The Effect Of Diapause And Cold Acclimation On The Cold Tolerance Of Aedes Albopictus Eggs

Aedes albopictus (Skuse), known as the'Asian tiger mosquito', originated in Southeast Asia and now has spread to more than 70 countries and regions in tropical, subtropical and temperate areas by the international trade transportation and road traffic systems. As an important insect vector, Ae. albopictus can spread dengue fever, Chikungunya fever and other diseases. With global warming issues becoming increasingly prominent, more and more people's attention has been attracted by the distribution and diffusion of Ae. albopictus and its consequent public health problems.In this study, laboratory populations of Ae. albopictus, were used to study the influence of different physiological states (diapause and non-diapause) and environmental conditions (cold-acclimated and non-cold-acclimated) onAe. albopictus eggs'cold tolerance. Compared the eggs'cold hardiness variation in different geographic populations of Ae. albopictus and the effect of cold acclimation on cold hardiness of eggs from different populations. Finally, quantitative PCR method was used to determine the heat shock protein mRNA expressions in Ae. albopictus diapausing period and during the response to low temperature stress. The results were as follows:(1) Diapause could improve cold tolerance of Ae. albopictus eggs, and cold acclimation also improved eggs'low temperature tolerance. But a further increase in cold acclimation time (30d and 60d) did not significantly enhance cold hardiness..(2) Ae. albopictus eggs survival was significantly higher at -4 ? than -5 ? for the same populations. Overall, the higher latitude populations of Ae. albopictus eggs had a higher cold survival rate.(3) Constant cold acclimation can improve cold survival of different populations ofAe. albopictus eggs. But different geographic populations of Ae. albopictus eggs, had different results after constant cold acclimation (10? 10d) or variable acclimation (10? 5d ? 5? 5d), further cold acclimation might not be suitable for all geographic populations.(4) Hsp70 and Hsp90 mRNA expression did not change significantly during diapause period of Ae. albopictus.Heat shock protein mRNA expression upregulated when other insects were in diapause state.(5) Whether it was diapausing or not, Hsp70 and Hsp90 mRNA expression of Ae. albopictus eggs were induced by cold exposure. But compared with non-diapausing eggs, Hsp70 mRNA of Ae. albopictus diapausing eggs was significantly upregulated (P = 0.001) by low-temperature stimulation, while Hsp90 mRNA was not obviously upregulated (P= 0.289). For diapause eggs, Hsp70 may play a greater role in cold hardiness when compared with Hsp90.(6) Cold acclimation did not affect upregulation of Hsp70 and Hsp90 mRNA expression of Ae. albopictus eggs induced by cold temperature.The heat shock protein transcript was just one aspect of the increased cold hardiness.(7) Both Hsp70 and Hsp90 played important roles in cold hardiness of diapausing and non-diapausing eggs of Ae. Albopictus. But Hsp70 was more important in diapausing eggs and Hsp90 was more important in non-diapausing eggs of Ae. Albopictus.