I used an windtunnel olfactometer with a lamp behind it instead of a Y-shaped one and it worked fine; and you are able to take different kinds of data (and the insect is allowed to behave normally an isn't forced into a tube). I built one like Ralph Peters used here:

http://www.eje.cz/pdfarticles/1654/eje_108_4_565_Peters.pdf

I was using a A 22 watts circular fluorescent day light lamp placed at approximately 20 cm height above of the Y-tube (vertical position) and it was korking fine.

If you plan to put plants in your chambers use full-spectrum lights. Regarding the lamp above the Y tube, you may want to use a lux meter to check that the light is the same on each arm of your olfactometer.

Jurgen, we are interested in insect pests of mushrooms and all of our olfactometer studies are completed in darkness. However, I would think that you can guarantee the absence of bias, the type of light source is not so important.

Diode light. Natural spectral composition incl. UV.

Hi Jürgen,

I agree with Bill. I would also prefer dimmable LEDs allowing the adjustment of the light intensity to the requierments of the study object . Additionally, with different sets of wave lengths, you can also simulate the spectral composition of the activity period of the insect.

I agree with Jurgen statement. Because we used that bio-assay on Psylla sp. using ordinary lamp.

I agreed with Jurgen statement.

We have a Knosys olfactometer and work in the dark phase of the animal in a dark room using a red light typical for photography.

Dear Bill and Sven,

thanks a lot for your quick answers and the helpful suggestions. Do you know a brand/manufacturer/model you could recommend?

Hello Jürgen,

I would first say that there might be no general answer to your question. My second comment is that your choice depends on the organism under study. Is it diurnal or nocturnal? Does it avoid light or not?

Therefore, I would choose a flexible system that allows you to change the light source depending on what you are studying at that moment. Additionally, in most cases I would choose a diffuse illumination, not point sources so that you provide light, but no visual object that could affect orientation. I think that Bill and Sven are right, LEDs seem to be the best available choice these days and control of intensity is highly desirable.

Good luck!

Dear Christian,

thank you for the paper and the idea with the windtunnel/olfactometer setting. This will be useful for some parasitoids, but not in all cases suitable for my main test organisms (e. g. moths, leaf beetles, ladybirds, psyllids, aphids, leaf- and planthoppers). Maybe I will try this setting with psyllids.

Dear others,

thank you for your helpful suggestions.

Dear Marcelo,

I mainly work with diurnal insects (see my answer to Christian) and sometimes with moths, which have their main activity during dusk or dawn, respectively. E. g. psyllids and cicadae are often highly attracted by light.

Once you have selected your light source, perform some trials to evaluate if it is homogeneous. I had once that issue with parasitoid wasps that were all going in the same arm mainly because of light intensity. A bias that could easily be solved once you are aware of.

LEDs are great. You can fine tune them and they are not toasting your organisms after a long exposure.

Jürgen, in the case of insects that are attracted to light, point sources might affect there behaviour during tests. Then, promoting homogeneous illumination (as much as possible) seems a good idea, so that they do not have light "references" to follow or avoid. I work with nocturnal insects and we record their behaviour using infrared-sensitive video cameras (they have inbuilt IR sources) with no additional need of other sources of illumination. Your moths might be studied with no other lights then.

Dear Debra,

I work with insects in my olfactometer but in case of nucturnal species the use of red light could be helpful. Thank you for this suggestion.

We have used full specturm ott lights: http://www.ott-lite.com/. Our y-tubes are placed inside a box with one open side for reaching in. The light is also in the box directly over the apparatus.

We use a small pinpoint light source just outside the inner junction of the Y in our olfactometer experiments with fussy day-active insects. Early on we had difficulty with light balance in the arms and sides of the Y tubes even in a carefully lit room where we assumed illumination was uniform.

We purchased sensorsrs to measure broad and narrow spectrums of light energy and found that our insect responses were influenced by small differences in light intensity. So, we turned the lights off and tried this pinpoint source that faciltated the responses as long as it was perfectly balanced (intensity), so that even the reflection off the interior of the arms was not biasing. We now use pinpoint phototaxis as well as upwind movement to test volatile stimuli in day-active insects in a fully darkened room. It makes responses more consistent and allows for a well-defined bioassay interval. Perhaps this is a bit simplistic and ignores everything that is wrong in terms of interactions, but our results are then validated quite consistently in field trials. We have also used the same light source and strategy in wind tunnel experiments. Explaining this for a four-choice olfactometer will take a lot more words, but the idea is similar, pinpoint light at the terminals of all arms, checking the intensity and balance of the light coming from each arm with the sensor placed directly facing the arm at the point of insect release.

This might not work well for many insects but has for day-active beetles, and pestiferous and parasitic hymenoptera.

Hi Dear

I worked with four –arms- olfactemeter,

And I studied repellency effect some of herbal plant against Potato tuber moth. and performed in the dark room. because ptm moth was activity night

I think by attention to your activity insect you are choice light or dark. Or type light

Good luck

Hi

Have you considered illumination used by reptile keepers i.e daylight strip lights which are available in different uv intensities. In addition, they also supply red and moonlight bulbs.

I agree that a diffuse light is better than a point source.

Sarah

I would definitely agree with Sarah Hart. In our lab we use only diffuse light for all the various bioassays. Note that even in diffuse light from above the experimenters light level will influence some insects, in my case open area walking bioassay w bark beetles:they preferred or rather spent more time on the side where experimenter with the darker clothing sat, this was clearly less when wearing white lab coats. I believe similar effects has been observed w parasitoid wasps?

It is necessary to use light conditions that are relevant for the insect and the behavioural process you want to study. If you use a point source it is usually good to use a simple screen arounsd the olfactomerer that minimize disturbance from the environment

Dear Jurgen

As you never know if your insects will be attract by light...the best way is to use inactic light (Type of the ones used in photo laboratory). Such as, you are sure that no bias will exist.

Cheers from Luc

Dear David,

thank you very much for your suggestions and explanations. Do you have photos or drawings of your different settings (Y-shaped olfactometer, 4-choice-olfactometer, windtunnel) indicating where the pinpoint light sources have been placed? Or a publication with a description? What kind of pinpoint light source did you use and where can I order it?

Cheers, Jürgen

I thank all contributers for their valuable comments and suggestions.

@ Bill

Could you expand on that a bit? Where do you get this LED? Thank you, Andreas

Hi Juergen,

In Berlin we used one central diffused light source right above the center of the 4-arm olfactometer in an otherwise darkened room (not sure you have ever worked there. That worked alright for Hymenoptera.

Cheers,

Tass.

Juergen (and Tassilo).

I think that the best is really in a dark room (really dark with no ray of light coming from a door or a window). And then to use inactinic lamp just above the junction of the arms. You've got the Philips model PF710 (I think 15W...but not sure) but some Osram models are also perfect. the price is around 15 to 20 Euros depending on sellers. At least it was working well for Drosophilas, but may be some insects will be totally inactive without "day" light?

Cheers from luc

During my experiments I work in a dark room and the olfactometer is protected by dark screen to avoid light interferences from electronical devices (i.e. computer screen etc.) and to reduce interferences from experimenter movements. I use infrared and/or diode light natural spectral composition depending on the insect or the day time I'm supposed to reproduce. If you are working with nocturnal insect or you are testing a specific nocturnal activity, biorhythm reversal before the experiment could help. All the light device should uniformly be placed around, above and below (for transparent olfactometer) of the setting. Some time if you are working on a transparent open arena, could be useful illuminating only from the bottom to overcome the insects natural flays.

Cheers from Cristiana

Hi Dear

I agree with Luc Legal that the best is really in a dark room

Hi,

For nocturnal insects, has someone observed behavior differences between a day experiment in a dark room with biorhythm reversed individuals vs. the same expe carried during the night with non-reversed individuals ?

Cheers

Curiously, may be I missed the point, Juergen did not tell whether he is going to work on diurnal or nocturnal insects?

For solitary bees, we have used full-spectrum OttLite® High Definition Task Lamp placed directly over the Y-tube. All olfactory-testing apparati (glass Y-tube, air pump, light fixture) are placed in a large box with one open side. We work in a room with no windows as well.