Vector Control Using Semiochemicals - Biological and Environmental Control of Disease Vectors - page 95

6 Vector Control Using Semiochemicals

James G. Logan, 1 * John A. Pickett 2 and Mary M. Cameron 1
1 London School of Hygiene & Tropical Medicine, London; 2 Rothamsted Research,
Harpenden, UK

6.1 Introduction

interactions that have been demonstrated to
show promise for vector control.

Many insects that vector pathogens, causing
human or animal disease, sense their environ-
ment by detecting olfactory stimuli, heat,
moisture and visual cues. These cues can provide
information about the location and quality of
conspecifi cs, hosts or breeding sites. It is
generally considered that, of all the senses used
by insects, olfaction plays the most signifi cant
role in their ecology. Indeed, this process is aided
by a multitude of sophisticated evolutionary
physiological and behavioural adaptations that
have given them one of the most sensitive and
selective olfactory systems on the planet. Stimuli
detected by the olfactory system are also known
as 'semiochemicals', defi ned as 'behaviour and
physiology-modifying chemicals' (Norland and
Lewis, 1976), and these are heavily involved in
many aspects of insect ecology. Since they are
vital to insect survival, semiochemicals could
provide an exciting and innovative way of
controlling vectors while minimizing the use of
potentially harmful chemicals that have toxic
modes of action. There are many dif erent types
of semiochemicals that can be utilized in this
way. A description of all semiochemical-
mediated interactions is beyond the scope of this
chapter, which instead focuses on only those

6.2 Semiochemicals

Semiochemicals can be divided into two groups:
(i) pheromones, which are involved in
interactions between individuals of the same
species (intraspecifi c interactions); and (ii)
allelochemicals, which are involved in inter-
actions between individuals of dif erent species
(interspecifi c interactions). In the context of
haematophagous insects, the most common
pheromones are 'releaser pheromones', which
induce a behavioural change in the receiving
insect (Norland and Lewis, 1976). Allelo-
chemicals can be subdivided into: (i) kairomones,
which are favourable to the receiver, but not the
emitter (e.g. carbon dioxide produced from a
vertebrate host which stimulates biting insects
or oviposition site cues); (ii) allomones, which
are favourable to the emitter but not the receiver
(e.g. human-derived natural repellents that act
to repel insects (Logan et al. , 2008); and (iii)
synomones, which are favourable to both the
emitter and receiver (e.g. plant-produced
attractants for sugar-feeding insects that also act
as pollinators).

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