Marijke Lenaerts, Tim Goelen, Caroline Paulussen, Beatriz Herrera-Malaver, Jan Steensels, Wim Van den Ende, Kevin J. Verstrepen, Felix Wäckers, Hans Jacquemynand Bart Lievens
When insects visit flowers looking for food, they commonly inoculate floral nectar with bacteria and yeasts. These microbes then gobble sugars and amino acids or convert them into other compounds which could change the nectar’s appeal for subsequent nectar-seeking insects such as pollinators and pest-controlling insects. In this study, we investigated whether nectar-inhabiting bacteria affect the longevity of a nectar-feeding insect by altering the chemistry of nectar. To this end, the aphid parasitic wasp Aphidius ervi, which feeds on nectar as an adult, was used as a study species. Bacteria significantly affected nectar chemistry by altering its acidity, sugar and amino acids composition/concentration and by adding compounds synthesized by the microbes. The three tested bacteria did not affect nectar consumption by the wasp over a nine-hour period of time. By contrast, bacterial modification of nectar affected insect longevity, but the outcome was largely dependent on the bacterial species, varying between neutral, beneficial or detrimental for the insects. Our results are not only interesting from an ecological point of view, but are also important from applied agricultural standpoints, given the large number of crops that rely on pollination and the diverse group of beneficial animals that depend largely on nectar for food.
Image caption: Capillary Feeder (CAFE) assay to test whether changes in nectar chemistry induced by the tested bacteria affect nectar consumption by insect parasitoids. Photograph credit: Marijke Lenaerts