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Thursday, 2 February 2012

Spider and other Insects Toxins:


Spider venom:


Spiders are active hunters and rely heavily on their Bites to paralyze and kill their prey before consuming it.They also bite in self defence.Most spider bites occur when humans unintentionally press up aganist spidera and receive a defensive bite.Only spiders of fairly large species possess chelicera (bitting mouth) long enough to penetrate human skin.


Most of the spider species venomenous but Only some 200 species in twenty genera (out of over 40,000 known species) are known to have serious, potentially lethal bites.


Neurotoxic venom:-----------------------------The majority of spiders with serious bites possess a neurotoxic venom of some sort, though the specific manner in which the nervous system is attacked varies from spider to spider.


Widow spider venom contains components known as latrotoxins, which cause the release of the neurotransmitter acetylcholine, stimulating muscle contractions. This can affect the body in several ways, including causing painful abdominal cramps, as well as interfering with respiration, and causing other systemic effects.


The venom of Australian funnel-web spiders and mouse spiders works by opening sodium channels, causing excessive neural activity which interferes with normal bodily function.


The venom of Brazilian wandering spiders is also a potent neurotoxin, which attacks multiple types of ion channels  In addition, the venom contains high levels of serotonin, making an envenomation by this species particularly painful.

Black widow spider
Funnelweb spider(Most poisonous spider)
Golden silk Spider
bird eating spider(Goliath bird eating tarantula)


The world's most venomous insect is an ant: 
but don't get the award for 'most venomous insect'. That prize goes to the harvester ant (Pogonomyrmex maricopa). The LD50 for harvester ant venom (in rodents) is 0.12 mg/kg. Compare that to a LD50 of 2.8 mg/kg for a honey bee (Apis mellifera) sting. Now... that's interesting, but the part I liked was that the researchers say that is "equivalent to 12 stings killing a 2 kg (4.4 lb) rat" (University of Florida Book of Insect Records). 


Insect venoms are comprised of amino acids, peptides and proteins. They may include alkaloids, terpenes, polysaccharides, biogenic amines (e.g., histamine), and organic acids (e.g., formic acid). Venoms also may contain allergenic proteins, which can trigger a potentially lethal immune response in sensitive individuals.

Fire Ants
Harvester Ant.


Blister beetles are beetles (Coleoptera) of the family Meloidae
  so called for their defensive secretion of a blistering agent, cantharidin. There are approximately 7,500 known species worldwide. Many are conspicuous and some aposematically colored, announcing their toxicity to would-be predators.

Black_blister_beetle

Red-head beetle : 
That appears to be a whiplash rove beetle, from the family staphylinidae. Contact collision with the beetle while travelling or sleeping, crushing it on the body or smearing with soiled fingers can cause conjunctivitis and severe dermatitis.


The haemolymph in the beetle’s entire body (except the wings) contains the most poisonous animal contact toxin in the world called pederin (C24 H43 O9 N) named in 1953.

Red Head Beetle.

Beetles-bombardiers :
 really deserve the name a “chemical lab”. They have two glands secreting poisoning substances. Each one is parted in two chambers and one common antechamber, the latter of which secrete two enzymes Secretory cells produce hydroquinones and hydrogen peroxide, which collect in a reservoir. When the beetle is in danger, great amount of substances secreted in the both chambers get into the antechamber, where runs a rapid chemical reaction. the catalases and peroxidases rapidly break down the hydrogen peroxide and catalyze the oxidation of the hydroquinones into p-quinones.The temperature rises to 100ยบ and the beetle fires the liquid through his anus in up to 30 cm distance with an enviable archery skill. Some species can produce 15-20 consequent shots. The poison is extremely dangerous for the eyes and the mucous membrane.

AustralianBeetles-bombardiers

Assassin bugs:  
Order Name:HemipteraFamily Name:Reduviidaegain their sinister name from their habit of lying in ambush for their insect prey. With speed and precision, this bug injects its victim with a lethal toxin that dissolves tissue. Although many bugs use their sucking mouthparts for sipping plant juices, some have evolved as predators. When the food supply is limited, this insect will give up its ambush routine for a more active approach.The saliva are generally made up of proteinous materials and several digestive enzymes which used to predigest .

assassin_bug_adult
assassin_bug_adult


Wasps:
It was found that the different genera of wasps are specified in hunting only one kind of insect or arachnid. Their knowledge about the anatomy of the victims is incredible. Wasps know the right places to sting; the targets are the nerve knots. For example the prey of Cerceris wasps is always only one kind of a beetle, Bothynodes punctiventris. Sphex wasps hunt crickets and have to sting them exactly on three point of the body. The Ammofia feed their larvae with caterpillars; there are 9 ganglions to paralyze in the body of those caterpillars. However, the most selfless ones are Pompius wasps, hunting the deadly poisonous for them tarantulas. Victims do not die and that is essential for the larva; it is alive but motionless. 


Wasps can often be seen in the settlements of people, so a wasp sting is a common poisoning. The neurotoxin cannot cause death but it can lead to a clinical picture equal to the one of a honeybee sting. Wasp sting is more dangerous as a rule. It is important to notice that the sting rarely remains in the skin and the wasp usually flies away freely. 

Wasp


Africanized honey bees: 
known colloquially as "killer bees", are a hybrid variety of the European honeybee (Apis mellifera), generated by a man-made breeding of the African honey bee, A. m. scutellata, with various European honey bees such as the Italian bee A. m. ligustica and A. m. iberiensis. These bees are far more aggressive than the European subspecies. Small swarms of Africanized bees are capable of taking over European honey bee hives by invading the hive and establishing their own queen after killing the European queen.

Africanized honey bees.

Tsetse fly:
sometimes spelled tzetze and also known as tik-tik flies, are large biting flies that inhabit much of mid-continental Africa between the Sahara and the Kalahari deserts. They live by feeding on the blood of vertebrate animals and are the primary biological vectors of trypanosomes, which cause human sleeping sickness and animal trypanosomiasis, also known as nagana. Tsetse include all the species in the genus Glossina, which are generally placed in their own family, Glossinidae.

Tsetse fly:

Anopheles Mosquito:
Mosquitoes are a terrible irritant and, because they feed on blood, can drive a person mad just by being outside in the right conditions. Eggs get laid and grow in stagnant areas of water and millions can hatch from one spot. But, the worst aspect of the mosquito is that it’s a carrier for blood-borne diseases, specifically: Malaria. Still numbering in the hundreds of million cases per year, malaria is responsible for more deaths than every other insect combined.

Anopheles Mosquito:

Giant Japanese or Asian Hornet:
This massive hornet can achieve lengths of 3 inches full grown and has been known, in numbers of only 20 or 30, to decimate an entire hive of honeybees. The sting can be lethal not just by allergic reactions but also due to its many toxins. Here are four interesting things about its sting:a: Its sting has a higher concentration of the pain-causing chemical called Acetylcholine than any other stinging insect.b: An enzyme in its venom can dissolve human tissue.c: Containing at least eight distinctly different chemicals, the venom itself produces one such that actually attracts others of its kind to the victim.d: Like all other hornets, it can sting repeatedly.

Giant Japanese or Asian Hornet





Scolopendra gigantea (also known as Peruvian giant yellowleg centipoop and Amazonian giant centipede): 
is the largest representative of the genus Scolopendra, regularly reaching lengths of 26 cm (10 in) and can exceed 30 cm (12 in). It inhabits the northern and western regions of South America and the islands of Trinidad, Puerto Rico, Saint Thomas, U.S. Virgin Islands, Jamaica, and Hispaniola.


It is carnivorous, feeding on insects, lizards, frogs, birds, mice, and even bats.It is also known to prey on tarantulas.The body consists of 21 to 23 segments which are coppery red or maroon in color, each with a pair of yellow-tinted legs; the legs are adapted for fast walking. The centipede has modified claws called forcipules which curve around its head and can deliver venom into its prey. The extremely potent venom, containing acetylcholine, histamine and serotonin (pain mediators), proteases and a cardiodepressant factor, is toxic to humans and causes severe swelling, chills, fever, and weakness. Although bites are painful, they are very unlikely to be fatal to humans.


Scolopendra gigantea (also known as Peruvian giant yellowleg centipede and Amazonian giant centipede):
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2 comments:

  1. interesting passage... :)

    ReplyDelete
  2. Spiders are not insects; they are arachnids. Insects and arachnids are both arthropods.

    Studying the mechanisms of the neurotoxins can help us understand how parts of the nervous system, neurons and synapses work by allowing us to see what happens when the venom interferes with one element. In addition to the ones already mentioned here, the toxins of cone snails, tetanus and botulism have interesting effects, as does tetrodotoxin which is produced by numerous animals including the pufferfish and the blue-ring octopus and is used in many neurophysiological experiments because it blocks sodium channels.

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