Can the Geranium Bronze Emphasis Type="Italic"C

Authors: Ambra Quacchia Chiara Ferracini Simona Bonelli Emilio Balletto Alberto Alma

Publish Date: 2008/02/20

Volume: 17, Issue: 6, Pages: 1429-1437

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Abstract

Cacyreus marshalli Butler is an invasive species in many parts of Europe and Mediterranean area In Europe its larvae normally feed on pelargoniums We investigated its potential to spread to native Geranium spp and evaluated the conservation risks that such a shift would pose for both native geraniums and cohabitant butterflies The host plant preferences of the Geranium Bronze were investigated under controlled conditions Studies included both nochoice and multichoice tests respectively using 9 and 6 Italian native Geranium spp Host plant preferences were evaluated by counting the number of eggs laid on individual plants and following butterfly development until adult emergence Under nochoice conditions at least one egg was recorded on each tested plant except for G phaeum L All the plants on which oviposition occurred were fully suitable for larval development The butterfly however clearly preferred three species ie G pratense L G sanguineum L and G sylvaticum L for oviposition In multichoice trials females laid at least one egg on all the tested plants with a preference for G pratense and G sylvaticum In presence of Pelargonium spp plants however no oviposition was observed on any Geranium spp We assessed offspring fitness measuring their wingspan No statistical differences were detected in the wingspan between adults emerged from Geranium and Pelargonium Cacyreus marshalli represents a potential threat for both native geraniums and for Geraniumconsuming lycaenids such as Aricia nicias Meigen and Eumedonia eumedon EsperThis research was part of the Interreg IIIALCOTRA project “Strategie di lotta biologica per contenere fitofagi esotici di recente introduzione nella zona transfrontaliera italofrancese a salvaguardia delle diverse realtà ambientali” and funded by Regione Piemonte and Regione Valle d’Aosta Finally we wish to thank an anonymous referee for his many useful comments

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