Plant Volatiles and Herbivore Induced Plant Volatiles from Chili Pepper Act as Attractant of the Aphid Parasitoid Aphelinus varipes (Hymenoptera: Aphelinidae)

Abstract

Plants have evolved a number of different chemical defenses, covering nearly all classes of (secondary) metabolites, that represent a major barrier to herbivory: some are constitutive; others are induced after attacks from herbivores (HIPVs) and may elicit the attraction of predators and parasitoids. Here, we studied how the female solitary endoparasitoid Aphelinus varipes responds to plant and host aphid volatiles in a series of experiments on five commercially important vegetables that were either healthy or infested with the aphid Myzus persicae: chili pepper, eggplant, crown daisy, Chinese cabbage and cabbage. The results for the olfactory responses of A. varipes showed that the presence of M. persicae increased the attraction of the endoparasitoid to the infested plants. In a second experiment, volatiles from highly attractive and repellent plants were obtained via headspace collection to investigate volatiles from healthy and aphid-damaged plants. The results for the differences in volatile profiles in response to aphid infestation in chili pepper cultivar were dominated by the volatile blends, including α-pinene, decanal and phthalic acid, while in cabbage they were dominated by isophorone. Moreover, when HIPVs with different concentrations were compared, α-pinene at a dose rate of 100 ng/μL attracted more parasitoids, and the comparison was useful to understand the mechanisms of plant secondary volatiles during aphid infestation and to provide new resources to control this insect pest. Overall our study shows how HIPVs can bolster tritrophic interactions by enhancing the attractiveness of parasitoids.

Dynamic distress calls: volatile info chemicals induce and regulate defense responses during herbivory

“…(2007) also reported the changes in the emission levels of terpene, ( E )-β-farnesene, upon infection of potato plants with Myzus persicae . Consistent emission of few fatty acid derivatives (hexanal, E-2-hexenal, Z-2-hexenal, and their alcohols, decanal and phthalic acid, and cis-hexen-1-ol), terpenoids (α-pinene, β-ocimene), and a benzenoid compound (methyl salicylate) during aphid attack has been reported in eggplant, chili, and tomato ( Digilio et al., 2012 ; Cascone et al., 2015 ; Ali et al., 2022 ). Consistent emission of limonene and ( E )-β-farnesene from Rhopalosiphum padi (Hemiptera: Aphididae)- infected rice has been reported to increase the resistance of crops against the pest ( Sun et al., 2017 ).…”

Defensive symbiont genotype distributions are linked to parasitoid attack networks

“…This indicates that plants have a limited role in shaping Hamiltonella distribution, at least among aphid species. Aphids on different plants might attract different parasitoid species due to changes in plant volatile profiles or Hamiltonella itself may modifying plant volatiles to attract different parasitoid species (Ahmed et al 2022;Ali et al 2022;Frago et al 2017), leading to plant associated Hamiltonella strains. It would be interesting to determine if plant-adapted aphid biotypes are attacked by different parasitoid species, as this may explain their tendency to carry different Hamiltonella strains.…”

Plants strike back: Plant volatiles and their role in indirect defence against aphids

“…Terpenoid detection by parasitic wasps depends on both the concentration and diversity of HIPVs. a‐pinene at a dosage of 100 ng/L can significantly increase the attraction of wasps (Ali et al, 2022), but high dosages of HIPVs can act as repellents for parasitic wasps (Ayelo et al, 2021).…”

“…This process of feeding on plant sap triggers a robust plant defence response in the form of the release of plant volatiles, including terpenes (de Vos & Jander, 2010). These volatiles released during aphid infestations are often referred to as aphid-triggered plant responses aimed at attracting carnivorous natural enemies of aphids (Ali et al, 2022). The presence of glandular trichomes is important for the biosynthesis and (Lange & Turner, 2013).…”