Oe

This topic contains 24 replies, has 10 voices, and was last updated by  JBrown 3 years, 7 months ago.

  • Creator
    Topic
  • #13176

    http://monarchparasites.uga.edu/whatisOE/index.html

    This has got really good info about OE and in mild cases crumpled/deformed wings are a sign of a diseased butterfly.

    Overcrowding of caterpillars and keeping them inside can cause this disease to spread. I know a lot of people are very precious about their monarchs, but we all need to have a good look at our habits and see what we can do to reduce OE in our stock we are releasing into the wild.
    Angie

Viewing 24 replies - 1 through 24 (of 24 total)
  • Author
    Replies
  • #47111

    JBrown
    Participant

    Provide a sheltered area where butterfly’s can wait out bad weather and hide from predators. This can be done by setting up a small area in the corner of your yard with lots of leaves and/or grass cuttings. You can even create a few nesting areas by putting a few small wooden boxes in the leaves.

    #28065

    jstsmile
    Participant

    thank you that helped i think it be the weather then it has been cold lately thank you

    #28064

    Jacqui
    Moderator

    Hi Jstsmile. Complicated question you ask! I don’t think that your plants can have Oe… it is passed from butterflies to butterflies (eggs) but perhaps it’s also airborne.

    I take it you’re in New Zealand? Very few caterpillars will complete metamorphosis successfully out of doors in the winter – they need maximum sunshine and warmth and shelter from the elements at this time of the year – so a lot depends on what part of NZ you’re in. I am in Auckland and have caterpillars on my plants. I am letting them do their own thing, not even checking up on them, and if they survive that’s fine. Two butterflies have emerged this morning.

    You might like to destroy the “trees” and start again, Jstsmile – a good time to do it, especially if you can buy some plants now, although they won’t be in the garden centres at this time of the year. I see someone on TradeMe is selling them and may be able to help with some new plants if you are in Auckland and get in touch with me, 09 551 3383. I could also come and look and see what’s happening, if you would like me to, too.

    By the way, check out the glossary on our website. Monarchs don’t form cocoons but chrysalises or chrysalides!

    Feel free to post here if you need more help. Others will also chip in with their thoughts, what they do, I’m sure.

    #28057

    jstsmile
    Participant

    hello i think my swan plants have the oe but wht do u do wth the caterpillars that are still on the tree they look healthy but after they cocoon up they go black as normal you can see the butterfly shape and colour of their wings but they dont hatch they just die in the cocoon do i destroy the trees and start again with seeds if so will the seeds off the tree itself carry the oe virus and what to do with the caterpillars that look healthy if you can help thank you

    #27602

    Darren
    Participant

    http://www.google.co.nz/search?q=monarch+oe
    About 1,280,000 results (0.07 seconds)

    #27592

    Jacqui
    Moderator

    Hi Clinton – it’s described in the Glossary on this website, see under Projects. It’s a pathogens that affects milkweed butterflies.

    #27588

    clinton9
    Participant

    What is “Oe” ???

    Clinton.

    #27560

    Darren
    Participant

    Jacqui do you have a link for those photos?

    #27558

    Jacqui
    Moderator

    Two new photos on Edith’s site about Oe, clearly showing the abdomen of a Monarch with Oe, and one without.

    Edith says “We could guess with almost 100% certainty whether one had OE or not by looking at the abdomen before taping it. Those with OE had blurry abdomens, the white wasn?t crisp and clear. As you can imagine with thousands of spores, the lack of white is due to black OE spores covering some of the white scales.”

    http://www.butterflyfunfacts.com/oe.php

    #25287

    Darren
    Participant
    #21184

    Jacqui
    Moderator

    New resource on Oe (haven’t looked at it – if someone has the time/inclination, would be good to know how useful it is for us).

    Jacqui

    http://www.springerlink.com/content/g628476036h20n90/

    #18263

    Jacqui
    Moderator

    Hey Shaun! Great to see you. I totally agree with you about ‘monoculture’, a lesson well learned.

    Keep coming back! We have missed you this season.

    J.

    #18261

    Shaun
    Participant

    I’d just like to make a wee comment in this thread.

    The original article is about rearing monarchs in artificial environments. As an ex professional ornamental fish breeder I know all about how disease can get out of hand very quickly in a monoculture situation.

    Animals can and do survive quite well with low-level infections of all sorts of contagious diseases. The only time it becomes really problematic is when they are crowded together. Normally, a parasite drops thousands of spores, (or whatever it’s propagation stage is) and only a few find a suitable new host to perpetuate the parasite. However, in a crowded monoculture most, if not all of the spores find homes. THAT is where the problem lies and that is where drastic measures are called for. Been there, done that.

    What it boils down to is that, as far as I know, none of us are rearing monarchs in an environment similar to the one used by the author of that article. Therefore the methods he uses aren’t applicable to us. Sure, we can learn from them. However, we don’t have to be so draconian about it.

    I hope everyone here is well, it’s been a while since i checked in. 🙂

    Cheers,

    Shaun.

    #18250

    Swansong
    Participant

    “and overnight Microsoft did some updates… and yes, you guessed it. Gone forever into cyberspace.”

    Now why does that sound sooOOOOoo familiar? I can’t tell you the number of times thats happened to me, especially if you’ve prepared a lengthy post. Murphys law. FWIW My solution is a cut and paste job from NOtepad. : )

    As for M$ well, Jacqui Im tempted to say get a Mac… : ) …only its just about 6 of one and 1/2 Doz of the other these days now that Billyware is well and truly found its way onto Macs, what with the Macs of recent years changing to intel chips etc etc but I digress…

    Mmmm Interesting points in your post. So going by these comments OE isn’t the problem we’ve come to think it is? Intersting too about the moisture and humidity, plus the relationship this plays with the toxicity of the latex! Wow. Lots of variables here.

    Swansong

    #18249

    Jacqui
    Moderator

    Oh I wrote a huge response to this, and forgot to press SEND POST – and overnight Microsoft did some updates… and yes, you guessed it. Gone forever into cyberspace.

    I know where you’re coming from Angie. If we are going to foster butterflies, we need to be well informed so that we do everything in our power to have healthy butterflies – I think we all want that. It’s common sense to be proactive about our health and our welfare, that of our families, our environment and our pets – so we need to know more about what affects them when something does hit.

    Edith Smith, one of the USA’s biggest butterfly farmers, and she also dedicates time to helping others, says about Oe that it is the easiest disease to eradicate, but she’s referring to her own population of butterflies, not worldwide. After reading what she’s written you m ay want to look at her website, http://www.butterfliesetc.com – here’s what she wrote:

    “I think that quite often people blame some of the problems their Monarchs have on Oe when it isn’t Oe at all.

    Because my site is so easily found in google searches by school teachers and everyday people who are looking for information about these type of problems, I have a lot of people write and ask about their butterflies that didn’t emerge right. I always ask them to send me a photo and a tape with scales (I send them to the Oe page on my site for directions too). Most of the time, there are no traces of Oe. The problems are from something else. Quite often we don’t find out the problem either!

    He… was a bit familiar with Oe. I told him that Oe was the easiest disease to eliminate and I couldn’t figure why they focused on Oe so much when it is one of the diseases that cause the least damage only in part because it is so easy to eradicate. I told him that he could give me heavily infected Oe Monarchs and in two generations, I could have him some good breeding stock. I told him a bit about NPV and other diseases and how I document through photographs some of the diseases in the wild.”

    Another interesting post came from Dale McClung, another Florida-based butterfly breeder, who wrote:

    “In nature, the morning dew evaporates with the sun rise. It is also usually the coldest time of the day, just before the sun comes up, and, as the caterpillars are colder, they consume less or not at all if the temperature is below 53 degrees. As far as rain, in nature, there is free flowing air and evaporation when the sun comes back out. In northern climates where common milkweed is, well, common, the leaves of the species do not hold water like tropical will. I can not tell you exactly how they behave in a storm, but I imagine they remain still while the rain drops are hitting the foliage and probably sheltered on the underside of the leaf. Evaporation after the storm also has a cooling effect that may naturally prevent them from feeding too voraciously for a short while as the water evaporates.

    However, in captivity, humidity is one of the most common problems. The monarch larva do best under dry conditions, the dryer, the better. In contained areas like a green house or rearing container, the humidity is always higher that outside unless the area used for rearing is air conditioned or there is a dehumidifier present. You can measure the humidity with an instrument called a hydrometer. I have some small ones I purchased at a cigar shop that are used in humidors for the cigars to measure the humidity to prevent the cigars from drying out. I placed one in a container and then moved it outside and noticed, on average, even with what appeared to be ample ventilation, the humidity was 15 percent higher in the container. Aside from evaporation from the plant material, also there is evaporation from the frass even with paper towelling lining the bottom.

    Which leads to the common compromise with rearing containers, balancing the humidity to prevent the plant material from drying too fast and the dryness necessary to keep the larva healthy. Many now use the “caterpillar castles” from livemonarch.com and keep the plant either in pots or cut and place in a water container (deli cup with an “X” cut in the lid for the plant stem).

    However, I would not mist any plant with any species of larva. The larva get all the water they need from the plant material it consumes and misting increases humidity dramatically.”

    Another post from Dale (to the same person):

    “With monarch larva, generally, the lower the humidity, the better. Also, try raising some inside in the air conditioning with lower humidity and general temperatures and see if there is a difference. I find that if you can keep the larva in the low seventies and in low humidity, they do better, but that is not the end all and beat all. The problem you are experiencing with monarch in central Florida, I am in St. Pete., also central Florida, I have nicknamed “the Florida malady” or “caterpillar-keel-over-itosis.” It is a function of our climate. However, it is also a function of location. Where I am in Pinellas County, being surrounded by water, we tend to have higher low temperatures and higher humidity. Rainfall is another factor. Although the larva do better (for me) during the dry conditions and lower temperatures of our winter months, when it is hotter and dryer, they do not. We do not get as much rain as many other parts of the state being located along the coast. Gaineville, in north Florida, actually gets more rain than St. Petersburg.

    I’ve been trying to find a solution for years now. I find that when the daytime high temperatures begin to climb over the eighty degree mark and this is usually April or May, monarch larva become unreliable if grown in ambient conditions here. The other aspect of this is the tropical milkweed. Those that grow under 50 percent shade in greenhouses have better luck with this species over time as opposed to plants in full sun outdoors. Farms in north Florida do better than those in central Florida as they are in a climate that on average is 10 degrees cooler. Also, as the plants used recover and are reused, they actually react to being attacked and become more toxic. The latex is after all a plant defense and sometimes the plant wins. As temperatures climb, the larva feed faster and grow faster. With the more rapid consumption combined with an increase in plant toxicity, the larva is poisoned. It is subtle. They first seem to lose their ability to taste the milkweed with their feet like the adults also taste with their feet. They no longer recognize the milkweed as food and stop feeding. I have no way of measuring the complex chemistry of the latex, and this observation appears to be a neurotoxin, but there is no record of neurotoxins in milkweed, the toxins are cardenolides which effect the heart.

    > From my experience, I know that in the winter the
    plants are relatively benign as far as handling and later in the summer I have to be very careful not to get the latex in my eyes when cutting and handling the plant. That is my only measure of this change.

    Michael Rich of Lukas Nursery’s Butterfly Encounter and I shared notes a few years ago as he was having similar problems with monarchs. He asked a botanist some questions and the botanist said that if the plants are dry, that is, not well watered, the latex will lose moisture and become more concentrated, so his recommendation was to be sure the plants were well watered. Ironically, during the height of the rainy season, late July and August, I have had the monarch larva rebound and do well for a period and then decline as the rainy season wanes. That doesn’t fit my other observations, but in those two months we average 6 inches or more of rainfall, actually 8 for August, the days are the longest and hottest, etc., and that correlates with the botanist’s suggestions.

    I wish I had some solid answer for you. I hope this post is not too discouraging. Not everyone experiences the same problems I do with monarchs in the warm weather. Unfortunately, I do not have the space to build an out building or lab which is what I need.

    You should know also that this is my own theory. Everyone, when the larva die, look for a “disease,” something introduced and therefore one should be able to control the situation with identification of the pathogen and a method of elimination. It is possible a pathogen is at work, but this problem follows an annual and predictable pattern related to seasonal climate changes. It follow more the growing season of the plants as opposed to a pathogen though with weakened larva, pathogens have better opportunity to develop. Caterpillars do not have an immune system as we do. Their basic defense against bacterial infections, etc., is that they grow and develop faster than a pathogen can multiply to the point of killing the larva. Of course, in warmer temperatures bacteria will multiply faster, but that does not fit with the fact that at the height of the rainy season, the hottest weather, the larva rebound for a time. It is only the difference in rainfall that is the variable.

    In the north where common milkweed is used, the problem seldom occurs with any significance. Tropical milkweed is measured to be 10 times more toxic than common. Let me know how things go. I hope your problem is just temporary. However, you should know you are not alone. I know of several operations experiencing the same issue right now.

    This is an interesting paper: http://www.springerlink.com/content/wcujxnre2efbku4k/

    Poisoned plusiines: toxicity of milkweed latex and cardenolides to
    some generalist caterpillars

    Department of Biology, University of Central Arkansas, Conway, Arkansas

    Summary. Larvae of Trichoplusia ni Hübner (Lepidoptera: Noctuidae) that ingested latex from Asclepias curassavica L. (Asclepiadaceae) often regurgitated and convulsed with spasms before becoming immobile and unresponsive. Some larvae required over a day to recover sufficiently to feed. Latices from four other plant species in three families were all deterrent, but none caused detectable poisoning. The toxicity of A. curassavica latex was evidently due to cardenolides because pure cardenolides had similar effects when ingested by T. ni. Other species of noctuid caterpillars (Rachiplusia ou Guenée, Anagrapha falcifera Kirby, and Autographa precationis Guenée) sometimes also suffered spasms and temporary immobility when fed A. curassavica latex. A more distantly related noctuid, Spodoptera ornithogalli, was deterred by the latex, but showed no overt physiological responses at the dosage tested. T. ni larvae failed to develop on intact leaves of A. curassavica, on leaves with latex canals deactivated by midrib severance, and on excised leaves. Similarly, larvae reared on excised A. syriaca L.
    A. curassavica leaves to the final instar died when transferred to
    leaves with either intact or severed midribs. The final instar larvae sometimes suffered from spasms and immobility even when confined on leaves with depressurized canal systems. Evidently, cardenolides stored outside the latex system suffice to poison larvae. We conclude that cardenolides in A. curassavica have potent physiological effects on some generalist caterpillars and that the presence of these compounds both inside and outside laticifers effectively protects the plant.”

    Remember – the botanical names of the common milkweeds available in NZ are:

    Asclepias curassavica = Tropical Milkweed, Silky Gold, or Silky Scarlet, sometimes bloodflower.
    Asclepias physocarpa is now Gomphocarpus physocarpus, Giant Swan Plant
    Asclepias fruticosus is now Gomphocarpus fruticosus, Swan Plant.

    There are a few others in NZ but few people have them.

    #18236

    I am not saying eradicate this disease, my aim is:

    – Get people understanding what OE is.
    – Be able to identyfy OE in heavly infested chrysilas and other stages of lifecycle
    – Start thinking about the ways we are breeding monarchs and if there is anything they we can do to reduce fatalities
    must run, will address other comments later

    Angie

    #18181

    Swansong
    Participant

    “The only way to eradicate parasites is to eradicate their hosts – clearly not a sensible option!”

    Exactly clair. Yes OE is very interesting and I will want to continue to learn about things like this as I have the time. Something I try to do is put myself in others shoes, so I don’t get all tunnel visioned and think that people should be “where I’m at” pertaining to a time line, as well as level of interest. When you say …

    “I doubt many of us would do this if it didn’t give us “real joy” ” ….

    that yes this is true, but I see that the budding joy for a newcomer also can be “squashed” because of all the PC red tape type of attitude that would have one chasing their tail in all the detail with the “must do” whitecoat approach described above which isnt bad in itself … but its just not for everyone.

    ..and let us not forget this… if we all did what they said to do about changing gloves often, imagine the effect on the landfills. Ive said before Im not an environmentalist, but I DO take offense to some things like all the plastics and similar products that have typically been with us only a relatively short time (in the last 100years or so) that get dumped. All the nappies, …etc etc is REALLY REALLY getting scary. In other words you dont have to be an environmentalist to have a good sensible responsible attitude.

    So what I’m trying to say is I think its good for an interest to be “nurtured” as it were, and that people can find their own level of committment in time. Obviously there will be different levels of committment to monarchs like anything. Thats why I strongly advocate that newbies dont overwhelm themselves with “too much” and to figure out what they can realistically cope with …. and at the same time taking nothing away from others who can raise monarchs in the hundreds or whatever.

    They are lovely creatures, monarchs, and I like all animals and birds and things, its just that I like some a bit more : ) … again… better not start me on ‘fishers….. ooooH yeah …

    Swansong

    #18178

    Anonymous

    Hey Swansong, what a cool attitude you have! I doubt many of us would do this if it didn’t give us “real joy” – and so it certainly does! I’m with you – I want the joy I feel to help rather than hurt the butterflies we love so much, so I want to do the very best I can. Your tips are helpful and sensible and I will do the same. It’s good to know about parasites like OE and do what we can to keep it down, but most living things have parasites – we could be seen as a parasite of a planet – that is how the universe works. The only way to eradicate parasites is to eradicate their hosts – clearly not a sensible option!

    #18172

    Swansong
    Participant

    Thanks Jacqui for your comments and link. : ) … Notwithstanding the fact that I’m a creationist not an evolutionist, yes, it was an interesting article, (for me) for the part that stuck to pure science.

    “(such as me in a rural situation, quite ” ….
    not sure what happened here jacqui, the rest of your sentence seems to have gone awol. Just for the record Ive noticed on accasions when Im posting, unless Im really onto it, I can lose whole paragraphs and I think its something to do with where I place the cursor…like sometimes I will put quotations marks around some text and it seems to happen then. Ive also noticed that sometimes though you click at the beginning of a line, that your cursor doesnt show.

    …but i digress

    Certainly this very day, I have tidied up my dining room, and done a big reorganize. Heres some practical tips as to what Ive done, and what I intend to do for anyone else who might like to pick up some ideas, that are not going to be too demanding and therefore striking a realistic balance (hopefully) of being responsible but not be scared off either with, as I say, the typically “tippy toey hard core environmentalist attitude of touch not and dont dare breath in the bush in case a fern frond gets a little outa place” type of thing, and OR the “whitecoat approach”. That being said I’m all for a realistically responsible attitude.

    1/ My favourite box which has been used for a number of years has now got the heave ho. It will be burnt. Each year I intend to simply just pick one up from the supermarket, and burn it at the seasons end. The idea of the beautiful big one I had designs on for specifically raising monarchs inside, has gone by the wayside is no more. For this year I’ve just counted 157 used dots, most with their empty shells still there. A potential breeding ground for disease. Interesting to note though, that I have not had anything other than what I would estimate to be be typically an unusual amount of casualties, supporting Gills thoughts in post 2. One disappointment….. oooOOOOoooo my unused dots that served for “surrogate dots” : ((((((((( !!!! Im tempted to pinch a couple and store em for next years fattie “lazies”. Sorry, Im just thinking “inventively” aloud as I write : )…… oh but hang on, what about if I put them in the freezer??? Me thinks thats a cool idea (excuse the pun : DDD)

    2/ Yep, I think its a good idea to burn:
    – any dead pillarz
    – any butterflies that have died of anything other than natural causes
    – any el weirdo chrysalis’ that havent made it, and all empty chrysalis shells.
    – my previous years dried gypsophila which I found the pillarz absolutely looove to make a J on, as well as it keeps them “off the streets” as it were, [ : ) ] in that it keeps them occupied (mostly ha ha) while frnatically looking for a place to hang. Strategies strategies!!! Of course this will mean I have to grow some each year. Not sure if theres a perennial version.

    3/ Anything that has died I intend to freeze until the next time we burn our rubbish, which we can do here rurally no probs. I realize this is/or might be, an issue for town folks. Im trying to think of a way that might allow them to be able safely dispose of these things.

    Finally, I realize thats some peoples goals/reasons in having monarches around may differ to mine. I must admit, rather than the “totally endangered species” focus, Im more promoting if you like to call it that, monarchs for the sheer joy and pleasure that they can give to people in a world that is sometimes a very hostile and mean place, where it gives me real joy if I can at least play a small part in making someone smile for a while. I also realize there is a bigger picture to all this, which some people may very well hold differing views about. I think too, if people want to study them and go to further lengths well good on them.

    Cheers
    Swansong

    #18171

    Jacqui
    Moderator

    Swansong, you make a good point. Any dead or diseased pupae should be disposed of just as you would a diseased plant or a noxious weed – by burning, say, or in the trash. ‘trash’ is a hard one to define for many people (such as me in a rural situation, quite

    Parasites are as much a part of Nature as butterflies, roses and other things we don’t like, including the common cold or influenza. By keeping ourselves healthy, or raising healthy animals/plants, we find they are less susceptible to disease/outbreaks which would weaken us/ours.

    An interesting article here, about the fact that parasites do not destroy their host, as they would be destroying the means by which they want to spread and parasitise others… if you know what I mean.

    http://www.sciencedaily.com/releases/2008/05/080512172907.htm

    Jacqui

    #18122

    Swansong
    Participant

    “Firstly, this sounds to me like quite a mission “

    Youre not wrong there clair, for example, who is going to do the following, to the letter? Do you do all of this wings? If not, then in the light of you saying “but we all need to have a good look at our habits and see what we can do to reduce OE in our stock we are releasing into the wild” what exactly do you do. Please enlighten us.
    ————————————————————————–
    Quote from link above:

    Tip # 1: Sterilize all materials that contacted larval and adult monarchs, including rearing containers, flight cages, and countertops, with 20% bleach solution. Soak plastic ware and fabric for a minimum of 4 hrs in a basin filled with bleach solution, and allow to soak overnight if possible. Bleach surfaces that contacted monarchs several times daily.
    Sterilize butterfly nets that may have contacted infected adults.

    Tip # 2. Always wear disposable gloves when handling milkweed, tubs, larvae and adults. Change your gloves frequently while working!

    End quote
    —————————————————————————-

    Just mentioning from Vicky Steels info in another thread, it seems this OE cant be eradicated. I tell you one thing Ive smartened up on, and thats be more studious about how I dispose of weak butterflies that have died or chrysalis’ that have turned black or whatever.

    Swansong

    #18120

    Anonymous

    Thanks for the link Angie. I know heaps of people who certainly count me in as being very precious about monarchs (and cats, and dogs, and birds, and trees, and….).

    While this bothers me not at all, I don’t want to do anything that would harm the monarch population, so I read the article with great interest – it’s a good one. Given that the magnification needed to see the spores is very low, I’m thinking about getting a little hand-held miniscope – you can get them for less than $25.

    My reading of the article gives me to understand that, in order not to spread this disease, I would need to destroy any infected butterflies along with the plant they came from and everything (eggs, larvae and chrysalides) on it – inside plant or out.

    Firstly, this sounds to me like quite a mission unless I raise only a very few butterflies each year, and secondly (and I realsie this shows how precious I am), I’m not entirely sure I could bring myself to do it.

    Is this what you do? It would be helpful (when you have the time) if you would describe what steps/precautions you take.

    The article demonstrates how to test butterflies – I presume the same method would work to test swan plants. Does anybody do this? Would love to hear what others do…

    #18119

    Swansong
    Participant

    Well I was wondering what you meant by “precious” as well. These were very interesting articles but by the time I finished reading them guess how I felt? Get rid of all my Monarchs inside, never have them again because I cant possibly be “qualified” enough unless I was prepared to set up a lab, buy a micropscope, and walk around in a white coat with rubber gloves on…. DO you seriously think everyone is prepared to do this? Please lets be practical here. Now Im not saying that we cant improve our situations by doing our best to be wised up about things like overcrowding, but Im doing what I do to help them out a bit, with the least amount of interferring I can. My population disappears as chrysalis’s outside as Ive many times stated on these forums. That is why I bring them inside mainly and I will continue to do so. Like Gill I’ve seen the same as far as casualties inside or out. They say that OE can only be really confirmed if you have a microscope, so how are we all to tell since they get it to varying degrees and sometimes you dont know at all because theres no visible clue. Moreover it looks like this thing has been with Monarchs for eons.

    I’m sure it will put people off doing their little bit for monarchs, which incudes the pure enjoyment of having them around, if they feel theyve got to set up things like a completely sterile environment inside, as I say like a lab environment.

    My 2 cents

    #18118

    Gilly
    Participant

    Not sure what you mean about ‘precious’ Angie…. overcrowding of caterpillars occurs in outside conditions as well as inside.
    I’ve seen outside ones also with disease. I’ve seen many a butterfly in the wild, emerge, in bad weather and end up with bad wings…. we humans are not perfect but neither is nature unfortunately.

Viewing 24 replies - 1 through 24 (of 24 total)

You must be logged in to reply to this topic.