Insect Control: Biological and Synthetic Agents - Index of

and the resolution of FAD was tested in dogs and
cats from single- and multiple-animal households
(Genchi et al., 2000). Flea infestation was examined
and FAD dermatitis lesions were ranked according
to severity of typical clinical signs. Flea numbers
dropped significantly after treatment of animals
from both single- and multiple-animal households.
In dogs clinical signs of FAD prior to treatment,
decreased from 38% to 16% by day 14, and 6%
by day 28, thus verifying a rapid adulticidal and
high residual activity that lasted at least 4 weeks.
There was an effective control of parasites, with
rapid improvement of allergy until almost complete
remission up to 28 days following the first application.
Recently studies on the effect of imidacloprid
on cats with clinical signs of FAD confirmed field
data published by Genchi et al. (2000). Clinical
signs of FAD, especially alopecia and pruritus were
resolved after monthly treatment using imidacloprid
(Keil et al., 2002) (Figure 28). Furthermore,
controlling FAD is enhanced when blood feeding
of fleas is reduced. This so-called ‘‘sublethal effect’’
or ‘‘antifeeding effect’’ was reported using very low
concentrations of imidacloprid (Rust et al., 2001,
2002).
3.10.1.4. Imidacloprid as combination partner in
veterinary medicinal products The ability of acaricides
to repel or kill ticks, before they attach to a
host and feed, is important for the prevention of
transmission of tick born pathogens (Young et al.,
2003). K9 Advantix TM , an effective tick control
agent (Spencer et al., 2003, Mehlhorn et al., 2003),
is a spot-on product containing 8.8% (w/w) imidacloprid
and 44% (w/w) permethrin. The mixture
repels and kills four species of ticks, including Ixodes
scapularis, for up to 4 weeks. It also repels and
kills mosquitoes, and kills flea adults and larvae.
3: Neonicotinoid Insecticides 103
Furthermore, a combination containing imidacloprid
10% (w/v) and permethrin 50% (w/v) in a
spot-on formulation, has repellent and insecticidal
efficacy, against the sand fly species (Phlebotomus
papatasi) (Mencke et al., 2003), ticks (I. ricinus,
Rhipicephalus sanguineus), and flea (C. felis felis)
(Epe et al., 2003) on dogs.
Another combination product, (Advantage
Heart TM (10% w/v imidacloprid plus 1% w/v moxidectin),
a macrolide antihelmintic, has been developed
as a spot-on for dermal application to kittens
and cats (Arther et al., 2003). It is intended for
monthly application for control of flea infestations
and intestinal nematodes, and for prevention of
feline heartworm disease. It controls and treats not
only established adult gastrointestinal parasites,
but also developmental stages, including fourth
instar larvae and immature adults of Toxocara cati
in cats (Hellmann et al., 2003; Reinemeyer and
Charles, 2003). Furthermore, the spot-on combination
is safe and highly efficacious against T. canis
and Ancylostomatidae in naturally infested dogs
(Hellmann et al., 2003), as well as against Sarcoptes
scabiei var. canis on dogs (Fourie et al., 2003).
3.11. Concluding Remarks and
Prospects
The discovery of neonicotinoids as a new class of
nAChR ligands can be considered a milestone in
insecticide research, and permits an understanding
of the functional properties of insect nAChRs. Up to
now the most current information regarding
nAChRs originated from research with vertebrate
receptors. The world market for insecticides is still
dominated by compounds irreversibly inhibiting
acetylcholinesterase, an important enzyme in the
CNS of insects. The market share of these inhibitors,
Figure 28 Resolution of signs of flea allergy dermatitis (FAD) in cats treated with imidacloprid over a 84-day study period (Keil
et al., 2002).