Effects Of Elevated CO₂ Concentration And Temperature On Biology Of Encarsia Formasa

Environmental changes have an important impact on growth,development,survival,and longevity of insects.The increase in temperature and carbon dioxide is the most significant feature of climate change in the 21st century.In this study,the growth,development,parasitization and emergence rate and specific age life table of Encarsia formosa were studied under ambient or elevated CO2 concentration（[CO2],400 ppm and 800 ppm respectively）and ambient or eleveted temperature（27±1oC/20±1oC light/dark and 34±1oC/27±1oC light/dark respectively）.The main results are described as follows:1.The developmental time of E.formosa was significantly affected by temperature and CO2 concentration.Under the same treatment,the development duration of successive three generations of E.formosa parasitizing different whitefly nymphs was significantly decreased with generation increase.The developmental time of E.fomosa was the shortest at elevated temperature and CO₂ combinations.2.Elevated temperature or CO₂ had a significant effect on parasitism rate of Bemisia tabaci first instar nymphs by E.formosa.CO2 enhancement greatly affected the parasitism rate of second and fourth instar nymphs of B.tabaci by E.formosa.The emergence rate of E.formosa was significantly affected by temperature and CO2.Under elevated temperature,elevated CO2 markedly reduced emergence rate in the second generation of E.formosa.3.The life table of E.formosa was constructed under four different treatments.The population characteristics were significantly affected by temperature and CO2.Under elevated temperature or CO2,the longevity,oviposition period,parasitism,average generation number were significantly decreased,but the intrinsic growth rate and finite rate of increase were markedly increased.Under temperature elevation,elevated CO2 significantly reduced developmental time,daily average parasitism rate,daily average eclosion rate,reproduction,survival and life expectancy;however,the intrinsic growth rate and finite rate of increase had no significant change.In general,elevated temperature and CO₂ were unfavorable to the survival and reproduction of E.formosa.The future climate changes could have an adverse effect on E.formosa population growth and biological control efficienty of B.tabaci.