Aphid parasitoid complex in potato in the context of IPM in Belgium.

Parasitic hymenoptera of potato aphids were collected and identified in 2000 and 2001 in 11 potato fields in Belgium. Nine Aphidiidae species, parasiting seven aphid species, were found: Aphidius ervi, Aphidius matricariae, Aphidius picipes, Binodoxys angelicae, Diaeretiella rapae, Praon abjectum, Praon gallicium, Praon volucre and Toxares deltiger. A. ervi and A. picipes were the dominant and sub-dominant species, with 54% and 28% of the primary parasite collected, respectively. Both species and T. deltiger were found on Aphis nasturti, Aulacorthum solani, Macrosiphum euphorbiae and Myzus persicae, the four most important aphid potato in Belgium. Parasitism rate of A. nasturtii and, to a lesser extent, M. euphorbiae was low compared to A. solani and M. persicae. Parasitism of A. solani was particularly high, with 63.5% in 2000 and 89.2% in 2001, and this species was the preferred host of several Aphidiid species. The abundance of alternative hosts as other crops pest aphids or non-pest aphids on wild plants in agroecosystems could explains the efficacy of these species. The biological control of A. nasturtii and M. euphorbiae by parasitic hymenoptera was poorer, and several studies need to be undertaken to find suitable parasitic hymenoptera species effective on these aphids and agro-environmental measures able to promote them.