Relationship of sorghum midge (Diptera:Cecidomyiidae) density to damage to resistant and susceptible sorghum hybrids [Contarinia sorghicola]

Three methods were used in 1980 and 1981 to investigate the relationship between adult sorghum midge, Contarinia sorghicola density and yield loss in one susceptible, ATx2752 x RTx430, and two resistant, ATx2755 x RTx2767 and ATx2761 x RTx2767, sorghum hybrids. By using natural infestation (method 1) and a sequential model (method 3), similar results were obtained: 1.5 g of grain lost (42 to 48 damaged spikelets) per ovipositing midge for the susceptible and 0.32 g (9 damaged spikelets) for the resistant hybrids. A technique using caged midges (method 2) resulted in less loss per midge than the other two methods: 0.54 g (16 damaged spikelets) for the susceptible and 0.14 g (4 to 6 damaged spikelets) for the resistant hybrids. This was due to reduced oviposition by midges in cages.