y)C5 34-7 (10 days) and AEB(Y) C 5-55-1 (7 days) respectively. Strong antibiotic effect of genotype E 30 was observed in terms of the least larval weight (20.53mg). The genotypes Basi local and HKI 164-4-ER-3 did not show much antibiosis as reflected from their maximum larval weight 48.32mg and 46.50mg respectively. The pupal weight ranged from 76.36-120.35 mg in the test genotypes. The leaf feeding symptoms in terms of leaf injury rating (LIR) at 21 days after infestation on a scale of 1 to 9, varied form 4.33-9. Positive correlations were observed between larval weight and LIR (0.52); pupal weight and LIR (0.20); pupal weight and larval recovery (0.27), whereas negative correlation were observed between larval weight and larval period (-0.49); larval weight and larval recovery (-0.46); larval period and pupal weight (- 0.40); and LIR and larval recovery (-0.21). The cumulative susceptibility level of genotypes indicated significant variation among genotypes against Sesamia which can be used to unravel the basis of resistance.