Friday, August 28, 2015

Parasitism and Symbiosis

Thousands of Hippodamia convergens converge on mountaintops 
In summer in the mountains of AZ, we often see huge congregations of Lady Beetles. They may migrate up to higher elevations to escape the oppressive heat in the valleys.
In the mountain meadows around Flagstaff, a little parasitic wasp is ready for them: Dinocampus coccinellae, a braconid wasp, stings a ladybug to oviposit. The wasp's larva then develops feeding on the beetle's heamolymph. Also transferred is a virus: D. coccinellae paralysis virus (DcPV for short). The virus multiplies in the developing wasp larva and eventually infects the ladybug's nervous system. At the time the wasp hatches and pupates, the virus immobilizes the ladybug. The brightly aposematic and toxic beetle is forced to stand guard over the silk cocoon that its former unwelcome guest has spun beneath it, basically providing protection for the pupa. The beetle is still able to move, but not to walk away. The DcP virus may actually enhance the deterrent effect by making the beetle twitch. In a recent study, no wasps without virus were found, so there was no test group to see what happens if the wasp pupa has to develop without its protector. Surprisingly, researchers did find that a fair percentage of beetles actually makes a full recovery. Who would have thought? It is not clear though if those recovered beetles are still able to reproduce. And would the be possible hosts to the same sp. of wasp again? Would they be immune to the virus the second time around?

The wasp cocoon in my photo was already empty, and the beetle looked quite healthy, if still tethered. Ready to go, actually. I found it and several others on a mountain meadow near Snow Bowl, Coconino Co. AZ  8/5/2015'

Original research by The topic was recently also treated by Eric Eaton in his blog and by National Geographic' website.

1 comment:

  1. Hi there
    Mensch, Du lebst wirklich in einer spannenden und sehr beeindruckenden Gegend. Ich war im Jahr 1992 mal in einem alten VW-Bus durch Arizona hindurch gefahren. Wie gut, dass ich damals noch nicht wusste, was da alles in der freien Natur so rumkrabbelt, ich bin nämlich ein grosser Angsthase, vor allem was Spinnen anbelangt. Alle anderen Insekten... ehm, hauptsächlich die kleinen ... finde ich wieder spannend und einfach nur faszinierend.
    Vielen Dank für Deinen lieben Besuch auf meinem Blog und auch die ermunternden Worte in Bezug auf mein Englisch, das doch eher Bescheiden ist *lach*. Ich schreibe auf Englisch um in Übung zu bleiben und es macht mir einfach Spass.
    Ich schicke liebe Grüsse über den Teich.