Vol. 12, Issue 9 (2023)

Author(s):
Pratap A Divekar, Suby SB and Pradyumn Kumar

Abstract:
Susceptibility of 10 elite maize inbred lines to maize stalk borer, Chilo partellus (Swinhoe) was evaluated using two screening methods viz., ovipositional preference by the gravid females and artificial infestation using neonate larvae based on the principles of antixenosis and antibiosis respectively. Different parameters of each screening method were correlated to find out the extent of relationship between them. The positive correlation of average egg mass received per plant and average number of eggs per plant with LIR and Larval weight was found non-significant among germplasm tested, but found significant with other susceptibility parameters like pupal weight, pupal recovery. The correlation of percent plants oviposited and percent leaves oviposited was observed significant with the antibiosis in parameters viz., LIR, pupal weight and pupal recovery. Considering these results, susceptibility indices (SI) were developed for antixenosis (SI_x), antibiosis (SI_b) and also, for cumulative susceptibility (SI_s) by combining both SI for antixenosis and antibiosis to incorporate all the parameters determining susceptibility. The extent of relationship between the indices were determined using correlation and it was observed that the correlation between (SI_x) and (SI_b) was 0.619, correlation between (SI_b) and (SI_s) was 0.805, those between (SI_x) and (SI_s) was 0.964 indicating that the greater contribution of antixenosis in determining susceptibility of a germplasm. But, if the data on the inbred HKI-1128 is removed, the values will become 0.974 and 0.194 for correlation between (SI_b) and (SI_s) and between (SI_x) with (SI_s), respectively. This may be due to the fact that in HKI-1128 antixenosis was contributing more. The results of the analysis indicate the need to adopt the combined susceptibility index (SIs) for better germplasm screening than the current approach, which relies solely on LIR or using antixenosis and antibiosis separately.