Butterflies and moths collect so much static electricity whilst in flight, that pollen grains from flowers can be pulled by static electricity across air gaps of several millimetres or centimetres. The finding, published in the Journal of the Royal Society Interface, suggests that this likely increases their efficiency and effectiveness as pollinators.
The University of Bristol team also observed that the amount of static electricity carried by butterflies and moths varies between different species, and that these variations correlate with differences in their ecology, such as whether they visit flowers, are from a tropical environment, or fly during the day or night. This is the first evidence to suggest that the amount of static electricity an animal accumulates is a trait that can be adaptive, and thus evolution can act upon it by natural selection.
That many animal species accumulate static electricity as they fly most likely through friction with the air is already known. What was not known is whether butterflies, moths, and other pollinators too accumulate sufficient static electricity, and if the accumulated static electricity can indeed attract pollen. If butterflies can carry electrostatic charges comparable to other proven pollinators such as bees and hummingbirds, then it is more likely that butterflies contribute to pollination.
To test this, the researchers studied 269 butterflies and moths across 11 different species, native to five different continents and inhabiting multiple different ecological niches. “Butterflies and moths accumulate a net electrostatic charge. All individuals measured, from various phylogenetic, ecological and biogeographical groupings, carried a net electrostatic charge, suggesting that electrostatic charging is a universal trait among the Lepidoptera,” they write. “This shows that despite their wingbeat frequency being about two orders of magnitude lower than most other insects, butterflies and moths are still capable of accumulating appreciable electrostatic charge.” Importantly, the magnitude of the net electrostatic charge on the Lepidopterans measured is sufficient to facilitate contactless pollination, they note.
