Sweet Trick, Hawkmoths

The fast-flying insects convert sugars from nectar into antioxidants, which can help heal the oxidative damage suffered by their hard-working muscles.

Bob Grant
Bob Grant
Apr 17, 2017

A male Carolina sphinx mothWIKIMEDIA, DIDIER DESCOUENSInsects belonging to Family Sphingidae, commonly referred to as hawkmoths, hover hard and eat sweet. As adults, hawkmoths subsist entirely on nectar from flowers, above which they flitter, beating their wings rapidly while inserting their straw-like proboscises into sugary storage compartments. But nectar is mostly sugar, mainly lacking the antioxidants necessary to protect muscle cells from the oxidative damage resulting from the high rates of aerobic respiration that fuels flight.

A team of researchers has detailed how one particular hawkmoth species, the Carolina sphinx moth (Manduca sexta), is able to keep its flight muscles functioning smoothly without the input of dietary antioxidants: the insect manufactures its own antioxidants from nectar. The team detailed its finding—that the hawkmoths shuttle glucose from nectar through the pentose phosphate pathway (PPP) to yield products that can protect against reactive oxygen species and heal damage from oxidative stress—in a paper published in Science in February. The sweet oxidative relief experienced by hawkmoths might be a characteristic shared with other animals,” wrote biologists Carlos Martinez del Rio and Michael Dillon, who were not involved in the study, in an accompanying perspective piece. “During migratory flights, animals experience prolonged bouts of strenuous activity, elevating oxidative stress.”

In 2015, researchers discovered that hawkmoths had another neat trick up their sleeves: they use olfactory receptors on the tips of their proboscises to sniff out suitable nectar sources.

Hat tip: Science News