sexta-feira, 9 de maio de 2008

Cupim









I have spent several years fighting a battle to get rid of any cupim, termites to you and I, in the garden and house, with largely good success, yet they have returned into one of the plants in the garden and I guess that it is bye bye to the plant, it needs to be dug up and burnt and the the ground dug for a depth of about a metre in order to get the main colony. The tell tale signs are their half round tunnels that wander the garden walls in search of dry dead wood, your house or furniture for example.

Human interaction
The result of an infestation is severe wood damage.
The result of an infestation is severe wood damage.

Because of their wood-eating habits, termites sometimes do great damage to buildings and other wooden structures. Their habit of remaining concealed often results in their presence being undetected until the timbers are severely damaged and exhibit surface changes. Once termites have entered a building they do not limit themselves just to wood, also damaging paper, cloth, carpets, and other cellulosic materials. Often, other soft materials are damaged and may be used for construction. Particles taken from soft plastics, plaster, rubber and sealants such as silicon rubber and acrylics are often employed in construction.

Termites usually avoid exposure to unfavourable environmental conditions. They tend to remain hidden in tunnels in earth and wood. Where they need to cross an impervious or unfavourable substrate, they cover their tracks with tubing made of faeces, plant matter, and soil. Sometimes these shelter tubes will extend for many meters, such as up the outside of a tree reaching from the soil to dead branches. Termite barrier systems used for protecting buildings aim to prevent concealed termite access, thus forcing the termites out into the open where they must form clearly visible shelter tubes to gain entry.

Termites can be major agricultural pests, particularly in Africa and Asia where crop losses can be severe but counterbalancing this is the greatly improved water infiltration where termite tunnels in the soil allow rainwater to soak in deeply and help reduce runoff and consequent soil erosion.

In many cultures, termites are used for food (particularly the alates) and termite nests are used widely in construction (the dirt is often dust-free) and as a soil amendment.

Humans have moved many wood-eating species between continents, but have also caused drastic population decline in others through habitat loss and pesticide application.

Avoiding termite troubles

Termite damage on external structure
Termite damage on external structure
Coptotermes acinaciformis Bivouac
Coptotermes acinaciformis Bivouac
Coptotermes acinaciformis Bivouac (after treatment)
Coptotermes acinaciformis Bivouac (after treatment)

Precautions:

  • Avoiding contact of susceptible timber with ground by using termite-resistant concrete, steel or masonry foundation with appropriate barriers. Even so, termites are able to bridge these with shelter tubes, and it has been known for termites to chew through piping made of soft plastics and even lead to exploit moisture. In general, new buildings should be constructed with embedded physical termite barriers so that there are no easy means for termites to gain concealed entry. While barriers of poisoned soil, so called termite pre-treatment, have been in general use since the 1970s, it is preferable that these be used only for existing buildings without effective physical barriers.
  • The intent of termite barriers (whether physical, poisoned soil, or some of the new poisoned plastics) is to prevent the termites from gaining unseen access to structures. In most instances, termites attempting to enter a barriered building will be forced into the less favourable approach of building shelter tubes up the outside walls and thus they can be clearly visible both to the building occupants and a range of predators. Regular inspection by a competent (trained and experienced) inspector is the best defense.
  • Timber treatment.
  • Use of timber that is naturally resistant to termites such as Canarium australianum (Turpentine Tree), Callitris glaucophylla (White Cypress), or one of the Sequoias. Note that there is no tree species whose every individual tree yields only timbers that are immune to termite damage, so that even with well known termite-resistant timber types, there will occasionally be pieces that are attacked.

When termites have already penetrated a building, the first action is usually to destroy the colony with insecticides before removing the termites' means of access and fixing the problems that encouraged them in the first place. Baits (feeder stations) with small quantities of disruptive insect hormones or other very slow acting toxins have become the preferred least-toxic management tool in most western countries. This has replaced the dusting of toxins direct into termite tunnels which had been widely done since the early 1930s (originating in Australia). The main dust toxicants have been the inorganic metallic poison arsenic trioxide, insect growth regulators (hormones) such as Triflumuron and, more recently, fipronil. Blowing dusts into termite workings is a highly skilled process. All these slow-acting poisons can be distributed by the workers for considerable periods (hours to weeks) before any symptoms occur and are capable of destroying the entire colony. More modern variations include chlorfluazuron, Diflubenzuron, hexaflumuron, and Novaflumuron as bait toxicants and fipronil and imidacloprid as soil poisons. Soil poisons are the least-preferred method of control as this requires much larger doses of toxin and results in uncontrollable release to the environment.

Termites in the human diet

The alates are nutritious, having a good store of fat and protein, and are palatable in most species with a nutty flavour when cooked. They are easily gathered at the beginning of the rainy season in Central and Southern Africa when they swarm, as they are attracted to lights and can be gathered up when they land on nets put up around a lamp. The wings are shed and can be removed by a technique similar to winnowing. They are best gently roasted on a hot plate or lightly fried until slightly crisp; oil is not usually needed since their bodies are naturally high in oil. Traditionally they make a welcome treat at the beginning of the rainy season when livestock is lean, new crops have not yet produced food and stored produce from the previous growing season is running low.

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