Effect of age dependent cold storage of factitious host Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) for their continuous production and Trichogramma chilonis (Ishii) (Hymenoptera: Trichogrammatidae) rearing

Abstract

In Asia Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) is widely used as a factitious host for the mass rearing of several bio-control agents viz. chrysopids, braconids, trichogrammatids and anthocorids. The age dependent cold storage amenability of C. cephalonica eggs was evaluated. At 5±1°C with a 24h of scotophase, 0 to 22h old eggs of C. cephalonica could be stored for up to 5days resulting in 83 to 94% hatching. Eggs of C. cephalonica are UV irradiated for mass rearing of T. chilonis. Four, eight, sixteen and twenty four-hour-old C. cephalonica eggs were stored at 5±1°C for different durations prior to and post-UV irradiation and tested for their amenability to parasitism by T. chilonis. Adult females of T. chilonis could parasitise 67–78% of eggs stored for up to 10days prior to UV treatment, while 74–78.2% parasitism was recorded in the case of eggs stored for 10days post-UV. The host eggs of all age groups stored for 20days (10days pre-UV and 10days post-UV) were effectively parasitised providing 83.8–88.4% parasitism. Eight and sixteen hour-old old host eggs stored for 30days (15days of pre-UV and 15days of post-UV) recorded 70–80% parasitism. The host egg storage technique developed through this study would be beneficial for insectaries to stock the host eggs, which can lead to uninterrupted production and supply of ‘Tricho-cards’, especially during seasonal high demand.