Quiescence

Quiescence for aestivation may be found in arid regions. For example, the larvae of the African chironomid midge, Polypedilum vanderplanki, inhabit temporary pools in hollows of rocks and become quiescent when the water evaporates. Dry larvae of this midge can "revive" when immersed in water, even after years of quiescence. The quiescent larva is in a state of cryptobiosis and tolerates the reduction of water content in its body to only 4%, surviving even brief exposure to temperatures ranging from +102°C to -270°C. Moreover, quiescent eggs of the brown locust, Locustana pardalina, survive in the dry soil of South Africa for several years until their water content decreases to 40%. When there is adequate rain, they absorb water, synchronously resume development, and hatch, resulting in an outburst of hopper populations. The above-mentioned examples are dramatic, but available data are so scanty that it is difficult to surmise how many species of insects can aestivate in a state of quiescence in arid tropical regions.

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