Study on the preference habitat of Trichogramma ostriniae: 1. Natural population distribution and dynamics of the parasitoid in different habitats.
Distribution and population dynamics of Trichogramma ostriniae in 17 crop habitats were studied by checking the parasitic rate of egg masses of mass-reared Ostrinia furnacalis. The newly laid egg masses (less than 12 h) on waxy paper were placed in plant leaves and taken back 3 days later to check the parasitic rates. Results showed that the distribution, occurrence and numbers of T. ostriniae varied in different habitats. The population of T. ostriniae was greatest and most persistent in a spring sweet potato field. Crops interplanted with legumes appeared to slightly increase the parasitic rate of T. ostrinae. The population size of T. ostriniae varied in different years and was especially affected by drought.