Backswimmers vs. Mosquitos: BHL Informs Research on Controlling Yellow Fever Mosquito Populations

Black and White drawing of a mosquito (yellow fever mosquito (Aedes aegypti))

The yellow fever mosquito (Aedes aegypti), under the synonym Stegomyia fasciata. Source: Howard, L. O. (Leland Ossian). Mosquitoes; how they live; how they carry disease; how they are classified; how they may be destroyed. 1901. Contributed in BHL from Smithsonian Libraries and Archives.

Aedes aegypti, dubbed the yellow fever mosquito, is a globally invasive, pervasive threat to human health. As the common name suggests, the species can carry a range of diseases, including not only yellow fever but also dengue, the Zika virus, and the chikungunya virus. It is responsible for an estimated 400 million infections each year.[1]

Originating in Africa, Aedes aegypti has spread across the globe, initially transported via ships carrying enslaved people to the Americas. Soon after, trade ships bearing goods like sugar from the Americas brought the species to Europe, and from there it eventually made its way to Asia by way of the Suez Canal. Aedes aegypti’s success is secured by its ability to survive in a range of tropical, subtropical and temperate regions and its threat is exacerbated by its ability to breed in clean water supplies and propensity to bite during the day, rendering protective bed nets ineffective. The effects of climate change are expected to increase A. aegypti’s potential range significantly, escalating the urgency of implementing effective species control methods.[1,2]

A blue insect with transparent legs perched on a light brown branch.

Notonecta indica perched on a piece of wood. Photo courtesy of: Gavin Campbell.

The aquatic insect Notonecta indica—a species in the family Notonectidae, commonly called backswimmers because they swim on their backs—preys on Aedes aegypti mosquitoes in the Americas. Gavin Campbell, a PhD candidate at the University of the West Indies in Jamaica, is researching this predator / prey relationship as part of his PhD. Specifically, Campbell hopes to quantify the control of Aedes aegypti by Notonecta indica by determining how many mosquitoes each adult predator can consume daily and throughout their lifetimes.

The Biodiversity Heritage Library (BHL) has been an invaluable resource for this research.

“Thanks to the articles from BHL, I was able to substantiate my data with the foundational data to prove that other researchers have found similar things,” shares Campbell. “Before I found the BHL resources, I was only able to find a single paper from 2020 that was able to offer anything close to my research. I am very grateful for these and other documents I have come across since then.”

Black man in a red shirt and white, gray, and yellow shorts standing in a pond with birds flying in the background.

Gavin Campbell, a PhD candidate at the University of the West Indies in Jamaica, collecting water samples from a pond as egrets fly around. Photo courtesy of Gavin Campbell.

Campbell has been studying the aquatic and terrestrial phases of temporary ponds since 2017, with the life history of Notonecta indica and its impact on mosquito populations being a major component of that research. As Campbell explains on his website, “temporary waters are bodies of water which recurrently dry”, ranging from the minute—”water inside a snail shell”—to the massive—”the sizes of lakes and rivers”. As these bodies may be “freshwater, brackish, saline and even hypersaline (saltier than the sea)”, a wide variety of species are adapted to live in these diverse ecosystems.[3]

Campbell regularly uses BHL to access historic documents related to his research, typically downloading selected pages as PDF files to read offline.

“BHL has been critical in providing me with baseline information for my research as the documents in question were difficult to find,” asserts Campbell.

Various species of illustrated insects (Notonecta species)

A variety of Notonecta species, including Notonecta indica (fig. 2). Source: Hungerford, H. B. The Genus Notonecta of the World. 1933. Contributed in BHL from Harvard University, Museum of Comparative Zoology, Ernst Mayr Library.

Of all of the titles in BHL’s collection, The Genus Notonecta of the World (1933) by H. B. Hungerford has had the greatest impact on Campbell’s research. Published in The University of Kansas Science Bulletin, the work attempted to assemble all available information about the Notonecta genus, noting that more than thirty years had passed since the last comprehensive account of the genus was published. The publication represented twelve years of research, during which Hungerford consulted both the original descriptions and the types in museums throughout North America and Europe in an effort to “account for every named species”. The work was illustrated in color by Kathleen Doering.[4]

The Genus Notonecta of the World helped Campbell perform species identifications and capitalize on various behavioral aspects. For example, Hungerford notes that eggs are deposited on hard surfaces. Campbell applied this knowledge to his own work by placing a mesh within his rearing container, which facilitated easy removal of eggs each day. Hungerford also provides useful details about Notonecta behaviour in natural environments. For example, in a pond which N. indica frequents during the rainy season, a large number of branchiopods are present, which Hungerford notes are a food source for N. indica’s younger stages. This thus serves as a contributing factor in their dispersal and biology.

The illustrations in The Genus Notonecta of the World were also useful for Campbell’s research, helping him identify organs and structures within individuals and distinguish males and females for successful mating and to help determine differences in mosquito consumption between males and females.

“The BHL was key to providing access to the valuable information in this publication, as few papers at present go into such detail on the family,” affirms Campbell. “Without the BHL providing access to this foundational article, I would have been set back and hindered in my research.”

With Aedes aegypti expected to pose continued, significant threats to human health, we are proud to know that BHL is empowering important research that can help scientists better-understand the species and implement effective control methods. As Campbell shares, “With a better understanding of the role of N. indica in mosquito control, I aim to create and support more habitats for these natural predators to suppress mosquito populations, using nature-based solutions to address the extensive effects of climate change.”

As Campbell’s testimonial demonstrates, immediate, online access to biodiversity literature is ever-more important, allowing research to proceed more quickly and efficiently and improving our ability to respond to the many crises facing our planet and our species today. We look forward to continuing to provide researchers like Gavin Campbell with the essential literature they need to empower their work—anytime, anywhere.


[1] Sokol, Joshua. “The Worst Animal in the World.” The Atlantic. 20 August 2020. Accessed on 3 June 2021.

[2] European Centre for Disease Prevention and Control. “Aedes aegypti – Factsheet for experts.” 20 December 2016. Accessed on 3 June 2021.

[3] Campbell, Gavin. “Ph.D.” Dragon in Flight. Accessed on 3 June 2021.

[4] Hungerford, H. B. “Preface.” The Genus Notonecta of the World. 1933. pp.6-9.

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Grace Costantino served as the Outreach and Communication Manager for the Biodiversity Heritage Library from 2014 to 2021. In this capacity, she developed and managed BHL's communication strategy, oversaw social media initiatives, and engaged with the public to excite audiences about the wealth of biodiversity heritage available in BHL. Prior to her role as Outreach and Communication Manager, Grace served as the Digital Collections Librarian for Smithsonian Libraries and as the Program Manager for BHL.