Chemical Ecology - Science topic

It is fine to use continuous variables in the Y matrix. I mentioned a binary response because of the way you framed your question. Both the X and Y matrices could be continuous, and for statistical reasons it is better that they are not binary. So use concentrations in X instead of presence/absence, and use your growth parameters in Y. Y can contain one or more variables. I am sure that there are good published tutorials on PLS-DA that would explain further.

Hello Ussawit: Mr Holloway has it right. On the other hand, you might try to null experiment to determine if the beetles' behavior is influenced by the light. Do it without beans. A random distribution is predicted. That's quicker than rearranging the whole apparatus. Best regards, Jim Des Lauriers

Hello, You need a table next to the mass spectra to confirm the compounds (attached as an attached file)

Do not know about antennal sensilla, but speaking in general, if you can see place of interest in optical microscope you can mount your specimen in a way that allow to cut through it. I prefer flat molds for such task, it's easy to use a microscope to orient a specimen in a proper way in a flat mold. After polymerization a semi-thin sections may be needed for precise location of place of interest.

Terraforming, especially for a planet like Mars, would take millions of years but is possible when the time comes that the Earth cannot supply the resources we need. It would start with manned missions to the planet (which we haven't even done yet and wouls cost billions of dollars). It would also involve changing the planet's atmosphere to alleviate the planet's current harsh atmosphere. Creating domes or structures that people could live should also be done before having people stay in the planet. Moreover, studies show that even after alleviating Mars' atmosphere, people may still need to wear body suits in order to breathe efficiently in the said planet. In conclusion, humans proliferating Mars is possible yet would entail sufficient preparation and funds.

You may try to use GCB (Graphitized Carbon Black) and or PSA (Primary Secondary Amine) to remove chlorophyll and other pigment also.

 Thank you Dr. Andreas Reinecke for your valuable discussion and suggestion. 

thank you

Ion traps in general use a mechanism called AGC (Automatic Gain Control) to prevent the trap from overloading. The ion injection time is set to maintain the optimum quantity of ions for every scan. AGC consists of a prescan and the following analytical scan. During the prescan the intesity of incoming ions is measured and used to determine the ion sampling time for the analytical scan. This leeds to an influence of coeluting analytes especially for in context with the LOD.

If the target analyte and interfering analyte have different retention times there should be no influence at all.

Three essential sets are required,the models may vary.

1. Air entrapping device or head space collection : for violates collection

2. GC and HPLC ,GC/MS : For characterisation of volatiles.

3. Olfactometer or wind tunnel.

Your insect rearing should lab should quite sound to maintain pure cultures for good results.

EAG etc may also be essential sometimes.

I think that a secondary part of your question (pupal production of chemical signals, received by conspecific individuals or individuals of other insect species) can find answers by exploring for instance two very wide fields of entomological research, i. e., a) communication among social insects inside their colonies and, b) relations parasitoid-host and predator-prey (as regards entomoparasitic and entomophagous insects looking for pupae). 

I can add that, for some insects, intraspecific communication by pharate adults (adults still into the pupal cuticle) is known or hypothesized, having the function to synchronize (together with other factors) adult emergence of more individuals.

Best regards,

Rinaldo Nicoli

Charles,

Which larva you are using for your study? Does they contain olfactory sensilla to perceive airborne volatiles in the GC effluent?

This paper on Spodoptera litura by FM. Poll et al. 2014 may help.

if you consider Wolbachia as an endosymbiont this might be one candidate as it interferes with sexual differentiation of several insect species and infects ovaries. But not sure about how it works, i.e. if it really influences ovary development or uses other mechanisms.

Use a Random Forest classifier. This approach will give you, among many other things, descriptive variables (in your case volatiles) for each class (here treated vs non-treated). Random forest can be found in the R package. For a nice description of the merits of this approach in analysing volatiles, see Ranganathan & Borges "Reducing the babel in plant volatile communication: using the forest to see the trees" Plant Biology 2009. 

 

 

You should also read the follow paper, and get more informations.

Schettgen, C., Schmidt, A. and Butte, W. 1999: Variation of accumulation and clearance of the peredioxin 5-chloro-2-(2,4-dichlorophenoxy)-phenol (Irgasan DP 300, triclosan) with the pH of water. Organohalogen Compounds 43, 49-52.

I think, I read in one of the research papers prefer to normal body temperature 37 C

Thank you very much.

We have been evaluating some pheromones on the market, but none have worked against the species of thrips in cardamom

Be prepared on 1 year delivery time from Syntech, Peter Ochenfels is very very busy.

I would like to elaborate on this question:

Let’s take the Mediterranean fruit fly, Ceratitis capitata, (Medfly) as an example. Usually in nature, one does not see this fly walk for more than a few centimeters on the fruit or the leaf surface. The majority of its movement is airborne. Its flying range may be from centimeters (inside that tree canopy) to several kilometers (like when crossing the Sea of Galilee, 12 Km across).

For me it seems wrong to consider same set of chemical cues for both activities. I think when the fly walks it responds to low volatile molecules with short range of activity or/and to contact cues. These cues become irrelevant a few meters above the top of the canopies.

If I am right, then it is wrong to use a glass Y- olfactometer, with inner diameter of several centimeters that forces the fly to walk, or to move about with short range jumps or flights, to detect the cues that this fly uses in a long distance flight.

Hi Seyed, what I do is to run a GLM with a binomial function (landing/no landing) considering each insect a replicate (1 or 0). You can do this rather straight forwardly using  the software "R" for example. Good Luck, Marco

Release rate is important because if the rate change the amount of total volatile also change as a result the attraction or replancy also change .i.e. 1ml/min and 1ml/30 sec is not same amount of volatiles pushing in the wind tunnel.

Because it is possible to measure many parameters from the 2D tracks that are recorded with Syntech tracksphere there is not a single response.The first point to consider is what kind of data you will extract from the raw tracks.

You  might be more interested in directionality, final vector length and vector angle,  or mean angles that  require circular statitstics.  But in case you need to compare two treatments that appears to show some attractivity, other parameters that measure a response "intensity" may be calculated directly or with R scripts working from the csv files: total walked distance, speed, both can be treated by standard statistics.  And you can also make distribution stats on the numbers of animals that for instance walk a minimal distance or show positive attraction. 

I agree with Sven that 5 replicates is far from enough.  Due to variability in insect behaviour, 30 replicates per treatment are recommandable. You can find examples of application in our paper Party et al  2013 PlosOne (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0052897)

In terms of actual chemical characterization, none have been described (to my knowledge). However, Fraker et al 2009 (Horm Behav) showed a nice neuroendocrine response from a skin-released compound in larval amphibians. Fish have been well described (e.g., ostariophysan alarm pheromone). The Fraker paper has a nice summary of what is known as well. I doubt my answer helps, but I would also love to know if you have any updates on this question.

I would analyze their headspace volatiles or SPME based extraction of their cuticular profile and after identification of the compounds would test them for ant behavior

Hi Vivek, Thank you for this wonderful question. I believe that B. mori's preference to increase egg laying on paper with EAD volatiles is something akin to the C. maculatus (cow pea weevil) preferring to oviposit on black eyed beans. I work with them. After splitting the primary population (lab based) onto different other bean types for over 3 years (e.g. mung, urid, nigerian honey, moth beans), there was a strong preference to the black eyed beans (personal observation) that could be maternally influenced. So, yes it could be (heritable) maternal effects. Look up some of Charles Fox's papers: adaptive maternal effects. Find some of his interesting articles attached with this answer. Hope this helps.

A few suggestions:

Poropak Q is a good material for collection of plant volatiles.

Regarding impurities: - connect your 'air' source to an activated charcoal column and confirm the eluting 'air' or any gas you tend to use is clean of impurities (you chould check this with a blank run in GC-MS of the elluting gas).

It is a good idea to treat the (inner surface of) glassware with trimethylsillyl chloride to block the -OH groups on the inner surfaces of your glass apparatus to avoid loosing the plant volatiles (which tend to stick to the Si-OH surface of the glass).

Ideally, remove the poropak Q or Hayesep-Q and do a head space sampling instead of using a solvent, since solvents also also carry some impurities. Otherwise, run a solvent blank to confirm which impurities come from the solvent.

Good luck in your efforts

Hello,

It is becoming more and more clear that the microbiota plays an astonishing role in animal and insects in particular. Usually, pheromones are produced by specific secretory cells. However, it would not be impossible that a primer released from such glands in a pouch could be finally transformed by microorganisms living in the pouch into the actual pheromone. An interesting side-question would be an the mechanism of inheritance of these micro-organims.

Best of luck with your experiments !

JLH

Thanks a lot Vivek.

There you go!

/m

Martin, first of all I would search for special purposed software. It could be easier than coding it yourself, maybe someone else here will recommend a specific program. For example, I know two papers that describe protein spectra registration: http://arxiv.org/pdf/1311.2105.pdf and http://membres-timc.imag.fr/Sophie.Lambert/papier/Spectrometry.pdf and the software SpecAlign http://bioinformatics.oxfordjournals.org/content/21/9/2088.long It is for mass spectrometry, but may work for other kinds of spectra as well.

As for your specific question:

If there was a peak or a number of peaks that were always present in both samples, an initial estimate for a and b could be obtained by linear regression. Otherwise they could be limited by reasonable ranges. Say if the drift was not expected to be more than 10%, parameter a would fall between 0.9-1.1 and b between 0.9*tmax - 1.1*tmax. The step by which these values could then be changed in a numerical optimization depends on typical peak width. If it is, let's say 0.1% of the chromatogram width, then a and b could be incremented or decremented by a number slightly smaller than 1/1000th (or 1/1000th of tmax for parameter b). In a brute force approach this would mean a little bit more than 100*100 = 10000 chromatogram similarity calculations for every combination of a and b, to find the best combination of a and b among them. I am quite sure this is not the most efficient apprach, though. However, because the peaks are discrete, one probably cannot do things like gradient search to get the optimum.

As a fallback solution, you could also just save the chromatograms as images and try to do registration with appropriate image registration software, probably using more sofisticated methods than the one above, e.g. like the MATLAB code here: http://www.softpedia.com/get/Science-CAD/Image-Registration-Technique-for-Recovering-Rotation-Scale-and-Translation.shtml or the code here http://www.doc.ic.ac.uk/~dr/software/

Of course, the image-based approach will necessarily be inefficient, because the spectra are really just curves, one-dimensinal objects and we are forcing them into a two-dimensional analysis. Best results should be obtained with solving the "non-rigid curve registration problem", as is the case in some of the papers in the first paragraph of this message.

The fridge is good, but I recommend getting your seeds into the extraction solvent to get the extraction started. If you don't plan on germinating any of them, but only want to preserve them, then they will preserve better in an alcohol solution anyway. This way, when you are ready to begin analyses, you just draw off a small aliquot and run it. If you don't see much, then let the samples sit at room temp for a month and try again. We've got a Geno-grinder which is awesome at pulverizing tissue for extraction. If your seeds have a thick seed coat, opening them up will speed the process. The other main question is how do you plan to analyze this chemistry? LC-MS is great for this, if you have access to one. Some prefer to use Thin layer chromatography but your options will be rather limited. It would be helpful if you tell us what types of equipment you have available.

Hi there, ARS no longer exists. We placed an order about a year ago for $3000. They were happy to take the money and vanished after that. We came to know afterwards that the company had shut for some time already and we apparently are not the only ones having paid for items we will never receive. My advice to you is to find a local scientific glassblower. They very often are very creative people and are happy to make stuffs that are a bit different from classic orders they receive from chemistry labs.

Thanks all for answering my question.

So because of this overlap in the olfaction and visual transaction pathways, shouldn't these two cues that are likely to interact, be studied simultaneously?

Diode light. Natural spectral composition incl. UV.

I do not understand. What is PET? polyethylene terephthalate?

I guess so, sample with those bags always contaminate plants. In case you do volatile sampling is best done in glass, no phthalates but to a lesser extent. I have a glass jar for potted plants adapted to volatile plant foliage is sampled only and is not sampled the soil. Do you want me to send a photo?

Hi Kennedy, when you get your system up and running you can view an EAG methodology video at J. Vis. Exp. 63: e3931. Good luck.

Look at here:

I hope some will help you.

In my opinion, both are same.

As you may know headspace (HS) volatiles can be collected by two ways 1. static HS collection 2. dynamic HS collection.

In static HS collection SPME or gas tight syringe injection is common way of volatiles collection from HS of a sample.

In case of dynamic collection, a stream of gas (mostly air) passed over a sample and HS volatiles are collected on an adsorbent packed in a tube.

In all the cases HS volatiles are collected. the second method (dynamic collection) can be called as aeration collection or extract as this in this air or some other gas use to push volatiles from the HS of a sample.

for reliable quantitative analysis, dynamic HS collection should be used if it work.

I am on the road without access to the literature, but there is a paper form Sylvia Dorn's group in Zurich that uses a color printer to create defined reflectances. RTC

I do not know about butterfly pheromone gland location. But the most reliable method to extract these pheromones is probably as follows: isolate the gland and crush it in a small vial with solvent. The pheromone is very likely to be hydrophobic (see literature), thus hexane would be a good bet to extract it. If it is polar, you can use methanol for example.

Vivek,

your question on " How will a organism know to do certain things without learning" is on the very basis of ethology. This is one of the aspects of the foundational work done by Konrad Lorenz and Niko Tinbergen (their work made them Nobel prize winners together with Karl von Frisch in 1973).

In fact we assume that behaviors called innate are based on genetically tranferred information contained in a species genome (which can, of course, have variability in certain genes/behaviors).

How this sets of genes determine behavior is currently a very "hot spot" in neuroscience. This means that we still mostly base our opinions on single gene models. For a real picture to be good enough we still need to work on gene networks, which might be a better basis to understand complex outputs such as behavioral or physiological traits. Unfortunately, the whole mechanistic view is not available to answer your question properly, but this does not disqualify the opinion that an innate behavior is a genetically based set of neuronal and motor responses triggered by key stimuli recognized by specific sensory receptors which are there probably due to selection pressures favoring their role.

All the best,

Dillman et al. 2012 PNAS... he looks at direct cues from hosts that attract EPN

You can go through this

J. A. A. Renwick., Experientia, 15 March 1989, Volume 45, Issue 3, pp 223-228, Chemical ecology of oviposition in phytophagous insects

As you may know, there are three importnat components to understand olfactory coding; Behavior, Physiology and Molecular Biology. For behavior in lab you need the olfactometer setups like flight windtunnel, Y-tube, T-maize, open arena etc. For physiological studies the most common techniques used are EAG, GC-EAD, SSR, GC-SSR, Calcium and Optical imaging, Intracellular, GC-MS etc. To study molecular biology the are different molecular instument and techniques are use, but all in all it depends on the availibility of fund and your interest and specialities to decide what is really needed and possible to buy it.

Totally agree with Padalia Sir......Ecospecies or Ecotypes are genetically distinct geographic variety, population or race in a species which are adapted to specific environmental conditions. Whereas, Chemotypes are chemically distinct entity or species with differences in their chemical composition or secondary metabolite composition.