J. S. Kennedy

Pheromone-regulated anemotaxis in flying moths.

Certain male moths flying upwind toward a scent-producing female appear to be guided anemotactically by optomotor reactions to the ground pattern. Loss of the odor stimulus changes the anemotactic angle from into wind to across wind with left-right reversals.

Zigzagging and casting as a programmed response to wind‐borne odour: a review

ABSTRACT. ‘Counterturning’ (meaning here the execution of a succession of alternating left and right turns) is the common feature in upwind zigzagging and cross‐wind casting by flying insects manoeuvring towards a small source of wind‐borne odour. Recent progress in understanding its control and function is discussed. Counterturning is internally controlled (‘self‐steered’) in the limited sense that, once initiated by a chemical stimulus, it continues without further changes in the chemical input both in clean air and in a homogeneous cloud of odour. As a reaction it appears to be the kind of chemotaxis distinguished as longitudinal klinotaxis, for which the stimulus is a difference of chemical concentration detected over time along the insects path, not across it. The new directions taken in response to the stimulus, being self‐steered in the above sense, have no necessary relation to the direction of the chemical gradient that provided the stimulus but are influenced by the visual cues generated by wind drift. In wind, the counterturning programme is modulated by changes in the chemical input and simultaneously integrated with anemotaxis, but it can then continue in similar form after the wind has ceased. Unambiguous evidence for these conclusions is so far available only for certain flying male moths responding to sex pheromone. The primary function of counterturning, of all amplitudes and in both zigzagging and casting, appears to be the regaining of contact with an elusive scent.

Guidance of flying male moths by wind-borne sex pheromone

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.

A reappraisal of insect flight towards a distant point source of wind-borne odor

This communication reappraises the behavioral evidence concerning insect flight toward a point source of wind-borne odor in the light of meteorological information not yet considered in this context. The horizontal tracks of puffs of smoke from a generator in the open air were videorecorded and found to continue along nearly straight lines from the source for at least 25 m, while the shifting wind direction caused the plume formed by the succession of puffs to “snake” to and fro. It is inferred from this and much previous work that within such a distance the wind will be aligned on the source of any wind-borne odor wherever the odor can be detected. This being so, a strategy of finding the odor source by flying roughly upwind on meeting the odor, but holding station against the wind with or without casting across it on losing the odor (odor-modulated anemotaxis), seems likely to be highly adaptive, whereas a strategy of flying along the plume (“odor-trail following”) seems unlikely since it would often take the flier in “wrong” directions and would be more disrupted by turbulence.

Light versus pheromone‐bearing wind in the control of flight direction by bark beetles, Scolytus multistriatus

ABSTRACT. A wind tunnel lit from above was used to measure the relative effectiveness of light as opposed to pheromone‐bearing wind in directing the flight of male S.multistriatus. Upward flight in the tunnel was overridingly phototactic not geotactic, while horizontally upwind flight toward the pheromone source was anemotactic not chemotactic, since the pheromone concentration was uniform in the tunnel. The flight tracks of newly‐emerged unfed and previously unflown beetles were preponderantly upwards and downwind; the longer the beetles had spent in flight activity beforehand, the more of them flew upwind.

Classification and nomenclature of animal behaviour.

MODERN work on the simpler forms of behaviour has gained much from the classification of reactions into different types. Its main achievement has been the separation of kineses from taxes. Fraenkel and Gunn have brought order into the subject with their book, “The Orientation of Animals: Kineses, Taxes and Compass Reactions” (1940). The following criticism is offered in the belief that they have provided a valuable point of departure for future work.