Spider mothers’ milk for babies


This 29 November 2018 video says about itself:

This small jumping spider is nursing her young with milk | Science News

Female Toxeus magnus spiders, native to tropical and subtropical areas in Asia, produce nutrient-rich milk to feed their young for weeks, even after the spiderlings begin to hunt on their own. Here, a 1-week-old juvenile nurses an area of its mother’s abdomen from which the milk is available.

Read more here.

From the Chinese Academy of Sciences Headquarters:

Mammal-like milk provisioning and parental care discovered in jumping spider

November 29, 2018

Summary: Researchers report milk provisioning in Toxeus magnus (Araneae: Salticidae), a jumping spider that mimics ants. Milk provisioning in T. magnus involves a specialized organ over an extended period, similar to mammalian lactation. The study demonstrated that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates.

Lactation is the production and secretion of milk for the young and is a mammalian attribute. However, there have been few examples of milk provisioning in non-mammals.

In a study published in the journal Science on November 30, researchers at the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences report milk provisioning in Toxeus magnus (Araneae: Salticidae), a jumping spider that mimics ants.

In a field study, researchers observed a jumping spider species whose breeding nest is composed of either several large individuals, with two or more adults, or one adult female and several juveniles.

“It’s a puzzling observation for a species assumed to be noncolonial. It’s possible that the jumping spider might provide either prolonged maternal care or delayed dispersal. We decided to test it,” said Dr. CHEN Zhanqi, the first author of the study.

The researchers assessed how offspring developed and behaved under maternal care both in laboratory conditions and in the field. No spiderlings were observed leaving the nest for foraging until they were 20 days old.

Closer observation revealed that the mother provided a seemingly nutritive fluid, hereafter called milk, to the offspring.

Milk provisioning in T. magnus involves a specialized organ over an extended period, similar to mammalian lactation. Observations under the microscope showed droplets leaking from the mother’s epigastric furrow where the spiderlings sucked milk.

The spiderlings ingest nutritious milk droplets secreted from the mother’s epigastric furrow until the subadult stage (around 40 days). If blocked from obtaining milk, the newly emerged spiders will stop development and die within 10 days, showing that milk is indispensable for offspring survival in the early stage.

Moreover, the researchers tested why parental care and milk provisioning were continued after 20 days when the spiderlings were able to forage for themselves.

The mother continued nest maintenance throughout, carrying out spiderlings’ exuviae and repairing nest damage. When receiving both maternal care and milk, 76% of the hatched offspring survived to adulthood (around 52 days).

Milk provisioning after 20 days did not affect adult survivorship, body size, sex ratio or development time, but the mother’s presence played a key role in assuring a high adult survival rate and normal body size. Thus, milk provisioning complemented their foraging in later stages.

Although the mother apparently treated all juveniles the same, only daughters were allowed to return to the breeding nest after sexual maturity. Adult sons were attacked if they tried to return. This may reduce inbreeding depression.

The findings show that in the jumping spider species, the mother invests much more than the male invests, predicting a female-biased sex ratio to be optimal for reproductive success with a polygamous mating system.

“Our findings demonstrate that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates,” said Dr. CHEN. “We anticipate that our findings will encourage a reevaluation of the evolution of lactation and extended parental care and their occurrences across the animal kingdom.”

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Newly discovered wasp turns spiders into zombies


This video says about itself:

30 May 2017

The Ichneumonid wasp Zatypota albicoxa (Hymenoptera, Ichneumonidae, Polysphinctini) lays a single egg on the house spider Parasteatoda tepidariorum.

The video shoes the attack of the wasp and the paralyzing sting in the underside of the spider’s prosoma. As soon as the spider is paralyzed, the wasp rubbs frequently on the spider’s opisthosoma with its ovipositor-sting, the ovipositor-sheaths being bent upward. In between the wasp makes some injections into the spiders prosoma, searching the right place for the injections at the border of the sternum between the coxae. Thereafter the front of the opisthosoma is rubbed again with the sting and the abdomen tip.

Finally, the wasp slides the tip of its abdomen in the gap between the spider’s prosoma and opisthosoma. A small drop of liquid (glue) runs out of the abdomen tip, followed by the egg itself. The egg is not expelled by the ovipositor, but directly from the tip of the abdomen. Then the wasp retires her abdomen, goes some steps away from the spider, comes back once again and has a last look to its egg. Then she cleans her front legs and goes away.

The spider will awake within the next 40 minutes and will at first continue its normal life. Some days later, the larva will hatch from the egg. It will suck slightly on the spider’s abdomen, at first without much growing. Finally, shortly before the spider is killed by the wasp larva, it will make a special web for the pupation of the wasp larva. Then in two days the ichneumonid larva sucks all the fluid from the spider and spins its own cocoon within this web.

From the University of British Columbia in Canada:

Newly discovered wasp turns social spiders into zombies

November 27, 2018

It sounds like the plot of the world’s tiniest horror movie: deep in the Ecuadorian Amazon, a newly discovered species of wasp transforms a “social” spider into a zombie-like drone that abandons its colony to do the wasp’s bidding.

That’s the gruesome, real-life discovery by University of British Columbia researchers, who detail the first example of a manipulative relationship between a new Zatypota species wasp and a social Anelosimus eximius spider in a study published recently in Ecological Entomology.

“Wasps manipulating the behaviour of spiders has been observed before, but not at a level as complex as this,” said Philippe Fernandez-Fournier, lead author of the study and former master’s student at UBC’s department of zoology. “Not only is this wasp targeting a social species of spider but it’s making it leave its colony, which it rarely does.”

Fernandez-Fournier was in Ecuador studying different kinds of parasites that live in the nests of Anelosimus eximius spiders, one of only about 25 species of “social” spiders worldwide. They are notable for living together in large colonies, cooperating on prey capture, sharing parental duties and rarely straying from their basket-shaped nests.

When Fernandez-Fournier noticed that some of the spiders were infected with a parasitic larva and spotted them wandering a foot or two away from their colonies to spin enclosed webs of densely spun silk and bits of foliage, he was puzzled. “It was very odd because they don’t normally do that, so I started taking notes,” he said.

Intrigued, he carefully took a few of the structures, known as “cocoon webs” back to the laboratory to see what would emerge from the depths.

To his surprise, it was a wasp.

“These wasps are very elegant looking and graceful,” said Samantha Straus, co-author of the study and PhD student in UBC’s department of zoology. “But then they do the most brutal thing.”

Using data gathered in Ecuador for different projects between 2012 and 2017, the researchers began to piece together the life cycle of the wasp and its parasitic relationship to the spider.

What they found was equal parts fascinating and horrifying: after an adult female wasp lays an egg on the abdomen of a spider, the larva hatches and attaches itself to its hapless arachnid host. It then presumably feeds on the spider’s blood-like haemolymph, growing larger and slowly taking over its body. The now “zombified” spider exits the colony and spins a cocoon for the larva before patiently waiting to be killed and consumed. After feasting on the spider, the larva enters its protected cocoon, emerging fully formed nine to eleven days later.

In other similar instances of parasitism, wasps are known to target solitary species of spiders like orb weavers and manipulate them into behaviours that are within their normal repertoire.

“But this behaviour modification is so hardcore,” said Straus. “The wasp completely hijacks the spider’s behaviour and brain and makes it do something it would never do, like leave its nest and spinning a completely different structure. That’s very dangerous for these tiny spiders.”

It’s not known how the wasps do this, but scientists believe it may be caused by an injection of hormones that make the spider think it’s in a different life-stage or cause it to disperse from the colony.

“We think the wasps are targeting these social spiders because it provides a large, stable host colony and food source,” said Straus. “We also found that the larger the spider colony, the more likely it was that these wasps would target it.”

Straus, who now sports a tattoo of the wasp, will return to Ecuador to investigate whether the wasps return to the same spider colonies generation after generation and what evolutionary advantage that might present.

Meanwhile, the wasps will likely continue their starring role in the spiders’ worst nightmares.

Spider removes pine needle from web


In this 22 November 2018 video, a European garden spider removes a pine needle from its web.

The needle hinders the spider in finding out whether there is a prey in the web.

After the needle was gone, the spider repaired the web.

Ilse Cameron in the Netherlands made this video.

How spiders make webs, video


This 20 November 2018 video shows a spider making its web.

Why do insects get stuck in webs, while the spider itself does not? Because not all of the web’s threads are sticky. There are sticky droplets on part of the threads, and the spider avoids these while moving around.

Herman Schoemaker in the Netherlands made this video.

Arachnophobia, how to fight it


This 26 October 2018 video says about itself:

10 Most Beautiful Spiders Found Around the World

When you imagine a spider, it’s probably a hairy, black or brown creature that immediately comes to mind. And unless you live in a particularly warm climate, these harmless beasts are probably the most popular spiders that frequent your hometown. These common creepy crawlers certainly aren’t fun to look. But while you might think that all spiders are like that, there are actually plenty of beautiful spiders all over the world that are worthy of our love and attention.

Forget what you thought you knew about spiders and keep an eye out for the creatures in this video, whose colors span the entire rainbow. Some of them are tiny, which just means that you’ll have to look carefully if you want to fully appreciate the plethora of colors that decorate their bodies. Others are bigger, which makes spotting them in the wild a lot easier.

From the University of Sussex in England:

An end to arachnophobia ‘just a heartbeat away’

October 30, 2018

Researchers have discovered that exposing people with phobias to their fear — for examples, spiders for those who have arachnophobia — at the exact time their heart beats, led to the phobia reducing in severity.

Hugo Critchley, Chair of Psychiatry at Brighton and Sussex Medical School (BSMS) and principle investigator, said: “Many of us have phobias of one kind or another — it could be spiders, or clowns or even types of food. Treatment usually involves exposing the person to their fear, but this can take a long time. Our work shows that how we respond to our fears can depend on whether we see them at the time our heart beats, or between heartbeats. You could say we’re within a heartbeat of helping people beat their phobias.”

In phobias, disproportionately intense, disabling anxiety is induced by specific situations or triggers.

Treatment is often prolonged and involves a graded exposure to fear-evoking stimuli, but has made some progress in recent years through the use of computerised therapy.

This new research shows that phobias can be treated more effectively by linking computerised therapy to the patients’ own heart rhythms.

Researchers at BSMS had previously revealed how bodily arousal signals that occur with each individual heartbeat can change the emotional impact of potential threats, for example, when experienced during a heartbeat they can appear greater.

In this proof-of-concept clinical trial, a computerised exposure therapy for spider phobia was combined with online measurements of heartbeats.

For one group of patients, pictures of spiders were presented in-time with heartbeats (during the signalling of cardiac arousal), while for another patient group, pictures of spiders were presented in-between heartbeats. A third control group saw spiders randomly in the therapy sessions.

Although there was some improvement among all patients, as you would expect in exposure therapy, those individuals exposed to spiders in-time with their own heartbeats showed a greater reductions in self-reported fear of spiders, anxiety levels and their physiological responses to spiders.

These improvements were also shown to depend on differences in how well an individual patient can accurately feel their own heart beating in their chest, suggesting a further way of tailoring the treatment to benefit each patient.