Behind this beautiful photo of a mosquito caught in amber, questions arise as to the origin of the obsession these bugs have with biting men, women and children. Two specimens of the Culicidae family, found in Lebanon in remarkable condition, date back to the early Cretaceous period, some 145 million years ago. In a study published on Monday, December 4, in Current Biology, a team of Lebanese and Chinese researchers explains that the two male mosquitoes studied possess "piercing mouthparts, armed with denticulate sharp mandibles."
The first author of this study is Dany Azar, from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences and the Lebanese University; this equipment shows that "these male fossils were likely hematophagous." In other words, they fed on blood sucked from other animals, whose skin they pierced with their distinctive mouthparts. An intriguing discovery, since today, among mosquitoes, only females are hematophagous.
It's not clear how long mosquitoes have been biting. In insects, hematophagy probably arose as a result of changes in feeding habits, with a shift from sucking plant fluids, such as flower nectar, to animal fluids. For example, the authors of the article note that "the exclusively hematophagous fleas seem to have diverged from Mecopterida," an order of insects that today feed on nectar.
The fossils examined in this study are contemporary with the appearance of flowering plants and their differentiation, resulting in "co-evolution between pollinators and flowering plants," Azar explained. But the existence of these blood-sucking males complicates an understanding of the transition from a nectarivorous species to a partially hematophagous one. Partially, because mosquitoes of both sexes feed well on flower nectar, while animal or human blood is a nutritional supplement for the female, contributing to the development of her eggs.
The Culicidae family includes over 3,000 species of mosquito. And in the mosquito phylogenetic tree, there's a gap that makes it impossible to clearly identify the stem group. Further fossil discoveries will be needed to complete the puzzle.