Mosquito in amber. Credit: Dany Azar
When a mosquito lands on you, first instinct is to swat it off before you get bit. There is a chance, however, that you won’t get bit—if its a male mosquito that has landed on you. Today, male mosquitoes feed only on plant juices to get the sugar they need for energy and survival. They do not bite, which also means they cannot transmit diseases. On the other hand, female mosquitoes seek out and bite hosts, as they need protein from blood for the development of their eggs.
While impossible to tell in the heat of the moment, harmless male mosquitoes look different than their bite-happy counterparts. For starters, males are smaller than females. They have bushy, hairy antennae, while females are a lot less hairy. Additionally, females have a more needle-like proboscis, which they use for biting, compared with males.
So while humans may not have to fear male mosquitoes, it looks like dinosaurs were not that lucky. According to new research, scientists have found the earliest-known fossil mosquito—which shows two males of the same species with piercing mouthparts, suggesting they likely sucked blood.
The mosquitoes, preserved in amber in Lebanon, are from the Culicidae family of arthropods, which includes over 3,000 species of mosquitoes. Molecular dating suggests the Culicidae first arose during the Jurassic, about 197.5 million years ago. But, the early fossil record is sparse. Previously, the earliest mosquito fossil was from the mid-Cretaceous. This new find is from the the early Cretaceous—about 30 million years earlier than the previous record.
The study, published in Current Biology, describes the two male mosquitoes with “piercing mouthparts, including an exceptionally sharp, triangular mandible and elongated structure with small, tooth-like denticles.”
The researchers say the presence of these parts suggests that male mosquitoes living during the Early to Late Cretaceous could have been strong enough to pierce the skin and feed on animal blood like their modern female descendants. If that’s true, it also changes what we know about hematophagy—the practice of animals feeding on the blood of other vertebrate animals.
Hematophagy in insects is thought to have arisen as a shift from piercing-sucking mouthparts used to extract plant fluids. For example, blood-sucking fleas likely arose from nectar-feeding insects. Now, this latest fossil find supports the idea that the evolution of hematophagy is more complicated than previously suspected.
“The benefit for Cretaceous male mosquitoes to feed on blood could have been to increase their capacity to fly and successfully mate, as is the case in extant females, but a reason for why this behavior was subsequently lost in males remains unknown,” write the authors in their paper.
One possible reason, supported by the age of the fossil, is the appearance of flowering plants in Lebanon. At the time when the two male mosquitoes became stuck in tree sap that eventually became amber, flowering plants were just beginning to flourish for the first time on the Cretaceous landscape.
“Lebanese amber is, to date, the oldest amber with intensive biological inclusions, and it is a very important material as its formation is contemporaneous with the appearance and beginning of radiation of flowering plants, with all what follows of co-evolution between pollinators and flowering plants,” said study author Dany Azar of the Nanjing Institute of Geology and Paleontology at the Chinese Academy of Sciences and Lebanese University.
This means it is possible that the first mosquitoes were all hematophagous; but that specific behavior was later lost in males—possibly due to flowering plants.