Compatibility of Heterorhabditis indica (Rhabditida: Heterorhabditidae) and Habrobracon hebetor (Hymenoptera: Braconidae) for biological control of Plodia interpunctella (Lepidoptera: Pyralidae)

Abstract

The potential for integrating the application of Heterorhabditis indica Poinar, Karunakar, and David (Homl strain) and release of Habrobracon hebetor (Say) in the management of the Indianmeal moth, Plodia interpunctella (Hübner), was investigated in the laboratory. A combination of the nematode and the parasitoid was observed to increase the mortality of P. interpunctella. The interaction between the nematodes and parasitoids was not antagonistic but could possibly be additive or synergistic. Release of parasitoids or application of nematodes alone generated between 62.25% and 71.25% mortality of the P. interpunctella larvae whereas combination of the two resulted in 98.0–99.25% mortality. The nematode was found to be virulent to the larvae of the parasitoid but not to the pupae and the adults. Adult female parasitoids that were exposed to both uninfected and nematode-infected P. interpunctella larvae in a free-choice arena were unable to distinguish between the two. In contrast, infective juvenile nematodes preferentially infected parasitized host larvae compared with healthy non-parasitized host larvae. Nematode reproduction was not significantly different in parasitized and non-parasitized host larvae. The combined application of H. indica and H. hebetor for the control of P. interpunctella may be beneficial if the detrimental effects of the nematode on the parasitoid can be minimized through optimum timing.