Functional Response of Habrobracon hebetor (Say) (Hym.: Braconidae) to Various Densities of Two Hosts, Ephestia kuehniella Zeller and Plodia interpunctella Hubner (Lepidoptera: Pyralidae)



The flour moth, Ephestia kuehniella Zeller and Indianmeal moth, Plodia interpunctella (Hubner) are reported as important pests of stored products in many countries throughout the world. In recent years Harobracon hebetor (Say) wasp has been employed as a biological control agent of the moths' larvae in peanut warehouses as well as in packaged cereal products. In this study the functional responses of H. hebetor to larvae of flour moth and Indianmeal moth were compared across a range of host densities (1, 2, 4, 8, 16 and 32 larvae/arena) and under some controlled conditions of 25±1°C, 65±10 RH and 14: 10 h (L:D). The resulting data were appropriately fit to type III functional response models in two parasitoid – host interactions, namely: (1) H. hebetor to last instar larvae of flour moth (b = 0.0327 h-1 and Th = 1.061 h), and (2) H. hebetor to last instar larvae of Indianmeal moth (b = 0.0296h-1 and Th = 1.045 h). The b value of H. hebetor to different densities of flour moth larvae was significantly greater than that of Indianmeal moth larvae; whereas the handling time (Th) of H. hebetor to larvae of flour moth was not significantly different as compared with the Indianmeal moth larvae. These results indicate that H. hebetor was the preferred larvae of flour moth in comparison with Indianmeal moth larvae.