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Bed Bugs

Bedbugs - what's the score?

Wall lice, bug flats, crimson ramblers, chinches, Norfolk Howards, mahogany flats, etc., etc.. The humble bed bug (Cimex

lectularius) has gained a place in world-wide folk lore and is universally reviled. Many years of onslaught in the UK had

reduced their populations significantly, but recently this troublesome pest has had a resurgence, both in terms of numbers

and in several instances of pesticide tolerance. Why? Let's begin with a review of the pest and its habits.

As man moved from a hunter-gatherer to living in urban settlements, many insects took advantage of this localised

situation. Initially, flies and beetles were attracted to food storage and preparation areas. Bed bugs moved in as the human

dwellings improved and became more permanent. They are closely related to the bat bug (Cimex pilosellus) and probably

first became associated with man when they were living in caves in Africa.

Humans (very much as they are now) were sought for a blood meal whilst they slumbered on the floor of the cave. The

bugs would locate their host by detecting their body heat and the carbon dioxide given off in their breath and through

their skin. Interestingly, there is still a species of bed bug (Leptocimex boueti) that still feeds off the blood of both humans

and bats in West Africa.

As civilisation evolved, the bed bug became our bed fellow, moving into our homes in ever increasing numbers. Sanitation

and personal cleanliness were offered as a defence against lice and other bodily pests. In 1602, Ulysses Aldrovandi, a

renowned social observer, reported that bed bugs were much more common in houses of the poor than in those of the

rich, because the rich had the means to keep their houses cleaner than those of the poor. In the late 1800s, bed bugs

were regarded as probably the most serious urban pest. Commercial pest control companies began to form in the larger

cities across Europe at this time. Their preparations ranged from chemicals that we would run a mile from today, to several

that we still recognise and use today - mercuric chloride in alcohol was regarded as an excellent treatment for bed bugs,

and pyrethrum and rotenone were beginning to arrive from the Orient.

In more recent times, the success of pesticides, such as organophosphorous compounds and pyrethroids, has meant

wide-scale eradication of bed bug populations. We realise now that dirty housing is not a pre-requisite for bed bug activity,

but it is thought that the unfortunate decline in social standards in some areas of the populous, coupled with an increase

in close-packed communities HMOs (houses of multiple occupancy, student accommodation, bed-sits and not forgetting

down-and-outs) have led to bed bug populations increasing significantly.

So what exactly is a bed bug? These insects are members of the order Hemiptera, the true bugs, which includes bugs

that attack house plants and pond skaters that live on the water's surface.

The bed bug has a simple or incomplete metamorphosis. Mating is a rough affair, with the male actually puncturing the

female's abdomen to inject sperm directly (a process known as "traumatic" insemination for obvious reasons!). A female

can lay up to 200 eggs over about two months. There are five nymphal stages which take 35 to 150 days to pass through,

depending on conditions. Adults are able to survive long periods in unoccupied houses or in furniture in store. In

desperation, they can survive on other species, such as poultry, sparrows, rats, mice and guinea pigs (which may explain

some long-term continued infestations). Adults that are well fed can then resist long periods of starvation - timescales of

nearly one and a half years have been recorded.

Nymphal instars take about three minutes to have a blood meal, but adults need over ten minutes to become engorged.

The mouthparts are adapted to form two pairs of stylets that puncture the skin. The outer pair is provided with barbs to

saw into the skin, and the inner pair form two tubes, one for sucking up the blood, and one for injecting saliva containing

an anticoagulant. A fully engorged adult can be 6-8mm long.

For many, the bite is painless, but some can detect it straight away. A typical red "wheal" is left by the biting insect,

caused by an allergic reaction to the saliva. The location of the bite(s) is very useful to a pest controller in diagnosing the

biting species. Flea bites are most commonly on the lower leg or ankle, whereas bed bug bites are often on the face, neck

arms or hands, and occasionally around the waist.

Where do they live? Within the urban ecosystem, there are three primary components, the human and non-human and

the physical structures. The habitat that is made up of human settlements is known as "Anthropobiocoenosis". Probably

the biggest word ever used in Pest Control News, this lengthy term means the part of the environment that has been

completely changed by man. It can even be sub-divided into "peridomestic" habitats, which are those outside dwellings,

and "domestic" habitats, which are located inside dwellings. The bed bug has invaded most areas of the latter category,

but principally those areas where we sleep. This is because time is needed to take a blood meal, and unless you are a

couch potato, humans do not sit still long enough for this to occur in the sitting room!

Control of bed bugs has always been relatively straightforward, although often a great deal of searching and a thorough

treatment or series of treatments was needed. However, in recent months, reports have been appearing in the national

press of "super infestations" of "resistant mutant bed bugs". This situation needs explaining.

It is known that the incidence of bed bugs is increasing, especially in London and in some of the university towns and

cities such as Cambridge. It is also known by a number of pest controllers that several populations are becoming very

difficult to treat successfully. Expressions like "pesticide-resistant" are thus bandied about. Such a term is not warranted.

True resistance is a biological term, meaning a population which, over time, has become "immune" to the effects of a

pesticide. This can only be conferred by surviving adults to their offspring and so takes time and several generations. The

instances reported in the press are more likely to be ones of "tolerance", whereby the bed bugs are able to tolerate a

pesticide and survive. (The offspring of these survivors would therefore be "resistant").

Like all treatments where a given product appears not to work, the selection of a pesticide from another group of active

ingredients if often the answer. Currently, the infestations that are causing some difficulty seem to be able to tolerate the

use of pyrethroids, and some are also carbamate-tolerant.

Nigel Binns, Biologist for Killgerm Chemicals Ltd., commented: "We are receiving a number of phone calls where

technicians are experiencing difficulty in controlling bed bug infestations. If they have used pyrethroids and/or

carbamates, a return to the use of organophosphorous pesticides usually does the trick. The down-side to this is that they

are often a little 'smelly', and so the customer should be advised. Organophosphorous pesticides that are approved for

use as public health products are perfectly safe in such situations, providing the technician follows the label

recommendations."

Finally, the bed bug does have predators. T. Pergande, a Union soldier in the American Civil War, reported that Pharaoh's

ants (Monomorium pharaonis) attacked and dismembered bedbugs in an infested quarters in Mississippi - perhaps this

is a novel form of biological control that we could choose to employ. Two infestations for the price of one!

Cockroach and dust mite

Many allergies are well-recognised and understood, but insect and mite allergies are still being examined. A study in 1997,

supported by the US National Institute of Allergy and Infectious Diseases (NIAID) conclusively demonstrated that the

combination of cockroach allergy and exposure to the insects is an important cause of asthma-related illness and

hospitalizations among children in U.S. inner-city areas.

"Some of the most vulnerable of our citizens, children in the poorest neighbourhoods of our large cities, suffer

disproportionately from asthma," says Anthony S. Fauci, M.D., NIAID director, in the report. "Allergy and exposure to

cockroach allergen clearly play an important role in the alarming rates of asthma-related sickness among these children."

"Reducing exposure to cockroach allergen, as part of a multi-faceted approach to asthma management, may be a cost-

effective way of reducing the burden of this serious disease," says Daniel Rotrosen, M.D., acting director of NIAID's

Division of Allergy, Immunology and Transplantation. "Simple and relatively low-cost interventions that have been explored

in the NCICAS, such as patient education, roach traps and child-safe insecticides, are potentially important."

The first five-year phase studied 476 of these children. The researchers measured levels of cockroach, dust mite and cat

allergens in the children's homes, and determined with allergy skin tests that 37 percent of the children were allergic to

cockroaches, 35 percent to dust mites, and 23- percent to cats. The investigators then assessed the severity of the

children's asthma over 12 months.

They found that children who were both allergic to cockroaches and exposed to high cockroach allergen levels were

hospitalised for their asthma 3.3 times more often than children who were allergic but not exposed to high levels of

cockroach allergen, or children who were exposed to high levels of cockroach allergen but who were not allergic. Children

who were both allergic and heavily exposed to cockroach allergen also missed school more often, needed nearly twice

as many unscheduled asthma-related medical visits, and suffered through more nights with lost sleep.

In addition, the activities of the adults who cared for these children were frequently disrupted. Researchers also collected

dust samples from each child's bedroom with a hand-held vacuum cleaner to measure the level of each allergen. While

most bedrooms had detectable levels of all allergens, 50.2% contained high disease-inducing levels of cockroach allergen

compared with 12.6% of rooms with high levels of cat allergen and 9.7% with high dust-mite allergen levels.

Even when families do all the right things at home, though, "...the biggest cockroach problem, in some cases, is at the

schools themselves," says Dr Jean Hanley-Lopez, Los Angeles Breathmobile Director. "In inner-city L.A. schools, students

have a high level of cockroach exposure," she says, "but I'm sure the school district is not even aware how big a problem

this is for students with asthma."

Dr. Thomas Platts-Mills, one of the NIAID researchers, mentions several difficulties. "People don't always understand that

they have cockroach allergies. Cockroach dust also disperses 'all over the house,' making it difficult to eliminate. Sprays

make a lot of asthma patients worse," Platts-Mills adds, "and you can use all the bait traps you want, but they won't work

if the cockroaches have a supply of food."

"It's all very well to have ambitions to decrease cockroaches," he concludes, "but we need more understanding of how

to do it." Dr. Richard Evans, an asthma specialist at Children's Memorial Hospital in Chicago agrees: "The one thing I

would do is help people get rid of cockroaches."

Dust mite allergy is an allergy to a microscopic organism that lives in the dust that is found in all domestic dwellings and

places of work. People are slowly recognising that dust mites and their droppings are perhaps the most common cause

of asthma and allergic rhinitis.

House dust is not a single substance but a cocktail of potentially allergenic materials. It may contain fibres from different

types of fabrics, feathers and other stuffing materials, dander from cats, dogs and other animals, bacteria, mold spores,

bits of plants and insects and other particles peculiar to an individual building. House dust also contains thousands of

microscopic mites which live in bedding, upholstered furniture, carpets etc. They thrive in summer and tend to die in

winter. However, in warm, humid environments such as a centrally-heated house, hospital or office, they continue to

thrive.

Each mite produces about twenty waste pellets a day, each containing a small amount of one of the most dangerous

chemicals known to science. Not only is the allergen of the house dust mite the usual cause of babies and small children

becoming asthmatic, it is also the commonest on a long list of irritants which cause existing asthmatics to have respiratory

symptoms.The constant presence of house dust mite droppings in the air inside homes keeps the lungs of asthmatics sensitive to

all the other factors which trigger asthmatic symptoms. If sufferers can avoid the dust mite allergen for a few months, then

usually the other factors lose much of their power.

Because mites are so tiny, their body water regulation is critical. As a result, the droppings they produce are very dry. The

average population per gram of dust is believed to be from 100 to 500, but can be up in the thousands. Egg-laying female

mites can increase the population by 25 to 30 every three weeks. Mites are equipped with sticky pads on the ends of their

feet, so they are able to burrow deep in carpet fibres and furniture where they hang on and are able to survive vacuuming.

Proteins in the dust mite droppings, called Der P1 and Der F1, are severe instigators of allergic response. When these

floating pellets are inhaled, they cause problems in the mite-allergic person. Even after the mite's death its faecal particles

remain in the home, and the mite's disintegrating body parts are still allergenic and easily airborne.

Although no environment is free of dust mites, there are specific steps you can take to reduce the number of these

creatures in your home. Many of these emanate from old wives' tales, but have their basis in fact:

Mattresses, box springs and pillows should be encased in non-allergenic, plastic-zipped casings. The zips should be

covered with adhesive tape. Wipe with a damp cloth or vacuum weekly. If there is more than one bed in a room, each

mattress should be encased. If bunk beds are used, the allergic child should sleep on the top bunk. Avoid using canopy

beds.

Use washable blankets, spreads and polyester or dacron pillows. Avoid feather pillows, down or padded comforters, wool

blankets and chenille spreads. Wash all bedding frequently in hot water (over 60 degrees centigrade). Don't use an

economy wash as mites survive in warm water, and you just end up with clean mites!

Ants

Understanding Ant Music

The ability to communicate through infochemical means, including pheromones, is at its highest among insects which live

in homogeneous communities - social insects. The ant in particular is distinguishable by its numerous exocrine glands

and the various chemicals it secretes as it relays information among its groups.

The largest ants have eyes located about 5mm from the ground whilst the smallest have eyes less than 1mm above the

ground and are unable to see beyond anything more than 5mm tall. Eyesight then, is not their strongest point. Ants

evolved from bees and they have developed acute olfactory senses which enable them to forage for food even in the

darkest situations. The ant senses environmental chemicals such as odours or non-volatile matter through physical

contact via its antennae. It then reacts according to the information the chemicals convey.

Chemical signals for species recognition

Insect species consist entirely of males and females with a male and female from each species reproducing. Sex

pheromones facilitate mating encounters however, how does an insect ascertain that the potential mate belongs to the

same species?

Dr Ryohei Yamaoka, of the Kyoto Institute of Technology has evaluated the important role infochemicals play in individual

identification among ants by observing their behaviour in their fascinating world. The team sampled cuticular waxes,

particularly hydrocarbons, from more than 500 species of insects including ants. They discovered that the composition of

these substances was species specific for all the insects sampled. They also discovered what happens when two ants

from different species meet and fight savagely. Only when the antennae of one ant actually touches its opponent's body

will the fighting begin. No matter how closely the two pass, unless the antennae of one touches the body of the other, no

fighting will occur. Ants do not recognise their opponents by vision, but by non-volatile chemicals on their bodies and they

also seem to confirm membership of the same species by detecting like-for-like hydrocarbons in the same way.

Different species of ants can live together

In order to live together, different species must change their previous recognition of their cohabitants as belonging to

different species. Slave maker ants (Polyergus samurai) invade nests where so-called hill black ants (Formica japonica) or

forest black ants (Formica sp.) live, attack and steal pupae and cocoons from them and bring their booty back to their

own nest. They attend to the pupae and cocoons until they hatch as well as nurturing the slave maker queens' eggs. In

the nest, slave maker ants avoid productive activity. They walk about lazily prompting slave ants to feed them.

Dr Yamaoka's team sampled cuticular hydrocarbons from two species of ants which live harmoniously in the same nest

as previously mentioned and discovered that slave maker ants can barely synthesize hydrocarbons natural to their own

species and receive the cuticular hydrocarbons they possess from slave ants through bodily contact. Accordingly, slave

maker ants take on the same hydrocarbons as those of their slave ants and are thus chemically camouflaged, rendering

them recognisable as cohabitants by their slave ants.

Signals which allow ants to identify mates from the same nest

The chemical discrimination ability of the ant is so great that it can distinguish not only ants of different species, but ants

from different nests (colonies). Cohabitants from the same nest are generally offspring of the same queen ant and share

the same kinship. However, other ants, even those from the same species, share no common kinship when they inhabit

different nests. Instead, they are intense rivals, competing for common food sources.

Ants from a given nest are believed to use individual or group odours, distinctive to the nest they inhabit, although the

composition of the chemicals involved remains undetermined. However, the composition of the hydrocarbons, which act

as a signal for species recognition, must be identical between residential and visiting ants, as they are members of the

same species... you would think.

The tests the team conducted bore interesting results. The profiles of composite hydrocarbons showed great variety from

one colony group of ants to another, or were distinct in each type of ant tested. There was also diversity in ants from a

queen-less nest. But samples taken from ants in the same nest with a queen were identical. This is due to the queen which

will entice nearby worker ants around her by use of a pheromone. In approaching, the workers initiate physical contact.

Accordingly, cuticular hydrocarbons are exchanged among a swarm of individual ants, leading to chemical consistency

of ants in the same colony.

Grooming

Grooming also plays a major part in "spreading" the same hydrocarbons among ants in the same colony. They use two

methods. One is to remove cuticular hydrocarbons from the partner by licking, then storing them in a special gland. The

other is to secrete them from the same gland for use in coating and grooming its own body.

Psocids

Psocids

"Sosids," as the proper pronunciation is, are booklice and there are over 3000 species of them to be found across the

world, although less than 50 are associated with human activities, including food storage and processing. But, their

significance as pests has increased over the last 35 years, which has been a matter of considerable interest to the Society

of Food Hygiene Technology, which ultimately led them to sponsor a survey among their members.

The results were published in 1984 and, although they helped to define the problem, they highlighted the need for further

research, as many questions about them still remain unanswered.

Psocids are widely distributed and typically favour dark places. They infest domestic premises, raw material stores,

manufacturing, distribution and retail premises; museums have also been infested and a wide variety of commodities may

be infested, including those which are of animal and vegetable origin, particularly farinaceous materials.

A four-fold problem

Nuisance - Psocids are a nuisance in industry because they interfere with production and threaten the integrity of

products, so reducing the quality and wholesome nature of the food.

They are typically associated with newly completed homes - damp building materials, plaster, etc., foster the growth of

mould on which the insects feed. Also, they are regularly encountered in food cupboards where they infest cereals, flour,

sugar, gravy thickener, etc..

Direct feeding damage - Psocids are not usually associated with damage caused by feeding activities, but direct

damage to commodities is possible and particular problems may be experienced when valuable articles, such as furs,

books, etc., become infested.

Transmission of micro-organisms - Micro-organisms and their spores will survive passage through the psocid gut and

may be carried on the surface of their bodies. Psocids may therefore, disseminate spoilage organisms, or even possibly

pathogens.

Health hazard -There is no evidence that psocids are vectors of disease. Nevertheless, they may eat tapeworm eggs

and harbour their larvae and so act as intermediate hosts for such parasites. Despite this, there is increasing evidence

that the insects may be a source of environmental allergens. The main impact of psocid infestations in homes is regarded

as psychological, with reactions which are occasionally disproportionate to any real threat.

Major Pest Species - L. bostrychophila is the major psocid pest encountered in domestic premises, accounting for over

90%, and is usually associated with consumer complaints. It is not generally found in commercial food handling

situations. The various psocid species tend to be associated with particular situations.

Environmental Factors - Psocids are vulnerable to dessication at humidities