Insect pollinators show constancy for different flower traits between the most‐ and less‐preferred plants: a case study of the long‐proboscid tangle‐veined fly

1. The coevolution of insect pollinators and their host plants is a typical example of natural selection; however, it remains unclear as to how insect pollinators avoid overdependence on one peculiar plant. As most insect pollinators exhibit a diet breadth when showing flower constancy, to determine the difference and similarity of most and less-preferred flowers by insect pollinators may be helpful to understand their trade-off between flower constancy and overdependence.

2. We addressed this question in the long-proboscid tangle-veined fly (Nemetrinus spp.). Dietary investigation indicates that the flies show constancy for the morphological characteristic of the Delphinium caeruleum, which is the most preferred plant for this Nemestrinidae fly that has blue, long-tubed flowers.

3. In a colour selection experiment, focal individuals showed obvious preference for white, which is the colour of less-preferred flowers by the fly in the natural environment. In a scent selection experi...