Agriculture Reference
In-Depth Information
resistance, and the introduction of a number
of non-chemical control systems, insecticide
sprays continue to be the most commonly
used bed bug control technique in most
countries. Most products for residual sprays
are typically diluted in water (although a
few may be diluted in organic solvents) and
applied using a compression sprayer. A fl at
fan nozzle is commonly used, although a
pin-stream nozzle may also be used where
cracks and crevices need to be treated.
Product approval and conditions of use
will vary from country to country. In
general, very few insecticide products are
approved for direct use on the bed linen.
Some products, however, have approval for
application to the mattress, provided the
mattress is then covered by a sheet before
use. Most products are approved for appli-
cation to the bed frame, to the room and
furniture within it, either as a spot treatment
or a more widespread application.
The objective of residual spraying is: (i)
to contact as many bugs as possible with the
spray itself; and (ii) to apply a residual fi lm
of insecticide to surfaces on which they
subsequently rest and walk.
A variety of sprayable formulations are
available, including suspension concen-
trates, wettable powders, suspo-emulsions,
micro-emulsions, emulsifi able concentrates
and others. In general, those formulations in
which the active substance is present in the
form of particles are likely to provide longer
persistence on porous surfaces.
Insecticide dusts typically contain either
carbamate or pyrethroid insecticides so
their effi cacy may be affected by bed bug
resistance to these insecticides.
However, in addition to conventional
insecticide dusts, desiccant dusts are also
available for bed bug control. These dusts
are based on silica, either of natural origin
(diatomaceous earth) or manufactured
amorphous silica. In both cases, the fi ne
particles of silica damage the wax layer on
the insect's cuticle, either by abrasion or
absorption, causing the insect to lose water
and die. The desiccant dust will last for
extended periods in dry, protected voids.
Having an essentially physical action, it is
active against both susceptible and
insecticide-resistant bed bug strains.
Fumigation for bed bug control
Fumigation is the use of toxic penetrating
gases to kill pests. Typically this is carried
out for control of food storage pests but in
the USA the fumigant sulfuryl fl uoride is
now also used to control bed bugs. Whole
buildings may be fumigated after careful
sealing or infested items such as furniture
may be transferred into a mobile fumigation
chamber. Sulfuryl fl uoride has been shown
to be effective against all life stages of the
pest (Miller and Fisher, 2008).
Systemic host treatments
For control of ectoparasites such as fl eas on
companion animals, systemic treatments of
the host are in widespread use.
Assuming that appropriate treatments
can be identifi ed, use of this approach for
control of bed bugs would require that the
humans affected by bed bugs take a
treatment (e.g. orally) in order to create
active levels of the material in their blood,
which would then kill the bed bug when
ingested. Clearly this is very unlikely to be
suitable for guests in a hotel setting but may
be feasible for those living in infested
premises.
Preliminary evaluation of the effi cacy of
ivermectin for this use has been reported
Insecticide dusts
A range of insecticide dusts is also used for
bed bug control. Insecticide dusts are dry
powders that are puffed or blown into bed
bug harbourages, where they can provide a
residual effect. Dusts may produce a
potentially unsightly whitish deposit so
their use is typically restricted to concealed
areas. Electrical sockets, gaps behind skirt-
ing boards or under fl oorboards, the under-
side of fi tted carpets and openings where
pipework passes through walls are all
typical usage areas.
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