Parasitoid complex of alfalfa aphids in an IPM int

Authors: Xavier Pons Belén Lumbierres Ribes Antoni Petr Starý

Publish Date: 2011/09/20

Volume: 84, Issue: 4, Pages: 437-445

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Abstract

Alfalfa aphids were monitored and aphid parasitism was determined in three cropgrowing seasons 2007–2009 in commercial alfalfa fields in valleys close to the Pyrenees where an intensive arable crop rotation is practised under nontillage and an integrated pest management system Acyrthosiphon pisum Therioaphis trifolii and Aphis craccivora were the aphid species colonizing alfalfa fields but their occurrence varied between years Thirteen Aphidiinae parasitoid species and four Aphelinidae from the genus Aphelinus sp were recorded Aphidius ervi was the prevalent parasitoid species associated with A pisum but Praon barbatum was also noticeable especially during the first year Trioxys complanatus and P exsoletum were the only species associated with T trifolii Lysiphlebus fabarum was the prevalent parasitoid species associated with A craccivora The occurrence of Lysiphlebus testaceipes parasitizing A craccivora on alfalfa is a new record for the study region because this parasitoid species had only been previously found on weeds Only A pisum and A craccivora were parasitized by Aphelinus sp Whereas A abdominalis and A semiflavus were associated with A pisum A chaonia and Aphelinus sp nr albipodus were associated with A craccivora Associations between aphid species and Aphidiinae or Aphelinidae parasitoid species emphasize that individual aphid species also possess individual parasitoid complexes guilds which do not interfere with each other in alfalfa Alloxysta victrix A macrophadna Alloxysta spp Asaphes suspensus A vulgaris Dendrocerus aphidum Pachyneuron aphidis and Syrphophagus aphidivorus were the hyperparasitoids associated with aphid–parasitoid complexes Our study showed A ervi T complanatus P exsoletum and L fabarum as potential candidate species which could provide biological control of their respectively aphid hosts in alfalfaThis research was partially funded by the Cooperativa Pirenaica de La Seu d’Urgell agreements CO8026 and CO9036 with the Universitat de Lleida Thanks are due to Ignacio Romagosa for helping with the statistical analysis and to Ramon Albajes for criticism of the manuscript We are also very grateful to Juli PujadeVillar Universitat de Barcelona for the identification of samples of Alloxysta species We further thank three anonymous reviewers for their valuable comments on the manuscript

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