The Olfactory Guidance of Flying Insects

Wright, R. H.

doi:10.4039/ent9081-2

Cited by 142 publications

(76 citation statements)

References 6 publications

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“…Therefore, it was suggested that it is in this shifting maze that the insect must find the active space containing those few signals that will lead it to its host plant. However, in the open air, it is turbulence rather than diffusion that determines the distribution of odorous molecules (Wright, 1958;Bossert & Wilson, 1963), and there is nearly always a prevailing wind to blow the odorous molecules away from the plant. Registering directional cues from odorous molecules is even more complicated for flying insects, as the movement of the air relative to the insect depends on the insect's own activity, and wind direction has to be registered in the absence of fixed markers (Finch, 1980).…”

Section: Discussionmentioning

confidence: 99%

Host‐plant selection by insects – a theory based on ‘appropriate/inappropriate landings’ by pest insects of cruciferous plants

Finch¹,

Collier²

2000

Entomologia Exp Applicata

544

347

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Seven hypotheses, including the 'Resource Concentration Hypothesis' and the 'Enemies Hypothesis', have been put forward to explain why fewer specialist insects are found on host plants growing in diverse backgrounds than on similar plants growing in bare soil. All seven hypotheses are discussed and discounted, primarily because no one has used any of them to produce a general theory of host plant selection, they still remain as hypotheses. However, we have developed a general theory based on detailed observations of insect behaviour. Our theory is based on the fact that during host plant finding the searching insects land indiscriminately on green objects such as the leaves of host plants (appropriate landings) and non-host plants (inappropriate landings), but avoid landing on brown surfaces, such as soil. The complete system of host plant selection involves a three-link chain of events in which the first link is governed by cues from volatile plant chemicals, the central link by visual stimuli, and the final link by cues from non-volatile plant chemicals. The previously 'missing' central link, which is based on what we have described as 'appropriate/inappropriate landings', is governed by visual stimuli. Our theory explains why attempts to show that olfaction is the crucial component in the central link of host plant selection proved intractable. The 'appropriate/inappropriate landings' theory is discussed to indicate the type of work needed in future studies to improve our understanding of how intercropping, undersowing and companion planting can be used to optimum effect in crop protection. The new theory is used also to suggest how insect biotypes could develop and to describe why pest insects do not decimate wild host plants growing in 'natural' situations.

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Section: Discussionmentioning

confidence: 99%

Host‐plant selection by insects – a theory based on ‘appropriate/inappropriate landings’ by pest insects of cruciferous plants

Finch¹,

Collier²

2000

Entomologia Exp Applicata

544

347

View full text Add to dashboard Cite

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“…Turbulence causes the plume to break up into strands of odor-laden air (filaments) interspersed with pockets of clean air where little or no odor is present (11,12). The physical intermittency of these filaments is a requirement for male moths to sustain their upwind progress; they will not continue to fly upwind upon entering a homogeneous cloud of pheromone (4, 13) but will if this cloud is alternated with swaths of clean air (14).…”

Section: Introductionmentioning

confidence: 99%

Reiterative responses to single strands of odor promote sustained upwind flight and odor source location by moths.

Vickers

Baker

1994

Proc. Natl. Acad. Sci. U.S.A.

273

211

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We characterized single upwind surges of flying male Helothis virescens moths in response to individual strands of pheromone generated experimentally in a wind tunnel. We then showed how this surge functions in this species as a basic 13.4-cm, 0.38-sec-long building block that is strung together repeatedly during typical male upwind flight in a normal pheromone plume. The template for a single iteration, complete with crosswind casting both before and after the straighter upwind surging portion, was exhibited by males flying upwind to pheromone and experiencing ifiament contactsjust frequently enough to produce successful upwind flight to the source, as hypothesized by an earlier model. Also as predicted, with more frequent filament contact by males, only the straightest upwind portions of the surges were reiterated, producing direct upwind flight with little crosswind casting. Electroantennogram recordings made from males in free Tfight upwind in a normal point source pheromone plume further support the idea that a high frequency offilaments encountered under the usual pheromone plume conditions promotes only these repeated straight surges. In-flight electroantennogram recordings also showed that when filament contacts cease, the casting, counterturning program begins to be expressed after a latency period of 0.30 sec. Together these results provide a plausible explanation for how male and female moths, and maybe other insects, fly successlly upwind in an odor plume and locate the source of odor, using a surging-casting, phasictonic response to the onset and disappearance of each odor strand.In the quest for understanding how male moths fly upwind and locate females (1-5) there have been suggestions (6, 7) that all odor-mediated flight in moths, including host plant location by females, may be explained by two programs, optomotor anemotaxis (2) and self-steered counterturning (8), that are turned on and modulated by odor fluctuations. It has also been pointed out (9, 10) that many other kinds of insects flying upwind to odor exhibit behavior somewhat similar to moths', and these other insects may also use these same mechanisms in odor-source location. Knowledge about the mechanisms used by moths should therefore be important for understanding the neuroethology of olfaction, the evolution of pheromone and host-plant-insect systems, and the potential application of pheromones in insect control.The physical structure of a pheromone plume created by a point source of odor is not a time-averaged homogeneous cloud. Turbulence causes the plume to break up into strands of odor-laden air (filaments) interspersed with pockets of clean air where little or no odor is present (11,12). The physical intermittency of these filaments is a requirement for male moths to sustain their upwind progress; they will not continue to fly upwind upon entering a homogeneous cloud of pheromone (4, 13) but will if this cloud is alternated with swaths of clean air (14).Recently, results from experiments investigating the highspeed beh...

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“…The 'zigzagging' paths of insects orientating to distant odour sources have long been a matter for study (Wright, 1958;Farkas & Shorey, 1972;Kennedy & Marsh, 1974). Such paths are most commonly observed in male moths flying upwind to sources of female sex pheromone (Kennedy, 1983).…”

Section: Introductionmentioning

confidence: 99%

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

Willis

Baker

1984

Physiological Entomology

154

110

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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.

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The Olfactory Guidance of Flying Insects

Cited by 142 publications

References 6 publications

Host‐plant selection by insects – a theory based on ‘appropriate/inappropriate landings’ by pest insects of cruciferous plants

Host‐plant selection by insects – a theory based on ‘appropriate/inappropriate landings’ by pest insects of cruciferous plants

Reiterative responses to single strands of odor promote sustained upwind flight and odor source location by moths.

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

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