| Some basic biological characteristics, the developmental zeros and the effective accumulative temperatures of the Aphelinus mali, an important parasitic natural enemy of the woolly apple aphid, Erisosma lanigerum were researched. These researches will lay a solid theoretical foundation for the propagation and augmentation of the parasitoid.The main biological characteristics, including parasitism rate,sex ratio and eclosion rate of the parasitoid were investigated in the apple orchard. The parasitism rate peaked at 83.8% in September. Moreover, the mean parasitism rate of the parasitoid remained stable, at 50% or so during all other sampling period except in May. The sex ratio was higher during the period of the last days of July and the first days of August, and the highest sex ratio was about 7.5:1. During the other periods the sex ratio was 2-4:1. The eclosion rates of the parasitoid varied during different months, were very low in the starting and the late periods of the year, often kept stable at above 50% before the middle ten days of September, declined after mid-September and approached to zero in November with the parasitoid entering the period of diapause.The parasitic behavior, the eclosion rhythm and the effect of spectrum and light intensity on the phototaxis of the parasitoid were investigated in lab. The parasitic behaviors of the parasitoid mainly include the successive six processes: host searching, changing the position of body, ovipositon probing, ovipositing, oviposition terminating, and trimming and resting. The lanose wax on the body surface of woolly apple aphid can promote the parasitoid to search the host, and removing the wax is also important step for the parasitoid to lay its egg. The parasitoid had a tendency toward the short light spectrums, mostly toward the purple wavelengths. The phototaxis of the parasitoid was accelerated with the increase of the light intensity. The eclosion of the parasitoid peaked at 5:00-7:00 and the rhythm was obvious. The researches showed that light play an important role in controlling some behaviors of the parasitoid.Developmental durations, developmental zeros and effective accumulated temperature of the parasitoid were calculated under the conditions of different temperatures with RH75%. The developmental durations of the parasitoid shorten with the increase of temperatures. The developmental zeros of overwintering generation female and male adult were 8.58℃and 8.22℃, respectively. The effective accumulated temperatures overwintering generation female and male adult were 148.72 day-degrees and 154.68 day-degrees, respectively. The developmental zeros of non-overwintering generation at the stage of immature, adult and the whole duration were 5.62℃, 6.68℃, 5.74℃(female) and 5.55℃, 4.76℃,5.52℃(male), respectively; The effective accumulated temperatures were 284.40 day-degrees, 39.32 day-degrees, 326.26 day-degrees(female) and 295.61 day-degrees, 37.14 day-degrees, 329.33 day-degrees(male) , respectively. |
