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American Cockroach - Periplaneta americana
Topic Started: Jun 6 2014, 06:35 PM (2,905 Views)
Taipan
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American Cockroach - Periplaneta americana

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Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Blattodea
Family: Blattidae
Genus: Periplaneta
Species: Periplaneta americana

The American cockroach (Periplaneta americana), also colloquially known as the waterbug, but not a true waterbug since it is not aquatic, or misidentified as the palmetto bug (see Florida woods cockroach for the differences), is the largest species of common cockroach, and often considered a pest. It is also known as the ship cockroach, kakerlac, and Bombay canary.

Distribution
Despite the name, none of the Periplaneta species are endemic to the Americas; P. americana was introduced to the United States from Africa as early as 1625. They are now common in tropical climates because human activity has extended the insect's range of habitation, and are virtually cosmopolitan in distribution as a result of global commerce.

History
Cockroaches date back to the Carboniferous period. Cockroaches are thought to have emerged on the supercontinent Pangaea, or on Gondwana, the daughter continent of Pangaea. The cockroach made many adaptations over the years to be able to survive the major die offs to which many species succumbed.

Characteristics
American cockroach adults grow to an average length of around 4 cm (1.6 in) and about 7 mm (0.28 in) tall. They are reddish brown and have a yellowish margin on the body region behind the head. Immature cockroaches resemble adults except they are wingless.

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The cockroach is divided in three sections; the body is flattened and broadly oval, with a shield-like pronotum covering its head. A pronotum is a plate-like structure that covers all or part of the dorsal surface of the thorax of certain insects. They also have chewing mouth parts, long, segmented antennae, and leathery fore wings with delicate hind wings. The third section of the cockroach is the abdomen.

The insect can travel quickly, often darting out of sight when someone enters a room, and can fit into small cracks and under doors despite its fairly large size. It is considered one of the fastest running insects.

In an experiment carried out at the University of California, Berkeley in 1991, a Periplaneta americana registered a record speed of 5.4 km/h (3.4 mph), about 50 body lengths per second, which would be comparable to a human running at 330 km/h (210 mph).

It has a pair of large compound eyes, each having over 2000 individual lenses, and is a very active night insect that shuns light.

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Risk to humans
The odorous secretions produced by American cockroaches can alter the flavor of food. Also, if populations of cockroaches are high, there will be a strong concentration of this odorous secretion. Cockroaches can pick up disease-causing bacteria, such as Salmonella, on their legs and later deposit them on foods and cause food infections or poisoning. House dust containing cockroach feces and body parts can trigger allergic reactions and asthma in certain individuals.

Habitat
American cockroaches generally live in moist areas, but can survive in dry areas if they have access to water. They prefer warm temperatures around 29 °C (84 °F) and do not tolerate cold temperatures. In residential areas, these cockroaches live in basements and sewers, and may move outdoors into yards during warm weather. These cockroaches are common in basements, crawl spaces, cracks and crevices of porches, foundations, and walkways adjacent to buildings.

Life cycle
American cockroaches have three developmental stages: egg, nymph, and adult. Females produce an egg case (ootheca) which protrudes from the tip of the abdomen. On average, females produces 9-10 ootheecae. Cockroach is paurometabolous. After about two days, the egg cases are placed on a surface in a safe location. Egg cases are about 0.9 centimetres (0.35 in) long, brown, and purse-shaped. Immature cockroaches emerge from egg cases in 6 to 8 weeks and require 6 to 12 months to mature. After hatching, the nymphs feed and undergo a series of 13 moultings or ecdysis Adult cockroaches can live up to an additional year during which females produce an average of 150 young.

Diet
American cockroaches are omnivorous and opportunistic feeders that eat a great variety of materials such as cheese, beer, leather, bakery products, starch in book bindings, manuscripts, glue, hair, flakes of dried skin, dead animals, plant materials, soiled clothing, and glossy paper with starch sizing. It is particularly fond of fermenting foods. They have also been observed to feed upon dead or wounded cockroaches of their own or other species.

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Control
Due to their large size and slow development, large infestations of these insects are not common within houses. However, during certain times of the year, these cockroaches may move inside a house from outside. In cold weather these cockroaches may move indoors, seeking warmer temperatures and food. Cockroaches may enter houses through sewer connections, under doors, around plumbing, air ducts, or other openings in the foundation. Cockroach populations may be controlled through the use of insecticides. It is also wise to cover any cracks or crevices through which cockroaches may enter. Also, always clean any spills or messes that have been made so that the cockroaches will not be attracted to the food source. Another way to prevent an infestation of cockroaches is to thoroughly check any material that is brought inside. Cockroaches and egg cases can be hidden inside or on furniture, in boxes, suitcases, grocery bags etc.
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Parasitic Wasp Turns Roaches into Zombie Slaves using Neurotoxic Cocktail

By Sana Suri, University of Oxford | June 05, 2014 02:48am ET

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Bow before thy master.

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

For decades, scientists have tried to understand the complex and gruesome relationship between the parasitic emerald wasp Ampulex compressa and its much larger victim, the common household cockroach Periplaneta americana.

At first glance, this parasite-prey relationship seems much like any other: the female wasp stings the cockroach, lays an egg on its abdomen, and once hatched, the hungry larva feeds on the cockroach. However, while most parasitic insects tend to paralyse their victims with a venomous sting, the emerald wasp instead manipulates the cockroach’s behaviour, essentially transforming it into a zombie slave.

With two stings the cockroach is left with the ability to walk, but is entirely robbed of the power to initiate its own movement. The wasp, now tired after administering two stings, regains its energy by cutting off the ends of the cockroach’s antennae, and drinking its blood. Revitalised, it then latches on to the stung cockroach’s antennae and, much like an obedient toddler being lead to his first day of school, the submissive insect follows the wasp’s orders.

In the meantime the wasp also lays an egg on the cockroach, which hatches after three or four days. The hatched larva chews its way into the cockroach’s abdomen, where it proceeds to eat the internal organs in a precise order. This ensures that the docile victim stays alive for the next four days, until the larva eventually forms a cocoon inside it.

With time, the fully-grown wasp emerges from the host’s body and continues this vicious cycle. Through it all, the stupefied roach, although able to move, shows no desire to struggle, flee, or fight, even as it is being eaten alive from the inside.

How to control a roach

This wasp-cockroach relationship has been documented as early as the 1940s, but it wasn’t until recently that scientists have been able to understand how exactly the wasp pulls off this precise behavioural manipulation.

The first sting, administered to a mass of nerve tissue in the cockroach’s thorax, contains large quantities of gamma amino butyric acid (GABA), and complementary chemicals called taurine and beta alanine. GABA is a neurotransmitter that blocks the transmission of motor signals between nerves, and, together with the other two chemicals, it temporarily paralyses the cockroach’s front legs. This prevents the cockroach from escaping while the wasp inflicts the second, more toxic sting directly into the roach’s brain.

It is the second sting that turns the cockroach into a zombie, and contains what Frederic Libersat and his colleagues at Ben Gurion University refer to as a “neurotoxic cocktail”. The venom of the second sting blocks the receptors for another neurotransmitter called octopamine, which is involved in the initiation of spontaneous and complex movements such as walking.

Libersat has shown that unstung cockroaches injected with an octopamine-like compound show an increase in walking behaviour. Those injected with a chemical that blocks octopamine, however, show a reduction in spontaneous walking, much like the victims of the wasp sting. Zombie cockroaches were also able to recover from their stupor and walk after they were injected with a chemical that reactivates octopamine receptors.

There is a fine distinction between the ability to walk, and the ability to initiate such a movement. The stung cockroaches in this instance are devoid of the latter, while their skills for the former seem intact, demonstrated by the fact that these poor creatures are entirely capable of walking to the wasp’s nest, but only when being led by the wasp.

Libersat and colleagues investigated this interesting phenomenon by placing stung cockroaches in potentially harmful situations and testing their escape reflexes. They found that cockroaches stung by the emerald wasps were soon deprived of any will to escape to safety even when electrocuted or drowned. However, their motor skills, measured by the contractions of their muscles when subjected to these dangers, were the same as unstung cockroaches, suggesting that the venom affects the decision rather than the ability to walk.

However haunting this behavioural manipulation is, one can’t help but appreciate the ingenuity of this tiny parasite, enabling it to incapacitate a much bigger victim. If the wasp were to paralyse the cockroach, it probably would not be able to carry it back to its lair. If it were to kill the cockroach, it would lose its source of fresh food. It has evolved to develop the most complex and precise weapon to overcome these two obstacles: venom that only targets the specific neural circuits which guarantee that its victim will walk obediently to its tomb, and stay alive while it is being devoured. And with no will to escape, these poor roaches help another generation of terrifying emerald wasps to be spawned.

http://www.livescience.com/46116-parasitic-wasp-turns-roaches-into-zombie-slaves-using-neurotoxic-cocktail.html
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