GENOTYPIC EFFECTS OF SORGHUM ACCESSIONS ON FECUNDITY OF SORGHUM HEAD BUG, CALOCORIS-ANGUSTATUS LETHIERY

Sorghum head bug (Calocoris angustatus Leth.) (Hemiptera: Miridae) is an important pest of grain sorghum in India. We studied the fecundity of head bug females reared for one to three generations on head bug-re sistant and head bug-susceptible genotypes during the 1988 and 1989 ra iny and 1988-89 post-rainy seasons. Head bug population increase was l ower for the first, second and/or third generation when the bugs were reared on IS 2761, IS 19955, IS 14334, IS 23748, IS 16357, IS 17610, a nd IS 21444 compared with the susceptible controls CSH 1, CSH 5, and C SH 9. These genotypes also suffered a low grain damage (damage rating (DR) less-than-or-equal-to 5) (except IS 2761) compared with the susce ptible controls (DR > 6). A marginal decrease in fecundity was observe d when the bugs were reared on IS 2761, IS 14334, IS 16357, IS 20740 a nd IS 17610 and then transferred to the susceptible control, CSH 1. So rghum genotypes having lower increase in bug population across generat ions, suffering low grain damage, and showing adverse effects on fecun dity can be used in breeding for resistance to head bugs.