Ok, just getting around to another post and some of the questions you guys had. I have been busy and this dinosaur of an internet connection here makes making a post quite a long task.
Ok, so yeah, that was the same caterpillar in the previous post, just a few days later. And the adult wasps haven’t emerged yet, but I suspect they will soon. And a cool fact about the Microgastrinae subfamily (a smaller group within the braconid parasitoids) is that some are polyembryonic. This means that all those wasp pupa you saw on the outside of the caterpillar in the last post developed from a single egg laid in the host! One egg is laid, which then divides within the host into many eggs. Quite bizarre. All other groups of parasitoids that are gregarious lay one egg per individual. So 10 emerging means 10 eggs were laid etc…
So, why study parasitoids? There are lots and lots of reasons, but I will only touch on a few here. The study I am working on is part of a Biological Survey and Inventory grant through the National Science Foundation. So the main objective is just as it sounds – a survey and inventory of caterpillars and their associated parasitoids. However we are rearing all of our parasitoids and so are gaining a wealth of previously unknown information about their biology. So we documenting what known species are here, finding loads of new species and discovering their biology and natural history in the process. Many insect species are described from specimens collected in traps and nets and you know nothing about it other than that it was flying on a certain date, not much else. Knowing the biology and natural history of a species opens up lots of other options and lays the framework for additional studies that can be done.
For example, if you want to protect an organism from extinction or endangerment you need to know what it needs to survive - where it lives, what it eats, when it is active etc… (this mostly applies to larger organisms, cause lets be honest no one is out there explicitly trying to protect parasitoids, although they are extremely important, and without a doubt species of parasitoids are going extinct as we speak, or i type, i guess). Another important reason to study the biology of parasitoids is their potential for use in biological control programs. Biocontrol is basically the use of organisms (insects, mites, plant diseases, weeds etc..) to control “pests”. Parasitoids are some of the most common biocontrol agents, especially for agricultural crop pests. So, rather than spraying chemicals to control crop pests for example you could find out what your pest is, what its parasitoid is, and then release the parasitoids to control your pest. It is actually a lot more complicated than that, but thats the gist of it. Ok, once again I could type on and on, but I will save more for later. But below are a couple of links to cool articles about parasitoids, thanks to Ryan!
http://www.sciencedaily.com/videos/2006/0702-wasps_mans_new_best_friend.htm
The above link is an article about the use of parasitoids as “sniffing dogs.” Seriously, wasps have a more acute “sense of smell” than dogs and can be trained in mere minutes. Coming soon at an airport near you.
www.sciencedaily.com/releases/2009/02/090216100425.htm
This link is an article about the use and presence of polydnaviruses in braconids. So when some groups of braconids (and ichneumonids) “sting” their host and inject their eggs, they also inject these little virus packets. These virus packets cause all kinds of effects on the host (and all beneficial to the wasp!) including immunosuppression, behavioral changes, metabolism changes and development changes. This is fascinating. So how do these wasps get the viruses to inject in the first place? Why it is integrated into the wasps own genome, of course. Think about that for a while, it is really amazing. Does anyone know of another example of a virus being beneficial to an organism? That wasnt rhetorical, if someone knows an example please let me know.
Ok, another post, with pictures, will follow soon.
Who would have known what wasps could do! I especially liked the video. Life would be so much better if we could use wasps for things like pesticides…etc. Keep up the good work!
By: JB Townsend on March 10, 2009
at 9:47 pm
Evidence that parasitoid wasps use viruses to their benefit is the most exciting things that I have ever heard about wasps—and I think wasps are pretty exciting on their own. I have never heard of a ‘beneficial’ virus. The current dogma generally holds that viruses can either be harmful or have no significant effect on their host. But then, viruses are so hard to study and so little is know about the ecology or the diversity of viruses that I wouldn’t be surprised if there actually are many beneficial viruses in nature. The closest thing to a beneficial virus I have heard of is a phage that infects Corynebacterium diphtheriae, the bacterium that causes diphtheria. Infection with this virus enables the bacterium to produce a toxin that makes it pathogenic. I wouldn’t say that this is particularly beneficial to the bacterium, since the toxin generally kills the bacterium’s host.
By: Lindsay Stubbs on March 16, 2009
at 1:58 pm