Effect of black bean aphid,<i>Aphis fabae</i>, on transpiration, stomatal conductance and crude protein content of faba bean

Abstract

Abstract This study was initiated to investigate effects of damage by 0, 5 and 10 aphids/plant on the physiology of faba bean plants throughout different feeding periods and at two plant development stages. Immediately following removal of Aphis fabae , measurements showed 84–229% increase in transpiration rate. These changes were proportional to the number of aphids and infestation duration. Injury by A. fabae caused the stomatal conductance to be much higher in the leaves of infested plants. Leaf stomatal conductance of the infested plants increased significantly by 51–224% depending on initial aphid densities and feeding intervals. This increase was proportional to the infestation level for each date. Length of infestation period and plant growth stage seemed to have no clear effect on stomatal apertures. Aphid feeding caused a damage of about 7–33% of crude protein levels in the leaf tissue. This reduction increased with increasing infestation levels and time, except for 28‐day‐old plants on 28 days. The physiological effects of aphid feeding on water vapour and chemical composition of damaged leaves are particularly serious when the population is high.