Nectar bacteria affect life history of a generalist aphid parasitoid by altering nectar chemistry

1. Nectar is a crucial energy resource that strongly mediates the interactions between plants and animal pollinators or plant defenders. Previous research has shown that nectar is commonly colonized by microorganisms, most commonly bacteria and yeasts, which can have a strong impact on nectar chemistry. However, at present little is known about the effects of microorganisms on the fitness of animals feeding on nectar.
2. We used three nectar bacteria representing different metabolic groups (Asaia sp., Lactococcus sp. and Rosenbergiella sp.) and the common generalist aphid parasitoid Aphidius ervi (Haliday) (Hymenoptera: Braconidae) to test the hypothesis that different nectar-dwelling bacteria affect nectar consumption and insect longevity differently by altering the chemistry of nectar.
3. Bacteria significantly affected nectar chemistry by altering its acidity, sugar and amino acids composition/concentration and by adding compounds synthesized by the microbes. Although inoculation w...