Abstract:

Pseudoregma bambusicola is a pest of Bambusa multiplex. In this study, population dynamics of P. bambusicola were investigated in one-year-old B. multiplex coupled with ecological factors such as natural enemies and weather. The aphids were observed to firstly infest the bottom of bamboo shoots in late May in 2008, and then disperse into the whole bamboo clusters quickly. Population density of the aphids was highest during the period from August to September in 2008, then declined, and it did not rise until the early March in 2009. The 1^st-4^th instar nymphae could be found contemporarily in the whole year yound, however the age ratio of the nymphae (the 3^rd-4^th instar population:the 1^st-2^nd instar population) was classified as two distinguishable stages, one from early October in 2008 to the mid-March in 2009 with the ratio of 0.932, the other in the rest time with around 0.5. In the meanwhile, the occurence of three dominant natural enemies was regular pattern dependent on time. The population density of Asilidae sp. was highest from March to May in 2008, and the peak of population density of Lemnia saucia occurred between August and September in 2008, and the population density of Taraka hamada showed two peak periods during separately from July to August in 2008, and from November of 2008 to February of 2009. Among the three natural enemies, only Taraka hamada could prey on bamboo aphids all-year-round, and other two predators overwintered in the weeds beside the bamboo clusters from December in 2008 to February in 2009. Precipitation had some effect on population density of the bamboo aphids to some extent, and around 8.33%-20% of the aphids in the infested bamboo clusters was removed by continuously heavy rainfall.

Key words: Pseudoregma bambusicola, population density, natural enemy, precipitation