Gravid syrphid females laid more eggs toward the generalist aphid over the specialist one.

The presence of intraguild competitor and sinigrin content of host plants negatively influenced oviposition preference of the test syrphid.

This study showed that specialist prey could promote specialization at the higher trophic levels.

Oviposition behaviour in aphidophagous hoverflies is a complex process that involves several cues (visual, auditory, olfactory and gustatory): our findings help clarify some of these factors.