A modified DNA barcode approach to define trophic interactions between native and exotic pentatomids and their parasitoids

Authors: GARIEPY, TARA - Agriculture And Agri-Food Canada; BRUIN, ALLISON - Agriculture And Agri-Food Canada; KONOPKA, JOANNA - Agriculture And Agri-Food Canada; SCOTT-DUPREE, CYNTHIA - University Of Guelph; FRASER, HANNAH - Ontario Ministry Of Agriculture; BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL); TALAMAS, ELIJAH - Florida Department Of Agriculture And Consumer Services

Submitted to: Molecular Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2018
Publication Date: 9/16/2018
Citation: Gariepy, T., Bruin, A., Konopka, J., Scott-Dupree, C., Fraser, H., Bon, M., Talamas, E. 2018. A modified DNA barcode approach to define trophic interactions between native and exotic pentatomids and their parasitoids. Molecular Ecology. 13(15):1-15. DOI: 10.1111/mec.14868.
DOI: https://doi.org/10.1111/mec.14868

Interpretive Summary: The brown marmorated stink bug (BMSB), Halyomorpha halys, which originated in Asia, has spread during the last decade throughout USA and Canada. It attacks a wide variety of economically important tree fruits, vegetables, and field crops, and potentially impacts trophic interactions among beneficial native insects, including bugs and parasitoids. To better estimate the impact of BMSB on trophic interactions, particularly the associations in natural habitats of a family of parasitoid wasps known as scelionids which parasitize the eggs of stink bugs, a large number and variety of naturally occurring stink bug eggs (> 2000 individual eggs) were collected in Canada and were analyzed using a DNA-based approach. Identification to the species level of large numbers of eggs using this DNA-based approach was straightforward and effective for more than 90% of the eggs as contrasted with classical techniques based on rearing and dissection. Eleven different stink bugs, including BMSB, were identified. Approximately 70% of their egg masses were parasitized and five scelionid parasitoids were identified. Surprisingly, 55% of BMSB were parasitized. This conclusively demonstrates for the first time that BMSB is attacked by a diversity of parasitoids, despite the subsequent failure of these parasitoids to develop. These results validate the use of this DNA-based barcode approach for evaluating host-parasitoid associations for stink bugs and demonstrate its utility for future BMSB field surveys in North America.

Technical Abstract: The establishment of the brown marmorated stink bug (BMSB) Halyomorpha halys (Stål) outside of its native range may impact native species assemblages, including other pentatomids and their scelionid parasitoids. This has generated interest in defining species diversity and host parasitoid associations in this system to better understand the impact of invasive alien species on trophic interactions in invaded regions. Information on scelionid pentatomid associations in natural habitats is lacking, and species-level identification of these associations can be tenuous using rearing and dissection techniques. Naturally occurring pentatomid eggs were collected in areas where H. halys has established in Canada and were analysed using a modified DNA barcoding approach to define species-level trophic interactions. Identification was possible for >90% of egg masses. Eleven pentatomid and five scelionid species were identified, and trophic links were established. Approximately 70% of egg masses were parasitized; parasitism and parasitoid species composition were described for each species. Telenomus podisi Ashmead was the dominant parasitoid and was detected in all host species. Trissolcus euschisti Ashmead was detected in several host species. Trissolcus brochymenae and Tr. thyantae were recorded sporadically. Parasitism of H. halys was 55%, and this species was significantly less likely to be parasitized than native pentatomids. The scelionid species composition of H. halys consisted of Te. podisi, Tr. euschisti and Tr. thyantae. Although these species cannot develop in fresh H. halys eggs, we demonstrate that parasitoids attempt to exploit this host under field conditions.