Mosquitoes can lay eggs in many ways: on the water surface, on dry substrates which are later submerged, by sticking them on the undersurface of aquatic plants. But the South American mosquito Sabethes albiprivus does it in a very unique way, as shown in a recent paper by a team of researchers of the Osvaldo Cruz Institute in Brazil.
Mosquitoes of the genus Sabethes live in the forests of Latin America, where they play a role as vectors of yellow fever in monkey populations. These mosquitoes breed in water collections accumulating inside plant cavities, such as tree holes or pierced, cut or broken bamboo. And here is the trick: instead of getting inside these cavities, the female keeps flying and “shoots” the eggs in the holes.
For the first time since 1955, when it was first reported, this unique behaviour has been filmed in Sabethes albiprivus by the team of researchers using a high-speed camera. The recordings showed that the female holds the egg while performing a series of quick up and down flights in front of the chosen plant cavity. When ready, the egg is thrown forward inside the hole by a very rapid movement of the abdomen (to the point that the mosquito proboscis and the tip of the abdomen nearly touch). The researchers estimate that the egg is shot at a speed of almost one meter/second, which is quite impressive considering the small size of a mosquito.
The researchers also developed a trap to collect Sabethes eggs in the field by using fallen seedless nuts from the monkey pot tree, a native species of the Amazon commonly found in forests and urban parks. These mosquitoes are very selective in choosing the place for laying their eggs: researchers found that damaged traps with a too large opening, or where the water was completely exposed, failed to collect large numbers of eggs.
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Vieira, G., Bersot, M.I.L., Pereira, G.R., de Abreu, F.V.S., Nascimento-Pereira, A.C., Santos Neves, M.S.A., Rosa-Freitas, M.G., de Albuquerque Motta, M., Lourenço-de-Oliveira, R., 2020. Oviposition in flight: the Sabethes albiprivus incredible egg-throwing behavior. biorXiv https://doi.org/10.1101/2020.01.31.927228