The sequential effects of feeding by grass bugs (Irbisia pacifica [Hemiptera: Miridae]) and of drought stress on the growth of 2 crested wheatgrasses (the hybrid Agropyron cristatum × desertorum and A. cristatum cv. 'Fairway') were investigated in a controlled greenhouse experiment. Growth rates of genotypes that were previously selected for resistance to grass bug feeding were not consistently greater than those of unselected genotypes when plants were exposed to bug feeding. Thus, the mechanism of resistance to bug feeding for the selected genotypes does not appear to be "tolerance," i.e., rapid growth rates that allow the resistant genotypes to compensate for damage to green leaves caused by bug feeding. In addition, previous bug feeding did not exacerbate the effects of drought stress on plant growth rates; droughted plants generally had lower growth rates, independent of the presence or absence of prior bug feeding. Thus, we suspect that the selection process may have inadvertently favored green, robust plants rather than true resistance to bug feeding.
Nowak, Robert S.; Hansen, James D.; and Nowak, Cheryl L.
"Effects of grass bug feeding and drought stress on selected lines of crested wheatgrass,"
Western North American Naturalist: Vol. 63
, Article 3.
Available at: http://scholarsarchive.byu.edu/wnan/vol63/iss2/3