| Scope of study. This study was undertaken to provide basic information on aphid induced physiological responses in cereals. The objectives of this study were: (1) to quantify the effects of aphid feeding on growth physiology and recovery of host plants, (2) to determine the relationships among visible plant responses to quantitative plant measurements to facilitate the development of predictive plant-damage evaluation indices for use in plant resistance screening, and (3) to determine the impact of aphid feeding on phloem function.;Findings and conclusions. Russian wheat aphid feeding disrupts the plant's water balance, causing significantly reduced turgor, which inhibits leaf unfolding and expansion, which was followed by cell bleaching. Detailed growth analysis showed, that after aphid removal, plants recovered quickly. During plant recovery, stem weight ratios were significantly reduced indicating that carbon partitioning to the stem was diminished to compensate for leaf and root growth. The most sensitive plant response measured was leaf area, and overall, plant stunting indices best predicted quantitative plant damage parameters. Aphid feeding did not interrupt phloem flow through leaf tissue. However, greenbugs significantly reduced $sp{14}$C movement which may indicate a general inhibition of membrane bound ATPase driven transport. Greenbug salivary material, injected during feeding, accumulated at the feeding site and in root tissue. The infested leaf tissue and root system sustained the greatest amount of damage, which supports the view that plant damage is may be caused by a salivary toxin. |
