Luteolin and quercetin affect aphid feeding behavior.

The flavone luteolin and the flavonol quercetin naturally occur in plants, providing some resistance against herbivores. However, despite suggesting the potential use of these compounds for plant protection, research on their relationship with aphids is limited. The aim of our study was to assess the effect of applying two flavonoids, quercetin and luteolin, at different concentrations, in vitro on the feeding behavior of the black bean aphid Aphis fabae Scopoli (Hemiptera: Aphididae). In most events associated with stylet activity, differences in probing behavior did not vary between the control gel and those with flavonoids. Higher concentrations of quercetin increased the number of penetrations, while lower concentrations of luteolin prolonged the first probing. The addition of flavonoids to the gels reduced passive ingestion. At a concentration of 0.1%, luteolin completely stopped salivation, and at 0.01%, it shortened the average duration of this activity. In events associated with active ingestion, differences in feeding behavior were observed between the control gel and those with quercetin at lower concentrations, affecting the time to the first stylet activity and the average time of active ingestion. Lower concentrations of luteolin prolonged the time to the first active ingestion, the duration of the first active ingestion, and the average time of this activity. Increased concentrations of quercetin and luteolin negatively affected aphid feeding behavior. Quercetin was better tolerated by A. fabae. A more noticeable effect was observed with an increase in luteolin concentration on the feeding behavior of A. fabae. These findings could be applied in biotechnological projects aiming to develop plants resistant to aphids and other herbivores. [ABSTRACT FROM AUTHOR]