This is a followup to Alan Lee's earlier article, Antheraea polyphemus Experiments and Observations
"Hi Bill,
"On January 3, 2008, I brought down my last sleeve of 2007. I had been watching them (Antheraea polyphemus larvae), and they were really big. I wanted to leave them out as long as possible. The low for January 2 was 27 F. The low for January 3 was 18 F.
"When I opened the sleeve on January 3, around 10:30am, the temperature had warmed to about 25 F, and all was as I expected. Some cocoons would be complete and the remainder of the caterpillars would be dead. There were fourteen complete cocoons, three translucent cocoons, twelve green caterpillars and one brown shriveled caterpillar.
"Of the complete cocoons, eight shook freely. Those eight had probably pupated prior to the cold. Pupation of the others had not happened yet. The caterpillars seen through the translucent cocoons were motionless but soft when pressed.
Of the twelve green caterpillars, five were soft and pliable and drooped over when held by one end. Seven were rigid as though frozen solid. They remained stiff when held up by one end and were "solid" when pressed. The shriveled caterpillar was discarded.
I kept the torpid, frozen caterpillars and took them home to show my wife and kids. After they had examined the larvae, I placed the caterpillars on the table to later feed to the chickens. Then the excitement began."
At 11:30 am, when I picked up the box of "frozen" caterpillars to take them outside, I noticed some movement. And sure enough, five of the caterpillars were intentionally crawling around! On further inspection, four others would flex to touch and three remained motionless. I checked the translucent cocoons, and even one of the encased larvae had resumed its spinning.
"I had heard fishermen say they would place catalpa worms (caterpillars) in the fridge the night before they went fishing, saying it made them easier to manage. They said they all "came back to life when they warmed up." So maybe polyphemus are the same. But 18 degrees is much colder than a fridge--that's a freezer!! So I placed a limb of oak over them and continued to watch. The notes below indicate how things progressed.
"Noon: Five had climbed up and were clasping limbs of the oak; five others would flex to the touch and two others remained motionless.
"12:10: Five were searching on the limbs, and the other seven would all flex to the touch.
"12:15: Five were searching, two more had climbed up and were clasping, the other five flexed to the touch.
"12:20: First frass dropped.
"12:30: Two more had climbed up and were clasping: now five were searching, four clasping, three crawling around.
"12:45: All twelve either clasping or searching in th eoak -- no eating noted. I checked the translucent cocoons and all three had enclosed larvae moving withone visibly spinning.
"3:00: Five caterpillars had dumped and were spinning up in the oak; one was eating; six were clasping very still.
"5:00 pm: Now three were eating, five were spinning and four were clasping.
"I went to work (night shift) and did not check again until morning.
"January 4: 8:00am: All translucent cocoons were opaque, five nearly complete cocoons on the limb, one beginning to spin up, four eating and two just clasping.
"Jan 5: 8:00am: six complete cocoons, two spinning, four eating
"Jan 6: 8:00am: eight complete cocoons, one spinning, three eating
"Jan 7: 8:00am: ten complete cocoons, one spinning and three eating
"Jan 8: 8:00am: eleven complete cocoons, andone had fallen off and was brought to me by the dog. It was dead.
"Jan 25: All fourteen cocoons from the original three translucent cocoons and twelve larvae seem to have good weight and sound during hand heft and shake test.
"I do not know if anyone has sent you any similar experience so maybe this wil be a good one for the website. Will they have different colours due to the cold exposure? I think I have read that some species have shown colour changes in response to cold exposure.
"If these do eclose and prove to be sexually viable, if there are colour changes, will these be passed on to the next generation?"
Many thanks to Alan for an interesting and well written
article. I am quite surprised that the larvae which appeared to have
been completely frozen were able to resume moving, feeding, spinning
and apparently pupating. Perhaps because this was a fall brood,
enzymes were already present in the larvae, preparing them for
winter diapause, that would enable them to endure such cold. I am not
sure that there would be a similar "resurrection"
if summer polyphemus larvae were exposed to the same cold, artificially
or otherwise.
It will be interesting to see if there is a colour change or if there are
any
other apparent differences.
If there are differences, I do not think they would be transmitted to
subsequent offspring, as I do not think there would be any changes
to DNA, but that remains to be seen.
Moths emerged from all of the cocoons of the "frozen" larvae.
All cocoons were taken out of cold storage at the same time, early May, and placed in the same
eclosion cage. The first moth emerged in mid June. Other eclosions were very sporadic throughout summer
and some moths did not eclose until late July and even early August. There did not appear to be any difference
in the appearance of these moths.
The sporadic eclosion pattern is a mystery!
Use your browser "Back" button to the previous page.