User:Colleenlu/Cimex lectularius

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Cimex lectularius is a species of Cimicidae (bed bugs). Its primary hosts are humans, and it is one of the world's major "nuisance pests".

Although bed bugs can be infected with at least 28 human pathogens, no studies have found that the insects are capable of transmitting any of these to humans. They have been found with methicillin-resistant Staphylococcus aureus (MRSA) and with vancomycin-resistant Enterococcus faecium (VRE), but the significance of this is still unknown.

Investigations into potential transmission of HIV, MRSA, hepatitis B, hepatitis C, and hepatitis E have not shown that bed bugs can spread these diseases. However, there is some evidence that arboviruses may be transmissible.

Bed bug bites or cimicosis may lead to a range of skin manifestations from no visible effects to prominent blisters. Effects include skin rashes, psychological effects, and allergic symptoms.

The spread of bed bugs has been previously controlled by common insecticides, but insect resistance has been a growing concern. Combination treatments, which combines chemical and non-chemical treatment techniques have been investigated in order to improve pest control. Heat treatment, a non-chemical treatment, has worked in controlling pests on the exterior of surfaces.

Life cycle[edit]
If feeding regularly, a female bed bug can lay between two and three eggs per day throughout her adult lifetime, which may last several months, allowing one female to produce hundreds of offspring under optimal conditions. The tiny (<1 mm) yellowish-white eggs are vase-shaped, and are laid within harborages where the insects rest between blood meals and spend virtually all of their time: although parasitic, they do not reside on their hosts and only contact them briefly for blood meals. Eggs typically hatch within 10 days at room temperature, but become non-viable below 14 °C (57 °F). Cimex lectularius goes through five immature life stages that each require a blood meal to develop and move on to the next stage. The life cycle occurs more rapidly at warmer temperatures, and more slowly at lower ones. Once the egg hatches, the larval form must take one blood meal per week as it completes each of its five to six molts. Once it completes the final molt, it will have reached the adult stage and can reproduce. Meals take several minutes to consume, and occur only under the correct conditions: darkness, warmth, and carbon dioxide. C. lectularius typically feed on hosts when they are asleep, they tend to feed exclusively on humans, and are obligate blood feeders. Newly hatched nymphs must consume a blood meal within two to three days or will die of starvation, whereas an adult can live for as long as six months between feedings.

Occurrence and Distribution[edit]
C. lectularius is found all over the world in almost every area that has been colonized by humans. In the past, bed bugs were particularly an affliction of the poor and occurred in mass shelters. However, in the early part of the modern resurgence it was the tourist areas that were impacted. Today, bed bugs have conquered quite diverse locations, ranging from hospitals, hotels to trains, cruise ships and even airplanes. Most commonly, bed bugs travel as stowaways in luggage, although they can be transferred via furnishing and other belongings, as well by spreading to adjoining properties. Since there are no mandatory reporting requirements, exact figures on the occurrence of bed bugs are unknown and, due to the stigma often associated, many infestations are simply not reported.

Pest Control
Bed bugs have previously been controlled by commonly used insecticides such as DDT, but have recently had a reappearance due to insecticide resistance. More specifically, bed bugs have developed a resistance to a specific class of insecticides called pyrethroids. A field study was done to investigate the effectiveness of current pest control products in multi-unit apartment complexes that are currently used by the pest management industry (pyrethroids and non-pyrethroid treatments). In both treatment groups, bed bugs populations were not able to be fully eliminated even after many applications of treatment of many products. This study raised the concern regarding the issue of failure to eliminate bed bug populations using the current treatments that are available for bed bugs. A way to combat strong resistance to treatments, such as pyrethroids, could be considering combined approaches (combining insecticides with sanitation and prevention education).

Although there are several modes of resistance to pyrethroids, previous studies have shown that detoxifying enzymes may play a role in the development of insecticide resistance in bed bugs. Many attempts have been made to combat this resistance, such as supplementing pyrethroid treatments with other chemicals such as piperonyl butoxide (PBO) and insect growth regulators (IGRs), which have been poorly successful due to inefficient rates of elimination and inconsistent termination results. The development of insecticide resistance has prompted the investigation of additional more effective pest control methods. To control the spread of bed bugs, alternative pest control methods to chemical treatment has included combination treatments which include chemical treatment combined with a treatment that does not involve chemicals, such as heat and cold treatment and vacuuming. A recent study from 2016 studied a specific application of heat treatment on luggages since bed bugs commonly spread from surface to surface on luggages during travel. This study found that at 75°C, bed bugs were killed within three minutes. Bed bugs do have a tendency to conceal themselves in crevices whenever possible. For bed bugs that had hidden in the stitching of luggages, they were killed within six minutes. Although heat treatment is not as effective at killing bed bugs that are not on the exterior of luggages, heat treatment can be considered as a possible treatment to effectively kill bed bugs on the exterior of surfaces. Historically, bed bugs have been controlled by entirely physical means which completely avoids the ever growing issue of insecticide resistance. Bed bugs are known to have been trapped by the leaves of bean plants. Extermination would occur the next morning by burning the leaves of the bean plants which now had bed bugs trapped on it. Bed bugs were able to be trapped by the leaves of bean plants due to the trichomes on the leaves of bean plants which could intertwine with the legs of the bed bug.