Effect of L‐3,4‐dihydroxyphenylalanine, ornithine and γγ‐aminobutyric acid on winter wheat resistance to grain aphid

The association between the concentrations of L‐3,4‐dihydroxyphenylalanine (L‐DOPA), ornithine, and γ‐aminobutyric acid (GABA) in winter wheat cultivars with their antibiotic resistance to the grain aphid Sitobion avenae (F.) (Hom., Aphididae) was studied. The antibiosis was measured under field conditions using the intrinsic rate of natural increase (rm). The content of the studied non‐protein amino acids was estimated in flag leaf at the beginning of anthesis growth stage. Highly significant negative correlations were found between the rm values and concentrations of L‐DOPA (r = −0.937) and ornithine (r = −0.907), but not with GABA (r = −0.363). The contribution of these allelochemicals to the resistance of the plants to insects is discussed.