Friday, July 11, 2014

P. larvae LC50 Pilot

Checked honey bee larva that was placed on the 5uL drop of 200 CFU/mL from 7-10-14 (24 hours ago). I viewed each second instar larva on the dissecting microscope/stereo microscope. It was surprisingly easy to identify if the larva was still alive.

If dead: will appear only to be a circulatory system (can see "veins"), dried up, or very tiny.
If alive: will appear cream colored, glistening in the scope, and will ungulate slightly if watched closely.

Unfortunately, a large number of the 50 larva were confirmed dead after 24 hours. For most of the dead larva appeared to only be a translucent bag containing a circulatory system.

There were only 8 confirmed alive larva and three questionably alive larva after 24 hours. That is between a 16-22% survival rate, which is horrible. It is incredibly likely that the large amount of death was due to transfer and the larva drying out.

Regardless, the remaining surviving larva were transferred to a new 24 well plate onto 10 uL of BAD using a camel hair paint brush. The larva was incubated in the anaerobic container at 35C. I will continue to monitor their growth, continue to feed them, and check their survival each day for eight more days.

I will have to rethink my transfer method for this experiment. Likely I will transfer the larva directly to the 24 well plate from the Jenter box at the USDA and then bring them back to NDSU to infect with P. larvae spores. Hopefully next week I will obtain more honey bee larva.

//EWW

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