Environment stress, plant quality and abundance of cereal aphids (Hom., Aphidae) on winter wheat.
1991
Honek A.
Environment stress in the course of wheat development caused modified plant stature. Below ground stress (poor soil quality and nutrition, drought) increased relative root size (root to shoot ratio). Above ground stress (crop density) had the reverse effects, the plants were tall and the leaves great. Any type of stress decreased plant size. This variation affected plant qualities important for performance of Metopolophium dirhodum (Walker), Sitobion avenae (F.) and Rhopalosiphum padi (L.). The abundance and impact on host plant of M. dirhodum and R. padi decreased with worsening plant quality (increasing root to shoot ratio and decreasing size). The abundance of S. avenae was little influenced, or even increased on low quality plants on poor soils. Proportions of different species in total aphid population also varied with plant quality and were similar in 1987-1989, even when annual variation of aphid abundance was great. Proportion of aphids present on ears from the total aphid population on a plant increased, and the one present on leaves decreased with worsening plant quality. The differences in aphid performance on low and high quality plants were related to variation in energy (dry mass) which a plant allocated to different organs. Factors which determine these differences, overall intensity of environment stress on a host plant and its partitioning among below and above ground organs, were thus general determinants of aphid abundance.
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