Population dynamics of greenbug biotypes “E” and “F” on Texas bluegrass

Abstract

AbstractCool‐season perennial forage grasses are known to serve as alternate hosts of the greenbug, Schizaphis graminum (Rondani) in the southern Great Plains of the USA. Texas bluegrass (Poa arachnifera Torr.) is a cool‐season perennial forage grass indigenous to this region and because of its persistence under grazing is being bred for improved forage production. An experiment was conducted to determine the population dynamics of greenbug biotype “E”, the predominant biotype found in this region and biotype “F” which is known to infest bluegrass species. Twenty‐five Texas bluegrass genotypes, three Kentucky bluegrass (Poa pratensis L.) genotypes, a Canada bluegrass (Poa compressa L.) genotype, two Texas × Kentucky bluegrass hybrids, and a Texas × Canada bluegrass hybrid were screened for their abilities to support greenbug population growth. Bluegrass species and genotypes varied significantly in their ability to support greenbug biotypes E and F. On the basis of higher aphid numbers, biotype E had a higher population growth rate as compared with biotype F on Texas bluegrass. Some Texas bluegrass genotypes were not included in both biotype trials due to lack of availability of uniform plant material for inoculation. Nine of 25 Texas bluegrass genotypes did not support biotype E greenbug population growth. Similarly, 13 of 22 Texas bluegrass genotypes did not support biotype F population growth. Both Canada and Kentucky bluegrass supported high populations of biotype F and interspecific hybrids varied in their host suitability to both biotypes.