Natural Incidence of Sesamia inferens Walker, in Sugarcane Germplasm

The pink stem borer Sesamia inferens (Walker) (Lepidoptera: Noctuidae) has attained pest status in recent years in the world collection of sugarcane germplasm maintained at the Sugarcane Breeding Institute Research Centre, Kannur, Kerala state, India. With a view to identify sources of resistance to the hitherto minor pest, which occurs during the early stage (March–June) of crop growth, the flowering accessions of Saccharum officinarum L. from the germplasm collection were screened against the borer under natural conditions for three consecutive years (2010–2013). Deadheart incidence was used as the parameter for screening and the genotypes were graded in four categories based on the level of incidence. Among all accessions across the years, the minimum incidence of the borer (1.47 %) was recorded in NG 77–93 while the maximum (29.41 %) was in 57 NG 111. Almost all the accessions harboured pink borer infestations with only one or two exceptions in individual years. Grouping of accessions on the basis of deadheart showed 17 (15.45 %) as resistant, 50 (45.45 %) as moderately resistant, 36 (32.72 %) as susceptible and 7 (6.36 %) as highly susceptible. Of the total accessions screened, New Guinea, Indonesia and Mauritius collections contributed 9.09 % (ten clones), 5.45 % (six clones) and 0.91 % (one clone) respectively to the resistant grade. The study also indicated that pink borer infestation starts in March, peaks by third week of May, gradually declines after the onset of monsoon and reaches the minimum by the second week of June. Nearly 60 % genotypes that showed resistance/moderate resistance to pink borer can serve as potential donors for resistance breeding programmes after confirmation using laboratory screening methods.