Parasitoid complex of alfalfa aphids in an IPM intensive crop system in northern Catalonia

Abstract

Alfalfa aphids were monitored and aphid parasitism was determined in three crop-growing seasons (2007)(2008)(2009) in commercial alfalfa fields in valleys close to the Pyrenees, where an intensive arable crop rotation is practised under non-tillage 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 alfalfa.

Attraction of Aphidius ervi (Hymenoptera: Braconidae) and Aphidoletes aphidimyza (Diptera: Cecidomyiidae) to Sweet Alyssum and Assessment of Plant Resources Effects on their Fitness

“…The parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) and the predator Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae) are among the most important natural enemies of this pest (Rabasse andvan Steenis 1999, Blümel 2004). These natural enemies have been recorded in spring in the production areas were orchards coexist with arable crops (Pons and Stary 2003, Miñarro et al 2005, Pons et al 2011 and both have been repeatedly found on M. persicae colonies in Prunus orchards early in spring (authors' unpublished data). However, M. persicae attacks Prunus sp.…”

Movement of three aphidophagous ladybird species between alfalfa and maize revealed by carbon and nitrogen stable isotope analysis

“…Conservation biological control involves the manipulation of the environment to enhance the effectiveness of natural enemies (Landis et al 2000) and is currently the only cost-effective biological control method in arable crops in many Mediterranean regions (Pons and Eizaguirre 2009;Pons et al 2011). The management of the environment may focus on the habitat, farm or landscape levels (Landis et al 2000), with scale-dependent effects on natural enemies (Tscharntke et al 2007).…”

Change in carbon stable isotope ratios of the predatory bug Orius majusculus after dietary shifts

“…The incomplete turnover of the d 13 C signature to the new food source until nearly 4 weeks reveals the origin of an insect that has moved from one crop to another many days before. This interpretation is only possible if the adjacent crops do not share pests, as in the case of maize and alfalfa (Pons et al, 1994(Pons et al, , 2011 and other C3 crops, and may help to understand insect spillover between these kinds of crop.…”