Effects of water pH on the growth and development of Aedes albopictus
Objective To investigate the effects of water pH on egg hatching,larva and pupa growth and development of Aedes albopictus,and to provide a new method for the control of Ae.albopictus.Methods In water of different pH(3.0,3.5,4.5,5.5,6.5,9.5,10.5,11.5,and 12.0),the development of mosquitoes through egg,larval,and pupal stages were observed.The hatching rate,larval survival rate,pupation rate,eclosion rate of pupae,and time for each developmental stage were recorded,and the effects of the pH of water on the development of Ae.albopictus in comparison with those placed in dechlorinated water were analyzed.Excel 2010 and SPSS 18.0 softwares were used for data collation and statistical analysis.Categorical data were described as rates,and continuous data were described as(x)±s.The Chi-square test and one-way analysis of variance were used for inter-group comparison.Results For pH≥10.5 or pH≤4.5,the hatching rate of Ae.albopictus eggs was significantly lower than that of the control group(pH=7.6±0.4)(χ2=1 646.693,P<0.001).The time to hatching was significantly longer at pH≥11.5(F=52.241,P<0.001).Compared with those of the control group(pH=7.6±0.4),the survival rate and pupation rate of the 4th-instar larvae of Ae.albopictus were significantly decreased at pH≥10.5 or pH=4.5(χ2=94.088,P<0.001;χ2=119.722,P<0.001),and the time to pupation was significantly prolonged at pH≥11.5(F=20.148,P<0.001).Compared with the control group(pH=7.6±0.4),the eclosion rate had no significant difference in each group(χ2=5.861,P=0.556),but the time to eclosion was significantly longer than that of the control group for pH≥10.5 or pH=4.5(F=150.398,P<0.001).Conclusion The suitable water pH for the growth and development of Ae.albopictus ranges from 5.5 to 9.5,beyond which the growth and development of Ae.albopictus can be offected.