Effects of intermittent and continuous pheromone stimulation on the flight behaviour of the oriental fruit moth, Grapholita molesta

Abstract

ABSTRACT. When male oriental fruit moths, Grapholita molesta (Busck) (Tortricidae), casting in clean air entered an airstream permeated with pheromone their flight tracks changed immediately on initial contact with pheromone, but after a few seconds returned to casting as if in clean air. The degree of change in the flight track was directly related to the concentration of pheromone. Although little net uptunnel movement occurred in response to the continuous stimulation provided by a uniformly permeated airstream, when an intermittent stimulus provided by a point-source plume was superimposed onto the permeated airstream moths were able to 'lock on' and zigzag uptunnel in the plume. The percentage of moths doing so corresponded to the difference between the peak concentration within the plume and the background concentration of pheromone permeating the airstream. Moths also locked onto, and flew upwind along the pheromoneclean-air boundary formed along a pheromone-permeated side corridor. Because a similar response was observed along a horizontal edge between a pheromone-permeated floor corridor and clean air, we conclude that the intermittent stimulation at the edge perpetuated the narrow zigzagging response to pheromone.

Antennal Resolution of Pulsed Pheromone Plumes in Three Moth Species

“…Some male moths require such a flickering signal to maintain their upwind flight toward a pheromone source (Kennedy et al, 1981;Willis and Baker, 1984;Baker et al, 1985). Therefore, the assessment of the sensory system's ability to resolve a rapidly flickering pheromone plume is of importance in understanding the relationships between male moth orientation maneuvers and the plume's fine-scale features.…”

“…Because the perception of intermittencies within the pheromone plume seems to be important to keeping moths of some species flying upwind (Kennedy et al, 1981;Willis and Baker, 1984;Baker et al, 1985), it is probable the temporal structure of the stimulus is conserved at a central level. Some…”

“…Studies with the tortricids Adoxophyes orana (Kennedy et al, 1981) and Grapholita molesta (Willis and Baker, 1984;Baker et al, 1985) in homogeneous pheromone clouds revealed that fluctuating pheromone stimulation was required for upwind flight. However, the males of the pyralid C. cautella fly upwind both in homogeneous clouds of pheromone (Justus and Carde, 2002) and along pheromone plumes pulsed at rates as high as 25 Hz (Justus et al, 2002a).…”

Dynamic use of optic flow during pheromone tracking by the male silkmoth, Bombyx mori

“…Male moths possess an astonishing ability to track a sex pheromone plume that is highly intermittent (Willis and Baker, 1984) and successfully locate its source over long distances (Collins and Potts, 1932;Wall and Perry, 1987). The male silkmoth Bombyx mori (Linnaeus 1758) exhibits pheromone-triggered walking behaviour that is divided into three sequential phases: surge, zigzagging and the loop (Fig.…”

Coding of periodic pulse stimulation in chemoreceptors

“…The importance of this periodic stimulation has been experimentally studied and shown to be a necessary condition of odorant perception, because the moth cannot orient in an artificially made uniform cloud. Behavioural (Kennedy et al, 1980(Kennedy et al, , 1981Vickers and Baker, 1992;Willis and Baker, 1984) and neurophysiological (Christensen and Hildebrand, 1988;Marion-Poll and Tobin, 1992;Rumbo and Kaissling, 1989) experiments indicate that the optimum frequency is in the range 1Á/10 Hz. Our aim in the present paper is to investigate to what extent this optimum frequency can be explained by the characteristics of the peripheral sense organs.…”