Studies on Fundatrix Emergence Period, Quantitative Change and Autumn Migrant Reproductivity of Chinese Horned Gall Aphid, Schlechtendalia chinensis

Chinese horned gall aphid, Schlectendalia chinensis, is a major species of Chinese gallnut aphids. Like other Rhus gall aphids, S. chinensis has six forms in its life cycle, including autumn migrant, overwintering larva, spring migrant, sexuale, fundatrix, and fundatrigenia. The spring migrants produce sexuale then fundatrix after mating in the processing of gallnut aphid artificial rearing. The fundatrix performs key role since it is the gall former among all forms. Its emergence periods and quantitative changes were observed in different preservation conditions. The results showed that the fundatrices emerged from April 19th to 22nd, March 31st to April 4th and April 7th to 10th, when the spring migrant bags were preserved in Emei (the natural distribution area), laboratory and basement of Kunming under room temperature, respectively. There were 19 days and 12 days ahead of time comparing to its natural distribution area when they were preserved respectively in laboratory and basement of Kunming. Generally, the fundatrix emergence period lasted for 4 or 5 days and the emergence amount within the middle 1 to 2 days may constitute more than 70% of the whole amount. The peak emergence time happened at 10:00-16:00 and its amount may account more than 80% of the daily emergence amount. Furthermore, new fundatrix has phototaxis to both the sunshine and light. In addition, the autumn migrant also plays an important role because it is the transfer type from its primary host, Rhus chinensis, to the secondary host, Plagiomnium maximovicgii. The results of the experiments indicated that the density, oviposition amount and fecundity of autumn migrant of middle size gall with the average size of 28.2±0.8 cm3 were 387.7±52.3 adults·cm-3, 26.4±3.8 larvae and 27.6±4.2 eggs, increased by 46.7%, 24.5% and 23.8% respectively compared to the small size gall with the average size of 5.4±0.3 cm3. The producing time of autumn migrant were more concentrated and lasted shortly when its winter host mosses were presented. The autumn migrants flying at 14:00 and 18:00 began to produce larvae after migration, then reached to the peak after 4 hours and the whole producing times lasted for 30 hours and 28 hours, respectively. However, the migrants flying at 8:00 began to produce larvae 2 hours after migration, then reached to the peak after 16 hours and the whole producing time lasted for 36 hours.