Byers, J.A. 2008. Active space of pheromone plume and its relationship to effective attraction radius in applied models. J. Chem. Ecol. 34:1134-1145.
pdf
Abstract--
The release rate of a semiochemical lure that
attracts flying insects has a specific effective attraction
radius (EAR) that corresponds to the lure’s orientation
response strength. EAR is defined as the radius of a passive
sphere that intercepts the same number of insects as a
semiochemical-baited trap. It is estimated by calculating the
ratio of trap catches in the field in baited and unbaited traps
and the interception area of the unbaited trap. EAR serves
as a standardized method for comparing the attractive
strengths of lures that is independent of population density.
In two-dimensional encounter rate models that are used to
describe insect mass trapping and mating disruption, a
circular EAR (EARc) describes a key parameter that affects
catch or influence by pheromone in the models. However,
the spherical EAR, as measured in the field, should be
transformed to an EARc for appropriate predictions in such
models. The EARc is calculated as (pie/2EAR2)/FL, where FL
is the effective thickness of the flight layer where the insect
searches. FL was estimated from catches of insects (42
species in the orders Coleoptera, Lepidoptera, Diptera,
Hemiptera, and Thysanoptera) on traps at various heights as
reported in the literature. The EARc was proposed further
as a simple but equivalent alternative to simulations of
highly complex active-space plumes with variable response
surfaces that have proven exceedingly difficult to quantify
in nature. This hypothesis was explored in simulations
where flying insects, represented as coordinate points,
moved about in a correlated random walk in an area that
contained a pheromone plume, represented as a sector of active space composed of a capture probability surface of
variable complexity. In this plume model, catch was
monitored at a constant density of flying insects and then
compared to simulations in which a circular EARc was
enlarged until an equivalent rate was caught. This demonstrated
that there is a circular EARc, where all insects that
enter are caught, which corresponds in catch effect to any
plume. Thus, the EARc, based on the field-observed EAR,
can be used in encounter rate models to develop effective
control programs based on mass trapping and/or mating
disruption.
Chemical Ecology