Common darter dragonflies in love, photo

This 5 September 2021 photo shows two common darter dragonflies mating in Leyduin nature reserve near Heemstede in the Netherlands.

Nelly Venhuis made this photo.

Dragonflies reveal United States mercury pollution

This 2013 video from the USA is about dragonflies.

From Dartmouth College in the USA:

Dragonflies reveal mercury pollution levels across US national parks

Local research project spurs first nationwide survey of the toxic metal

July 22, 2020

A citizen science program that began over a decade ago has confirmed the use of dragonflies to measure mercury pollution, according to a study in Environmental Science & Technology.

The national research effort, which grew from a regional project to collect dragonfly larvae, found that the young form of the insect predator can be used as a “biosentinel” to indicate the amount of mercury that is present in fish, amphibians and birds.

The finding will make it easier to conduct mercury research and could lead to a national registry of pollution data on the toxic metal.

“Researchers needed a proxy for fish since that is what people and animals eat,” said Celia Chen, director of Dartmouth’s Toxic Metals Superfund Research Program and a co-author of the study. “Fish can be hard to work with for a national-level research program, so it’s helpful to be able to focus our research on dragonfly larvae.”

Dragonflies occupy diverse freshwater habitats across six continents and have tissues that take up mercury in its toxic form. As predators, dragonflies operate in the food web in a manner that is similar to fish, birds and amphibians that also accumulate mercury in their body tissues.

The study includes data from thousands of larval dragonfly specimens collected from nearly 500 locations across 100 sites within the U.S. National Park System. The survey was collected from 2009 through 2018 as part of the national Dragonfly Mercury Project.

“The support of citizen scientists around the country created the opportunity for this study to have such significance. This is a terrific example of how public outreach around science can bring results that help the entire country,” said Chen.

Methylmercury, the organic form of the toxic metal mercury, poses risks to humans and wildlife through the consumption of fish. Mercury pollution comes from power plants, mining and other industrial sites. It is transported in the atmosphere and then deposited in the natural environment, where wildlife can be exposed to it.

Fish and aquatic birds are commonly used to monitor mercury levels but are difficult to work with in a large-scale project because of their size, migratory patterns, and the diversity of species. Dragonfly larvae are easy to collect and make the citizen science research project possible.

“It is extremely rewarding to assist teachers and their students to engage in data-driven, real-world research impacting their communities. I see a lot of enthusiasm from students eager to take part in ‘real’ science,” said Kate Buckman, a research scientist who serves as Dartmouth’s coordinator for the citizen science program.

As part of the decade-long study, researchers came up with the first-ever survey of mercury pollution in the U.S. National Park System. The research found that about two-thirds of the aquatic sites studied within the national parks are polluted with moderate-to-extreme levels of mercury.

The finding of mercury within park sites is not an indicator that the source of pollution is in the parks themselves. Mercury is distributed widely within the atmosphere and is deposited in the protected areas as it is in other water bodies across the country.

Given that the parks studied stretch across the entire U.S., including Alaska and Hawaii, the findings reflect levels of mercury throughout the country.

“To date, we have not conducted such a broad scale survey on mercury in the U.S. The beauty of the dragonfly data set is that it is national, covers a huge area with different systems, and has the potential to create a national baseline of mercury pollution information,” said Chen.

The study also found that faster-moving bodies of water, such as rivers and streams, featured more mercury pollution than slower-moving systems including lakes, ponds, and wetlands.

According to the paper: “Collectively, this continental-scale study demonstrates the utility of dragonfly larvae for estimating the potential mercury risk to fish and wildlife in aquatic ecosystems and provides a framework for engaging citizen science as a component of landscape [mercury] monitoring programs.”

In the citizen science project, students and park visitors conduct field studies and collect the dragonfly specimens. National Park rangers help guide the citizen scientists through the protected sites.

The original project was launched by Dr. Sarah Nelson at the University of Maine and the Schoodic Institute in 2007. Dartmouth’s Toxic Metals Superfund Research Program developed a regional effort in New Hampshire and Vermont in 2010. The project was expanded nationally by the National Park Service and the U.S. Geological Survey.

The citizen science project in the Upper Valley region of New England typically runs in the fall with participation from high school students in New Hampshire and Vermont.

Researchers from the USGS, National Park Service, University of Maine, Appalachian Mountain Club and Dartmouth participated in this study. Collin Eagles-Smith from the USGS served as the paper’s lead author. Sarah Nelson who launched the original project is now director of research at the Appalachian Mountain Club.

Young black tern eats dragonfly

This 7 July 2020 video is about a young black tern eating a dragonfly brought by a parent.

John van der Waal from Tienhoven in the Netherlands made this video.

Dragonfly transforms from larva to adult

This 9 June 2020 shows a four-spotted chaser dragonfly transforming from larva to adult.

Ronald van Dijk in the Netherlands made this video.

Hairy dragonfly becomes adult, time-lapse video

This 6 May 2020 video shows a hairy dragonfly emerging from its pupa to start its adult life.

Chris Ruijter in the Netherlands made this time-lapse video.

How dragonflies survive bacteria

This 2017 video says about itself:

Dragonfly wings are covered in bacteria-killing nanopillars, and scientists are taking inspiration from them to make smarter anti-bacterial surfaces.

From the University of Bristol in England:

Insect wings hold antimicrobial clues for improved medical implants

April 6, 2020

Some insect wings such as cicada and dragonfly possess nanopillar structures that kill bacteria upon contact. However, to date, the precise mechanisms that cause bacterial death have been unknown.

Using a range of advanced imaging tools, functional assays and proteomic analyses, a study by the University of Bristol has identified new ways in which nanopillars can damage bacteria.

These important findings, published in Nature Communications, will aid the design of better antimicrobial surfaces for potential biomedical applications such as medical implants and devices that are not reliant on antibiotics.

Bo Su, Professor of Biomedical Materials at the University of Bristol’s Dental School, who authored the research said:

“In this work, we sought to better understand nanopillar-mediated bactericidal mechanisms. The current dogma is that nanopillars kill bacteria by puncturing bacterial cells, resulting in lysis. However, our study shows that the antibacterial effects of nanopillars are actually multifactorial, nanotopography- and species-dependent.

“Alongside deformation and subsequent penetration of the bacterial cell envelope by nanopillars, particularly for Gram-negative bacteria, we found the key to the antibacterial properties of these nanopillars might also be the cumulative effects of physical impedance and induction of oxidative stress.

“We can now hopefully translate this expanded understanding of nanopillar-bacteria interactions into the design of improved biomaterials for use in real-world applications.”

Funded by the Medical Research Council, the implications of the research are far-reaching. Prof. Su explains:

“Now we understand the mechanisms by which nanopillars damage bacteria, the next step is to apply this knowledge to the rational design and fabrication of nanopatterned surfaces with enhanced antimicrobial properties.

“Additionally, we will investigate the human stem cell response to these nanopillars, so as to develop truly cell-instructive implants that not only prevent bacterial infection but also facilitate tissue integration.”

Dragonflies of the Alhambra, Spain

This 3 February 2020 video from Spain says about itself:

In the ponds of Alhambra, the Iberian bluetail dragonfly reigns supreme. With multi-faceted eyes and physics-defying wing flaps, no insect is safe from its predatory instincts.

This 5 2020 video from Spain is called Alhambra Offers Both Nature and History in One Package.

Top 5 Animal Superpowers

This 18 January 2020 video says about itself:

Top 5 Animal Superpowers! | BBC Earth

How can a dragonfly see in slow-motion, or a giant rat‘s super sense of smell detect tuberculosis? We’ve pulled some of the most incredible animal abilities from the BBC Archive for our latest compilation.

Damselfly, dragonfly evolution, new resesarch

This 2014 video is called The Secret World of Dragonflies.

From the University of Minnesota in the USA:

Glimpse into ancient hunting strategies of dragonflies and damselflies

January 16, 2020

Dragonflies and damselflies are animals that may appear gentle but are, in fact, ancient hunters. The closely related insects shared an ancestor over 250 million years ago — long before dinosaurs — and provide a glimpse into how an ancient neural system controlled precise and swift aerial assaults.

A paper recently published in Current Biology, led by University of Minnesota researchers, shows that despite the distinct hunting strategies of dragonflies and damselflies, the two groups share key neurons in the circuit that drives the hunting flight. These neurons are so similar, researchers believe the insects inherited them from their shared ancestor and that the neurons haven’t changed much.

Gaining insight into their ability to quickly process images could inform technological advancements. These findings could inform where to mount cameras on drones and autonomous vehicles, and how to process the incoming information quickly and efficiently.

“Dragonflies and damselflies are interesting from an evolutionary point of view because they give us a window into ancient neural systems,” said Paloma Gonzalez-Bellido, assistant professor in the Department of Ecology, Evolution and Behavior in the College of Biological Sciences and senior author on the paper. “And because there are so many species, we can study their behavior and compare their neural performance. You can’t get that from fossils.”

A noticeable difference between dragonflies and damselflies is the shape and position of their eyes. Most dragonflies today have eyes that are close together, often touching along the top of their head. Whereas damselflies sport eyes that are far apart. The researchers wanted to know whether this made a difference in their hunting habits, and if it affected how their neural system detects moving prey.

Researchers found:

• dragonflies and damselflies hunt prey differently, with dragonflies using a higher resolution area near the top of their eyes to hunt prey from below and damselflies leveraging increased resolution in the front of their eyes to hunt prey in front of them;
• in dragonflies with eyes that merge at the top, the eyes work as if they were two screens of an extended display (i.e. the image of the prey, which would be equivalent to the mouse pointer, can fall on either the left or the right, but never in both screens at the same time);
• damselflies eyes work as duplicated screens, where the prey image is seen by both eyes at once (i.e. they have binocular vision);
• both designs have pros and cons, and their presence correlates with the type of prey and the environment;
• despite different strategies, the neurons that transfer information about a moving target from the brain to the wing motor centers are nearly identical in the two groups — indicating they were inherited from the common ancestor.

The different hunting strategies pay off in different environments. Dragonflies tend to hunt in an open area, leveraging the contrast of the sky to help them spot their target. Although they can’t calculate depth using two images, they rely on other cues. Damselflies tend to hunt among vegetation, where the selective pressure for fast reaction may be absent, or the need for depth perception stronger.

Researchers are now looking to understand how the extended versus duplicated images are calculated in the brain, and how the information is implemented into muscle movements.

“There is still a lot we do not understand,” said Jack Supple, first author and a recent PhD graduate from Gonzalez-Bellidos laboratory. “We do not know how these neurons coordinate all the different muscles in the body during flight. If we tried to build a realistic robotic damselfly or dragonfly tomorrow we would have a difficult time.”

In addition to examining the differences amongst the two insect families, researchers continue to explore differences in species within each family. “While most dragonflies have eyes close together, there are a handful of species with eyes far apart,” said Gonzalez-Bellido. “Some of them are abundant in Minnesota and we are eager to leverage the new flight arena to study their behavior in a controlled setting.”

Researchers aim to collect at Cedar Creek Ecosystem Science Reserve and Itasca Biological Station and Laboratories this summer, both areas with diverse populations of dragonflies and damselflies.

Brown hawker dragonfly deposits eggs

This 4 August 2019 video from England is about a brown hawker dragonfly depositing eggs in Rodley Nature Reserve.