Susceptibility of Macrosiphum euphorbiae to the parasitoid Aphidius ervi: larval development depends on host aphid genotype

The potato aphid, Macrosiphum euphorbiae Thomas (Hemiptera: Aphididae: Macrosiphini), is a common polyphagous aphid in Europe and North America. However, the factors influencing potato aphid dynamics and susceptibility to natural enemies are largely undescribed, particularly in relation to facultative endosymbiotic bacteria, which can provide protection against parasitism and disease in some aphid species. This study investigated whether potato aphid susceptibility to one of its principal natural enemies, the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae), varied in relation to aphid genotype and/or endosymbiont presence. Parasitism and aphid fitness assays were conducted on clonal lineages of aphids, harbouring their natural endosymbiont infections, collected over 3 years from separate geographic locations. Parasitized aphids were dissected to quantify parasitoid oviposition, larval development, and mummification. Amongst the 19 clonal lines of M. euphorbiae tes...