# Evaluation of Pupal Parasitoids Trichomalopsis ovigastra and Pachycrepoideus vindemiae as Potential Biological Control Agents of Bactrocera dorsalis

## TL;DR

Researchers found that the parasitoid wasp Trichomalopsis ovigastra is a strong candidate for controlling the invasive fruit fly Bactrocera dorsalis in northern China.

## Contribution

The study reveals T. ovigastra's superior parasitism of B. dorsalis and environmental resilience compared to P. vindemiae, suggesting its potential as a biocontrol agent.

## Key findings

- T. ovigastra showed nearly 50% parasitism of B. dorsalis, compared to less than 0.3% by P. vindemiae.
- T. ovigastra had shorter developmental times and greater tolerance to environmental stressors like temperature extremes and desiccation.
- B. dorsalis has invaded northern China, but no native parasitoids have been reported there, making T. ovigastra a promising local biocontrol candidate.

## Abstract

Parasitoid wasps are well-known biocontrol agents, and discovering new species and examining their biological traits are essential to fully exploring their potential for pest management. In northern China, we collected Trichomalopsis ovigastra Sureshan & Narendran (Hymenoptera: Pteromalidae) directly from the field. This parasitoid species had previously only been described morphologically. In this study, we investigated additional biological characteristics of T. ovigastra and compared them with those of Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae), a well-known parasitoid wasp of Diptera insects. Our results indicate that T. ovigastra exhibits stronger parasitism of both Drosophila melanogaster Meigen (Diptera: Drosophilidae) and Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), shorter developmental times, and higher resistance to environmental stressors. Given the invasion of B. dorsalis into northern China and the absence of reported parasitoids in this region, our findings suggest that T. ovigastra could be a potential biocontrol agent for this invasive pest.

Parasitoid wasps are vital for biological control, and while new species continue to be discovered, evaluating their biological characteristics is crucial for realizing their potential for pest management. Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) is a well-studied parasitoid of dipteran pests, while Trichomalopsis ovigastra Sureshan & Narendran (Hymenoptera: Pteromalidae) has been only morphologically described. To assess its biocontrol potential, we compared the biological traits of T. ovigastra and P. vindemiae using Drosophila melanogaster Meigen (Diptera: Drosophilidae) and Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) as hosts. T. ovigastra showed significantly higher parasitism rates, especially against B. dorsalis, where T. ovigastra achieved nearly 50% parasitism, compared to less than 0.3% by P. vindemiae. When using D. melanogaster as the host, no significant differences were observed between T. ovigastra and P. vindemiae in offspring sex ratio or adult longevity; however, T. ovigastra exhibited a shorter developmental duration and greater tolerance to temperature extremes, starvation, and desiccation. Notably, B. dorsalis has expanded its range from southern to northern China; however, no native parasitoids of this pest have been reported in the newly invaded northern regions. T. ovigastra, collected from northern orchards and capable of parasitizing B. dorsalis, thus shows promise as a biocontrol agent. These findings highlight the potential of locally occurring parasitoids, although field validation is still required.