Abstract:
The
increasing need to study insect flight behaviour in the
natural environment has led to the
development of a relatively inex-
pensive remote sensing instrument (IRADIT) . Flying insects
dfferentay iumjmted, under a light cmations, in a intense
ba of
pulsed near infra-red radiation and detected using a gated
image intensifier - CIV system at a rate of 5OHz.
This thesis details the methods
employed for extracting insect
oo-ordinates from the' CI video signals, 'using low~oost electronic
circuits ad micro
computer (Apple II+) , and for the immediate analysis
and
display of two-dimensional insect flight trajectories, whilst
rejecting environmental and system noise.
Flight trajectories are often dominated by the immediate local
wind. A new
low-cost sensitive three dimensional digital anemometer
system hs be developed for use with the IRADIT system, providing
the data
required to allow the vector wind to b immediately subtracted
and
interesting aspects of flight behaviour to b revealed.
The IRADIT - Anemometer
system ws tested i the field, on insects
above wheat. _ Small insects with membzßanous wing areas as small as
5mm2 were
readily detected and tracked over distances of the order
of l at
ranges up t 15m against a mid-day sky background. Subse-
quent computer analysis of stored insect track and wind data oonfirmed
that the effects of immediate local wind cn b smdied or canoelled
out.
Examples of insect flight behaviour are described.
The
relatively low cost of the IRADIT system and the practical
features in its
design result in a powerful new tool for use by the
field
entomologist.
