Abstract:
The parasitoid Trichogramma brassicae Bezdenko is used for inundative releases in
biological control programs against lepidopteran pests in agro-ecosystems. Age-specific
functional responses of T. brassicae to different egg densities (5, 10, 20, 30, 40, 60, and 80)
of sterilized eggs of Ephestia kuehniella at 23±1°C, 60±5% RH, and 16:8 h (L:D
photoperiod ) were studied. E. kuehniella densities were separately presented to a single
mated female of T. brassicae (1-day-old). The egg densities were replaced every day until
the parasitoid died and each density was replicated 20 times. A type III functional
response was obtained for the one-day-old females and a type II for two- to nine-day-old
ones. Results show that parasitoid age influences searching efficiency and handling time.
Searching efficiency (a´) varied as adult parasitoids aged. In contrast, handling time
increased with age. The lowest and highest values were obtained in days 1 and 9 of the
parasitoid's life, respectively. The maximum rate of parasitism (T/Th) decreased
significantly with an increase in parasitoid age. It was concluded that T. brassicae females
were most efficient at early ages of their life and might be capable of efficiently
suppressing lepidopteran pest populations.
Keywords: Age-specific parasitism, Biological control, Host density, Parasitoid, Search rate
