Attraction of Female Pediobius imbreus (Hymenoptera: Eulophidae), a Parasitoid of the Oil Palm Bagworm, Metisa plana (Lepidoptera: Psychidae), Towards Flowering Plants

Several flowers, namely Antigonon leptopus, Senna cobanensis, and Turnera subulata, are commonly grown at oil palm plantations as insectary plants. Flowers produced by these plants are believed to attract parasitoids, which can parasitize and control the population of the oil palm bagworm, Metisa plana (Lepidoptera: Psychidae) in the oil palm plantations. However, the attractiveness of these flowers to the parasitoids has not been evaluated. For the first time, we conducted Y-tube olfactometer bioassays on female Pediobius imbreus (Hymenoptera: Eulophidae), a common parasitoid of M. plana to determine its preferences towards several flowers, including A. leptopus, Bidens pilosa, S. cobanensis, and T. subulata. We also analyzed the volatile compounds from the most attractive flower, which is B. pilosa, using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). Results from the Y-tube olfactometry bioassays showed that female P. imbreus were attracted to the four flowers. However, female P. imbreus was most attracted to B. pilosa significantly (P < 0.05) as compared to S. cobanensis, A. leptopus, and T. subulata. GC-MS qualitative analysis of B. pilosa confirmed the presence of 43 volatile compounds, categorized into four major classes: terpenoids, fatty acid derivatives, phenylpropanoids, and other classes. The potential functions of these volatiles were discussed in relation to parasitoid food-searching behavior. This study provides fundamental insights into the flower preferences of parasitoids, which could be applied to enhance pest management strategies.