Ancient Bloodsuckers Revealed: Male Mosquitoes Fed on Blood Too

Mosquito Head in Amber

In a groundbreaking study reported in Current Biology, researchers have found the earliest-known fossil mosquitoes in Lebanese amber, revealing that ancient male mosquitoes likely fed on blood. Credit: Current Biology/Azar et al.

Researchers have unearthed the oldest fossil mosquitoes in Lebanese amber, showing that ancient male mosquitoes were likely blood-feeders. This finding from the Lower Cretaceous period sheds new light on the evolution of mosquitoes and their relationship with flowering plants.

Researchers reporting in the journal Current Biology on December 4 have found the earliest-known fossil mosquito in Lower Cretaceous amber from Lebanon. What’s more, the well-preserved insects are two males of the same species with piercing mouthparts, suggesting they likely sucked blood. That’s noteworthy because, among modern-day mosquitoes, only females are hematophagous, meaning that they use piercing mouthparts to feed on the blood of people and other animals.

“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 that follows of co-evolution between pollinators and flowering plants,” says Dany Azar of the Nanjing Institute of Geology and Palaeontology at the Chinese Academy of Sciences and the Lebanese University.

Mosquito in Amber

Mosquito in amber. Credit: Dany Azar

A New Perspective on Mosquito Evolution

“Molecular dating suggested that the family Culicidae arose during the Jurassic, but previously the oldest record was mid-Cretaceous,” says André Nel of the National Museum of Natural History of Paris (Muséum National d’Histoire Naturelle de Paris). “Here we have one from the early Cretaceous, about 30 million years before.”

The Culicidae family of arthropods includes more than 3,000 species of mosquitoes. The new findings suggest that male mosquitoes in the past fed on blood as well, according to the researchers. They also help to narrow the “ghost-lineage gap” for mosquitoes, they say.

Implications and Future Research

Female mosquitoes are notorious for their blood-feeding ways, which has made them a major vector for spreading infectious diseases. 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. But the evolution of blood feeding has been hard to study in part due to gaps in the insect fossil record.

Head, ventral view; scale bar 100 mm Credit: Current Biology/Azar et al.

In the new study, Azar, Nel, Diying Huang, and Michael S. Engel describe two male mosquitoes with piercing mouthparts, including an exceptionally sharp, triangular mandible and elongated structure with small, tooth-like denticles.

They report that the mosquitoes’ preservation in amber extends the definitive occurrence of the mosquito family of insects into the early Cretaceous. It also suggests that the evolution of hematophagy was more complicated than had been suspected, with hematophagous males in the distant past.

In future work, Nel says the team wants to learn more about the “utility” of having hematophagy in Cretaceous male mosquitoes. They’re also curious to explore “why this no longer exists,” he says.

Reference: “The earliest fossil mosquito” by Dany Azar, André Nel, Diying Huang and Michael S. Engel, 4 December 2023, Current Biology.
DOI: 10.1016/j.cub.2023.10.047

Funding: National Natural Science Foundation of China

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