Image credit: compostion by Mark Thomson/Wellcome Sanger Institute, using photos taken by James Gathany/CDC and Amy E. Lockwood, MS/CDC
Use this simple guide to tell your mosquitoes apart this World Mosquito Day.
There are several thousand species of mosquitoes in the world, but far fewer can transmit diseases like malaria. More specifically, only female mosquitoes in the genus Anopheles can carry human malaria. Knowing which species of mosquitoes we are dealing with is very important for public health, as it gives an idea of the risk of diseases that may be circulating in the area.
Entomologists who study these pesky culprits are familiar with their distinguishing features and can identify different species based on their anatomy and behaviour. This is why misidentifications make bug experts squirm! Even the news, media, and scientific outlets often get it wrong by posting pictures of the wrong species when discussing malaria.
None of the mosquitoes shown in the news stories below carry malaria
Mosquitoes possess distinct characteristics that aid in their identification. Their bodies are divided into three main segments: the head, thorax, and abdomen. The head houses its sensory organs, including compound eyes, antennae, and a proboscis used for feeding. Meanwhile, the thorax is where the wings and legs are attached, enabling their swift and agile flight.
When it comes to identifying specific mosquito species, it's crucial to pay attention to subtle differences. Anopheles, Aedes, and Culex are among the most common mosquito genera encountered globally. Anopheles mosquitoes can be distinguished by their palps (sensory organs found near the proboscis), which are elongated and about as long as their proboscis. Aedes mosquitoes, responsible for transmitting diseases such as dengue and Zika, possess a distinctive black-and-white pattern on their legs. Culex mosquitoes, carriers of West Nile virus, usually have a more uniform appearance, with dark-coloured bodies and narrow, elongated wings.
Based on this information, how can you identify a malaria-carrying mosquito? Entomologists may be the experts, but you can also tell Anophelines apart from other mosquito species using the three Ps:
1. Palps
Anophelines have two large structures next to their proboscis called palps. This means they look like they have three tubes sticking out of their heads. The palps of other common species tend to be much reduced.
mosquito_species_comparison_University_of_California_Press
Mosquito species comparison chart. Carpenter, S. J. & LaCasse, W. J. Mosquitoes of North America (north of Mexico). University of California Press, 360 (1955).
2. Posture
Anophelines tend to rest and bite with their heads, thoraxes, and abdomens all in a line. Aedes and Culex rest and bite hunched over, making an upside-down V.
Anopheles albimanus mosquito feeding with its body in a straight line with head down and tail up. Image credit: James Gathany / CDC
Aedes aegypti mosquito feeding with its head and tail pointing down so that it makes an inverted v shape. Image credit: James Gathany / CDC
3. Pattern
Anophelines come in lots of different colours, but never stark black and white stripes. That tells you right away you’re looking at an Aedes, which can carry yellow fever and dengue, but not malaria.
Aedes albopictus. Image credit: Lauren Bishop
Aedes agegypti mosquito. Image credit: James Gathany / CDC
Anopheles sinensis mosquito. Image credit: James Gathany / CDC
Anopheles gambiae mosquito. Image credit: James Gathany / CDC
While this guide can help tell mosquitoes that carry malaria apart from those that don’t, it’s not always that simple. Anopheles species come in hundreds of known variations, and they can look remarkably similar. So entomologists rely on supplementary tools to confirm the precise identity of these elusive insects.
The ANOSPP Project is a collaborative project between researchers at the Sanger Institute and partners working in malaria-endemic countries. The project aims to inform and improve disease control by studying the diversity of mosquito species that transmit human malaria. Using cheap, non-destructive and targeted DNA sequencing and specially designed amplicon panels, malaria researchers can precisely identify different species of Anopheles mosquitoes. The aim is to improve understanding of their population patterns and malaria transmission across Africa. The researchers can also detect the presence and species of malaria-causing Plasmodium parasites within the mosquitoes.
Shedding light on mosquito identification is the first step towards understanding their impact on human health. We hope to inspire greater awareness and appreciation for the efforts aimed at combating mosquito-borne diseases.
