Effects of Abiotic Factors on HIPV-Mediated Interactions between Plants and Parasitoids

Abstract

In contrast to constitutively emitted plant volatiles (PV), herbivore-induced plant volatiles (HIPV) are specifically emitted by plants when afflicted with herbivores. HIPV can be perceived by parasitoids and predators which parasitize or prey on the respective herbivores, including parasitic hymenoptera. HIPV act as signals and facilitate host/prey detection. They comprise a blend of compounds: main constituents are terpenoids and “green leaf volatiles.” Constitutive emission of PV is well known to be influenced by abiotic factors like temperature, light intensity, water, and nutrient availability. HIPV share biosynthetic pathways with constitutively emitted PV and might therefore likewise be affected by abiotic conditions. However, the effects of abiotic factors on HIPV-mediated biotic interactions have received only limited attention to date. HIPV being influenced by the plant's growing conditions could have major implications for pest management. Quantitative and qualitative changes in HIPV blends may improve or impair biocontrol. Enhanced emission of HIPV may attract a larger number of natural enemies. Reduced emission rates or altered compositions, however, may render blends imperceptible to parasitoides and predators. Predicting the outcome of these changes is highly important for food production and for ecosystems affected by global climate change.

Rootstock affects the blend of biogenic volatile organic compounds emitted by ‘Hass’ avocado

“…Herbivore-induced plant volatiles (HIPVs) are emitted after herbivory (Arimura et al, 2011;Gols, 2014;Heil, 2014); thus, specific odor cues are exploited by predators and parasitoids. In addition, HIPVs are modified by arthropod species, herbivores density, genotypes and plant cultivars, plant ontogeny, and abiotic factors (Hare, 2010;Hare and Sun, 2011;Proffit et al, 2011;Becker et al, 2015;Clavijo, 2016;Rioja et al, 2016).…”

Can plant–natural enemy communication withstand disruption by biotic and abiotic factors?

“…It is possible that effects of abiotic factors on natural enemy recruitment vary depending on the magnitude of the stress and its impacts on the plant metabolism, with severe stress having stronger effects due to constraints in resource availability and allocation affecting HIPV production and release. For example, existing studies show that mild drought increases HIPV emissions or has no effect, whereas severe drought decreases emissions (Becker et al., ; Lavoir et al., ; Peñuelas & Staudt, ). Moreover, responses may vary for individual plant species, as some plants have evolved unique adaptations to stress, and the presence or absence of stress‐tolerance traits will determine the threshold levels for a particular species (Bray, ; Pareek, Sopory, Bohnert, & Govindjee, ; Wang, Vinocur, & Altman, ).…”

“…It is evident that individual abiotic factors affect HIPV emission, but there is much potential for interaction among them, leading to different outcomes from those caused by a single stress or those expected by additive effects (Becker et al., ; Bezemer et al., ; Peñuelas & Staudt, ). Studying these interactions among abiotic factors is necessary, especially in scenarios of global warming where multiple abiotic stress factors are likely to occur simultaneously.…”

Promises and challenges in insect–plant interactions

“…Another recent focus of multitrophic interactions research is to assess the effects of abiotic conditions, such as temperature and drought, on multitrophic interactions (Pineda et al, 2013;Becker et al, 2015;Pincebourde et al, 2017), which is relevant in the context of both climate change (see section 'Global changes put the heat on insect-plant interactions') and understanding of how multitrophic interactions vary along gradients, such as latitude and elevation (Descombes et al, 2017). Multitrophic interactions have traditionally been investigated at smaller scales, such as an individual plant or a local plant patch (Stam et al, 2014).…”