Herbivore‐induced plant volatiles and tritrophic interactions across spatial scales

Abstract

SummaryHerbivore‐induced plant volatiles (HIPVs) are an important cue used in herbivore location by carnivorous arthropods such as parasitoids. The effects of plant volatiles on parasitoids have been well characterised at small spatial scales, but little research has been done on their effects at larger spatial scales. The spatial matrix of volatiles (‘volatile mosaic’) within which parasitoids locate their hosts is dynamic and heterogeneous. It is shaped by the spatial pattern of HIPV‐emitting plants, the concentration, chemical composition and breakdown of the emitted HIPV blends, and by environmental factors such as wind, turbulence and vegetation that affect transport and mixing of odour plumes. The volatile mosaic may be exploited differentially by different parasitoid species, in relation to species traits such as sensory ability to perceive volatiles and the physical ability to move towards the source. Understanding how HIPVs influence parasitoids at larger spatial scales is crucial for our understanding of tritrophic interactions and sustainable pest management in agriculture. However, there is a large gap in our knowledge on how volatiles influence the process of host location by parasitoids at the landscape scale. Future studies should bridge the gap between the chemical and behavioural ecology of tritrophic interactions and landscape ecology.

An odorant receptor mediates the attractiveness of cis‐jasmone to Campoletis chlorideae, the endoparasitoid of Helicoverpa armigera

“…HIPVs are important cues that help parasitoids find their hosts (Turlings et al ., ; Aartsma et al ., ; Turlings and Erb, ). They consist of complex compounds from different chemical classes, but little is known about the ORs that are tuned to these cues.…”

Intraspecific variation in herbivore‐induced plant volatiles influences the spatial range of plant–parasitoid interactions

“…While the movement ecology and perceptual range of larger animals, such as ungulates, have been relatively well studied (Zollner and Lima , Fryxell et al ), few studies have assessed the spatial scale of volatile emission and effects on the foraging behaviour or attraction of arthropods (Aartsma et al ). Most field studies using HIPV blends assess the attraction of insects to a point source and quantify insect attraction at or close to the point source (reviewed by Aartsma et al ). While this provides information on which HIPV compounds or blends attract certain insects, it does not tell us from which distance these insects are attracted.…”

Promises and challenges in insect–plant interactions

“…However, multitrophic interactions at these smaller scales are embedded in a landscape of small food webs that are connected to each other via dispersal and other processes (Poisot et al, 2012). The effects of this spatial context should be included in studies of multitrophic interactions (Aartsma et al, 2017).…”