Friday, December 21, 2012

Don't eat that!

     One of the big pushes that has come up in popular science is to use insects as a food source for humans because of their high protein, low fat, and relatively low ecological impact. In fact, I wrote a blog post about it a few months ago. However, insects have been eaten by other animals for millions of years, and may provide the majority of the nutrition in their diets. Which brings me to two topics we're going to write about today: insect chemical defense against getting eaten, and chemical warfare.
       The first part is because my dog-owning friends have sent me images of potentially toxic beetles that they found their dogs munching on, or about to munch on. Even though domestic dogs primarily are carnivores, its well known that many dogs will eat other stuff if they can get their paws on them. Garbage, scraps...etc. It should be no surprise then that many dogs, if given the opportunity, will eat bugs. Especially if it peaks their hunting instinct, and they get to chase them around. There is a whole blog article musing about why dogs eat bugs, but for the most part its not really that dangerous. But, what if the beetle they do decide to go after IS actually a problem? Well, the two beetles that my friends sent me images of actually CAN cause a problem, and here is why.
Black Blister Beetle. Image of Epicauta pennsylvanica by Bruce Marlin. From
       There is a group of beetles that we have here in Oklahoma and the United States called the Blister Beetles (Meloidae), and they get their name because in their blood they have a caustic chemical called cantharidin. This chemical, when secreted by the beetle in self defense, can actually burn your skin or even cause blisters (hence their name). Blister beetles can be anywhere from 2cm to as large as 6-8cm (the size of a quarter or so). The largest group of these beetles we usually run into here in Oklahoma is in the genus Meloe, called the Oil Beetles. These big, black beetles with a very large, bulbous abdomen ("butt" area), and are usually found wandering along the ground since they cannot fly. There are other beetles in the group that aren't as big and tend to be more rectangular in shape (see here for more info about the various kinds in North America), but all blister beetles tend to have big, round heads that are wider than the area behind the head, giving them an upside down, exclamation point appearance (!).
        My friend that caught her dog actually munching on the beetle before spitting it out unfortunately had her dog dealing with some of the symptoms of the cantharidin: upset stomach, hurting mouth, and other irritation. My other friend caught the beetle before her puppy could find it. Its unlikely that the dogs would die from eating one beetle, but if enough are eaten they can get fatal cantharidin poisoning, which is a major problem in horses.
        Not all animals have problems with poisonous insects, however. Poison dart frogs, for example, actually use the poison in the bugs they eat to make the poison on their skin to protect themselves. In fact, the poison in some dart frogs are some of the strongest poisons known on earth! How the frogs get the poison from their diet to their skin without dying from it is still an active area of research. However, its known that captive-bred dart frogs are not nearly as poisonous as their native colleagues because they don't have access to poisonous insects from their native habitat.
Briefly holding a wild Dendrobates auratus I found in Costa Rica, outside of our hotel in Manuel Antonio. The owner of the hotel, who knew of the population, had tried to hold one of the frogs to keep it away from some plumbing being re-done near a wall against the forest, trying to protect it. Apparently he held it so long the toxins leached into his skin just holding it. The story goes that one of his workers found him passed out on the floor, with the frog happily hopping all over him on its way back to the forest after. He was fine, and the frog was too.
Captive poison dart-frog, which doesn't have the toxins.
   In the tropics there are many cases of chemical warfare between insects and their predators, with poison dart frogs being the masters by beating the system. Those of us who live in the temperate regions of the world also have toxic insects, but few animals that can beat their system and not be affected by the poison or use it in another way. There are examples of animals here in North America that can, which I'll write more about later, but dogs are not one of them.
     If you have a dog here in Oklahoma, 99% of the bugs and beetles your dog may eat are not going to be a problem for them. You are more likely going to have problems with your dog eating garbage, poop, coffee, or chocolate than you are with a small beetle. However, if you do find a beetle that looks like the Blister Beetle above and your dog is showing some symptoms of an upset stomach, you may want to have your dog checked out due to the exposure to cantharidin. More than likely it will be nothing, but better safe than sorry.
       Have a Happy Holiday!

Friday, December 14, 2012

Its the season for Mistletoe...

    'Tis the season...for mistletoe. Every office Christmas Party or other Holiday-themed event in December has a sprig of the plant hanging from a hook in the ceiling. Both maligned and loved by single people, the tradition goes that once you stand under the mysterious green plant you are obliged to give a fellow trespasser a kiss. Its a plant both ardent...and avoided at the same time, depending on the person.
    So what exactly IS mistletoe, and why are we talking about it in our Recent Invertebrates Blog? Well, to start with the former, mistletoe is in the Santalales order of plants. Many of these plants (but not all) are known for their parasitic lifestyles. Most of us know what animal parasites are - they feed on animal hosts, taking their nutrients. However, most people don't know what plant parasites do. Plant parasites also take nutrients from other plants (hosts), and depend on their hosts for sugars and minerals that they can't get themselves. Chlorophyll, which is the chemical in plants that generates sugars and energy from sunlight while giving plants their green color, is often absent in parasitic plants. Since they just take the nutrients from their hosts, they don't need to generate the sugars themselves. The mistletoe found around here in North America, Phoradendron sp., is still green however, which may be due to it being a hemi-parasitic plant (it doesn't get ALL of its nutrients from its host tree, just some). In Europe the mistletoe plant is from a different genus, Viscum.
Phoradenron juniperinum, image taken by Stan Shebs and posted on
    You can find mistletoe in a lot of trees throughout North America as dense green clumps high up in the branches. They are most obvious in winter since trees drop the rest of their leaves and the mistletoe is the only green things left, which is maybe why they were selected out as Christmas decorations. If you are able to look at the plants more closely, however, you might see a little green bug, Viscacoris. These bugs are only found on mistletoe, and were named after the family of plants that the American mistletoe was thought to belong to, the Viscaceae. In North America there are about four species, and they are a similar green color to the plant but turn yellowish as it fades.
Viscacoris species on the bottom half. Image by Christiane Weirauch.
     However, mistletoe is not the only parasitic plant out there, and Viscacoris is not the only bug to feed on them. Many parasitic plants belong to the family Santalaceae, which include the very weird but oddly pretty plants and are often found in Australia. Another hemi-parasitic plant from Australia is Exocarpos sp., which requires another tree to survive by feeding from the tree's roots.
Exocarpos cupressiformis, from
   Found only on this tree are bugs of the genus Exocarpocoris. These bugs are from Australia, and have really unique structures found on bugs from nowhere else in the world.
Exocarpocoris praegracilis, from Discover
   Another parasitic mistletoe plant with weird plant bugs on it is Amyema miquelii. This plant is also found in Australia and has unique reddish flowers. Found on this plant are another group of bugs from the genus Hypseloecus sp. These bugs are also reddish like the flowers of the plant to blend in. They also are only found on these plants.
Hypseloecus neoamyemi, from Discover
     Why are these bugs only found on mistletoe? We are still investigating that. Many insects co-evolved with certain plants over time and maintain close ties. Its believed that insect pollination, for example, was one of the leading drivers for flowering plant evolution. Maybe these bugs stayed with these plants because of the nutrients they had, and became so closely tied to them that they are now reliant on them.
      So, next time you are under the mistletoe and you're not really that interested in kissing the person you're with under it, instead maybe point up to the plant and tell them that there are tiny bugs that are found only on mistletoe. While they are distracted by how cool that is and are looking for them, you can sneak away!
     Happy Holidays!

Friday, December 7, 2012

Living Jewelry

     As Christmas shopping continues here in the United States, fancy jewelry is on the minds as possible gifts. Most of the TV channels that I get have various commercials for Jared's Jewelry, Kay Jewelers, etc. all advertising their various diamonds, rubies, and other exotic and expensive wares as potential Christmas, New Years, and engagement gifts. Diamonds are forever, after all...not coffee makers or other gadgets that break, right? The message is to get something different, something that will really blow the receiver's socks off. Well, what if you could get bedazzled jewelry, but that its either from living insects or actually is a living insect?
Zoropheridae beetles used as living jewelery. Image by Shawn Hanrahan from TAMU and found on
 In some cultures, its possible to actually purchase what is considered "living jewelry", called The Mexican Maquech Beetle, in Mexico. These beetles, which are also called Ironclad beetles because their exoskeletons are so hard, were sometimes used as jewelry by gluing rhinestones to their backs along with a chain, and then then the chain was pinned to a blouse. The insect then crawled, tethered, all along your shirt as living jewelery. As adults they only eat rotting wood and occasionally need water, so they are pretty hardy beetles that could last crawling along your blouse for long periods of time fairly easily. For more information about these beetles and the culture surrounding them, check out this link and video:

So, next time you look at another jewelry commercial on TV and you think you want to buy something really special, you could get one of these uniquely decorated beetles as jewelry instead!