A Molecular Approach to Unravel Trophic Interactions Between Parasitoids and Hyperparasitoids with Pecan Aphids

Authors: Slusher, Eddie; Cottrell, Ted; GARIEPY, TARA - Agriculture And Agri-Food Canada; Acebes-Doria, Angelita; COMA, MARINA - University Of Oviedo; TOLEDO, PEDRO - University Of Georgia; SCHMIDT, JASON - University Of Georgia

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Parasitic wasps can be important agents for biological control, however, there are numerous challenges in understanding how they interact with their host species as well as other organisms in their environment. Understanding host-parasitoid interactions is important in order to improve biological control services. Parasitic wasp/host interactions are poorly explored in many systems including large perennial tree systems such as pecan. The pecan systems is especially of interest as it contains multiple species that interact with each other including three species of aphid (yellow pecan aphids, blackmargined aphid, and black aphid) and one primary parasitic wasp. However, little is known about the other key players in these interactions. Using DNA extracted from parasitized aphid (a.k.a mummies), we were able to used barcoding and metabarcoding techniques to characterize the southeastern pecan aphid-parasitic wasp food web for the first time. Based off our results we were able to confirm the presence of the three pecan aphid species and it's primary parasitic wasp. In addition, we also found evidence of an additional primary parasitic wasp and eight hyper parasitic wasps that parasitize the primary parasitic wasps. Our results reflect similar studies that show heavy pressure on primary parasitic wasps from hyper parasitic wasps. This was the first time that many of these species have been characterized, and represents a novel approach to analyze the pecan aphid-parasitic wasp food web in both pecans and the tree nut system in general.

Technical Abstract: Advances in molecular ecology can overcome many challenges in understanding parasitoid-host interactions in the agro-ecosystem; however, relatively few cropping systems have been explored with this technology. An initial genetic characterization of the key-players in a given system is critical in order to take advantage of trophic interactions or improve services such as biological control. The pecan system is a large tree perennial system containing multiple interacting species, and little is known of this food-web or associated arthropod communities. As a first step to characterizing pecan food webs, we focus on aphid species and their associated parasitoids. Based on DNA barcoding results, we verified three species of aphid, of emerged parasitoids from mummies we identified one primary parasitoid family, and five hyperparasitoids. Applying metabarcoding to aphid mummies and combining the data with full DNA barcodes reveals a complex food web of three aphid species, two primary parasitoids, and upwards of eight hyperparasitoids. The read data indicates primarily we find on primary parasitoid in aphid mummies at around 43% of mummies collected and amplified, and 8% hyperparasitism. Although further research is needed on a broader spatial scale, our results suggest multiple hyperparasitoids and potentially quite a complex set of interactions between the three aphid species. This was the first time that many of these species have been characterized, and represents a novel approach to analyze the pecan aphid-parasitoid food web in both pecans and the tree nut system in general.