A. Mafraneto et Tc. Baker, ELEVATION OF PHEROMONE RESPONSE THRESHOLD IN ALMOND MOTH MALES PREEXPOSED TO PHEROMONE SPRAY, Physiological entomology, 21(3), 1996, pp. 217-222
High percentages of naive Cadra cautella (Walker) (Lepidoptera: Pyrali
dae) males not pre-exposed to pheromone flew upwind to sources contain
ing 50 ng (83%) and 500 ng (97%) of pheromone, but not to sources cont
aining 5 mu g (23%) and 50 mu g (4%). Of the naive males that flew upw
ind in response to 50 ng sources, 67% located and landed on the source
, whereas fewer than 19% of the naive males that flew upwind in respon
se to higher doses located and landed on the sources. A 2-minute pre-e
xposure of C.cautella males to a spray cloud containing 50 ng, 500 ng,
5 mu g or 50 mu g of pheromone, induced shifts in response levels suc
h that in wind-tunnel bioassays performed 1 h later, there was an incr
ease in the doses that optimally elicited upwind flight and landing on
the source that was proportional to the pre-exposure dose. Few of the
pre-exposed males flew upwind to (10-43%) and landed on (0-33%) 50 ng
sources, whereas they now perferentially flew upwind to (58-81% and 5
2-73%) and landed on (33-68% and 55-60%) pheromone sources of doses of
500 ng and 5 mu g, respectively. Therefore preexposure to pheromone p
romoted a shift of threshold for response, and not an overall reductio
n in responsiveness to pheromone.