Bees, butterflies, and other pollinators are essential for maintaining healthy ecosystems, as they rely on floral nectar for energy. However, recent studies show that nectar is more than just a sugar-rich liquid; the micro-components within nectar can significantly influence insect flower preferences, affecting the interactions between plants and insects in the ecosystem.

Researchers from the Wuhan Botanical Garden (WBG) of the Chinese Academy of Sciences conducted a study in a species-rich alpine meadow in China to investigate how nectar amino acids (AAs) influence pollinator behavior. They analyzed the composition of 21 nectar AAs across 40 different plant species and assessed their impact on the visitation frequency of over 200 insect species. Their findings were published in the journal Plant Ecology.

The researchers discovered that while the nectar of most plants contained all 21 AAs, the relative concentrations of these amino acids varied significantly among species. Using Bayesian phylogenetically generalized mixed models, the study indicated that the presence of certain amino acids, such as γ-aminobutyric acid (GABA) and methionine, significantly affected how often pollinators visited the flowers.

"We found that social bees, the dominant pollinators in the study meadow, are particularly attracted to nectar rich in GABA and methionine," explained Prof. YANG Chunfeng. "We hypothesize that GABA may enhance cognitive functions like memory and learning in these bees, making them more efficient foragers in the Hymenoptera order." 

Moreover, the study revealed variances in preferences among different types of flies within the Diptera order. For example, muscoid and meat flies preferred nectar with high proline concentrations, while horseflies negatively responded to nectar high in arginine. These differences can be attributed to the insects' feeding strategies and nutritional needs, illustrating the complexity of plant-pollinator interactions.

This study highlights the significant role of nectar amino acids in shaping the dynamics of plant-pollinator networks, offering new insights into the mechanisms that maintain biodiversity. 

The effect of different amino acids (AAs) in nectar on the visitation frequency of social bees (a), solitary bees (b), hoverflies (c), muscoid flies (d), meat flies (e), horseflies (f), Lepidoptera (g), Coleoptera (h). (Image by WBG)