Effects Of Temperature Variation On The Biological Characteristics Of Grapholita Molesta (Busck)

Temperature variation is closely related to the occurrence dynamics of Grapholita molesta. To explore the effect of temperature variation on the occurrence dynamic and biological characteristics of G molesta, we investigated the occurrence dynamics of G molesta from 2013 to 2015 in Taian, and studied the biological characteristics of G molesta at constant temperature and fluctuating temperatures.1. The occurrence dynamics of G molesta from 2013 to 2015 in TaianFrom 2013 to 2015, G molesta had five generations per year. The first eclosion time of adults was earlier in advance year by year. In monoculture peach orchard, the time of eclosion peak of each generation was slightly different during the three years,2014 was the earliest, and the peak time of the third and fourth generations of 2015 was early than 2013. There had increasing trend of the number of eclosion peaks of G molesta in 2014 and 2015. Quantity of the overwintering and first generation were correlated to temperature variation.2. Effects of female-male couples on the longevity and fecundity of G molesta adultsThe oviposition dynamics and longevity of 1 couple,3 couples,5 couples and 7 couples adults in 200 mL space were studied. The highest longevity of adults (16.11 d) was observed in one couples. There was no significant difference between the longevity of male adults and female adults except 7 couples. Maximum value of daily average fecundity of female adults of all treats were observed in 3 d to 6 d, and the highest fecundity (25.16 eggs) appeared in 5 couples. The maximum value of duration of egg-laying (20 d) was observed in 3 couples, and the highest fecundity per single female was 141.80 eggs in 5 couples. After comprehensive analysis, the suitable couples giving full play of maximum fecundity of G molesta was in 5 couples in 200 mL space.3. Effects of different temperatures on the development and fecundity of G molestaLife tables of the experiment population of G molesta were established at 19?,22?, 25?,28? and 31? with a photoperiod of 15L:9D and relative humidity of 60%. The developmental durations of the eggs, larvae, pupae and adults were decreased with increasing temperature, and the developmental durations of prepupa decreased at first and then increased with the minimum value observed at 25?. The highest age-stage survival rate was observed at 22?. Fruit-boring rates, eggs laid per female, net reproductive rates, intrinsic rates of increase and finite rates of increase were increased at first and then decreased with increasing temperatures; the maximum values existed in 25?. At 19? to 28?, R0 and r were above one, but the result was contrary at 31?, which indicated that the number of population was decreased at 31?, but had increasing trends at 19?-28?.4. Effects of constant temperature and fluctuating temperatures on the development and fecundity of G molestaTo study the effects of constant and fluctuating temperatures on the development and fecundity of G molesta, we constructed two-sexual life tables at 22?,22±3? and 22±5?. The longest developmental durations of the eggs, larvae, prepupae, pupae and adults were observed in 22±3?, while the shortest developmental durations in 22?. The highest survival rate of G molesta was observed in 22?. The largest value of daily fecundity was 10.9 eggs in 22±5?, while the highest value of total eggs of single female was 91.85 eggs in 22±3?. The maximum value of net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (?) were existed in 22?. These results indicated that 22? was more suitable for the development than the fluctuating temperatures, and 22±3? was more suitable for the egg-laying of adults.5. Biological characteristics of G molesta under field conditionsThe biological characteristics of G molesta at field-simulated conditions were analyzed by two-sexual life table from July to September, and the population dynamic without sex pheromone treatment and with sex pheromone treatment within 80d and 180d were simulated according to the data of the two-sexual life table. The developmental durations of eggs, larvae, prepupae, pupae and adults from July to September were 3.34 d,14.56 d,3.02 d,6.41 d and 15.28 d, respectively. Daily fecundity of female was highest at early time of oviposition. Net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (?) and mean generation time (T) were 10.79 offsprings,0.0734 d-1,1.0761 d-1 and 32.41 d. We also simulated the population dynamics without sex pheromone treatment and with sex pheromone treatment, and found the number of G. molesta population withr sex pheromone declined significantly after 80 d. These results showed that it was applicable to predict the real field population dynamics of G molesta using field-simulated conditions, so sex pheromone had better effectiveness to reduce the population during short period.