Jewel scarab beetles look like gold, why?


This video says about itself:

Jewel Scarab in Costa Rica -Chrysina

4 February 2014

Here is a video of a lovely creature I came across during a rain forest exploration. I love insects and this one really took the cake. It’s body was was a like a mirror that reflected all the colors around it.

From the University of Exeter in England:

Secret of why jewel scarab beetles look like pure gold, explained by physicists

‘All that glitters is not gold,’ finds research program into way jewel beetles reflect light

June 15, 2017

The secrets of why Central American jewel scarab beetles look like they are made from pure gold, has been uncovered by physicists at the University of Exeter.

The ornate beetles, which have a brilliant metallic gold colour, are highly valued by collectors. But until now the reasons behind their golden iridescent hue, have not been fully understood.

University of Exeter physicists specialising in colour and light have done experiments exploring the origin of the scarab beetles’ striking metallic golden appearance, showing that the golden beetles have a unique ‘optical signature’. The structure of the beetle and its armour uniquely manipulates the way the light is reflected so that it looks like pure gold.

Their results are published in the Journal of the Royal Society Interface.

Professor Pete Vukusic, a physicist specialising in light and colour, led the research which involved experiments and advanced modelling. He found that the golden appearance is due to the high reflectiveness of the beetles’ exoskeleton, which also manipulates a property of the light called its polarisation: the orientation of the reflected light wave‘s oscillations.

The scientists mapped the optical signature of the beetle’s Chrysina resplendens‘ colour, and found it was unusually ‘optically-ambidextrous’, meaning that it reflects both left-handed and right-handed circularly-polarised light.

Professor Vukusic said: “The brilliant golden colour and distinctive polarised reflection from the scarab beetle Chrysina resplendens sets it completely apart from the hundreds of thousands of other beautiful and brightly coloured animals and plants across the natural world. Its exoskeleton has a bright, golden appearance that reflects both right-handed and left-handed circularly-polarised light simultaneously. This characteristic of Chrysina resplendens appears to be an exceptional and wonderfully specialised characteristic in currently known animals and plants. It will serve as a valuable platform from which bio-inspired optical technologies can spring.”

The golden jewel beetle is prized by collectors because of its resemblance to the precious metal.

Other scarab beetles, valued by ancient cultures such as the Egyptians for use as amulets which were sometimes wrapped in the bandages of mummies, are a jewel-like green and blue colours. The vast majority of brightly-coloured beetles tend to be green and do not reflect polarised light. These beetles, in comparison to the brilliant golden colour of Chrysina resplendens, lack much more specialised aspects of their exoskeleton’s finely detailed structure.

Dr. Ewan Finlayson, research fellow on the project, said: “We were drawn to the study of this jewel scarab not only by its striking metallic golden appearance, but also by its ability to control a less obvious property of the reflected light: the polarisation. We have learned that there is great subtlety and detail to be found in these optical ‘signatures’ and in the elaborate natural structures that generate them.”

The golden jewel scarab beetle Chrysina resplendens, mainly found in the Americas, has evolved an exoskeleton that contains intricate nano-structures that are responsible for its appearance.

The spacing of the repeating layers of the nano-structures is found to vary over a specific range through the exoskeleton — a key property that causes the simultaneous reflection of a range of visible colours. It is this fact that explains the very bright reflection as well as the golden hue.

The nano-structured exoskeleton is composed of natural materials including chitin and various proteins. In addition to their brilliant reflectiveness, these structures are remarkable in the way they manipulate the way polarised light is reflected.

Their nanostructures produce circularly-polarised light, where the orientation of the light’s oscillations rotate as the light travels. The two possible directions of rotation are referred to as left handed and right handed.

The experiments build on the work of an early American scientist called Michelson who, in 1911, looked at the polarised reflection from many different Chrysina beetles, and on the work of Anthony Neville (then at Bristol University) in 1971, who began looking more closely at Chrysina resplendens.

There are around 100 species of Chrysina jewel scarab, which are found exclusively in the New World, mostly in Mexico and Central America. The species Chrysina resplendens is found in Panama and Costa Rica. Chrysina scarabs typically live in mountain forests. The larvae feed on rotting logs of various tree species, while the adults feed on foliage. The larval form lasts for several months to a year, and pupation takes a month or two. After the adult emerges it lives for about a further three months, although this span probably varies between species.

One explanation for the highly-reflective appearance of the beetle exoskeleton is crypsis: the ability of the animal to blend in to its surroundings.

Dr Martin Stevens, Associate Professor of Sensory and Evolutionary Ecology at the University of Exeter and an expert in animal vision, colour change and camouflage, said: “It is not absolutely clear why these beetles are a bright golden colour, but one option is that it somehow works in camouflage under some light conditions. The shiny golden colour could also change how the beetle is seen as it moves, potentially dazzling a would-be predator. There are many species which are iridescent but jewel beetles are one of the most charismatic and brightly coloured, and their colour might be used in mating. However, it is not clear how other beetles see the gold colour and reflected light. Many small mammals would not be able to distinguish the golden colour from reds, greens, and yellows, but a predatory bird would likely be able to see these colours well.”

Beautiful American dung beetle video


This video says about itself:

Meet a Beautiful Beetle That Loves to Eat Poop | National Geographic

15 June 2017

Watch an entomologist search beneath piles of bison poop for rainbow scarabs, a beautiful dung beetle native to North America.

How ladybugs fold their wings


This video says about itself:

How to pack wings like a ladybug | Science News

13 June 2017

Ladybugs are experts at packing a lot of junk in their trunk. See how it’s done in the video above. Read more here.

Ladybug mating season video


This 18 April 2017 video is about a seven-spotted ladybug couple mating.

Ruud van Loenen in the Netherlands made this video.

Dinosaur age beetles, parasites of ants


This video says about itself:

3 October 2014

Beetles have been known to invade ant colonies.

Now, scientists have discovered a 52-million-year old fossil of a beetle preserved in amber, which is the oldest example of that species ever found.

The beetle is part of a group that preys on ants by living along side them in the nest and then eating their eggs, or taking over their supplies.

There are around 370 species of beetles that participate in this kind of behavior, and experts say there could be several hundred more that haven’t yet been discovered.

Other predators give off pheromones that trigger the ants defense system to take down any threats.

These certain kinds of beetles are somehow able to avoid that, and live a comfortable life in the nest with the ants.

Lead researcher Joseph Parker, a research associate at the American Museum of Natural History and postdoctoral researcher at Columbia University is quoted as saying: “These beetles live in a climate-controlled nest that is well protected against predators, and they have access to a great deal of food, including the ants’ eggs and brood, and most remarkably, liquid food regurgitated directly to their mouths by the worker ants themselves.”

The fossil is believed to be the first of its kind, with marked differences between the beetle’s body and those of modern species.

And now, an even older beetle with a similar lifestyle has been found.

From Science News:

Beetles have been mooching off insect colonies for millions of years

99-million-year-old amber shows two species that pilfered from ancient ants and termites

By Laurel Hamers

4:00pm, April 24, 2017

Mooching roommates are an ancient problem. Certain species of beetles evolved to live with and leech off social insects such as ants and termites as long ago as the mid-Cretaceous, two new beetle fossils suggest. The finds date the behavior, called social parasitism, to almost 50 million years earlier than previously thought.

Ants and termites are eusocial — they live in communal groups, sharing labor and collectively raising their young. The freeloading beetles turn that social nature to their advantage. They snack on their hosts’ larvae and use their tunnels for protection, while giving nothing in return.

Previous fossils have suggested that this social parasitism has been going on for about 52 million years. But the new finds push that date way back. The specimens, preserved in 99-million-year-old Burmese amber, would have evolved relatively shortly after eusociality is thought to have popped up.

One beetle, Mesosymbion compactus, was reported in Nature Communications in December 2016. A different group of researchers described the other, Cretotrichopsenius burmiticus, in Current Biology on April 13. Both species have shielded heads and teardrop-shaped bodies, similar to modern termite-mound trespassers. Those adaptations aren’t just for looks. Like a roommate who’s found his leftovers filched one too many times, termites frequently turn against their pilfering housemates.

Triassic beetle discovery in Dutch Winterswijk


This video from the USA says about itself:

New Evidence Connects Dung Beetle Evolution to Dinosaurs

4 May 2016

Dr. Nicole Gunter, invertebrate zoology collections manager at The Cleveland Museum of Natural History, discusses research that uncovered an evolutionary connection between dinosaurs and dung beetles. The findings place the origin of dung beetles in the Lower Cretaceous period, with the first major diversification occurring in the middle of the Cretaceous.

By Janene Pieters on April 25, 2017 – 12:25:

A very rare fossil of a beetle that lived in the Netherlands 200 million years ago was found in a quarry in Winterswijk, according to a scientific publication in Paläontologische Zeitschrift written by paleontologists from Utrecht University,

From Paläontologische Zeitschrift:

New fossil insects from the Anisian (Lower to Middle Muschelkalk) from the Central European Basin (Germany and The Netherlands)

22 April 2017

Abstract

The Palaeozoic–Mesozoic transition is characterized not only by the most massive Phanerozoic mass extinction at the end of the Permian period, but also its extensive aftermath and a prolonged period of major biotal recovery during the succeeding Middle to Late Triassic.

Particularly, Anisian insect species from units of the Lower to Middle Muschelkalk from the Central European Basin are rare.

The Anisian is from 247.2 million years ago until 242 million years ago. So, older than the ‘200 million years ago’ of the Janene Pieters article.

The specimens described here originated from the Anisian Wellenkalk facies (Lower Muschelkalk), Vossenveld Formation of the Winterswijk quarry, The Netherlands, and from the orbicularis Member (lowermost Middle Muschelkalk, Anisian) of Esperstedt near Querfurt (Saxony-Anhalt).

Thus, the described insect remains from Winterwijk and Esperstedt expand our knowledge about Middle Triassic terrestrial arthropod communities and their palaeodiversity. A new species of Chauliodites (C. esperstedti sp. nov) is introduced.