Biological potential of predator <i>Orius similis</i> and parasitoid <i>Encarsia formosa</i> in combination on <i>Bemisia tabaci</i> : a greenhouse cage assay

<i>Bemisia tabaci</i> is one of the most important agricultural pests worldwide, and the combined application of multiple natural enemies such as predators and parasitoids can potentially control <i>B. tabaci</i>. The study examined whether the predator <i>Orius similis</i> and the parasitoid <i>Encarsia formosa</i> can synergistically control <i>B. tabaci</i> (crop: kidney bean). The greenhouse cage method was used to release <i>O. similis</i> and <i>E. formosa</i> alone or in combination in different ratios. The combined release of <i>O. similis</i> and <i>E. formosa</i> synergistically decreased the <i>B. tabaci</i> population when compared with <i>O. similis</i> or <i>E. formosa</i> alone. Additionally, <i>O. similis</i> + <i>E. formosa</i> decreased the number of <i>E. formosa</i> black pupae and adults in each crop stage. However, the niche overlap index of <i>E. formosa</i> with <i>B. tabaci</i> nymphs in the <i>O. similis</i> + <i>E. formosa</i> group was higher than in the <i>E. formosa</i> group. Grey correlation analysis revealed that the correlation degree between natural enemies and <i>B. tabaci</i> was the highest when the <i>O. similis</i> and <i>E. formosa</i> release ratio was 1:3. These findings indicate that the combined release of <i>O. similis</i> and <i>E. formosa</i> synergistically controlled <i>B. tabaci</i> with the release ratio 1:3 being optimal for field application.