Compatibility assessment between four ethanolic plant extracts with a bug predator Orius horvathi (Reuter) (Heteroptera: Anthocoridae) used for controlling the western flower thrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

The western flower thrips, Frankliniella occidentalis (Pergande) attacks a large number of crop plants. The current insecticides have caused resistance in insects and have caused outbreaks of thrips. In many instances, alternative methods of insect management and natural products, offer adequate pest control and pose fewer hazards. Several species of minute pirate bugs of the genus Orius play a significant role in the biological control of a large number of thrips species, such as F. occidentalis. In this study, the insecticidal activity of four ethanolic plant extracts (Cercis siliquastrum L., Calendula officinalis L., Peganum harmala L., Melia azedarach L.) in integration with Orius horvathi (Reuter) were evaluated for controlling F. occidentalis. The present research aimed to find plant extracts with a good impact on F. occidentalis but which have fewer side effects on O. horvathi. The results showed that P. harmala extract can be considered compatible with the natural enemy for controlling thrips. When the predatory bugs O. horvathi, were released three days after P. harmala extract spraying, the integration was more effective. While the P. harmala plant extract plays an important role in thrips control, it is necessary to consider the specified time interval between the application of the P. harmala plant extract and the release of the O. horvathi predatory bugs. The ethanolic extract of M. azedarach caused a balance between the pest population and the natural enemy. This result is very important in an Integrated Pest Management (IPM) program because this ethanolic extract of M. azedarach had lower side effects on the natural enemy. This means that an integration of plant derived chemicals and the natural enemy, O. horvathi, can effectively control thrips.