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Abstract In parasitoid systems, resource competition can significantly impact developmental outcomes. This study investigates how larval competition and host characteristics influence development in the acoustic parasitoid fly Ormia ochracea, using the house cricket Acheta domesticus as a host. We experimentally manipulated larval load (1 vs. 2 larvae per host) and recorded host sex and size to assess their effects on pupation and eclosion (adult hatching) success, as well as pupal and adult fly size. While double infestations increased total yield (0.78 vs. 0.54 flies per host), larvae developing without competition exhibited higher relative pupation and eclosion success and produced larger pupae and adult flies, indicating greater individual fitness. Although female host crickets yielded larger pupae, resource competition was the dominant factor shaping developmental outcomes. These results highlight the trade-offs between reproductive yield and offspring fitness driven by resource competition and validate the commercially available A. domesticus as a viable host.
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This content will become publicly available on July 10, 2026
Reproductive anatomy and embryogenesis of a viviparous, phonotactic, parasitoid fly
Abstract Ormia ochracea (Bigot 1889) is a phonotactic parasitoid fly that targets a variety of field cricket species as hosts for their developing young. Female flies locate their hosts by tracking a male cricket’s courtship song. Viviparous larvae are then deposited on or near the host which they then pierce and penetrate, completing larval development within the cricket’s abdomen. Here, we describe Ormia male and female reproductive tracts exposed through micro-surgery and imaged with a variety of microscopic techniques. We also describe for the first time, both embryonic and early larval development that takes place within the female flies’ “uterus.” Special note is made of the phenomenon of intra-uterine embryonic growth, and prospects for accessing gametes or germ-cells for molecular engineering are discussed.
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- Award ID(s):
- 2144831
- PAR ID:
- 10614552
- Editor(s):
- Onstad, David
- Publisher / Repository:
- Oxford Academic
- Date Published:
- Journal Name:
- Annals of the Entomological Society of America
- ISSN:
- 0013-8746
- Subject(s) / Keyword(s):
- parasitoid, fly, embryo, development, uterus
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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