Influence of phenolic acids isolated from blackcurrant and sour cherry leaves on grain aphid [Sitobion avenae F.]

Effect of plant phenolics isolated from leaves of blackcurrant (Ribes nigrum L.) and sour cherry (Prunus cerasus L.) as potential biopesticides against the grain aphid was examined. The extracts from the sour cherry contained a twice higher level of salicylic acid than extract from leaves of the blackcurrant. Moreover, concentration of chlorogenic acid was higher in sour cherry and the content of tannic acid within both plant tissues was at the same level. Both examined extracts had a negative effect on development of the grain aphid when the aphid fed on wheat plants sprayed with 1.0%, 2.5% and 5.0% solutions. The length of prereproductive period (time from birth to maturity) of the aphids was extended from 5.9 days on control plants (not sprayed) to 8.1 days, when the aphids were fed on the treated plants. Apterous females of Sitobion avenae fed on sprayed plants showed lower fecundity and lower values of intrinsic rate of natural increase.