Age-specific oviposition behavior of Trichogramma brassicae on Ephestia kuehniella under laboratory conditions

Abstract

Biological characteristics especially oviposition behavior of parasitoids are one of the most important factors to determine their efficiency to suppress a pest population. In this study, age-specific oviposition pattern, parasitism rate, hatch rate, and sex ratio of Trichogramma brassicae on Ephestia kuehniella were evaluated at temperature of 25±1ºC, 70±5% relative humidity and a 16 h light: 8 h dark photoperiod. The results showed that younger T. brassicae (1st-4th days) moved throughout the cardboard and often parasitized eggs which placed in the central part, but female parasitoid of T. brassicae moved straight on cardboard and parasitized closer eggs in the end days of life (5th and 6th days). The maximum daily parasitized eggs by T. brassicae was 13.03±0.56 at the beginning of its oviposition period. Then, it decreased significantly with adult female age. The female age influenced hatch rate (%) of T. brassicae eggs. Its values were ranged from 95.07±0.82% (1st day of oviposition period) to 42.78±6.43% (6th day of oviposition period) in different days of adult female age. The highest values for sex ratio were estimated to be in the first 3 days of adult female life. The femalebiased sex ratio decreased significantly with increasing adult female age. For efficient mass rearing of T. brassiace on E. kuehniella, parasitoids should not be kept more than three days in cultures because the progeny becomes male-biased and parasitism rate decreased significantly after 3rd days. Results of this study show good potential of T. brassicae and it suggest for mass rearing and to use in augmentative biological control program.