Resistance and susceptibility of some wheat lines to bird cherry-oat aphid <Emphasis Type="Italic">Rhopalosiphum padi</Emphasis> (Hemiptera: Aphididae)

Bird cherry-oat aphid, Rhopalosiphum padi (L.), is one of the most serious pests of cereals, with an almost worldwide distribution. A primary screening test was carried out to gauge the resistance or susceptibility of 40 wheat lines to R. padi, and follow-up experiments were conducted to determine the development and fecundity rates of R. padi on eight lines. The forty wheat lines examined were classified into two major classes and four subclasses: A (e.g., ERWYT 87-1) and B (e.g., ERWYT 87-20, ERWYT 87-11), with the highest average number of aphids 14 days after infestation, subclass C (e.g., ERWYT 88-8, ERWYT 87-6, ERWYT 87-4), with the lowest average number of aphids, and subclass D (e.g., ERWYT 88-12, ERWYT 88-13), with intermediate status. Aphid nymph developmental time and survival both differed among the wheat lines. Differences were also observed in the fecundity of R. padi, the intrinsic rate of increase (r _m), and other parameters among the wheat lines tested. The highest and lowest values of r _m were obtained for ERWYT 87-1 and ERWYT 88-8 (0.36 and 0.26 nymphs/female/day, respectively). Three lines (ERWYT 87-4, ERWYT 87-6, ERWYT 88-8) were relatively resistant to R. padi, which could prove useful in the development of IPM programs for this aphid in wheat fields.