Varietal resistance in Sorghum to midge, Contarinia Sorghicola Coquillett (Diptera: Cecidomyiidae)

Abstract

The midge, Contarinia sorghicola Coquillett, is a major pest of grain sorghum in many areas of Asia, Africa, Australia, Europe and America. Literature documenting the status of research on the biology, behaviour, and field and cage screening techniques is reviewed. Numerous germplasm entries have been evaluated and many resistant sources are identified from various midge screening programmes. A high degree of resistance was found in nine working groups viz., Caudatum, Durra, Caudatum/Nigricans-Zerazera, Caudatum/Kafir (Hegari), Nigricans, Caffrorum-Darso, Durra-Nigricans, Durra-Nandyal and Caudatum-Bicolor. The identified resistant sources and the midge resistant varieties released from the breeding programmes are listed. Studies on the mechanisms of resistance showed predominance of antixenosis for oviposition over adult attraction and variable degrees of antibiosis. The morphological characters and biochemical factors associated with resistance have been explored. Short and compact glumes which remain closed during anthesis conferred resistance. The tannin content in the ripening sorghum grain is related to resistance against the larva. The inheritance of resistance showed quantitative nature. The open and closed glume character expression indicated its dominance and recessiveness, respectively. Short glume character can be used as an useful genetic marker. Pedigree and modified pedigree breeding systems were suggested to transfer high level of midge resistance into agronomically acceptable types for selection and hybridization.