Australian beetles’ colours, new study


This video from Australia says about itself:

25 February 2017

A slideshow of leaf beetles in the genus Paropsisterna.

From the Yale-NUS College in Singapore:

Beetles’ bright colors used for camouflage instead of warning off predators

First study to examine beetle colouration in their natural habitat prompts discovery

December 4, 2017

NUS College Postdoctoral Fellow Eunice Tan has discovered that the bright colour patterns of beetles are not a warning signal to predators as previously believed, but actually a form of camouflage, turning an old assumption on its head. Dr Tan, along with four collaborators from Australia and Spain, examined 51 species of Australian leaf beetles in their natural habitats, and discovered that each beetle’s colour pattern is similar to the host plants that the beetle lives on, suggesting that those conspicuous colours help the beetle blend in with the plants it inhabits. The study was recently published as an open-access article in the peer-reviewed journal Frontiers in Ecology and Evolution.

As the first ecologist to examine the colour patterns of live leaf beetles in relation to their host plants, Dr Tan contextualised the colour patterns of beetles to their natural habitats, which allowed her to challenge the prevailing theory among coleopterists — scientists who study beetles — that the bright colours of leaf beetles developed as a deterrent signal to predators. These colourful markings were assumed to be a warning to predators against eating the beetles, which are able to secrete poisonous chemicals in self-defence. However, this idea was based on earlier studies, which focused on using museum collections of beetle specimens for their analyses. While this method affords researchers a large number of samples, the discolouration of deceased specimens made accurate colour analysis of the beetles impossible. Furthermore, such methodology also fails to take into account the colouration of each beetle’s natural environment.

Dr Tan and her team spent 17 months photographing live beetles in 32 locations across four Australian states, in order to compare each beetle’s colouration to the colour of the leaf it was found on. Taking into account the evolutionary relationship between the different beetle species, Dr Tan discovered that different species of beetles had colour patterns similar to those of their host plants. This suggests that the colourations have a camouflaging effect, rather than serving an aposematic (predator-deterring) function. This camouflage effect was particularly pronounced in beetles which fed on multiple types of plants, as they had to blend into many different environments.

“It was long thought that conspicuous colour patterns served to advertise the distastefulness of an organism to its predators. However, we have found that this cannot be the sole reason that conspicuous colour patterns developed in leaf beetles. In general, the beetles had colouration similar to that of their host plants, suggesting that there is natural selection at play and therefore some evolutionary advantage for these beetles to use camouflage as a defensive strategy against predators,” shared Dr Tan.

Through her field studies, Dr Tan also observed the impact of ecological factors on the evolution of different beetle species’ colouration patterns. Dr Tan’s study found that both larger and smaller beetle species in her sample had similar levels of colour contrast against their backgrounds. However, the larger beetle species were more likely to be found in darker environments than their smaller cousins, suggesting that they were employing a hiding strategy against predators, despite having similar conspicuous colouration to their smaller cousins. An ecological property, the brightness of the environment, was therefore a potential factor influencing the evolution of beetle colouration.

Taken together, the findings of this study “point to a complex suite of factors driving natural selection, such as types of predators and host plant choice, which affect the evolution of colouration in leaf beetles,” said Dr Tan. Challenging the assumption that the sole explanation for bright coloration in leaf beetles is meant to ward off predators, Dr Tan postulated that the variety of anti-predator strategies in leaf beetles that she has found may explain their successful spread into a variety of habitats.

Advertisements

New beetles discovered in Borneo


This video says about itself:

A documentary exploring the diversity and conservation of one of the world’s last remaining true wildernesses, Maliau Basin in Borneo. Filmed Jan – March 2016 by Matt Jarvis.

Recently, there was an expedition by Naturalis museum in the Netherlands to the Maliau Basin in Sarawak in Malaysia, on Borneo island. They discovered five beetle species, new for science.

Probably, they discovered many more species new for science. However, the scientists in the expedition were specialists of some beetle families and did not know everything on other beetles and animals. So, further research on what they found may discover much more.

An extensive web site, in Dutch, about the expedition is here.

American oil beetles video


This video from the USA says about itself:

American Oil Beetles – Blister Beetles

14 October 2017

Do not ever touch these beetles! Bizarre bugs indeed! I happened upon about a dozen of these beauties in a fall mating frenzy centered around two very large females full of eggs.

Fortunately I did not step on them in the middle of the trail. They are called Blister Beetles because they emit an oil that will burn the skin if you pick them up. The poison they contain is among the strongest known. Cantharidin is an odorless, colorless fatty substance of the terpenoid class, which is secreted by many species of blister beetles. It is a burn agent or a poison in large doses, but preparations containing it were historically used as aphrodisiacs. In its natural form, cantharidin is secreted by the male blister beetle and given to the female as a copulatory gift during mating. Afterwards, the female beetle covers her eggs with it as a defense against predators.

Research has illuminated the piecemeal patterns of recolonization among a hardy species of beetle regularly affected by managed burns: here.

Brazilian beetles threatened by climate change


This 2014 video says about itself:

Macraspis bivittata (Scarabaeidae – Rutelinae – Rutelini) scarabs or scarab beetles, Santo Amaro da Imperatriz, Santa Catarina, Brazil.

From the University of York in England:

Tropical beetles face extinction threat

October 17, 2017

Climate change is putting many tropical high altitude beetles at risk of extinction, warn an international team of scientists.

Research by the University of York, the Federal University of Rio de Janeiro (UFRJ) and the Federal University of Goiás has found that two plant-eating beetle groups — weevils and leaf beetles — are particularly vulnerable to climate change.

The researchers surveyed a number of insect groups at different altitudes in the Brazilian Atlantic Rainforest, an area known for its high diversity of plant and animal species.

They found that a large proportion of species, mostly from the diverse herbivorous beetle groups, are only found at higher altitude. This puts these species at high risk of extinction as they have nowhere to go when the climate gets warmer.

Dr Peter Mayhew, of the University of York’s Department of Biology, one of the investigators, said: “Previous research has shown that species are moving uphill as the climate warms and that tropical mountain species may be particularly vulnerable because they will become restricted to smaller and smaller areas in a warming planet.

“Our study showed that the most diverse herbivorous beetle groups — the weevils and leaf beetles — are highly specialised to high altitudes, which means their favoured temperatures may disappear in a warmer world. This puts them at high risk of extinction.”

The study was carried out in the Serra dos Órgãos National Park in the state of Rio de Janeiro in Brazil and the results published in the journal Insect Conservation and Diversity.

Insects make up the most diverse group of species in rainforests, but until now little was known about how various insects might be affected by climate change.

Professor Margarete Macedo, one of the research leaders at the Federal University of Rio de Janeiro (UFRJ), said: “Almost nothing is known about elevational specialisation in tropical rainforest insects and our aim was to see how different insect groups varied. This in turn may indicate their risk of extinction from climate change.”

The researchers sampled 697 species of insects, using many different trapping techniques such as sticky traps, pitfall traps and tent-like ‘Malaise’ traps. They discovered that 32 per cent of the species sampled were only found in the highest vegetation zones.

Dr Vivian Flinte, from UFRJ, did much of the collecting, sorting and identification. She said: “It has been a huge team effort over many years to get the data we have now, but we have only just skimmed the surface of what is out there.”

Dr Mayhew added: “Even though the area we studied is in a national park, the species in it are not protected from climate change. Because most of these species are poorly known, their extinction may largely go undocumented, but we will have lost them nonetheless. It makes it all the more important to limit future climate change as much as possible.”

New diving beetle species discovered


The two beetle species

This picture shows the two species which scientists have shown are genetically divergent, Meladema coriacea (left) and Meladema lepidoptera (right). Credit: David Bilton – University of Plymouth.

From the University of Plymouth in England:

‘Hiding in plain sight:’ Discovery raises questions over scale of overlooked biodiversity

October 17, 2017

Scientists have used cutting-edge DNA technology and museum samples collected over the past two centuries to reveal a new species of diving beetle living in streams around the Mediterranean.

Meladema coriacea is among Europe’s largest water beetles and has been considered common across the south of the continent and in North Africa since the early 19th century.

But academics from the University of Plymouth and the Institute of Evolutionary Biology in Barcelona have now shown what was long thought to be one common species is actually two.

Using DNA sequence data and detailed analysis of morphology, they have described a new species — Meladema lepidoptera — which appears virtually identical to Meladema coriacea at first glance, but is very divergent genetically.

Meladema lepidoptera is restricted to Corsica, Sardinia, adjacent small islands and some areas of the Italian mainland, where it apparently occurs to the exclusion of Meladema coriacea.

David Bilton, Professor of Aquatic Biology at the University of Plymouth, led the study having first collected samples of the beetles in the late 1990s.

He said: “We began studying the genetics of these beetles to try to understand how animals had colonised islands — we certainly weren’t looking for, or expecting, a new species. Meladema are some of the largest and best-known water beetles in Europe, so we were very surprised with the genetic results suggesting that there were two species hiding under what everyone thought was only one.”

The new species was in fact ‘hiding in plain sight’, since a study of material from a number of European museums revealed specimens of the newly identified species had been collected as long ago as the mid-19th century. But without the genetic data, these had all been thought to belong to the one, common, species.

Genetic data on more specimens, and a careful study of the appearance of the beetles themselves, has now allowed scientists to identify subtle, but consistent, ways in which the two species differ. This includes the precise sculpturing of their wing cases, with lepidoptera’s appearing rather like the interlocking scales on a butterfly’s wing, hence its name.

Dating based on the DNA analyses suggests that Meladema originated approximately 14.4 million years ago, and that the current species appeared more recently, separating around 1.5 million years ago, perhaps as a result of climate and sea level changes during ice ages.

Professor Bilton added: “This is only one new species, but it’s been hiding amongst one of the largest, most obvious freshwater species in Europe, in an area we have supposedly explored pretty thoroughly. The fact that discoveries like ours are still possible emphasizes how little we know about the biodiversity of this planet, something which should be a major priority, particularly when so much of it is threatened by human activity. To effectively conserve biodiversity, we need to understand what’s out there, because ignorance can lead to the wrong decisions being made about species and habitats.”

Dung beetle rolls dung ball


This 12 October 2017 video shows a dung beetle rolling a dung ball to its nest. There, the female will lay an egg in the ball. When the larva will hatch from the egg, the dung will be its food. Everdien van der Bijl made this video on the Ginkelse heide nature reserve near Ede town in the Netherlands.

Madagascar whirligig beetles, from the Triassic till now


This video says about itself:

This video shows the Malagasy striped whirligig beetle (Heterogyrus milloti) in its habitat in Ranomafana National Park, Fianarantsoa, Madagascar, during the 2014 expedition.

From the University of Kansas in the USA:

Meet Madagascar‘s oldest animal lineage, a whirligig beetle with 206-million-year-old origins

October 4, 2017

Summary: A new study suggests the Malagasy striped whirligig beetle Heterogyrus milloti boasts a genetic pedigree stretching back to the late Triassic period.

There are precious few species today in the biodiversity hotspot of Madagascar that scientists can trace directly back to when all of Earth’s continents were joined together as part of the primeval supercontinent Pangea.

But a new study in the journal Scientific Reports suggests the Malagasy striped whirligig beetle Heterogyrus milloti is an ultra-rare survivor among contemporary species on Madagascar, boasting a genetic pedigree stretching back at least 206 million years to the late Triassic period.

“This is unheard of for anything in Madagascar“, said lead author Grey Gustafson, a postdoctoral research fellow in ecology & evolutionary biology and affiliate of the Biodiversity Institute at the University of Kansas. “It’s the oldest lineage of any animal or plant known from Madagascar.”

Gustafson and his co-authors’ research compared the living striped whirligig found in Madagascar with extinct whirligig beetles from the fossil record. They then used a method called “tip dating” to reconstruct and date the family tree of whirligig beetles.

“You examine and code the morphology of extinct species the same as you would living species, and where that fossil occurs in time is where that tip of the tree ends,” he said. “That’s how you time their evolutionary relationships. We really wanted the fossils’ placement in the tree to be backed by analysis, so we could say these are the relatives of the striped whirligig as supported by analysis, not just that they looked similar.”

Gustafson noted one major hurdle for the team was the “painful” incompleteness of the fossil record for establishing all the places where relatives of the striped whirligig beetle once lived.

“All of the fossils come from what is today Europe and Asia — we don’t have any deposits from Madagascar or Africa for this group of insects,” he said. “But they likely were very widespread.”

Today, whirligig beetles are a family of carnivorous aquatic beetles with about 1,000 known species dominated by members of a subfamily called the Gyrininae. But the Gyrininae are young upstarts compared with the striped whirligig beetle, the last remaining species of a group dominant during the time of the dinosaurs. This group according to Gustafson was decimated by the same asteroid impact that cut down the dinosaurs and caused the Cretaceous-Paleogene extinction event.

“The remoteness of Madagascar is what may have saved this beetle,” Gustafson said. “It’s the only place that still has the striped whirligig beetle because it was already isolated at the time of the Cretaceous-Paleogene extinction event — so the lineage was able to persist, and now it’s surviving in a marginal environment.”

Even today, the ageless striped whirligig beetle keeps its own company, preferring to skitter atop the surface of out-of-the-way forest streams in southeastern Madagascar — not mixing with latecomers of the subfamily Gyrininae who have become the dominant whirligig beetles on Madagascar and abroad.

Indeed, Gustafson is one of the few researchers to locate them during a 2014 fieldwork excursion in Madagascar’s Ranomafana National Park.

“This one is pretty hard to find,” he said. “They like these really strange habitats that other whirligigs aren’t found in. We have video of them in a gulch in a mountain range clogged with branches and debris — there are striped whirligigs all over it.”

Unfortunately, the KU researcher said the remote habitats of the striped whirligig beetle in Malagasy national parks were threatened today by human activity on Madagascar.

“It’s a socioeconomic issue,” Gustafson said. “In the national park where first specimens of the striped whirligig beetle were discovered, there are local people who use the forest as a refuge for zebu cattle because they’re concerned about zebu being robbed. Their defecation can disturb the nutrient lode in aquatic ecosystems. Part of the problem is finding a way for local people to be able to make their livelihood while preserving natural ecosystems. But it’s a hard balance to strike. A lot of original forest cover also has been slashed and burned for rice-field patties to feed people.”

Gustafson hopes the primal origins of the striped whirligig beetle can draw attention to the need for protecting aquatic habitats while conceding that conservation efforts usually are aimed at bigger and more cuddly species, like Madagascar’s famous lemurs, tenrecs and other unique carnivorans.

“One of the things that invertebrate species suffer from is a lack of specific conservation efforts,” he said. “It’s usually trickle-down conservation where you find a charismatic vertebrate species to get protected areas started. But certain invertebrates will have different requirements, and right now invertebrate-specific conservation efforts are lacking. We propose the striped whirligig beetle would make for an excellent flagship species for conservation.”