animal behaviour

New oviposition behaviour spotted in parasitoid wasp

A female Eupelmus messene used her ovipositor to drill through the wall of a polystyrene Petri dish and laid her egg outside the dish.

The thin, flexible, and mobile ovipositor of some female insects, perfected over thousands of years of evolution, can carry substances and drill into various substrates. Although its structure is well studied, many of its functions remain a mystery.

Researchers from Saratov State University and Moscow State University spotted interesting, unusual oviposition behaviour in the parasitoid wasp Eupelmus messene: it used its ovipositor to drill through the wall of a polystyrene Petri dish and lay an egg outside the dish.

Drilling with the ovipositor through a plastic wall of a Petri dish by Eupelmus messene (A), a newly laid egg into the external environment (B), and UV fluorescent biological substance inside the perforations (C). ov – ovipositor, per – perforation, egg – egg.

This is the first time such behaviour has been observed and recorded.

E.messene is a parasitoid of the gall wasp Aulacidea hieracii, which forms a gall on the stems of the hawkweed Hieracium×robustum. The female of E.messene then drills the walls of the gall with its ovipositor in search of a gall wasp larva and, upon finding it, lays an egg next to it.

The researchers reared 56 females from galls of H.×robustum collected near Saratov, Russia. Of them, they placed 18 in Petri dishes without host galls, and later observed five of those wasps drilling into the walls of the Petri dishes.

The team followed the behaviour of one wasp: drilling each perforation in the polystyrene wall took more than two hours, during which the insect often paused to eat, drink water, or wash. In the end, it managed to completely pierce the plastic wall and lay an egg on the outside of the Petri dish. It drilled multiple holes, even after being transferred to a different Petri dish.

Eupelmus messene drilling the wall of the polystyrene Petri dish. Video by Matvey I. Nikelshparg, Evelina I. Nikelshparg, Vasily V. Anikin, Alexey A. Polilov

“We distinguished four steps of drilling: pushing movements, rotational movements, ejection movements, as well as the cementing step. However, in natural gall, we never observed ejection movements. We suppose that such a type of movement is required to rake out plastic particles, which is unnecessary for more elastic plant gall substrate,” write the authors in their study, which was published in the Journal of Hymenoptera Research.

After laying the egg, the female carefully cemented the drilled perforation with an unknown biological substance, likely to keep it safe from the impacts of changing temperatures, water, and microorganisms.

Unlike galls, which usually have an opaque and dense structure, the transparent Petri dish provided a clear view of the whole drilling and oviposition process, allowing the researchers to study it closely.

It is still unknown why the wasp behaved this way, but the scientists believe we can learn a lot from this observation: “Studying in detail the drilling behavior of parasitic mycrohymenopterans can be useful in medicine for the creation of minimally invasive guided probes in neurosurgery, the development of orthopedic surgical instruments, needle biopsies using functionally graded tools,” they write in their paper.

Research article:

Nikelshparg MI, Nikelshparg EI, Anikin VV, Polilov AA (2023) Extraordinary drilling capabilities of the tiny parasitoid Eupelmus messene Walker (Hymenoptera, Eupelmidae). Journal of Hymenoptera Research 96: 715-722. https://doi.org/10.3897/jhr.96.107786

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Tag team: a tale of two Antarctic blue whales

For the first time, the satellite tracks of two Antarctic blue whales, tagged a decade ago, have been published in the open-access Biodiversity Data Journal.

Ten years ago, Dr Virginia Andrews-Goff was riding the bowsprit of a six-metre boat, as a 30-metre, 120-tonne Antarctic blue whale surfaced alongside.

That day in the Southern Ocean, she became the first and, so far, the only person, to deploy satellite tags on two of these critically endangered and rarely sighted giants.

Scientists approach a 30 metre blue whale in their six metre boat. **©Kylie Owens/Australian Antarctic Division**

At the time, her success added weight to a case in the United Nations International Court of Justice, demonstrating that scientific research on whales could be conducted without killing them.

Dr Andrews-Goff and her colleagues at the Australian Antarctic Division have now published the two satellite tracks generated by that 2013 work, in the open-access Biodiversity Data Journal.

This is a unique data set that was incredibly challenging to get.
Dr Virginia Andrews-Goff

The tracks give an insight into the animals’ movement and behaviour on their feeding grounds, and illustrate the significant logistical challenges needed to successfully locate, tag, and track Antarctic blue whales.

“This is a unique data set that was incredibly challenging to get, and, unfortunately, for 10 years no-one has been able to generate more data,” Dr Andrews-Goff said.

“We know very little about the movement and distribution of Antarctic blue whales, where they migrate, where they forage and breed, and we don’t understand the threats they might face as they recover from whaling.”

Two satellite tagged Antarctic blue whales have provided the first insights into the movement and behaviour of these critically endangered ocean giants on their feeding grounds. **©Australian Antarctic Division**

Part of the issue is that the animals are incredibly difficult to find. Commercial whaling in the 1960s and ‘70s killed about 290,000 Antarctic blue whales, accounting for 90% of the population. By the late 1990s, the world’s population of Antarctic blue whales was estimated at 2280 animals.

Back in 2013, the research team used novel acoustic tracking techniques to detect blue whale calls and hone in on their location from up to 1000 kilometres away. Once the whales were in sight (in two separate locations), an expert crew manoeuvred close to their fast-moving targets.

The satellite tags showed that the whales travelled 1390 kilometres in 13 days and 5550 kilometres in 74 days, with an average distance of more than 100 kilometres per day.

“The two whales did entirely different things, but what became obvious is that these animals can travel really quickly,” Dr Andrews-Goff said.

“If you consider how far and fast these animals moved, protecting the broader population against potential threats will be tricky because they could potentially circumnavigate Antarctica within a single feeding season.”

his map shows the movement of two satellite tagged Antarctic blue whales. The track on the bottom right are the movements of one whale over 13 days. The other three tracks capture segments of movement by the second whale over 74 days. The tag for this second whale did not transmit data consistently, resulting in data gaps throughout the tracking period.
The blue portions of track show where the whales were moving quickly and directly, suggesting they were in transit, while the orange locations show where they slowed down and appeared to be searching or foraging. ©Australian Antarctic Division

Since the tracks were obtained, new analytical methods have added some behavioural context to the data.

Two movement rates were observed – a faster ‘in transit’ speed averaging 4.2 km/hr and a slower speed of 2.5 km/hr, thought to correspond with searching or foraging.

“It looks like the whales might hang around in one area to feed and then move quickly to another area and hang around there for another feed,” Dr Andrews-Goff said.

“There may be certain areas that are better feeding grounds than others. From a management perspective, it would be good to understand what is it that makes these areas important?”

Even at a sample size of two, Dr Andrews-Goff said the satellite tracks will assist the International Whaling Commission’s management of Antarctic blue whales, by providing initial insights into blue whale foraging ecology, habitat preferences, distribution, movement rates, and feeding. These will inform an in-depth assessment of Antarctic blue whales due to begin in 2024.

Original source:

Andrews-Goff V, Bell EM, Miller BS, Wotherspoon SJ, Double MC (2022). Satellite tag derived data from two Antarctic blue whales (Balaenoptera musculus intermedia) tagged in the east Antarctic sector of the Southern Ocean. Biodviersity Data Journal 10: e94228 https://doi.org/10.3897/BDJ.10.e94228

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Accidental tree wound reveals novel symbiotic behavior

Despite significant movement restrictions during the first wave of the pandemic in Panama City, a group of curious high school students roamed their neighborhood drilling holes into Cecropia trees and documenting how Azteca alfari ants responded to damage to their host plant.

During the pandemic, five curious high school students accidentally discovered how Azteca alfari ants respond to damage to their Cecropia host trees. Photo by Donna Conlon

One afternoon, during the early days of the COVID-19 pandemic in Panama, a bored teenager with a slingshot and a clay ball accidentally shot entry and exit holes in a Cecropia tree trunk. These are “ant-plant” trees, which famously cooperate with fierce Azteca ants; the trees provide shelter and food to the ants, and in exchange the ants defend their leaves against herbivores. The next morning, to his surprise, the Azteca alfari ants living within the Cecropia trunk had patched up the wound.

This unexpected occurrence drove five curious high school students, with time on their hands, to participate in the Smithsonian Tropical Research Institute’s (STRI) volunteer program, and they enlisted STRI scientist William T. Wcislo’s help in devising their experiment. Despite significant movement restrictions during the first wave of the pandemic, they roamed their neighborhood drilling holes into Cecropia trees and documenting the ants’ responses to the damage.

They found that as soon as the plants had holes drilled into them, the ants ran to the wound area and began patching it up. Within 2.5 hours, the size of the hole had been significantly reduced and it was often completely repaired within 24 hours.

Although some Azteca ants are known to defend their Cecropia host plants against herbivores, these new results, published in the Journal of Hymenoptera Research, reveal that not only do the ants behave in ways to minimize damage to their hosts, but when damage does occur, they actively work to fix it, particularly when their brood is directly threatened.

“I was totally surprised by the results,” says William Wcislo. “And I was impressed by how they developed a simple way to test the idea that ants repair damage to their home.”

*Azteca* ant and *Cecropia* plant responses to wounds in the stems a a sealed hole after 24 hours, but not yet filled in to the stem surface (arrow) b a fully patched and filled-in hole after 24 hrs, oozing sap from the ant-sealed wound (arrow) c a natural plant scar surrounding a 6.4 mm hole that was fully sealed by the ants, approximately 5 months later d a hole in a plant without ants after 24 hrs, showing the green wall of the opposite side of the stem (arrow).

Sloths and silky anteaters often visit Cecropia trees and their sharp toenails sometimes pierce the wood, so the researchers speculate that these occurrences, which are far more common and ancient threats to the Cecropia than teenagers shooting clay balls at them, could have led Azteca alfari ants to evolve the observed repair behavior when their host plant is damaged.

Their experiment also left them with new questions, since not all of the ant colonies repaired the damage to their host plants. Understanding what factors influence the ants to take action could be the subject of future research for these budding scientists, although perhaps to be addressed after graduating from high school.

“Sometimes messing around with a slingshot has a good outcome,” said lead author Alex Wcislo. “This project allowed us to experience first-hand all the intricacies behind a scientific study. All in all, it was a great learning experience, especially considering the difficulties associated with fulfilling this due to COVID-19.”

Research article:

Wcislo A, Graham X, Stevens S, Toppe JE, Wcislo L, Wcislo WT (2021) Azteca ants repair damage to their Cecropia host plants. Journal of Hymenoptera Research 88: 61-70. https://doi.org/10.3897/jhr.88.75855

Beetle named after actress & biologist Isabella Rossellini for her series about animals

A new species of beetle with remarkably long genitalia that hint at a curious evolutionary “sexual arms race” has been described from Malaysian Borneo.

The new insect was named after actress and biologist Isabella Rossellini in honour of her stage shows and Webby Award-winning series of films about animal reproduction, featured on SundanceTV.

The species is described by scientists Menno Schilthuizen and Iva Njunjic of Naturalis Biodiversity Center and Universiti Malaysia Sabah, and Michel Perreau, Sorbonne Université, Paris. Their paper is published in the open access journal ZooKeys.

The new species, Ptomaphaginus isabellarossellini, finds a place among the 30 known species of round fungus beetles (subfamily Cholevinae) recorded by the authors from the island of Borneo. Of these, there are a total of 14 which had remained unknown to science until now.

The reason why the scientists named this particular species after the famous actress is its genitalia. The beetle’s penis carries a long, whip-like thread, called flagellum, whereas the female has a similarly long tube leading up to a sperm storage organ.

Lead author Menno Schilthuizen, who himself has previously released a simultaneously educative and entertaining book about the evolution of genitals, says that such exaggerated male and female genitalia often betray an “evolutionary sexual arms race”.

On the male side, natural selection favours longer genitalia because of the ability to directly reach the female’s sperm storage organ. However, female beetles would rather retain their right to favour the DNA of a certain mate over the rest. The upshot is that, over long periods of evolution, penises get longer and vaginas get deeper. Similar evolutionary genital exaggeration is also known in rove beetles and ducks.

“This is better than winning the Oscar,” says honoured Isabella Rossellini.

The Italian-born actress, filmmaker, author, philanthropist, and model has even featured the new beetle in her new Link Link Circus stage shows. Dealing with animal behaviour, the series will be touring theaters in Europe this fall.

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Original source:

Schilthuizen M, Perreau M, Njunjic I (2018) A review of the Cholevinae from the island of Borneo (Coleoptera, Leiodidae). ZooKeys 777: 57-108. https://doi.org/10.3897/zookeys.777.23212