From field screening of two international nurseries of the sorghum shootfly (Atheriaona saccata), seven promising cultivars were selected for investigating the mechanism(s) of resistance. These cultivars were IS 1054, IS 1082, IS 2146, IS 2195, IS 2312, IS 3962 and IS 5613. CSH-1, a hybrid variety from India, was used as a susceptible control. Results from observations on larval development and mortality and the longevity and fecundity of resulting females when released on either CSH-1 or the parent cultivars are reported.
Mortality among the first-instar larvae was very high on IS 2146 followed by IS 2312 and IS 5613. IS 2146, IS 3962 and IS 2312 sustained the least growth of larvae. The larvae in these cultivars were often confined to the upper region of the central shoot.
The survival rate of flies from IS 2146 was very low, and the longevity was significantly reduced in the case of flies from IS 2146 and IS 2195. The preoviposition period was significantly longer when flies were released on IS 1082 and IS 2312. Fecundity of the flies did not differ significantly when released on CSH-1; however, it was significantly reduced when released on parent cultivars in all cases except IS 1054. It is concluded that IS 2146 possesses strong antibiosis for the sorghum shootfly followed by IS 2312 and IS 5613.