This is how aphids detect food | A chemoreceptive protein analysis with Dr. Dykstra | Part 4 of 4
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- Опубликовано: 7 сен 2022
- In this final installment of a 4-part series, AEA Scientific Advisor Dr. Thomas M. Dykstra explains his research into the chemoreceptors of aphids and how it affects their ability to detect and taste food.
Watch Part 1: • Here's the problem wit...
Watch Part 2: • Toward a new theory of...
Watch Part 3: • Deciphering the Insect...
Dr. Dykstra received his B.S. in entomology from Cornell University in 1990. He traveled down to the University of Florida and received his M.S. in entomology (1994) and investigated the neurophysiology of pheromone production in moths. Continuing at the University of Florida, he received a Ph.D. in insect bioelectromagnetics under Dr. Philip S. Callahan in 1997.
Immediately following his degree, Dr. Dykstra started his own laboratory (Dykstra Laboratories, Inc.) in 1997 which more broadly investigates bioelectromagnetics ranging from bacteria to humans. Predominantly, he studies insect olfaction (how insects smell) from the standpoint of bioelectromagnetics and has developed a new theory based on the fusion of biophysics and neurophysiology.
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Please let’s ask Dr Thomas to make more video like this!!! Super knowledgeable ...I been studying entomology 2 semesters I don’t even hear about this important staff.Respect!!!
Brilliant work Thomas really good!👍
We're glad you enjoyed it, Bill. Stay tuned for more...
- The AEA Team
Great talk.
Is it envisageable to spray calcium on old leaves to avoid the aphids sucking them after the application?
I think the most fascinating part for me is that Dr. Dykstra didn't evaluate or share any literature about aphid physiology that is readily available which answers several of these questions proposed about how aphids detect and process sugar and nitrogen and locate hosts. I myself have even conducted some of the tests in these references.
At 19:00 Dykstra states that aphids can't get sugars like sucrose in the phloem tissue, which has not been my experience nor that of researchers like the insect physiology specialists:
"The dominant compounds in phloem sap are carbohydrates, especially sugars. Sucrose is a major transport sugar in most plants... It accounts for 95% or more of phloem sugars in species with apoplastic phloem loading reaching concentrations of 0.5-1.5 M." - Advances in Insect Physiology, S. J. Simpson.
Should note that 1 Mole of sugar is ~342g of sugar/1000 mL of water, which is ~34% brix sucrose by mass. So 1 M of sugar is extremely high brix based on the graphic presented earlier.
At 24:14 Dykstra states that aphids do not use the sugar they feed on, and tentatively concludes they are not good at detecting sugar in any significant way. However, many researchers have confirmed that aphids do indeed detect sugar, especially sucrose, and use enzymes like sucrase to break them down into smaller sugars, that are then converted into the insect "blood sugar" trehalose. They sequester a lot of the sugar they consume, but much of these metabolically processed sugars are excreted because the processing is extremely efficient in order to keep their bodies osmotically stable.
"Dietary sugars are important, not only as the principal source of carbon but also because they are the single, most important nutritional determinant of aphid feeding rate. The rate at which aphids ingest food varies inversely with the dietary concentration of sucrose (Mittler and Meikle, 1991; Douglas et al ., 2006b) (Fig. 6.2). This response generally is interpreted as a compensatory feeding response, i.e. that aphids can compensate behaviourally, at least partially, for low dietary sucrose by feeding at higher rates. Overlaying this feeding response, sucrose acts as a phagostimulant, i.e. sustained feeding by aphids depends on the presence of dietary sucrose. As a result, aphids feed at a progressively increasing rate with declining sucrose concentration to a minimal concentration of 0.05-0.2 M (varying with species and conditions), below" - Nutrition and Symbiosis, Helmut van Emden.
"The single most perplexing issue in aphid nutrition is the high rate at which the unbalanced diet of phloem sap is transformed into new aphid biomass. As this chapter summarizes, key factors are the speed and efficiency with which aphids assimilate, or otherwise dispose of, ingested nutrients. For example, aphids on many plants ingest a surfeit of sucrose. The sucrose is hydrolysed to completion in the gut lumen and, within 15-20 min of ingestion, the hydrolysis products are assimilated across the gut wall to the haemolymph (so they are used), or transformed to oligosaccharides that pose no obvious osmotic hazard to the aphid, and voided via honeydew. In a comparable fashion, ingested amino acids are rapidly assimilated or voided. This efficiency is compatible with the aphid’s absolute nutritional requirement for essential amino acids only because the symbiotic bacteria Buchnera provide the aphid with supplementary essential amino acids."
At 26:00 Dykstra proposes that aphids are not interested in sugar, but nitrogen. However the aphid microbiome is famous for housing bacteria that create essential amino acids for aphids and not needing them in the plant.
"The chief nitrogenous compounds utilized by aphids are free amino acids derived from two sources: the phloem sap and the symbiotic bacteria in the aphids. Amino acids are the dominant nitrogenous compounds in the phloem sap of most plant taxa, and aphids assimilate them very efficiently. Additionally, aphids derive a supplementary supply of essential amino acids from the symbiotic bacteria in their tissues. The three core lines of evidence are that:
-Aphids do not have a dietary requirement for many essential amino acids e.g. (Douglas et al., 2001; MacDonald 2001; MacDonald et al., 2011).
-The isolated bacteria are capable of essential amino acid synthesis (Sasaki and Ishikawa, 1995; C.W. Russell 1995; C.W. Russell et al., 2013). ., 2013).
-Amino acids synthesized by the bacteria in aphid tissues are translocated to the aphid partner (Douglas, 1988; C.W. Russell, 1988; C.W. Russell et al., 2013).
-Buchnera genome contains genes coding enzymes in the essential amino acid biosynthesis (Shigenobu et al., 2000)." - Nutrition and Symbiosis, Helmut van Emden.
Tell us why every grower you consult has purple petioles. Then you'll have your duh moment. When you realize the difference between healthy brix and immobilized sugars.
@@flavannoyed3585 Based on your description, you are not familiar with my clientele. Apoplastic phloem sugars like the sucrose described is mobilized by the SWEET family facilitators.
I think you guys may actually agree on more than disagree, surprisingly. Firstly, you may have just misheard him talking about phloem tissue sugars, he said you CAN find sugars like sucrose in the phloem. He was just posing the question for the listener to get them thinking. He was asking what type of sugars might aphids be attracted to, since there are so many different forms of sugar in phloem tissue. Secondly, when he was bringing up not being able to detect sugars, he was talking about olfactory receptors specifically, it's possible that they taste sugars but don't smell them, like humans, this simply wasn't brought up in this presentation because the presentation is about how insects, and aphids in particular, smell for their food, not taste it. When he brought up honeydew, I'm pretty sure he was trying to get across that aphid forage seeking behavior isn't primarily determined by sugar. If they have enough sugar to survive while secreting a significant amount even on an unhealthy plant with less than ideal sugar levels, then so long as they have a living plant to feed on they're getting enough sugar. He's not saying that aphids don't need sugar at all, that would be insane, he's saying that they get such an excess of sugars that it isn't what they primarily seek out when looking for which plant in particular to feed on, because all of them have adequate sucrose, they choose one plant over another based on different factors. And finally, when he was talking about nitrogen, he wasn't talking about amino acids in particular, he was talking about any and all nitrogenous compounds, such as ammonium, nitrites, nitrates, peptides, and so on. The fact that aphids can synthesize their amino acids does not necessarily mean that they have no need for nitrogen input, in fact it's kind of the opposite, nitrogen is necessary for the synthesis of amino acids. Unless aphids have the capability to get all of their nitrogen requirements from the atmosphere via their microbiome, they need an input of nitrogen from their food. He specifically points out ammonia is one thing they're attracted to, so it would be implied by that fact alone that aphids can use ammonia to synthesize their amino acids. Now with all of that I'm pretty sure you two still would seemingly disagree on the effect of sucrose concentration on aphid feeding, with him taking the stance that aphids don't seek out sucrose and you taking the stance that their feeding behavior depends on sucrose, but I think that that could very simply be resolved by just taking gustatory receptors in to account rather than just olfactory receptors, and the fact that by the time the sugar is low enough that the aphids leave entirely to find a new plant, the plant probably will not be able to recover. Recognizing that, it's obvious that aphids would leave a plant when its sugar is too low, and recognizing that all living plants have enough sugar to feed an aphid, it's obvious that sugar isn't what they'd be mainly smelling out for to find their food, because everything would already have enough sugar.
why would aphids specialize with a plant if the plant sap is only sucrose. I always get the feel like you just are looking to disagree for whatever reason. Must be that is just what internet trolls do
@@smileysgarden Plant sap is not only sucrose of course. Nutrients, proteins, and other compounds are also transferred through sap. Sucrose is the most common carbohydrate in the phloem of most plants. Aphids break this sugar down and use it to create trehalose for metabolic energy.
"The dominant compounds in phloem sap are carbohydrates, especially sugars. Sucrose is a major transport sugar in most plants... It accounts for 95% or more of phloem sugars in species with apoplastic phloem loading reaching concentrations of 0.5-1.5 M." - Advances in Insect Physiology, S. J. Simpson.
Most aphids specialize on a few plants, while others are generalists that can feed on many plants, such as the Pea Aphid mentioned in the video. Adaptations in different plants influence the development of different aphids.
"chemical defences are not universally effective against phloem-feeding insects. Some aphid species detoxify the compounds, eliminate them via the honeydew or sequester them in their tissues (Dixon, 1998) and the sequestered compounds can additionally confer protection from predators (e.g. Rothschild et al., 1970)." -The Nutritional Physiology of Aphids, Angela E. Douglas
Some aphids, like Paracletus cimiciformis, feed on other insects like ants rather than plants even.
Congratulations Dr Dykstra, great presentation. Sheeers
A long while ago I read about a mystery that for humans some agents like hydrogen sulfide smell the same as other agents possibly mercaptane or pyridine although they share no chemistry and it turns out that they have overlaping Coherant Aantistokes Raman Spectra which are complementary to IR spectra. Could this mean that all animals have similar resonant olfactory sensing mechanisms? I think the same argument of diffusion time through a nasal mucosal moist layer applies. Of course comparing human DNA with insect DNA could be a pointer.
Was thinking the samething in laymens terms especially in a different video that said certain plant health produced certain frequency and insects were attracted to the frequency
@@calisingh7978 his argument that insects react in the order of a few milliseconds to smell cannot come from diffusion through a micron of water that would take at least a second. Because of this problem it has to happen in another way. Because he has mechanical and electrical features of the proteins involved in the conversion at the nerve end he can use a model to predict at what multiple frequencies these proteins are likely to resonate with electromagnetic radiation which is the IR spectrum. From some species it is know what agents they react to and you have to play some with intensities and protein resonances to see if this would sum up as a large number of resonances and if I'm correct they also need some resonances for suppressing different agents that the species have no interest in and gives positive signals with other resonances.
So maybe a localized high concentration agent has a same signal as a larger more dilute larger volume because the IR signal would similar in size. But it could be different for tasting than for smelling..... If I understand right if a plant is surrounded by ammonia it might give off a signal of incomplete photosynthesis or rather incomplete protein synthesis and this sign of unhealthy plants could be detected from feet from a small plant or about the size of the plant as distance, without this insect really in contact with the agent. IR light travels with light speed so it would be instant regardless of distance.
I believe that animals all evolved with a equal sense of smell as it is probably the most essential for survival. So probably the mechanism of resonance is all across the animal kingdom. Even in water or seawater some parts of spectra are transparent allowing for this to work there. And as compliment I heard or read somewhere that hydrogen sulfide smells (rotten eggs) smells for humans indistinguishable from a totally different chemical structure I think pyridine or mercaptane and it surprised biologists because totally different structure, but the special resonance of CARS (Coherent Anti-stokes Raman spectroscopy) (with a coherent LASER line chemicals scatter shifted wavelengths (positive and negative) and these wavelength shifts can be calculated much like IR scpectra. There is a quantum-mechanical reason why some wavelengths are in the CARS spectrum or the IR spectrum or in both but the frequency calculation is the same.
I try to think of an experiment to prove that only the IR spectrum is enough to make the insect sense an agent and go to it or maybe if a cloud of agent would be released at such a larger distance that it could not transport far enough for detection. I think of a dessert site where off wind release a large cloud of ammonia from a metal cylinder or see if a weather balloon is IR transparent enough to attract the insects attention.
This is very interesting, Herman. Thank you for contributing to the discussion!
- The AEA Team
@@AdvancingEcoAgriculture As a complete dutch outsider to agriculture I stumbled onto your collection of videos on youtube looking for ways to help a friend with ecological pest control in her city vegetable garden near Eindhoven. I had no idea how it works but I understand now how it can be done with sap analysis. I also understand you got the idea from Wageningen University. Even the first step Brix already is a nice tool to start with. Also the many leaf quality and distribution is so interesting for me .
As a physics engineer I worked with a CARS laser system to detect negative hydrogen ions (H2-) in plasma so I understood what they meant with CARS spectrum when I read about the similarities in H2S and other compounds. I'm sorry I have no clue where I got it from.
I have problems with our dutch government setting ammonia concentration standards to absurdly low levels like heather that normally is temporary (transition biome) and hope we can get some sense into our politicians. We wil be voting early 2023 for provinces and senate and I think it will be a landslide against these crazy norms. the senate can block this. I hope we also get AEA like support to help farmers transition in their own speed and time to do it in an economic responsible way, especially by example.
Since about 3 years I buy my frozen meat at a farmer close by and being on a low carb /keto diet I hope he has a future.
Subscribed done...
We're happy to have you along for the journey!
- The AEA Team
loved it . thanks for helping understand about Gods wonderful creation
Fabulous information! Excellent speaker!
We're glad you enjoyed, Sally Lynn. Thanks for listening!
- The AEA Team
Love this guy
Finally saw John Kempf @1:01:06
I work in an organic farm and we have lots of types of grass hoppers and they dont damage the vegetables
Have enjoyed all four of these presentations immensely. Thank you so much for sharing your research and thanks AEA for supporting it.
So, soybean aphids are attracted to GMO soybeans with low Brix, excess ammonium and nitrates and not sugar. Got it. So, besides the obvious of hiring the AEA team, what general recommendations would you make to the soybean farmer?
Interplant perennials with the soy and transition to multispecies tree crops:)
@@PO-po5de Yes!
Following up on this, Mary-we're so glad to hear that you found this series to be so helpful. We have an excellent approach that can help with soybean production. Even if you're not able to use AEA products, it can give you a great idea of what nutrients are most impactful at a given growth stage; check it out: 8619203.fs1.hubspotusercontent-na1.net/hubfs/8619203/Soybean%20Approach%20and%20Budget.pdf
Hope this helps! - The AEA Team
Yes! So excited for this! I have some excellent aea content for tomorrow's work schedule! Thank you aea!
Brilliant. Love listening to you!!
Bugs do and eat what natural has always done lol
Excellent presentation, thanks for sharing!
Brix in no way shape or form makes your plants immune to insects, disease, or anything else. I have witnessed many different insects feeding on a variety of plants at 12 or higher brix levels.
Wrong
May have been more accurate to say it's doesn't always prevent pests rather than "in no way". It is more reasonable to think it has some effect. However I do not doubt you are right aabout it being overstated in the video. I have seeen ants unsuccessfully try to farm aphids on a very healthy plant so sometimes there are other reasons involved outside of brix. They didn't last on the very healthy plant very long. Something wiped them out without inputs other than compost tea.
I have the opposite experience.
Interesting feed back as I am just learning everything I appreciate all views and appreciate his research.
@@sharkswimmer7114 Same observations here. After 12+ years in organic agriculture I've seen pests 'beholden' to the brix level, as well as flipping the table about brix related assumptions in severe drought, as another example. I don't think these intelligent fellas would defend any hyperbolic sounding statements too dogmatically.
Thank you Dr. Dykstra and AEA
Regarding the first question by Tom, at the end of the presentation asking about BB. As a pro market gardener, BB works better for me during the summer, I’m in Japan. Getting it to stay on cabbages is tough I find, and it needs to be reapplied. I don’t have any aphid problems, just the odd caterpillar cabbage white from time to time. My main pest is flea beetle.
Thank you for sharing, Dale! With flea beetles, we've found that ensuring adequate beneficial bacteria and fungi is extremely crucial to get those microbial ecosystems going. Good luck :)
- The AEA Team
just a reminder that this episode is complete BS and has been disproven in over 100 white papers