Original paper
Combined release of the predator Orius similis and the parasitoid Encarsia formosa enhances biological control of Bemisia tabaci
Zhang, Bo; Patcharin, Krutmuang; Vivekanandhan, Perumal; Kong, Jiao; Zhang, Jin-Long; Yang, Nian; Zhou, Ya-Ting; Zhang, Xiao-Ming
Entomologia Generalis Volume 46 Number 1 (2026), p. 109 - 120
published: Mar 31, 2026
published online: Jan 28, 2026
manuscript accepted: Nov 23, 2025
final revised version received: Oct 23, 2025
manuscript revision requested: Oct 2, 2025
manuscript received: Jul 18, 2025
ArtNo. ESP146004601011, Price: 29.00 €
Abstract
The predatory bug Orius similis prefers to prey on the early-instar nymphs of Bemisia tabaci, while the parasitoid Encarsia formosa targets the late-instar nymphs. Consequently, complementary release strategies of both these natural enemies may be a promising tactic to increase downward pressure on B. tabaci populations and enhance current biological control strategies. This hypothesis was tested by examining different release ratios of natural enemies under different temperature regimes within the laboratory and under more natural conditions using cage studies in the field. The results from this study indicated that when O. similis and E. formosa were released in ratios of 1:1, 1:2, and 1:3, the parasitism of E. formosa was higher than when it was released alone, whereas the predation of O. similis was lower than its solitary release. At 19, 22, 25, 28, and 31 °C, the responses of O. similis and E. formosa to B. tabaci nymphs were consistent with a type II functional response. The combined release of O. similis and E. formosa had the strongest control efficacy on B. tabaci nymphs at 28 °C. The effectiveness of different release ratios of O. similis and E. formosa on the control rate of B. tabaci nymphs was ranked as follows: 1 O. similis + 3 E. formosa > 1 O. similis + 2 E. formosa > 3 O. similis + 1 E. formosa > 2 O. similis + 1 E. formosa > 1 O. similis + 1 E. formosa > O. similis > E. formosa. Additionally, cage tests demonstrated that the combined release of O. similis and E. formosa effectively controlled the B. tabaci population. The 1:3 release ratio yielded superior control compared to other ratios. Therefore, when releasing O. similis and E. formosa in the field, it is recommended to do so at temperatures between 25 °C to 31 °C, with a ratio of 1:3, to significantly enhance the control of B. tabaci.
Keywords
biological control • combined release • functional responses • nymphal stage targeting • predator-prey interaction • parasitoid • temperature effect