Performance of the Cabbage Aphid, Brevicoryne Brassicae (L.), On Water-Stressed Rape Plants, in Relation to Changes in Their Chemical Composition.

Lack of water increases the total amino acid content of the leaves and phloem sap of rape plants. The concentration of proline, in particular, increases and is strongly negatively correlated with relative water content. Lack of water also causes a decrease in total carbohydrates, but appears to have no significant effect on total phenolics. Water stress increases the rate of development of aphids born on the plant. but as stress becomes pronounced, the insects become restless. No consistent effect on fecundity was observed, and survival was very high, regardless of water-regime, up to the time the plants became so wilted as to be rejected by the insects.