Abstract: Scutellista caerulea Fonscolombe is one of the important natural enemies of Parasaissetia nigra Nietner. The wasp is an ectoparasitoid that oviposits eggs on the abdomen of the host and the hatching larva feeds on the host eggs that are produced under the abodemon. The biological characteristics of this wasp, including mating behaviors, parasitic behaviors, development, and preference for host instars were observed indoors. The results show that the whole mating behaviors of the wasp consisted of 4 phases:searching and courtship, pre-copulating, copulating, and post-copulating. The parasitic behaviors of the wasp could be divided into five steps, i.e., host searching, antennal detecting, ovipositor penetrating, ovipositing, and cleaning after oviposition. Duration of the parasitic behaviors of a wasp decreased with the number of parasitism in the range of 1 to 3, but increased when the number of parasitism of a wasp exceeded 3 times. At temperature of 25-27℃, S. caerulea generation lasted 28-30 d, of which the periods of egg, larv and pupa were 3, 9-10 and 16-17 d, respectively. S. caerulea preferred the black adults of P. nigra the most and the newly emerged adults of P. nigra the lowest. Host age had significant effects on the development and propagation of S. caerulea. When the hosts were from newly emerged adults to black adults, development duration of the wasps decreased with host age, while the number of emerged wasps increased with host age. The development duration reached the maximum of 31.8 d and the minimum of 27.5 d when the hosts were newly emerged adults and black adults, respectively. The number of emerged offsprings reached the maximum of 117.3 and the lowest of 36.3 when the hosts were black adults and newly emerged adults, respectively. Host age had no effect on sex ratio of S. caerulea. These results show that the black adults of P. nigra are the most suitable host for S. caerulea and can provide a basis for further propagation and utilization of this wasp.

Key words: Scutellista caerulea, Parasaissetia nigra, parasitism, rubber, mass rearing