Rearing and releasing the egg parasitoid Cleruchoides noackae, a biological control agent for the Eucalyptus bronze bug

Abstract

Biological control is a major tool for forest insect pest management. We initiated a biological control program for the Eucalyptus bronze bug, Thaumastocoris peregrinus, with the egg parasitoid Cleruchoides noackae. Parasitized eggs were imported from a mass rearing in Brazil, and a rearing colony was set up. The wasp was reared in plastic tubes each containing ten individuals that were offered 100 eggs of the bronze bug and a solution of water and honey. During 30 generations, rearing quality parameters were compared against expected quality standards set a priori, based on information from other rearing colonies. We also assessed the effect of temperature on developmental time, measured as the first day of emergence of adult parasitoids, as well as the relation between host-egg abortion and parasitization by C. noackae, and the evolution of the sex ratio of the emergent wasps within a single generation. Field releases were made yearly during summers in commercial plantations, starting in March 2013. Survival and emergence rates were either stable or increased throughout 30 generations. The percentage of females was slightly above 50%. Rearing at 18 °C and 20 °C took longer than at 22 °C, but productivity was similar. Host-egg abortion was increased by parasitization. The proportion of females increased as the emergence period progressed. Field surveys in two sites revealed that the wasp survived for two years. Field-collected parasitoids exhibited better quality indices than individuals from the laboratory rearing. Results indicate that biological control of the bronze bug with C. noackae is feasible with this rearing and release protocol.