Host immunity, non-reproductive effects and kelptoparasitism from novel interactions: a case study with the fruit fly parasitoid Psyttalia fletcheri (Hymenoptera: Braconidae)

Authors: RAMADAN, MOHSEN - State Of Hawaii; Hoelmer, Kim; Wang, Xingeng

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2023
Publication Date: 7/25/2023
Citation: Ramadan, M.M., Hoelmer, K.A., Wang, X. 2023. Host immunity, non-reproductive effects and kelptoparasitism from novel interactions: a case study with the fruit fly parasitoid Psyttalia fletcheri (Hymenoptera: Braconidae). Biological Control. https://doi.org/10.1016/j.biocontrol.2023.105307.
DOI: https://doi.org/10.1016/j.biocontrol.2023.105307

Interpretive Summary: Fruit flies are economically important invasive horticultural pests worldwide. Biological control has been one of the safest, most environmentally benign, and cost-effective methods for sustainable and areawide management of invasive pests. Four notorious fruit fly species invaded Hawaii during the last century. Many natural enemies (parasitic wasps) have been introduced from different regions into Hawaii for the biological control of these invasive pest fruit flies. This has resulted in some novel interactions and outcomes between different natural enemies and pests in the aftermath of pest invasions and natural enemy introductions. We found that a single introduced natural enemy, the parasitic wasp Psyttalia fletcheri, is the most suitable natural enemy of one of the four invaded pests, Zeugodacus cucurbitae, and corrected some erroneous host records for this parasitic wasp.

Technical Abstract: Interactions between a parasitoid and its host may result in successful parasitism or non-reproductive effects (unsuccessful parasitism due to host immunity and/or parasitoid-induced host mortality, especially in a novel interaction). Previous parasitism by a suitable parasitoid may suppress a host’s immune response, allowing a non-suitable parasitoid to develop from the host (kleptoparasitism). This study illustrated these interactions and outcomes between the solitary larval endparasitoid Psyttalia fletcheri (Hymenoptera: Braconidae) and its co-evolved (Zeugodacus cucurbitae) and novel (Bactrocera dorsalis, B. latifrons, and Ceratitis capitata) (all Diptera: Tephritidae) hosts in the aftermath of biological control introductions against these invasive pests in Hawaii. We demonstrated that the parasitoid could accept all four hosts for oviposition. As a reproductive host, however, B. dorsalis was not suitable, as the parasitoid’s eggs and first instars were encapsulated and melanized and only 0.4% of the parasitoid’s progeny developed to adults; B. latifrons was moderately suitable, with a 15.3% emergence rate; while C. capitata was as suitable as Z. cucurbitae. After B. dorsalis was parasitized first by its effective parasitoid, Diachasmimorpha longicaudata (Hymenoptera: Braconidae), 1.9% of P. fletcheri offspring developed to adults in B. dorsalis. Similarly, Z. cucurbitae was not suitable for D. longicaudata, but after Z. cucurbitae was first parasitized by P. fletcheri, followed by D. longicaudata, 1.1% of the latter species developed to adults. Parasitization by unsuitable parasitoids induced high host mortalities in those cases. A ten-year survey did not recover any P. fletcheri from 22,359 puparia of B. dorsalis, B. latifrons, and C. capitata collected from various host fruits on the Hawaiian Islands, and this parasitoid emerged only from Z. cucurbitae. We discuss the implications of these results for host specificity assessments in biological control of tephritid fruit flies.