A Comparison On Adaptation To Extreme Temperatures In Longnan And Taian Population Of The Cabbage Beetle Colaphellus Bowringi (Coleoptera: Chrysomelidae)

The cabbage beetle, Colaphellus bowringi Baly (Coleptera: Chrysomelidae) is aserious pest of crucifers in China. In this thesis, temperature stress resistance in differentgeographical population of C. bowringi and the effects of acclimation temperatures onthe cold and heat tolerance in this beetle were investigated. At last, the effects of extremetemperatures on reproductive biology for the survival individuals in this beetle were alsodetermined.1. Temperature stress resistance in different geographical population in thecabbage beetle C. bowringiTo determine the tolerance of C. bowringi to different extremely high or coldtemperatures, extremely temperature stress resistance of Longnan (LN) and Taian (TA)population were undertook, which was based on the basis of diapause biology studies.The results show that the cold tolerance of Taian population was stronger than Longnanpopulation and viec versa, the heat tolerance of Longnan population was stronger thanTaian population significantly. The temperature stress resistance of Longnan (LN)population was affected by developmental temperature and physiological statussignificantly. With the increase of developmental temperature, the tolerance to extremehigh temperature showed a tendency to strengthen, as for the extreme low temperaturetolerance ability, however, it was significantly weakened. The meantime of temperaturestress resistance was also affected by eco-physiological status of developmental fordiapause. The temperature stress resistance for diapausing adults was stronger thannondiapausing adults. And the results showed that the heat tolerance of the individualswhich diapause was induced by long day-length is stronger than the adults, which wasinduced by short day photoperiod. And, as for the cold tolerance, vice versa, the diapausethat was induced by short day photoperiod is stronger than long day-length induceddiapausing adults.2. Effects of acclimation temperature on the cold and heat tolerance in C. bowringiThe results of effect of acclimation temperature on the cold and heat tolerance in C.bowringi indicated that optimal temperature for generating protection against cold shockinjury occur in cold acclimation at0C, and for heat tolerance, acclimation at35C,indiapausing individuals. Meantime, optimal temperature for generating protection againstheat shock injury occur in cold tolerance after acclimation at-5C and heat acclimation at40C in diapausing individuals. However, in nondiapausing individuals, no temperaturesprotected effect was found in against cold shock injury after acclimation, and there isonly heat acclimation against heat shock injury. The results have determined the plasticity of cold tolerance and heat tolerance in diapausing individuals. The presentresults indicate nondiapausing individuals do not have cold tolerance plasticity and theheat tolerance was limited. Otherwise, the protective response of high temperatureacclimation is achieved much more rapidly than the protective response elicited by lowtemperature acclimation. Under these experimental conditions the high temperatureprotection is eroded more rapidly than the low temperature protection, also, which isrelated to eco-physiological status on diapausing or not.3. Effects of extremely temperatures treatment on reproductive biology in C.bowringiTo determine the effect of extreme temperature treatment on aspects of thereproductive biology of the C. bowringi, such as adult longevity, oviposition, the pairednondiapasing adults were transferred into a petri dish which was surviving nuder2or4hours of extremely temperature treatments. Longevity and oviposition was recorded daily.The results showed that with the increase of extreme high temperature, oviposition wassignificantly reduced and longevity shortened obviously. The peak period of ovipositionwas around twelfth day after adults emergence. With the increase of extreme hightemperature treatments, the duration of oviposition was shortening significantly. The totalnumber of eggs laid by each female was significant decreased than the control for theindividuals that were surviving after2or4hours treatment at36C or42C. The similartendency was also showed in the individuals which was surviving after2or4hourstreatments under extremely low temperature, the oviposition is less than the controlgroup after surviving-5C,-8C and-10C treatment, respectively. There was nodifference in the fecundity or longevity in male and female adults at relatively favorabletemperatures from25to28C. However, the oviposition and longevity were significantlyaffected by the temperature stress in nondiapausing individuals, which was survive afterthe low or high temperature treatment.