Mass rearing of Habrobracon hebetor Say (Hymenoptera: Braconidae) on larvae of the Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae): effects of host density, parasitoid density, and rearing containers

Habrobracon hebetor Say (Hymenoptera: Braconidae) is a larval ecto-parasitoid of several species of Lepidoptera in the family Pyralidae including the Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), and other pyralid pests of post-harvest commodities and finished food products worldwide. Rearing methods for H. hebetor were investigated in a series of laboratory experiments designed to develop a mass rearing procedure for H. hebetor as a biological control agent against P. interpunctella and other stored products pyralid moths. The effects of parasitoid density, host density and the size of the rearing containers on adult progeny production and secondary sex ratio of H. hebetor were tested. In parasitoid density experiments, a density of eight male–female pairs of H. hebetor produced a higher number of progeny (188 adults) on 50 last-instar P. interpunctella larvae than the densities of one and two pairs of H. hebetor. Similarly, in a host density experiment, a density of 50 last-instar P. interpunctella larvae produced a significantly higher number of parasitoid progeny (160 adults) among the tested host densities when two pairs of H. hebetor were used. In experiments that assessed the size of the rearing containers, a glass jar with a volume of 236.6 ml (8 U.S. ounce “jelly jar”), produced a relatively higher number of parasitoid progeny (166 adults) than other sizes of containers when two pairs of H. hebetor were used. The parasitoid’s secondary sex ratio was female-biased in all experiments and there were no significant effects on sex ratio from variation in parasitoid density, host density, or size of the rearing containers.