Integrative Taxonomy to Assess the Parasitoid Complex of the Jumping Plant-Louse Cacopsylla pulchella (Hemiptera: Psyllidae) on Cercis siliquastrum in Central and Southern Italy

TL;DR

This study identifies the main parasitoid and hyperparasitoids of a plant-louse pest in urban areas using both physical and genetic analysis.

Contribution

The study confirms Prionomitus mitratus as the primary parasitoid and provides new genetic data for parasitoid species.

Findings

Prionomitus mitratus is the main parasitoid of Cacopsylla pulchella.

Two Pachyneuron species and Anastatus bifasciatus act as hyperparasitoids.

New genetic data for Prionomitus mitratus was generated and made publicly available.

Abstract

In this study, we used an integrative approach to investigate the complex of parasitoids associated with the jumping plant-louse Cacopsylla pulchella, a common sap-sucking pest of the Judas tree (Cercis siliquastrum) in urban areas. We identified Prionomitus mitratus as the main parasitoid of the pest, with two species of Pachyneuron acting as hyperparasitoids. By combining morphological identification with DNA analysis, we confirmed species identities and generated new genetic data for public databases. These findings enhance our understanding of the natural regulation of C. pulchella and support future taxonomic research on parasitoids in anthropogenic areas.

Urban green spaces host complex arthropod communities, in which natural insect antagonists play a key role in regulating pest populations. The jumping plant-louse Cacopsylla pulchella is a sap-sucking pest widespread across Europe that attacks Cercis siliquastrum L., which is commonly used as an ornamental tree. Heavy infestations may contribute to host tree decline and cause indirect damage in urban environments by reducing aesthetic value and by extensive deposition of honeydew secretions on surrounding surfaces. As with many phytophagous insects occurring in urban contexts, information on the natural enemies of this species remains limited, particularly in Italy, and requires further documentation. Here, we investigated the parasitoids associated with C. pulchella in central and southern Italy based on surveys conducted between 2022 and 2025. Specimens were obtained from infested plant material and identified using an integrative taxonomic approach combining detailed morphological examination with DNA barcoding. Prionomitus mitratus was confirmed as the primary parasitoid of C. pulchella, while two species, Pachyneuron muscarum and Pachyneuron aphidis, were identified as hyperparasitoids. In addition, a single specimen of Anastatus bifasciatus was also recorded emerging from the psyllid as a hyperparasitoid. Molecular analyses generated the first publicly available mitochondrial and nuclear sequences for P. mitratus. For Pachyneuron, molecular results showed variable correspondence with available reference sequences, reflecting the uneven representation of species-level data for Pteromalidae in public databases. By integrating morphological and molecular evidence, this study clarifies trophic relationships within the C. pulchella parasitoid complex. It provides vouchered molecular references to support future taxonomic and ecological research in urban ecosystems.

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