WHEAT GENETIC-CONTROL OF HESSIAN FLY (DIPTERA, CECIDOMYIIDAE) IN MOROCCO

Hessian fly, Mayetiola destructor (Say), causes about 30% yield reduct ion on both durum wheat and bread wheat in Morocco. Major effort has b een put on host plant resistance for control of this pest. Field and g reenhouse experiments demonstrated that resistance genes H5, H11, H13, H14H15, H21, H22, H23, H25, and H26 are very effective. They all expr ess antibiosis as a mechanism of resistance, whereby first instars die after they start feeding on plants carrying resistance genes. By cont rast, H7H8 and H9 are only moderately resistant against Hessian fly in Morocco. Five other sources of resistance in bread wheat were identif ied: Massira, BT92P1.20: NS732/Herm, L222, L254 and ADC14. All of thes e resistance genes have been incorporated into Moroccan wheats. Two br ead wheat cultivars, Saada (H5) and Massira (tolerant), were released to farmers in 1989 and 1994, respectively. Two bread wheat lines carry ing H13 and H22 genes and L222 are in registration yield trials. No so urce of resistance for Hessian fly in durum wheat was identified. H5 a nd H11 genes, located on the A genome, have been transferred from brea d wheat to drum wheat. H21 and H25 genes, located on B genome, are bei ng transferred from bread wheat to durum wheat.