Pre-release risk assessment of the egg-parasitoid Gryon pennsylvanicum for classical biological control of Leptoglossus occidentalis

Authors

  • P. F. Roversi,

    Corresponding author
    1. Consiglio per la Ricerca e la sperimentazione in Agricoltura, Centro di Ricerca per l'Agrobiologia e la Pedologia, Florence, Italy
    • Correspondence

      P. F. Roversi (corresponding author), Consiglio per la Ricerca e la sperimentazione in Agricoltura, Centro di Ricerca per l'Agrobiologia e la Pedologia, Via di Lanciola 12/a, 50125 Florence, Italy. E-mail: piofederico.roversi@entecra.it

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  • G. Sabbatini Peverieri,

    1. Consiglio per la Ricerca e la sperimentazione in Agricoltura, Centro di Ricerca per l'Agrobiologia e la Pedologia, Florence, Italy
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  • M. Maltese,

    1. Consiglio per la Ricerca e la sperimentazione in Agricoltura, Centro di Ricerca per l'Agrobiologia e la Pedologia, Florence, Italy
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  • P. Furlan,

    1. Consiglio per la Ricerca e la sperimentazione in Agricoltura, Centro di Ricerca per l'Agrobiologia e la Pedologia, Florence, Italy
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  • W. B. Strong,

    1. Kalamalka Forestry Centre, British Columbia Ministry of Forests, Lands and Natural Resource Operations, Vernon, BC, Canada
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  • V. Caleca

    1. Dipartimento di Scienze Agrarie e Forestali, Università degli Studi di Palermo, Palermo, Italy
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Abstract

Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae) is a North American conifer seed pest that was accidentally introduced to Europe. In the Mediterranean area, it threatens the production of Pinus pinea Linnaeus seeds. The egg-parasitoid Gryon pennsylvanicum (Ashmead) (Hymenoptera: Platygastridae), the main natural enemy in the native range of L. occidentalis, was imported from British Columbia to Italy. Pre-release risk assessments were made under quarantine conditions by no-choice tests conducted with naïve and experienced G. pennsylvanicum offering single eggs of target and non-target species for varying exposure times (1, 4, 48 h). G. pennsylvanicum successfully parasitized from 75% to 100% of the target host eggs. Only one female specimen of the egg-parasitoid emerged from a non-target egg (Gonocerus juniperi Herrich-Schaeffer, Heteroptera: Coreidae). Two dead female specimens were found, one inside an egg of Coreus marginatus (Linnaeus) (Heteroptera: Coreidae) and one in an egg of Camptopus lateralis (Germar) (Heteroptera: Alydidae). All three cases occurred at the longest oviposition exposure time. Results obtained with this conservative approach suggest that the risk to non-target species of releasing G. pennsylvanicum in Italy is low.

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