Progress in the biological testing of Sorghum Midge (Contarinia spp.)

Successful emergence of examples of Contarinia sp. and associated parasites has been obtained at Rothamsted Experimental Station from midge-infested heads of sorghum received from India (Mysore State) and West Africa (Ghana).Since typical pre-mating behaviour was observed on all of the few occasions when newly emerged males and females from the two continents were confined together, and actual mating was obtained between a male from Ghana and two females from Mysore in rapid succession, it is concluded that inter-mating will take place under suitable environmental conditions, although in the present series of experiments such conditions were rarely present.It has not yet been possible to test the fertility of such inter-matings or to prove biologically that the species of Contarinia concerned is the C. sorghicola (Coq.) of Texas, although on morphological grounds there are apparently no reasons for their separation.Two species of parasites, a Tetrastichus sp. (group of flavovarius, auct.) and Eupelmus popa Gir., were reared from the Indian material, and another species of Tetrastichus (group of flavovarius, auct.) and E. popa were reared from the West African material.