̽��ֱ�� of Cambridge - insects

Cambridge Festival Speaker Spotlight: Charlotte Andrew

zs332 — Thu, 06 Mar 2025 16:33:35 +0000

Charlotte Andrew is a PhD student in the Insect Biomechanics Group in the Department of Zoology. Her research explores the mechanical implications of weather conditions on insect trapping in carnivorous plants.

Swarming cicadas, stock traders, and the wisdom of the crowd

sc604 — Thu, 01 Feb 2024 14:36:51 +0000

Pick almost any location in the eastern United States – say, Columbus Ohio. Every 13 or 17 years, as the soil warms in springtime, vast swarms of cicadas emerge from their underground burrows singing their deafening song, take flight and mate, producing offspring for the next cycle.

This noisy phenomenon repeats all over the eastern and southeastern US as 17 distinct broods emerge in staggered years. In spring 2024, billions of cicadas are expected as two different broods – one that appears every 13 years and another that appears every 17 years – emerge simultaneously.

Previous research has suggested that cicadas emerge once the soil temperature reaches 18°C, but even within a small geographical area, differences in sun exposure, foliage cover or humidity can lead to variations in temperature.

Now, in a paper published in the journal Physical Review E, researchers from the ̽��ֱ�� of Cambridge have discovered how such synchronous cicada swarms can emerge despite these temperature differences.

̽��ֱ��researchers developed a mathematical model for decision-making in an environment with variations in temperature and found that communication between cicada nymphs allows the group to come to a consensus about the local average temperature that then leads to large-scale swarms. ̽��ֱ��model is closely related to one that has been used to describe ‘avalanches’ in decision-making like those among stock market traders, leading to crashes.

Mathematicians have been captivated by the appearance of 17- and 13-year cycles in various species of cicadas, and have previously developed mathematical models that showed how the appearance of such large prime numbers is a consequence of evolutionary pressures to avoid predation. However, the mechanism by which swarms emerge coherently in a given year has not been understood.

In developing their model, the Cambridge team was inspired by previous research on decision-making that represents each member of a group by a ‘spin’ like that in a magnet, but instead of pointing up or down, the two states represent the decision to ‘remain’ or ‘emerge’.

̽��ֱ��local temperature experienced by the cicadas is then like a magnetic field that tends to align the spins and varies slowly from place to place on the scale of hundreds of metres, from sunny hilltops to shaded valleys in a forest. Communication between nearby nymphs is represented by an interaction between the spins that leads to local agreement of neighbours.

̽��ֱ��researchers showed that in the presence of such interactions the swarms are large and space-filling, involving every member of the population in a range of local temperature environments, unlike the case without communication in which every nymph is on its own, responding to every subtle variation in microclimate.

̽��ֱ��research was carried out Professor Raymond E Goldstein, the Alan Turing Professor of Complex Physical Systems in the Department of Applied Mathematics and Theoretical Physics (DAMTP), Professor Robert L Jack of DAMTP and the Yusuf Hamied Department of Chemistry, and Dr Adriana I Pesci, a Senior Research Associate in DAMTP.

“As an applied mathematician, there is nothing more interesting than finding a model capable of explaining the behaviour of living beings, even in the simplest of cases,” said Pesci.

̽��ֱ��researchers say that while their model does not require any particular means of communication between underground nymphs, acoustical signalling is a likely candidate, given the ear-splitting sounds that the swarms make once they emerge from underground.

̽��ֱ��researchers hope that their conjecture regarding the role of communication will stimulate field research to test the hypothesis.

“If our conjecture that communication between nymphs plays a role in swarm emergence is confirmed, it would provide a striking example of how Darwinian evolution can act for the benefit of the group, not just the individual,” said Goldstein.

This work was supported in part by the Complex Physical Systems Fund.

Reference:
R E Goldstein, R L Jack, and A I Pesci. ‘How Cicadas Emerge Together: Thermophysical Aspects of their Collective Decision-Making.’ Physical Review E (2024). DOI: 10.1103/PhysRevE.109.L022401

̽��ֱ��springtime emergence of vast swarms of cicadas can be explained by a mathematical model of collective decision-making with similarities to models describing stock market crashes.

Ed Reschke via Getty Images

Adult Periodical Cicada

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Spanish butterflies better at regulating their body temperature than their British cousins

sc604 — Tue, 09 Jan 2024 04:32:22 +0000

Butterfly populations in northern Spain are better than their UK counterparts at regulating their body temperature, but rising global temperatures may put Spanish butterflies at greater risk of extinction.

Cambridge experts on UK drought and climate change

lw355 — Tue, 16 Aug 2022 09:25:55 +0000

From pollinators to profits, food to fires, here's what Cambridge experts say about the impacts of water scarcity – and what it signals about our changing climate.

Mighty mites give scrawny beetles the edge over bigger rivals

sc604 — Wed, 06 Mar 2019 00:00:17 +0000

In a study featuring a miniature ‘gym’ for beetles (complete with beetle treadmills), researchers from the ̽��ֱ�� of Cambridge found that beetles who consistently lose out to members of their own species have the most to gain by forming a mutually-beneficial cross-species partnership.

̽��ֱ��researchers studied the relationship between the burying beetle and the tiny mites that hitch a ride on their backs. ̽��ֱ��researchers found that mites function like a warm jacket on smaller beetles, and cause them to heat up when the beetles exercise. This made them more successful in face-offs with larger opponents.

For larger beetles, the mites actually reduced their level of fitness. They needed no help from mites to win ownership of a dead body and then lost out because the beetle larvae had to compete with mites for food. ̽��ֱ��results are reported in the journal Evolution Letters.

Relationships between two species where both benefit – such as flowering plants pollinated by insects – is known as mutualism. These relationships are widespread and are key to maintaining biodiversity and ecosystem function, but they are highly variable.

“When the costs of a mutualistic relationship start to outweigh the benefits, it will break down,” said Syuan-Jyun Sun, a PhD candidate in Cambridge’s Department of Zoology and the paper’s first author. “We wanted to find out if competition within species might be one of the reasons why we see such variety in mutualistic relationships.”

In competitions for food or a mate, there will inevitably be winners and losers. ̽��ֱ��Cambridge researchers wanted to test whether ‘losers’ might be more likely to have a mutualistic relationship with another species in order to gain an advantage over their stronger rivals. At the same time, ‘winners’ may not need any help to win battles, so a mutualistic relationship wouldn’t bring any advantage and might even break down into a form of parasitism.

̽��ֱ��researchers tested this idea with experiments on burying beetles and their mites. ̽��ֱ��mites Poecilochirus carabi are benign passengers on their host burying beetles Nicrophorus vespilloides. ̽��ֱ��beetle flies around, seeking out the bodies of freshly dead small animals like mice and birds. Both the beetle and the mites onboard use the dead body as food for their young.

However, beetles face fierce competition for the ownership of a carcass, such as a dead mouse, and smaller beetles often lose the territory to larger rivals. Since the beetles need the carcass to breed, how do smaller beetles manage to reproduce?

“We wondered whether mites could give these ‘losers’ a helping hand in fights over a carcass,” said Sun. In the lab of Professor Rebecca Kilner in Cambridge, the researchers staged contests over a dead mouse between two beetles that were matched in size. One carried mites, while the other did not. They filmed the fights with infrared thermography, and found that beetles with mites were hotter and more aggressive, and therefore more likely to win.

To investigate how such thermal benefits arose, the researchers built a ‘gym’ for beetles and exercised them on custom treadmills. Beetles either carried mites, or a weight that was equivalent to the mites, or they carried nothing.

“We found that carrying extra weight caused beetles to generate extra heat as they exercised,” said Sun. “We also discovered that this heat was trapped by the mites because the mites form an insulating layer when travelling on beetles.”

These effects were most pronounced for smaller beetles because mites covered a relatively larger surface area than on large beetles, suggesting that mites are likely to be disproportionally beneficial to smaller beetles.

To test this idea directly, the researchers again staged fights between two beetles over a dead mouse. This time, the two rivals differed in body size. They also let beetles lay their eggs on a mouse, with and without mites.

̽��ֱ��researchers found that small beetles were much more likely to win a fight for a carcass when they were carrying mites. However, the mites slightly reduced the beetles’ reproductive success, because they competed with beetle larvae for carrion. Nevertheless, the huge benefits of acquiring a carcass for reproduction outweighed these small costs. For smaller ‘loser’ beetles, mites are mutualists because they increase beetle fitness.

̽��ֱ��findings were different for larger beetles. They needed no help to win a carcass, so they gained nothing from associating with mites. To make matters worse, they then lost fitness to the mites when they bred alongside each together on the carcass. For larger ‘winner’ beetles, mites are antagonistic rather than mutualistic because they reduce beetle fitness.

̽��ֱ��research was funded in part by the Cambridge Commonwealth Trust, the Royal Society and the European Research Council.

Reference:
Syuan-Jyun Sun et al. ‘Conflict within species determines the value of a mutualism between species.’ Evolution Letters (2019). DOI:10.1002/evl3.109

Smaller beetles who consistently lose fights over resources can gain a competitive advantage over their larger rivals by teaming up with another species.

When the costs of a mutualistic relationship start to outweigh the benefits, it will break down

Syuan-Jyun Sun

Burying beetle (Nicrophorus vespilloides) with mites (Poecilochirus carabi)

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Butterflies are genetically wired to choose a mate that looks just like them

ta385 — Fri, 08 Feb 2019 10:35:48 +0000

A team of academics from the ̽��ֱ�� of Cambridge, in collaboration with the Smithsonian Tropical Research Institute in Panama, observed the courtship rituals and sequenced the DNA from nearly 300 butterflies to find out how much of the genome was responsible for their mating behaviour.

̽��ֱ��research, published in PLOS Biology, is one of the first ever genome studies to look at butterfly behaviour and it unlocks the secrets of evolution to help explain how new species are formed. Scientists sequenced the DNA from two different species of Heliconius butterflies which live either side of the Andes mountains in Colombia. Heliconians have evolved to produce their own cyanide which makes them highly poisonous and they have distinct and brightly coloured wings which act as a warning to would-be predators.

Professor Chris Jiggins, one of the lead authors on the paper and a Fellow of St John’s College, said: “There has previously been lots of research done on finding genes for things like colour patterns on the butterfly wing, but it’s been more difficult to locate the genes that underlie changes in behaviour. What we found was surprisingly simple – three regions of the genome explain a lot of their behaviours. There’s a small region of the genome that has some very big effects.”

̽��ֱ��male butterflies were introduced to female butterflies of two species and were scored for their levels of sexual interest directed towards each. ̽��ֱ��scientists rated each session based on the number of minutes of courtship by the male – shown by sustained hovering near or actively chasing the females.

Unlike many butterflies which use scented chemical signals to identify a mate, Heliconians use their long-range vision to locate the females, which is why it’s important each species has distinct wing markings. When a hybrid between the two species was introduced, the male would most commonly show a preference for a mate with similar markings to itself. ̽��ֱ��research showed the same area of the genome that controlled the coloration of the wings was responsible for defining a sexual preference for those same wing patterns.

Dr Richard Merrill, one of the authors of the paper, based at Ludwig-Maximilians-Universität, Munich, said: “It explains why hybrid butterflies are so rare – there is a strong genetic preference for similar partners which mostly stops inter-species breeding. This genetic structure promotes long-term evolution of new species by reducing intermixing with others.”

̽��ֱ��paper is one of two published in PLOS Biology and funded by the European Research Council which brought together ten years of research by Professor Jiggins and his team. ̽��ֱ��second study investigated how factors including mate preference act to prevent genetic mixing between the same two species of butterfly. They discovered that despite the rarity of hybrid butterflies – as a result of their reluctance to mate with one another – a surprisingly large amount of DNA has been shared between the species through hybridisation. There has been ten times more sharing between these butterfly species than occurred between Neanderthals and humans.

Dr Simon Martin, one of the authors of the second paper, from the ̽��ֱ�� of Edinburgh, explained: “Over a million years a very small number of hybrids in a generation is enough to significantly reshape the genomes of the these butterflies.”

Despite this genetic mixing, the distinct appearance and behaviours of the two species remain intact, and have not become blended. ̽��ֱ��researchers found that there are many areas of the genome that define each species, and these are maintained by natural selection, which weeds out the foreign genes. In particular, the part of the genome that defines the sex of the butterflies is protected from the effects of inter-species mating. As with the genetics that control mating behaviour, these genes enable each butterfly type to maintain its distinctiveness and help ensure long-term survival of the species. But can the findings translate into other species including humans?

Professor Jiggins said: “In terms of behaviour, humans are unique in their capacity for learning and cultural changes but our behaviour is also influenced by our genes. Studies of simpler organisms such as butterflies can shed light on how our own behaviour has evolved. Some of the patterns of gene sharing we see between the butterflies have also been documented in comparisons of the human and Neanderthal genomes, so there is another link to our own evolution.”

“Next we would like to know how novel behaviour can arise and what kind of genetic changes you need to alter behaviour. We already know that you can make different wing patterns by editing the genes. These studies suggest that potentially new behaviours could come about by putting different genes together in new combinations.”

References

Martin, S et al. Recombination rate variation shapes barriers to introgression across butterfly genomes. PLOS Biology; 7 Feb 2019; DOI: 10.1371/journal.pbio.2006288

Merrill, R et al. Genetic dissection of assortative mating behavior. PLOS Biology; 7 Feb 2019; DOI: 10.1371/journal.pbio.2005902

Male butterflies have genes which give them a sexual preference for a partner with a similar appearance to themselves, according to new research.

There’s a small region of the genome that has some very big effects

Chris Jiggins

Heliconius melpomene amaryllis

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Bats to the rescue

ta385 — Thu, 13 Dec 2018 08:00:00 +0000

READ THE STORY HERE

A new study shows that bats are giving Madagascar’s rice farmers a vital pest control service by feasting on plagues of insects. And this, a Cambridge zoologist believes, can ease the pressure on farmers to turn rainforest into fields.

Courtesy of Adrià López-Baucells

Peters' wrinkle-lipped bat.

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Neglected baby beetles evolve greater self-reliance

ta385 — Fri, 28 Sep 2018 09:01:00 +0000

In gardens, parks and woods across the UK, the Sexton burying beetle Nicrophorus vespilloides quietly buries dead mice and other small vertebrates to create edible nests for its young.

Most parents remove the animal’s hair and slash the flesh of the carcass to help their newly-hatched larvae crawl inside. Typically they also stay on to defend and feed them, but levels of care vary and larvae can survive without their parents.

In a laboratory in Cambridge’s Zoology Department, researchers exploited the insect’s unusual natural history to establish two starkly different experimental populations and explore how parental behaviour drives evolution.

̽��ֱ��study, published today in the journal Nature Communications shows that larvae evolve distinctive adaptations in response to the different levels of parental care.

̽��ֱ��scientists behind the research exposed hundreds of beetles to two levels of parental care, over 13 generations. In a No Care environment, parents were removed as soon as they had prepared their mouse carcass nest but before their larvae had hatched. By contrast, in the Control environment, the parents were allowed to care for their young until they were ready to leave home.

̽��ֱ��researchers found that when parents fed meat to their babies’ mouth-to-mouth, the larvae evolved relatively smaller mandibles. These horizontally-aligned bladelike jaws play a vital role in the larva’s life, enabling them to enter the carcass and feed on the flesh once inside, but they are less important when parents help their young to feed.

“By contrast, when the parents were removed from their young and larvae were forced to self-feed, the larvae evolved significantly larger jaws to compensate for the lack of help,” said Benjamin Jarrett, who led the study.

Many previous studies have shown that social interactions in animals can drive evolutionary change through arms races which cause traits to become increasingly exaggerated. But animals also cooperate and it has been argued that when one individual contributes more, this can diminish traits in the less active social partner. Rarely, however, has direct evidence of this process been obtained.

So what are the larval mandibles like in natural populations, where the level of parental care is very variable from family to family? Here the researchers found that larval jaws are consistently large on average, regardless of the size of the larva.

“They seem to be anticipating the worst possible scenario of receiving no help at all. This looks like a conservative bet-hedging strategy for survival,” said Jarrett.

“Whether parents eventually decide to stay or go, the larva are equipped with large jaws and so can fend for themselves if necessary.”

̽��ֱ��laboratory’s experimental populations of beetles are continuing to evolve and are now in the 35th generation of experiencing different levels of parental care.

“Our ongoing research investigates the importance of the social environment in evolution. We are watching the way that evolution unfolds in these experimental populations and they constantly teach and surprise us,” said Professor Rebecca Kilner, senior author of the paper.

“ ̽��ֱ��better our understanding of how evolution works, the better able we are to predict how animals will evolve in a changing world”.

Reference:
Benjamin Jarrett et al. 'A sustained change in the supply of parental care causes adaptive evolution of offspring morphology.' Nature Communications (2018). DOI: 10.1038/s41467-018-06513-6

A new study reveals that when burying beetle larvae are denied parental support, they evolve bigger jaws to compensate.

Our ongoing research investigates the importance of the social environment in evolution

Rebecca Kilner

Courtesy of tomhouslay.com

Sexton beetle and larva

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