Study on the selective behavior of female Habrobracon hebetor toward volatile compounds of its Host Plodia interpunctella

In tritrophic systems involving stored grains, hosts, and parasitoids, host-derived volatile compounds play a key role in host location by parasitoid wasps. The host-searching and orientation behavior of Habrobracon hebetor (Say) toward the Indian meal moth Plodia interpunctella is largely regulated by these volatile cues. To investigate the effects of volatiles emitted by larvae of different developmental stages of P. interpunctella and their habitat-related substrates on the host-selection behavior of female H. hebetor, behavioral assays were conducted using a Y-tube olfactometer. Three physiological states of female parasitoids were tested, including unmated females, mated females without oviposition experience, and mated females with oviposition experience. In addition, volatile compounds from the host larvae and their habitat were identified using gas chromatography-mass spectrometry (GC-MS). Electroantennogram recordings and behavioral bioassays were further performed to screen and verify compounds that showed significant attractiveness to female parasitoids.The results showed that female H. hebetor of different mating and parasitic states exhibited significant preferences for mature larvae of P. interpunctella. The selection rates for mature larvae were 57.78%, 81.11%, and 85.56% for unmated females, mated females without oviposition experience, and mated females with oviposition experience, respectively. In addition, mated females with oviposition experience showed a significant attraction to diets damaged by P. interpunctella, with a selection rate of 72.22%, suggesting that host habitat cues also play an important role in host localization.Further analyses combining GC-MS identification, electroantennogram recordings, and behavioral assays revealed that female H. hebetor showed the strongest electrophysiological responses to D-limonene among the tested compounds. The electroantennogram amplitudes of unmated females, mated females without oviposition experience, and mated females with oviposition experience reached 0.95, 1.00, and 1.33 mV, respectively. Behavioral experiments further demonstrated that D-limonene significantly attracted female parasitoids, with the highest selection rates observed at a concentration of 1 μg/μL. At this concentration, the selection rates were 56.67%, 60.00%, and 87.78% for unmated females, mated females without oviposition experience, and mated females with oviposition experience, respectively. The results provide a theoretical basis for improving the efficiency of biological control of P. interpunctella using H. hebetor in stored-grain ecosystems.