Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2002
Publication Date: 7/1/2002
Citation: J. Agric. Urban Entomol. 19(3):133-140 (July 2002) Interpretive Summary: Bird cherry-oat aphids (BCOA) and other cereal aphids are pests of wheat and vectors of barley yellow dwarf virus, which causes a serious disease in wheat and subsequent yield loss. Host-plant resistance to aphids can be economical and may be especially advantageous in crops with a narrow profit margin such as wheat. We evaluated 3 types of plant resistance to bird cherry-oat aphids among 8 varieties of wheat, including 6 with resistance to other cereal aphids and 1 with resistance to BCOA. Winged and wingless BCOA preferred settling on varieties other than MV4. Winged BCOA preferred the varieties Halt, TAM 110, and Vista more than KS92WGRC24, GRS 1201, STARS-9303W or TAM 107. They also preferred varieties GRS 1201 and TAM 107 to STARS-9303W. Wingless BCOA preferred the varieties GRS 1201 or TAM 110 to KS92WGRC24, STARS-9303W, TAM 107 or Vista. They also preferred HALT to KS92WGRC24 or TAM 107. In 2 rounds of another experiment, the time to reproduction for BCOA did not differ among wheat accessions. In 1 round o that experiment, however, BCOA produced more nymphs on accession KS92WGRC24 than on GRS 1201, Halt, MV4, STARS-9303W, or Vista. BOCA's rates of increase were lowest on TAM 110 and highest on KS92WGRC24 in the first round, and lowest on MV4 and highest on TAM 107 in the second. The development of winged vs wingless forms of aphids is influenced by environmental factors that can include the type of host plant. However, when newborn BCOA were placed on seedlings stars, the proportion maturing into winged vs wingless adults did not differ among varieties, which indicated that these varieties did not affect the differential production of winged forms. Modest levels of resistance to R. padi may limit infestations and indirectly slow the spread of barley yellow dwarf.
Technical Abstract: Host-plant resistance to cereal aphids may be especially advantageous in crops with a narrow profit margin such as wheat (Triticum aestivum L.). We evaluated resistance (antibiosis, antixenosis, and the differential production of alate aphids) to Rhopalosiphum padi (L.) among eight wheat accessions, including six with resistance to other cereal aphids and one with resistance to R. padi. Accessions differed in antixenosis to both alate and apterous R. padi. Among the accessions, MV4 was the most antixenotic to either alatae or apterae. With alatae, the accessions KS92WGRC24, GRS 1201, STARS-9303W and TAM 107 were antixenotic compared to Halt, TAM 110, and Vista. The accession STARS-9303W was also more antixenotic to alatae than GRS 1201 or TAM 107. With apterae, KS92WGRC24, STARS-9303W, TAM 107 and Vista were antixenotic when compared to GRS 1201 or TAM 110. KS92WGRC24 and TAM 107 were also more antixenotic to apterae than Halt. In two rounds of an antibiosis experiment, time to reproductio for R. padi did not differ among wheat accessions. In one round, the number of nymphs differed among wheat accessions, as R. padi produced more nymphs on accession KS92WGRC24 than on GRS 1201, Halt, MV4, STARS-9303W, or Vista. Intrinsic rates of increase of R. padi ranged from 0.338 on TAM 110 to 0.391 on KS92WGRC24 in the first round, and from 0.356 on MV4 to 0.395 on TAM 107 in the second. When R. padi were placed on seedlings as first instars, the proportion that developed wings did not differ among accessions in two rounds of this experiment. Moderate to low levels of resistance to R. paid in accession MV4 may limit infestations and indirectly slow the spread of aphid-transmitted diseases such as barley yellow dwarf.