Guidance of flying male moths by wind‐borne sex pheromone

Abstract

ABSTRACT. On passing from clean air into a homogeneous cloud of sex pheromone in a wind tunnel flying male Adoxophyes orana (F.v.R.) (Lepidoptera: Tortricidae) turned more or less upwind and reduced the time and distance between their switchings of track from one side of the wind line to the other. These responses became adapted under the constant pheromone stimulation in the cloud, thereby arresting upwind progress; but the adapted moths would now ‘lock‐on’ to an added pheromone plume and advance upwind along it. Moths also locked‐on to the border of a pheromone cloud, not by turning back on losing the scent as previously supposed but by initiating the above programme of small‐amplitude, crosswind movements (reversing anemomenotaxis). The onset and cessation of the pheromone stimulus produced anemotactic responses that differed quantitatively within a continuum, not two distinct kinds of response as previously supposed. The behavioural mechanism whereby uniform permeation of an area with synthetic sex pheromone can prevent males from finding females is reconsidered.

Olfaction in vector-host interactions

“…Temporal characteristics of ORN responses to odours are another feature of odour coding, which is especially important to enable odour discrimination while flying or walking upwind (Baker 1985, Kennedy et al 1981, Kramer 1992. A response is called phasic if the frequency of firing action potentials decreases abruptly shortly after the onset of the excitation response.…”

“…An intermittent frequency of odour stimulus is often essential in order to elicit a behavioural response (Baker et al 1985, Kennedy et al 1981. For example, a homogeneous plume of CO 2 is sufficient to activate upwind flight behaviours in Ae.…”

“…This can be explained by the fact that the temporal intermittency of an odour signal is important for driving the orientation behaviour of an insect (Baker 1990, Baker et al 1985, Kennedy et al 1981, Vickers and Baker 1994. In all insects studied so far, PNs are able…”

Antennal Resolution of Pulsed Pheromone Plumes in Three Moth Species

“…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).…”

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.…”