A molecular approach to unravel trophic interactions between parasitoids and hyperparasitoids associated with pecan aphids

TL;DR

This study uses DNA barcoding and metabarcoding to uncover complex food web interactions among aphids, parasitoids, and hyperparasitoids in pecan agroecosystems.

Contribution

The study is the first to characterize multiple hyperparasitoid species attacking a single primary parasitoid in pecan aphid systems using molecular methods.

Findings

Three aphid species, two primary parasitoids, and up to eight hyperparasitoid species were identified in pecan food webs.

Multiple hyperparasitoid species attack a single primary parasitoid, potentially reducing biological control effectiveness.

Molecular approaches revealed a complex trophic network previously unknown in pecan agroecosystems.

Abstract

Advances in molecular ecology can overcome many challenges in understanding host–parasitoid interactions. Genetic characterization of the key-players in systems helps to confirm species and identify trophic linkages essential for ecological service delivery by biological control agents; however, relatively few agroecosystems have been explored using this approach. Pecan production consists of a large tree perennial system containing an assortment of seasonal pests and natural enemies. As a first step to characterizing host–parasitoid associations in pecan food webs, we focus on aphid species and their parasitoids. Based on DNA barcoding of field-collected and reared specimens, we confirmed the presence of 3 species of aphid, one family of primary parasitoids, and 5 species of hyperparasitoids. By applying metabarcoding to field-collected aphid mummies, we were able to identify multiple species within each aphid mummy to unravel a complex food web of 3 aphids, 2 primary parasitoids, and upward of 8 hyperparasitoid species. The results of this study demonstrate that multiple hyperparasitoid species attack a single primary parasitoid of pecan aphids, which may have negative consequences for successful aphid biological control. Although further research is needed on a broader spatial scale, our results suggest multiple species exist in this system and may suggest a complex set of interactions between parasitoids, hyperparasitoids, and the 3 aphid species. This was the first time that many of these species have been characterized and demonstrates the application of novel approaches to analyze the aphid-parasitoid food webs in pecans and other tree crop systems.

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