BIOTYPE COMPOSITION OF HESSIAN FLY (DIPTERA, CECIDOMIIDAE) POPULATIONS FROM ARKANSAS, GEORGIA, ILLINOIS, NORTH-CAROLINA AND VIRGINIA

Fourteen populations of Hessian fly, Mayetiola destructor (Say), from Arkansas, Georgia, Illinois, North Carolina, and Virginia were evaluat ed for biotype composition, and two Arkansas populations were tested f or response to Hessian fly resistance genes or gene combinations H3, H 5, H6, H7H8, and H9 to H19 in wheat. The biotype composition of Hessia n fly populations was estimated by confining individual gravid females on the four wheat differential cultivars 'Monon' (H3)1 'Magnum' (HS), 'Caldwell' (H6), and 'Seneca' (H1H8). The response of Arkansas fly pop ulations to resistance genes was evaluated in replicated tests with wh eat germplasm lines or cultivars homozygous for these genes. Hessian f ly populations from Arkansas were predominately biotype L, with low le vels of biotypes F, G, J, M, and O, depending upon population. Biotype L was predominant in the Illinois, North Carolina, and Virginia popul ations, although biotype D was present in populations from extreme sou thwestern Illinois and Virginia and North Carolina. Biotypes Ct, J, L, M, and O were identified from the west-central Georgia population col lected at Griffin, while only biotypes M and O were identified from th e southwestern Georgia population, collected at Plains. All fly popula tions were virulent to resistance genes H3, H5, and H6, while the sout hwestern Georgia population was avirulent to H7H8. Plants with single resistance genes H9 to H19 varied significantly (P less than or equal to 0.05) in their resistance to the two Arkansas populations. Plants w ith single resistance genes H9, H10, H13, H14, and H16 to H19 conditio ned resistance (88 to 100%) to both populations, while plants with sin gle genes H11, R12, or H15 were susceptible to one or both populations . Wheat germplasm lines developed in the Purdue/USDA program that carr y single gene resistances H9, H13, H14. and H16 to H19 should provide useful sources of resistance for developing improved wheat cultivars a dapted to the mid-south and southeastern United States.