The two-spotted spider (Tetranychus urticae) is an important pest of many agricultural crops. Laboratory bioassayswere conducted to determine the toxicity of Pyflubumide and Cyenopyrafen against three populations of T. urticae collectedfrom apple orchards. The adults and eggs of three populations all showed susceptibility to Pyflubumide and Cyenopyrafen,as the 50% lethal concentration (LC50) values were all lower than each of the recommended concentrations. There wereconsiderable differences in susceptibility of the acaricides between eggs and adults in different populations. Pyflubumideshowed highest toxicity to adults of Yeongju population (LC50 = 1.40 mg/l) and eggs of Andong population (LC50 =0.54 mg/l). Cyenopyrafen showed lowest toxicity to adults of Andong population (LC50 = 20.29 mg/l) while displayedhighest toxicity to their eggs (LC50 = 2.64 mg/l). These results suggested that T. urticae had not developed resistancein these three regions, Pyflubumide and Cyenopyrafen can serve as alternative chemical candidate for integrated mite managementin apple orchards.

Asitic apple leafminer, Phyllonorycter ringoniella Matsumura, is an important pest in apple orchard, however its reproductive characteristics and seasonal adaption is poorly understood. The longevity and fecundity of P. ringoniella were investigated at seven constant temperatures (13.7, 15.6, 20.5, 23.7, 26.1, 30.2, and 32.3℃), 60-80% RH, and a photoperiod of 14:10 (L:D) h. Female adult longevity increased as the temperature decreased. The highest fecundity was obtained at 15.6℃ (65.2 eggs/female), and the fecundity decreased as temperature increased. The oviposition model were comprised by four components: adult aging rate model, total fecundity model, age-specific oviposition rate model, and age-specific survival rate model. Female adult aging rates were well described by an inverse second-order polynomial function and the total fecundity model was well described by an extreme value function. Age-specific cumulative oviposition rate was well fitted to a three-parameter Weibull function and age-specific survival rate to a sigmoid function, respectively. The model would be useful in developing population model for P. ringoniella and establishing management strategy against P. ringoniella in apple orchards.

Asiatic apple leafminer, Phyllonorycter ringoniella Matsumura (Lepidoptera: Gracillariidae) is an important insect pest in apple orchard, however little is known about its demography and relationship with environmental factors. The effect of five constant temperatures (13.3, 15.3, 20.7, 26.1, and 30.0℃) on the demography of P. ringoniella was examined based on jackknife randomization method in the laboratory. The lowest (34.0%) and highest (63.3%) survivorship of immature stages occurred at 30.0 and 20.7℃, respectively. Sex ratio was estimated to be 0.5 and was unaffected by the temperature. Mean developmental times of immature stage were inversely related to temperature and varied from 25.9 days at 26.1℃ to 76.4 days at 13.3℃. Female adult longevity was longest at 15.3℃ (18.6 ± 0.96 days) and shortest at 30℃ (5.4 ± 0.27 days). The highest (86.24) and lowest (13.59) gross fecundity rate occurred at 15.3 and 30.0℃, respectively, while daily egg production displayed its highest (6.48) and lowest (2.12) values at 26.1 and 30.0℃, respectively. The highest net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) obtained at 20.7℃ were 12.43, 0.064, and 1.067, respectively. Mean generation time (T) decreased with increasing temperatures from 85.24 days at 13.3℃ to 30.48 days at 30.0℃. Doubling time (DT) varied significantly with temperature and the shortest value (10.75 days) was obtained at 20.7℃. The life expectancies of female adult were estimated to be 16.2, 18.6, 10.8, 7.2, and 5.4 days at 13.3, 15.3, 20.7, 26.1, and 30.0℃, respectively. This study was the first time to report demographic biology of P. ringoniella, thus it provide potential direction for future research on P. ringoniella and its natural enemies in apple orchards.

The apple leaf miner, Phyllonorycter ringoniella(Lepidoptera:Gracillariidae),is an important pest of apple trees in Japan, Korea and China. It is very important to know the development time of overwinter pupae for predicting the adult spring emergence in apple orchard. In total 556 damaged leaves caused by P. ringoniella were collected three times in two locations, Pohang and Mungyeong, and then were reared in five incubators with 10, 15, 20, 25, and 30℃, RH 60±5%, and a photoperiod of 16:8 (L:D) h, respectively. There were larvae, pupae of P. ringoniella and its parasitoids inside these damaged leaves. Larval population was 44% inside the curled leaves, but found all dead. Pupal population was 41%, but 41% were found dead. Parasitism was 14.5% ranged from 4.5 to 17.9%. This means that the winter survival was only 23.9%. Surviving pupal developmental rate was linearly related to the temperature treated. Lower threshold was estimated to 3.58℃ with degree-day accumulation to adult emergence of 153.8 DD. From this information, adult emergence was predicted during early April. However this estimation was only based on the partial data from which current experiments are on-going. Further sophisticated research outcome will produce better understanding of the overwintering moth development and its modeling.