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Aug 12, 2018 17 tweets 6 min read Twitter logo Read on Twitter
For tonight's #DeepDive, let's talk a little bit about how insects use venom *and* poison for various things.

The divisions can be weird, and there's a lot of ways that venoms and poisons can be used!

Thanks to @RosemaryMosco for comic permission!…
When we think of venom or poison, we typically think about the act of eating...and for good reason.

Venom/poisons are used to either help something eat, or keep something from being eaten.
The only exception to this that I'm aware of is the mating of the African rock scorpion.

During mating (2:10 in this video), the male stings the female.

This species doesn't use venom to hunt, so the exact reason behind this behavior is unknown.

The distinction between venom and poison isn't always so clear-cut. Venom can function as a poison under the right circumstances.

For example, sometimes ants will deliver formic acid straight into bite wounds. Sometimes, they just spray it everywhere.

For simplicity, we can divide eating into five stages:

1/2) Detection/Identification-finding the prey
3.) Approach-getting close to the prey
4.) Overpowering-subduing the prey
5.) Consumption-actually eating the prey

Venom or poison can be used at any of those last three stages
Poisons and venoms which are irritants, like in the ant example above, are usually intended to keep predators from getting close enough to eat.

Jellyfish can do something similar...releasing clouds of nematocysts into the water around them.
To overpower something, you don't necessarily need to kill it outright. You just need to make it unable to run away/fight.

Ampulex compressa appears to put it's prey into a very deep sleep to let it's larvae feed.

In insects, most venoms aren't designed to kill.

In fact, in parasitic wasps, the venom is used to subdue the prey by disrupting the host's immune system. In some species, there's no outward indication of the sting.
In social insects, however, venom is intended to kill. Aphids have a venom which causes the predator's immune system to kill the predator.

Poisons used to overpower prey are relatively rare, although they do exist.

One example would be the lethal farts that Berothids use to capture their prey.

H/T to @bug_gwen for this amazing article.…
A second example would be glow-worms, tiny flies which glow to attract prey to their webs.

They coat these webs in oxalic acid, which dissolves the exoskeleton just enough to cause their prey to die of dehydration.
The 5th stage of eating-consumption-is where a lot of poisons come into play.

Venom can be used to make an animal avoid something, and poison can be used to make it sick.

Most predators can learn to avoid 'bad' things.
Poison can be used in two ways to interfere with consumption.

First, some insects contain compounds which can irritate sensitive membranes. Paederus beetles, a tiny orange rove beetle, can destroy skin with it's chemical defenses.
On a less severe level, many poisons taste bad. For example, the quinones which make millipedes taste bad can also stain skin...even though they're not going to kill people outright.
The other main way that insects use poison is to fundamentally alter the physiology of potential predators.

This hornworm feeds on toxic plants, and stores the toxins it eats to defend itself.
Venoms and poisons are used in roles that revolve around eating...either to subdue prey with the intention of eating it or to subdue a predator to keep from being eaten.

It's also thought that venom is introduced through an injury (bite/sting) and poison is eaten or smeared.
Even though nature has a funny way of producing gradients, this definition produces a consistent and important series of differences we can use to tell the difference.

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More from @BugQuestions

Aug 26, 2018
Yeah, we get pictures/videos of this occasionally.

Ants don't really do 'funerals'; even the dead in their own colonies are put into a garbage dump rather unceremoniously.

There's a handful of possibilities for this behavior...
1.) They may be attempting to bury it, especially if it's on a hard surface.

Lots of ants bury large food items to protect it from scavengers, other ants, and to absorb liquid which comes out from the prey.
2.) The critter happened to fall into the colony's trash pile.

Ants put waste (dead ants, poop, shedskins, etc) into a large pile called a 'midden pile' which functions just like our landfills.

If something ended up in that pile, they could be moving stuff out of the way.
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Aug 25, 2018
I think this problem hits at the heart of the issue when it comes to Eckbom's, because it's often not about infestations.

This deserves it's own thread to describe how complicated this problem is, and how poorly understood it is.
So...first, I believe that these people are accurately describing their perceptions of medical issues.

Urban IPM Extension people can go through samples to find insects, inspect homes for infestations (bed bugs, fleas, etc), get someone to do skin scrapings for Scabies, etc.
However, after that, they need to be passed onto a doctor.

Often times, attempts at self-treatment can cause skin irritation. Pesticide poisoning can also cause crawling sensations.

Brain tumors, autoimmune diseases, even cold weather can do this as well.
Read 4 tweets
Aug 25, 2018
Scientists make their living using their brains to interpret data.

So what happens when that organ breaks, and a respected researcher becomes mentally ill?

In this week's second #DeepDive, let's explore the case of Jay Traver.

CW: Mental illness
Jay Traver was one of the early entomological pioneers. Her career centered mainly around aquatic insects, specifically mayflies.

Most of her work-which is still cited to this day-revolved around describing the lifecycles of mayflies.
In 1951, Traver published a paper where she claimed to have experienced an infestation by a mite called Dermatophagoides scheremetewskyi.

This is a mite which lives in homes, and although it causes allergic reactions, it was known at the time to not be parasitic.
Read 15 tweets
Aug 24, 2018
A new meme going around FB claims the WoodLouse Spider is a "deadly new species" wrecking havoc in the Southern US

It's a completely harmless spider, but it still has a neat story to tell.

For the first of this week's two #DeepDives, let's explore the biology of Dysdera crocata
So, for the first tweet in this series, let's put these rumors to rest with data.

There's a lot of verified bites from D. crocata in the medical literature-which is rare. One person allowed themselves to be purposely bitten multiple times.

No deaths; everyone was just fine.
D. crocata gets it's name-the woodlouse spider-from it's food.

They live in dark, moist, areas and are adapted to feeding on sow bugs...sometimes called rollie-pollies.

They use those huge mandibles to foil the isopod's defensive rolling.

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Aug 21, 2018
It is with a heavy heart that we announce that one of our colleagues, Vazrick Nazari, has been arrested for possession of child pornography.

We cannot tolerate exposing our followers to this sort of person, and have blocked him from our feed.…
We did consult him for help with moth IDs here on Twitter, and although there's no way we could have known he was doing this, we still feel the need to apologize for exposing our readers to-and let's just put it as bluntly as possible-an alleged child predator.
We try to be careful about who we consult, and let into our conversations.

Unfortunately, it's not always possible to know what's going on behind the scenes.

Needless to say, we will not be requesting any more assistance from this person.
Read 4 tweets
Aug 18, 2018
With Glyphosate being in the news due to a recent court ruling, let's take this opportunity to explore the history of pest control in this week's #DeepDive.

It's a huge and complex topic, so the best we can do is a brief overview.
It's not really known when humans started using pesticides.

The first agricultural societies began about 10,000 BCE, with several independent shifts around the world from relatively nomadic lifestyles to those tending crops.
The first records of pesticides being used is in Sumeria, where they used elemental sulfur to control crop pests.

This is largely an accident of geography; Sulfur deposits are abundant in a stretch between Mosul and Fatha...which allowed easy access.
Read 27 tweets

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