An herbivore-induced plant volatile reduces parasitoid attraction by changing the
smell of caterpillars
#MMPMID29774237
Ye M
; Veyrat N
; Xu H
; Hu L
; Turlings TCJ
; Erb M
Sci Adv
2018[May]; 4
(5
): eaar4767
PMID29774237
show ga
Herbivore-induced plant volatiles (HIPVs) can mediate tritrophic interactions by
attracting natural enemies of insect herbivores such as predators and
parasitoids. Whether HIPVs can also mediate tritrophic interactions by
influencing the attractiveness of the herbivores themselves remains unknown. We
explored this question by studying the role of indole, a common HIPV in the plant
kingdom. We found that herbivory-induced indole increases the recruitment of the
solitary endoparasitoid Microplitis rufiventris to maize plants that are induced
by Spodoptera littoralis caterpillars. Surprisingly, however, indole reduces
parasitoid recruitment when the caterpillars themselves are present on the
plants. Further experiments revealed that indole exposure renders S. littoralis
caterpillars unattractive to M. rufiventris, leading to an overall reduction in
attractiveness of plant-herbivore complexes. Furthermore, indole increases S.
littoralis resistance and decreases M. rufiventris parasitization success. S.
littoralis caterpillars are repelled by indole in the absence of M. rufiventris
but specifically stop avoiding the volatile in the presence of the parasitoid.
Our study shows how an HIPV can undermine tritrophic interactions by reducing the
suitability and attractiveness of caterpillars to parasitoids.
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