Global warming might make less biting, itching, scratching

From the University of Montreal , something that might actually be a good thing if true. If warmer temperatures make mostly male insects, then this might also apply to mosquitoes, and only the females bite. OK, it’s a bit of a stretch, but no more so than the press release.

Temperature influences gender of offspring

New study on parasitoid reveals that heat favours production of male progeny

Whether an insect will have a male or female offspring depends on the weather, according to a study led by Joffrey Moiroux and Jacques Brodeur of the University of Montreal’s Department of Biological Sciences. The research involved experimenting with a species of oophagous parasitoid (Trichogramma euproctidis), an insect that lays its eggs inside a host insect that will be consumed by the future larvae.

“We know that climate affects the reproductive behaviour of insects. But we never clearly demonstrated the effects of climate change on sex allocation in parasitoids,” Moiroux explained.

The study was carried out in collaboration with Guy Boivin of the Horticulture Research and Development Centre of Agriculture and Agri-Food Canada, and published in the May issue of the journal Animal Behaviour.

Cold impairs gender selection

As in bees, wasps, and ants, the gender determination of Trichogramma parasitoids is called “haplodiploid,” that is, fertilized eggs produce female offspring, while unfertilized eggs produce male offspring, summarizes Moiroux. “It is possible to predict whether the parasitoid will lay a son or daughter by observing the presence or absence of a pause in its abdominal contractions at the time of spawning,” he says. “A pause means the egg will be fertilized. Conversely, the absence of a pause means the egg will not be fertilized.”

To know whether this particular behaviour is modified by climate, the researcher exposed female Trichogramma to three different temperatures: 34°C (high), 24°C (medium), and 14°C (low). The study found that when it was hot, females deliberately produced more males than at medium temperature – at 34°C, the number of males produced increased by 80%.

The ability of Trichogramma to “program” the sex of their offspring is compromised, however, when the temperature is cold. “There was a physiological stress that was not related to the females’ choice,” notes Moiroux. “They intended to spawn as many females as during medium temperature, but the eggs were not fertilized after all. There were therefore more males produced at low temperature.”

Increasing fitness

In insects, fitness is positively correlated with the size of an individual, and this relationship is greater in females than in males. “Larger females live longer and have higher fertility, whereas males are relatively less penalized than females when they are small,” Moiroux said. “It is therefore advantageous for mothers to have the largest female offspring possible and use hosts that will produce smaller offspring for males.”

However, in a hot environment, offspring are smaller. This is why females tend to use hosts found in hot areas to produce males and reserve hosts in colder areas (e.g., in the shade of hedges) to produce females.

Biocontrol

As part of this study, which was funded by the Ouranos Consortium, Moiroux tried to understand the possible role of global warming on the relationship between crop pests and their natural enemies – parasitoids and predators. Among the issues addressed, he sought to determine whether there is an effect of “phenological asynchrony” between parasitoids and their hosts, and therefore an impact on the availability of host eggs and on pest control by their natural enemies. “Predators and parasitoids are more sensitive to climate change, and this is why many researchers expect an increase in episodes of phenological asynchrony. This could be very harmful to crops if hosts escape the control of their natural enemies,” he said.

In Quebec, the European corn borer is a pest that farmers face every year. The parasitoid Trichogramma, for its part, is an ally since its larvae kill this insect host. “It is of the utmost importance to clearly identify harmful and beneficial insects in the field in order to adopt an appropriate strategy for integrated pest management,” Moiroux said. He will now be looking at which species of soybean pests could come to Quebec in the coming years due to climate change.

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33 thoughts on “Global warming might make less biting, itching, scratching

  1. There is literally nothing these guys won’t argue from both ends on. How can there be less biting mosquitoes if there is already more mosquito born malaria due to globull warmongering?

  2. I’ve got bad news – I live in the tropics (well close enough – 25 south) near a large park with a lake. The warmth, even the blazing hot, humid tropical summer, where the temperature rarely drops below 30c / 86 in daytime, does not appear to reduce the number of mosquito bites :-). It actually seems to encourage the b*ggers.

  3. Not just insects, some reptiles too! Back before everything was blamed on CO2 (hey, I wonder if CO2 concentration…), people discovered gator gender was dependent on incubation temperature.

    http://www.nature.com/nature/journal/v296/n5860/abs/296850a0.html says in part:

    Here we demonstrate by laboratory and field experiments, that in A. mississippiensis: (1) Sex is fully determined at the time of hatching and naturally irreversible thereafter, and depends on the temperature of egg incubation, temperatures less than or equal to30 °C producing all females, greater than or equal to34 °C yielding all males. (2) The temperature-sensitive period is between 7 and 21 days of incubation. (3) Natural nests constructed on levees are hotter (34 °C) than those constructed on wet marsh (30 °C), thus the former hatch males and the latter females. (4) The natural sex ratio at hatching is five females to 1 male. (5) Females hatched from eggs incubated at 30 °C weigh significantly more than males hatched from eggs incubated at 34 °C.

    Then they wax a bit ecstatic. No mention of impact of CAGW though:

    The occurrence of temperature-dependent sex determination in alligators has wide-ranging implications for embryological, teratological, molecular, evolutionary, conservation and farming studies as well as for theories relating to the extinction of other Archosaurs.

  4. geez, now I’m going to have to do down to the gun shop and change from O-O buckshot down to number 4’s as the males are smaller. Mosquito shooting – Minnesota’s top summer sport.

  5. Kind of on-topic (global warming causes everything), last night on CBC news a story about the pollen season being delayed this year because of the cold spring. This has resulted in a compressed season producing the same amount of pollen in a shorter period of time – a super-dose of pollen, which is negatively affecting allergy sufferers and people with asthma more than usual. OK so far.

    The story ended with … and as these winters become more common [due to global warming] this problem is only going to get worse… [Huh?] Back to you Peter…

  6. The ability of Trichogramma to “program” the sex of their offspring is compromised, however, when the temperature is cold. “There was a physiological stress that was not related to the females’ choice,” notes Moiroux.

    ===

    How do they even imagine they know what the “females’ choice” may be?

    This sounds to me like a programmed response to environmental conditions. Perhaps less offspring survive during cold periods so more females are produced to compensate. A bit like plants produce more fruit when stressed. Just more crap science. As long as you can get the magic words “due to climate change” in there, you’ll get published.

    “…. in the coming years due to climate change.”

    Blah, blah, blah. There’s next year’s grant money sorted.

  7. This is just more of what is becoming a psychosis. Whatever way it changes it’s bad.

    “If the current trend continues .. Blah, blah, blah. ”

    What they fail to see is the life on this planet has seen far worse than 0.7 degree C change in 100 years and nature in all its forms is very well adapted to cope.

    Far from being “compromised” they’ve probably just found one way in which this species, like the rest of life on Earth is equipped to adapt to change, not being threatened with extinction by the slightest change.

  8. Steve:” last night on CBC news……pollen… which is negatively affecting allergy sufferers and people with asthma more than usual. ”

    Yes, and if it was a warmer sprint we’d be hearing : the longer spring means alergy suffers are affected for a longer and longer period. This will only get worse as these conditions become more common in a warming world.

    I’m sure they must these boilerplate articles are ready written, they just paste in whatever the latest “finding” is.

  9. I live at about 22N on a smallish island in Hong Kong. In contrast to Eric Worrall, as a very subjective observation, I have found that our mosquitoes are less prevalent when the temperature gets above about 30C. Eric, your mozzies must be following the Australian rule that everything in nature tries to kill you.

  10. And now on the BBC:
    Study: UK cities becoming mosquito-friendly habitats

    http://www.bbc.co.uk/news/science-environment-27491891

    “Changes to UK urban areas provide habitats for mosquitoes, including species known to spread malaria and West Nile virus, a study suggests.
    Warmer ambient temperatures and more water containers in gardens are bringing mosquitoes into closer contact with people, say scientists.
    UK mosquitoes are human disease-free but the team says more of the insects breeding in urban areas increases the chances of a potential outbreak.”

    Meanwhile:
    The history of malaria in England

    http://malaria.wellcome.ac.uk/doc_WTD023991.html

    “Malaria in England may date back to Roman times, and outbreaks even occurred after the First World War. Mary Dobson discusses the English rise and fall of this ‘tropical’ disease.”

    ‘By the late 1800s, the causes of malaria were becoming clear, with the discovery of malaria parasites and the role of mosquito vectors. Ronald Ross, credited with discovering the key role of mosquitoes in the transmission of malaria, attempted to eradicate malaria from England around the First World War era; he enlisted ‘mosquito brigades’ to eliminate mosquito larvae from stagnant pools and marshes.
    A second key figure, S P James, took a different approach. According to Dr Dobson, he believed that “malaria will only disappear with improvements in housing and the separation of mosquitoes from humans.” James became better known for his use of malaria as a form of therapy for syphilis – the high temperatures induced by the infection destroyed the syphilis bacterium. His survey work conducted on malaria in north Kent – after the First World War – revealed that as many as 500 civilians were affected by a mini malaria epidemic, triggered by the import of parasites by soldiers stationed in Thessalonika.
    Since the 1950s, locally transmitted malaria has essentially died out. However, the number of imported cases of the disease has risen from 200 in the 1970s to over 2000 today, largely because of the growth of global travel. So can we expect another malaria epidemic in England? Probably not, suggests Dr Dobson. “We’ve moved so far forward in terms of our environment and housing conditions that it would not take long to break the malaria transmission cycle.”‘

    Then there is this:

    http://www.dailymail.co.uk/health/article-135634/Doctors-malaria-alert.html

    Doctors put on malaria alert
    by JAMES CHAPMAN, Daily Mail
    “Doctors across Britain were warned last night to be vigilant for a malaria outbreak after at least one person was infected by a mosquito from abroad.
    Public health officials say the patient, who works at Heathrow Airport, has not recently travelled abroad and probably became infected by a malarial mosquito which arrived on an airliner from sub-Saharan Africa.
    The case is the first of its kind in Britain for almost 20 years and has prompted calls for airlines to be more vigilant with planes returning from countries where the disease is endemic.
    Large areas of England and Wales are now officially at risk from malaria after a Department of Health study concluded that global warming has made some parts an ideal home for diseasecarrying mosquitoes. The areas at greatest risk are the Thames Estuary, Essex, South-East Kent, the Somerset Levels, the Severn Estuary and the Fens.”

    And this from Wikipedia:
    “Mosquitoes are very widespread, occurring in all regions of the world except for Antarctica.[37] In warm and humid tropical regions, they are active for the entire year, but in temperate regions, they hibernate over winter. Arctic mosquitoes may be active for only a few weeks as pools of water form on top of the permafrost. During that time, though, they exist in huge numbers and can take up to 300 ml of blood per day from each animal in a caribou herd.[11]
    Only Iceland is claimed not to have mosquitoes.[56] Other sources, however, report having suffered mosquito bites in Iceland during the summer.
    Eggs from strains in the temperate zones are more tolerant to the cold than ones from warmer regions.[57][58] They can even tolerate snow and subzero temperatures. In addition, adults can survive throughout winter in suitable microhabitats.[59]
    Means of dispersal[edit]
    Worldwide introduction of various mosquito species over large distances into regions where they are not indigenous has occurred through human agencies, primarily on sea routes, in which the eggs, larvae, and pupae inhabiting water-filled used tires and cut flowers are transported. However, apart from sea transport, mosquitoes have been effectively carried by personal vehicles, delivery trucks, trains, and aircraft. Man-made areas such as storm water retention basins, or storm drains also provide sprawling sanctuaries. Sufficient quarantine measures have proven difficult to implement. In addition, outdoor pool areas make a perfect place for them to grow.”

  11. The life lesson here is that females suck your blood, so gentlemen hold on to your wallet.

  12. “The study found that when it was hot, females deliberately produced more males than at medium temperature – at 34°C, the number of males produced increased by 80%.”

    “but the eggs were not fertilized after all. There were therefore more males produced at low temperature.”

    So, when it’s hot they choose to make more males…and when it’s cold they accidentally make more males….

    ….the three bears……it’s a miracle the stupid bugs exist at all

  13. New liberal headline: “Global warming sexist say Montreal scientist.”
    Yet another evil produced by CO2.
    CO2 is really a war on women.

  14. Whether an insect will have a male or female offspring depends on the weather, according to a study led by Joffrey Moiroux and Jacques Brodeur of the University of Montreal’s Department of Biological Sciences.
    It’s only weather, not climate.

  15. Haven’t read yet (hrt), but I’m guessing the ration changes, but population stil goes up.

  16. So, CAGW is going to be “catastrophic” if temperatures increase by “perhaps” 2 deg C in perhaps 100 – 200 – 300 years, so we will find out what happens if we increase insect fertilization test temperatures by +10 deg C and minus 10 deg C compared to today. That is, after all, the report scenario, right?

    Well, I can assure you, if I increase the temperature in my bedroom by 10 deg C (+22 F from 74 summertime to 96 F), my wife will not behave the same way as when the temperature is decreased by 10 deg C (from 68 F winter to 46 F)!

    Ain’t a whole lot of matin’ goin’ on in either “test” case.

  17. What happens in Trichogramma euproctidis stays in Trichogramma euproctidis.

    Each one of a MILLION insect species is different and every one is unique in some way. Each species responds to their environment in different ways.

    As a little known aside, malaria outbreaks in the Yukon were common in Dawson during the gold rush. There is no need for warming to spread malaria toward the poles since species that spread the disease are common and already in such tropical places like Sweden, Finland, Northern Russia, or Newfoundland. Virtually all of Europe, Ireland, and the rest of Europe is already home to mosquitoes capable of spreading malaria.

    http://www.cdc.gov/malaria/about/biology/mosquitoes/map.html

  18. Is it just possible that as the climate changes insect acclimatization, adaptation can change? I already saw acclimatization with the Australian fruit fly juveniles. Maybe over a relatively short period we are back to square one.

    Some creatures during the PETM went through madness, extra munching (lack of nutritious leaves apparently) and thrived and diversified. Maybe more itching to come. :)

    Abstract
    ZHAO Yu-long et al – Advances in Earth Science – 2007
    The impacts of the Paleocene-Eocene thermal maximum (PETM)event on earth surface cycles and its trigger mechanism
    The Paleocene-Eocene Thermal Maximum (PETM) event is an abrupt climate change event that occurred at the Paleocene-Eocene boundary. The event led to a sudden reversal in ocean overturning along with an abrupt rise in sea surface salinity (SSSs) and atmospheric humidity. An unusual proliferation of biodiversity and productivity during the PETM is indicative of massive fertility increasing in both oceanic and terrestrial ecosystems. Global warming enabled the dispersal of low-latitude populations into mid-and high-latitude. Biological evolution also exhibited a dramatic pulse of change, including the first appearance of many important groups of ” modern” mammals (such as primates, artiodactyls, and perissodactyls) and the mass extinction of benlhic foraminifera…..
    22(4) 341-349 DOI: ISSN: 1001-8166 CN: 62-1091/P
    —————-

    Abstract
    Systematics and Biodiversity – Volume 8, Issue 1, 2010
    Kathy J. Willis et al
    4 °C and beyond: what did this mean for biodiversity in the past?
    How do the predicted climatic changes (IPCC, 2007) for the next century compare in magnitude and rate to those that Earth has previously encountered? Are there comparable intervals of rapid rates of temperature change, sea-level rise and levels of atmospheric CO2 that can be used as analogues to assess possible biotic responses to future change? Or are we stepping into the great unknown? This perspective article focuses on intervals in time in the fossil record when atmospheric CO2 concentrations increased up to 1200 ppmv, temperatures in mid- to high-latitudes increased by greater than 4 °C within 60 years, and sea levels rose by up to 3 m higher than present. For these intervals in time, case studies of past biotic responses are presented to demonstrate the scale and impact of the magnitude and rate of such climate changes on biodiversity. We argue that although the underlying mechanisms responsible for these past changes in climate were very different (i.e. natural processes rather than anthropogenic), the rates and magnitude of climate change are similar to those predicted for the future and therefore potentially relevant to understanding future biotic response. What emerges from these past records is evidence for rapid community turnover, migrations, development of novel ecosystems and thresholds from one stable ecosystem state to another, but there is very little evidence for broad-scale extinctions due to a warming world. Based on this evidence from the fossil record, we make four recommendations for future climate-change integrated conservation strategies.
    DOI: 10.1080/14772000903495833

  19. BioBob says:
    May 22, 2014 at 9:24 am

    What happens in Trichogramma euproctidis stays in Trichogramma euproctidis.

    Each one of a MILLION insect species is different and every one is unique in some way. Each species responds to their environment in different ways.

    I spent some time trying to think of a short comment on this very issue and you said it all. Thanks!

    Insects live in wood, the dirt / Earth, water, sand, air, leaves, some long lived, some short lived, some parasites, some hunters, some gatherers and so on………………………..

  20. Global warming might make less biting, itching, scratching

    Global warming will mean MORE ‘biting, itching, scratching’ I am afraid. I live in the tropics and I have lived in London. Biting, stings, scratching is the norm I’m afraid – it’s what happens when breeding rates / biodiversity increases due to warmer weather / climate.

    Eat a mango in central London in mid July and do the same in Queensland and see what happens. Forget our inconveniences, think about life thriving.

  21. When the rainy season arrives and temperatures SHOOT UP there is a sharp increase in the number of insects in my local. I always dread the hot, humid months which are full of flies, mosquitoes, rampant spiders and bees. This is a good thing despite my inconveniences. Would Al Gore ever talk like this? Of course not because he wants to make over 1 billion Dollars. What’s 2 large houses between global warming friends. We have a planetary emergency between hypocrites.

  22. Jimbo says: May 22, 2014 at 3:50 pm
    Is it just possible that as the climate changes insect acclimatization, adaptation can change?

    —————-

    Yepper. Takes only about 25 generations for a SNP to completely spread in the entire (small) population of insects. [see studies of insect resistance from Pimentel et al]
    25 generations is about 1.5 years in tropical insects, 400-500 years for humans.

    However, for most environmental variability like these, insects hardly need a genetic basis for changes. Differential production & modes of action of enzymes and proteins or simple behavioral change (eg resting in sheltered locations) within an individual lifespan is possibly enough to deal with these kinds of nothings. If it was worth a literature search, someone could possibly find the answer already out there.

  23. @ Jimbo

    Actually, I now recall that newly introduced Dengue, Yellow Fever, Chikungunya vector Aedes albopictus has enlarged its usual northern range in the USA far into the temperate zone (Minnesota to Maine) by a recent adaptation for cold tolerance.

    ALL since it was introduced into Houston in 1985. Not bad for a supposedly tropical mossie.

  24. Also, mosquitoes use CO2 (from respiration) to hone in on their human and animal victims. It stands to reason that a higher background concentration of CO2 will make it harder for them to find their prey.

  25. At this time in Central VA, it’s’ finally getting into the 80s with a few mosquito bites. By August, when it’s 90s temp and 90s humidity, you can’t hear yourself think for all the roaring around your head. Granted, they do tend to lay low until dark. Luckily, the gators don’t get up this far.

  26. Eric Simpson says: May 22, 2014 at 7:24 pm
    It stands to reason that a higher background concentration of CO2 will make it harder for them to find their prey.

    —————–

    So you would think. But mosquitoes are not so simple-minded despite their tiny little itsy bitsy teeny ‘brains’. Different species & different ages respond to different organic molecules, heat, motion, prey color, as well as CO2 at different times and different distance from the prey. It’s quite interesting to read reviews of CO2 traps made by qualified scientists. Certain species in one trap but few in another and vice versa and so on. But they all agree on one thing: the traps don’t actually decrease the number of or eliminate bites !! FAIL

  27. Jimbo says:
    May 22, 2014 at 4:11 pm
    Global warming might make less biting, itching, scratching

    “Global warming will mean MORE ‘biting, itching, scratching’ I am afraid. I live in the tropics and I have lived in London. Biting, stings, scratching is the norm I’m afraid – it’s what happens when breeding rates / biodiversity increases due to warmer weather / climate.”

    Have you been to Scotland in the summer or any of the northern tundras for that matter? There is too much emphasis placed on average temperature changes whereas I have suffered mosquito bites every year of my life in the UK and each summer does not have a consistent temp. We have removed huge areas of wetlands in the UK and these were where Malaria was prevalent. In more recent years people removed ponds from their gardens for fear of toddlers falling in and drowning and probably convenience. So if people are now putting ponds back in and having water buts then we can only ever return to a mosquito population the same or less than before because there just isn’t the wet surface area available anymore and temperature is not the driver, its abundant standing water and abundant warm blooded food supply.

  28. Just to reiterate with this extract from Wikipedia:
    “Arctic mosquitoes may be active for only a few weeks as pools of water form on top of the permafrost. During that time, though, they exist in huge numbers and can take up to 300 ml of blood per day from each animal in a caribou herd.”

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