Towards development of a parasitoid cottage industry of the parasitoid wasp Habrobracon hebetor (say): optimum rearing and releases conditions for successful biological control of the millet head miner Heliocheilus albipunctella (De Joannis) in the Sahel

Abstract

Augmentative biological control by the parasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is the most promising strategy to control millet head miner, Heliocheilus albipunctella (De Joannis) a major insect pest of pearl millet in the Sahel. As H. hebetor survival is somehow challenging during the nine month long off-season when the host, H. albipunctella is in diapause, there needs to be a sufficient supply of parasitoids for fresh release each year. Therefore, the aim of this study was to establish a small-scale parasitoid rearing process adjusted to the Sahel conditions that can be scaled-up as necessary. We conducted experiments to fine-tune and standardize the rearing technique of H. hebetor for cottage industrial use. The results showed that parasitoids fed with 30% honey solution and supplied daily with one late-larval-stage Corcyra cephalonica Stainton (Lepidotera, Pyralidae) produced highest number of progeny. The optimal times for mating and egg fertilization, was achieved when a male and female pair was confined for 24 h in a 30-cc vial. Our findings indicated that, compared with the conventional rearing method -2 females supplied once with 25 C. cephalonica larvae-, this new method resulted in 14-times greater parasitoid production. Furthermore parasitoid female can be stored for up to three weeks at fluctuating 23–32°C temperature and 25%–80% relative humidity for numbers accumulations prior to on-farm augmentative releases without altering its fitness.