Biology 3660A/B Lecture 19: 3601 Lec 19.docx
20 Jun 2015
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Insect cold tolerance: chill susceptibility insect die of cold without freezing, above super freeze point, freeze avoidance insects cannot survive internal ice formation, same level as super freeze point, freeze tolerance insects can survive being frozen, under super freeze point, strategies, scp>llt. Experiment and objective: assess the larvae tolerance to hypoxia, baseline meaningful for comparison, model oxygen exchange in gall, factors that should be influential, directly measure oxygen level in wild galls, actual situation. Tolerance methods: larvae exposed to decreasing o2 levels, estimate oxygen levels when metabolism and activity fall, critical oxygen level (pc, larva metabolism started decreasing 9. 5kpa and stopped at 3. 6kpa, insects have good hypoxic tolerance abilities, 9. 5kpa not severely low, some can 1kpa extremophiles, measured by co2 production monitored by optical sensor. Gall structure: skin, mature cortex, fresh cortex parenchyma and nutritive layer, very metabolically active, larval chambers, transition occurs from outside to inside, a lot of gas spaces.
