Studies On The Parasitoids Of Hemiberlesia Pitysophila Takagi (Homoptera: Diaspididae) And Their Control Effectiveness

Hemiberlesia pitysophila Takagi is a kind of dangerous quarantine pest, which has caused serious damage to forests, and the utilization of parasitoids is an available approach to prevent H. pitysophila from damage and spreading. In this research, on the base of investigations on parasitoids of H. pitysophila in Fujian Province, the biological characteristics and sensory systems of the two important parasitoids Encarsia amicula Viggiani et Ren and Coccobius azumai Tachikawa, were studied. The interspecific competition between E. amicula and C. azumai, and the functional response of C. azumai were also analyzed. Moreover, a method to collect and release C. azumai was set up and the effectiveness of parasitoids on H. pitysophila was evaluated by life table. The main results obtained were as follows:1. The parasitoids of H. pitysophila in Fujian Province were found with 6 species belonging to 4 genus in Aphelinidae. E. amicula, E. citrina (Craw) and Aphytis sp. are primary parasitoids, and Marietta carnesi (Howard), Ablerus perspeciosus (Girault) and Ablerus chionaspidis (Howard) are hyperparasitoids, the two latters are reported as hyperparasitoids of H. pitysophila for the first time. Another parasitoid, C. azumai, introduced from Japan into Fujian Province in 2002, has already established to control H.pitysophila efficiently.2. C. azumai lay eggs with both gamogenesis and parthenogenesis. The females are primary parasitoids of H.pitysophila, which are reproduced by gamogenesis. The males are reproduced by parthenogenesis, hyperparasitizing on the mature larvae or pupae of self individuals or others. E. amicula lay eggs with parthenogenesis. The major phases of oviposition of C. azumai and E. amicula are searching, test, inserting host by ovipositor, laying eggs, drawing out ovipositor and cleaning. The reproductive systems of just emergent female C. azumai and E. amicula were dissected for illustrating. The ovary of C. azumai consists of 3 ovarioles on each side, so is E. amicula. The ligament, composed of terminal filament, of C. azumai is separate, while that of E. amicula joints to median ligament.Daily egg-laying allocation of C. azumai and E. amicula was studied, which indicated that C. azumai may lay most of eggs within the first to the fourth day after emergence, reaching the maximum on the second day with 3.8 eggs while fed on 20% honey solution and 2.6 eggs while fed on nothing. E. amicula may lay lots of eggs on the day emergence with 5.9 eggs while fed on 20% honey solution and 2.4 eggs while fed on nothing. Meanwhile, E. amicula preferred pregnant hosts and the hosts at the preoviposition duration, and had no choice of the hosts at the postoviposition duration.C. azumai could distinguish the hosts parasitized by conspecific parasitoids, but could not distinguish the ones parasitized by E. amicula. E. amicula may lay eggs repeatedly in the hosts parasitized by conspecific...