Rivers D B., Lee R E., Denlinger D L.
Department of Biology, Loyola College in Maryland, 4501 North Charles Street, Baltimore, USA
J Insect Physiol. 2000 Jan;46(1):99-106. doi: 10.1016/s0022-1910(99)00106-7.
Supercooling points (SCPs) and low temperature survival were determined for diapausing and nondiapausing larvae of the ectoparasitoid Nasonia vitripennis. Neither nondiapausing nor diapausing larvae could survive tissue freezing. The SCP profiles were nearly identical for nondiapause-destined (-27 degrees C) and diapausing larvae (-25 degrees C), but these values were not indicative of the lower limits of tolerance in either type of larvae: larvae were killed by chilling at temperatures well above the SCP. Diapausing larvae could withstand low temperature exposures 3-8 times longer than their nondiapausing counterparts. Low temperature survival was enhanced in diapausing and nondiapausing larvae by their encasement within the puparium of the host flesh fly, SARCOPHAGA CRASSIPALPIS: the LT(50)s determined for nondiapausing and diapausing larvae enclosed by fly puparia were 2-3 times higher than values calculated for larvae removed from the puparia. Additional low temperature protection was gained through acquisition of host cryoprotectants during larval feeding: nondiapausing parasitoid larvae that fed on diapausing flesh fly pupae with high levels of glycerol were able to survive exposure to a subzero temperature 4-9 times longer than wasps reared on nondiapausing fly pupae that contained lower quantities of glycerol. Alanine may also contribute to the cold hardiness of N. vitripennis, as evidenced by the fact that larvae feeding on diapausing fly pupae both contained higher concentrations of alanine and exhibited greater cold hardiness. The results thus demonstrate that several critical features of cold hardiness in the wasp are derived from biochemical and physical attributes of the host.
测定了体外寄生蜂丽蝇蛹集金小蜂滞育和非滞育幼虫的过冷却点（SCPs）及低温存活率。非滞育和滞育幼虫均无法在组织冻结的情况下存活。非滞育幼虫（-27℃）和滞育幼虫（-25℃）的SCP曲线几乎相同，但这些数值并不代表任何一种幼虫的耐受下限：幼虫在远高于SCP的温度下因低温而死亡。滞育幼虫能够承受低温暴露的时间比非滞育幼虫长3至8倍。将滞育和非滞育幼虫置于宿主肉蝇（肥须亚麻蝇）的蛹壳内，可提高其低温存活率：对于被蝇蛹包裹的非滞育和滞育幼虫，所测定的半致死温度（LT(50)）比从蛹壳中取出的幼虫计算值高2至3倍。幼虫取食期间获取宿主的抗冻剂可获得额外的低温保护：取食富含甘油的滞育肉蝇蛹的非滞育寄生蜂幼虫，能够承受零下温度暴露的时间比取食含较低甘油量的非滞育蝇蛹所饲养的黄蜂长4至9倍。丙氨酸可能也有助于丽蝇蛹集金小蜂的耐寒性，这一事实表明，取食滞育蝇蛹的幼虫体内丙氨酸浓度更高，且耐寒性更强。因此，结果表明该黄蜂耐寒性的几个关键特征源自宿主的生化和物理特性。
