Hessian fly (Diptera : Cecidomyiidae) larval survival as affected by wheatresistance alleles, temperature, and larval density

摘要

The effects of allelic dosage of wheat resistance genes; larval density; and temperature on the expression of resistance and on Hessian fly, Mayetiola destructor (Say), larval survival was studied in a growth chamber. Wheat plants homozygous and heterozygous for resistance genes H3, H5, H7H8, H9, H10, and H11 expressed a high level of resistance as indicated by levels of plant damage. Plants heterozygous for the H6 gene were only moderately resistant. Little or no larval survival occurred on resistant plants homozygous and heterozygous for the H13 and H22 genes. However, significantly more larvae survived on resistant plants heterozygous for the H3, H5, H6, H7H8, H9, H10, or H11 genes compared to the corresponding homozygous plants. Thus, larval survival on resistant heterozyous plants rather than levels of plant damage appears to be the best criterion to determine if a resistance gene has complete or incomplete dominance. Wheats with resistance genes H1H2, H7H8, H11, and H13 expressed a high level of resistance across all egg (larval) densities (5, 10, 20 eggs per plant) and temperature. Larval survival increased on resistant plants having H1H2 and H7H8 genes as egg density and temperature (18, 24, 28 degrees C) increased, with the highest survival recorded at 24 degrees C. Little or no larval survival occurred on resistant plants carrying the XII or H13 genes across density and temperature treatments.