The Study Of Genetic And Biological Characteristics In The Body Color Mutant Of Mythimna Separate(Walker)

Body color mutants of Mythimna separate(Walker) were found in a laboratory and in the wild. This essay is mainly about biological and ecological characteristics and evolutionary adaption meaning of the mutants, it indicates variation of the mutant in the genetic characteristics, the overwintering ability, the ability of flight and the adaption to environmental factors such as temperature, it provides theoretical basis to the rule of occurance in the field,forecasting and integrated control. The major progresses obtained from these studies are summarized as follows:1.The main difference between the mutant and the normal form was the body color of the adults, the body color of the mutant was all redder than the one of normal form. There were no significant differences between the mutant and normal form in the body color of eggs, larva and pupae,but the pupae of mutant became blacker than the normal form when it will became a moth. The results of hybridization experiment were that it consisted with Mendelian, monogenic autosomal recessive inheritance. Though there were significant differences between the mutant and the normal form in body color, they can mated and breed each other. It proved that they still belonged to the same species and the mutant came from the normal form.2. Experiment about supercooling point of the mutant and the normal form indicated the ability of cold-resistant and the overwintering stage of the mutant. The supercooling point of larva was:2nd instar <1st instar<3rd instar<4th instar<5th instar<6th instar, the supercooling point of 6th instar was the highest,-7.67±1.7℃.the one of 1st instar was the lowest,-16.22±2.3℃,and these were significant differences between the supercooling point of 2nd larva and the others(p<0.05).The supercooling point of 3rd to 5th instar was not so(p>0.05).The one of pupae was the lowest in all stages,-16.79±3.8℃.It indicated that the overwintering stage of the mutant was pupae, just liked the normal form; the cold-resistant of moth was medium level and it was not influenced by gender.3. There were some changes to the mutant in adaption to temperature and physiological characteristics. There were better adaption at below 21℃,but not at above 29℃.The reasons were likely the heat effect. Development threshold temperature of the mutant was lower, so the mutant could occur at high altitude and high latitude region, spring or winter. High temperature was harmful to growth and development and breeding populations, so the damage of the mutant will be lighter at tropical region and local high temperature season. The bigger egg laying amount, shorter developmental duration, heavier pupae weight and bigger appetite of the mutant lead to better adaption to environment. If the environment is fit, the mutant will damage the environment more heavily.4.The tethering experiment indicated the flight capacity of the mutant, the results showed that the flight capacity of the mutant was obviously weaker. At 13℃、17℃、21℃、25℃, there were no significant differences between the normal form and the mutant(p>0.05). At 29℃、33℃, there were significant(p<0.05). At 33℃, their flight speed was the highest. At every temperature, there were significant difference in the rate of residual wing(p<0.05). The mutant had the higher rate of residual wing than the normal form. At 33℃, the one of the mutant was 36.23%.