Drought-induced acclimatization of a fast-growing plant decreases insect performance in leaf-chewing and sap-sucking guilds

Abstract

An initial destabilization of functions triggered by drought stress in plants is followed by acclimatization and acquisition of tolerance; however, knowledge remains limited on drought-mediated changes in plant quality for herbivores. We tested whether a water-stressed fast-growing plant negatively affects host-specialist insects in both sap-sucking and leaf-chewing feeding guilds. Collards (Brassica oleracea var. acephala) were grown in wellwatered, slightly water-stressed and severely water-stressed conditions. Decreasing soil moisture adversely affected plant development, assessed as a reduction in leaf number and size, stomatal size and relative water content. Severely stressed plants had less fiber and glucosinolates; however, they showed more total nitrogen and lipids. Larval survival, pupal weight, reproductive rate (Ro) and rate of population growth (r) were lower when the leaf-chewing Plutella xylostella was reared with severely stressed collards. In multiple-choice tests, moths laid fewer eggs on leaf discs of collard that were exposed to drought. The fecundity of the sap-sucking Brevicoryne brassicae was higher and the development of alates was lower when insects were fed on plants kept in well-watered regime as compared to slight-stress and severe-stress. Despite higher nitrogen content and fewer glucosinolates, a higher level of leaf surface wax in severely stressed collards possibly decreased food quality for both herbivores. Thus, hostspecific herbivores of different guilds showed similar responses to drought-stressed, fast-growing plants. Waterstressed crops could discourage the attack of specialist insects, but the intensity of the stress that is required to achieve this effect will greatly reduce crop production, in terms of plant growth or foliage increment.

Phenotypic biomarkers of climatic impacts on declining insect populations: A key role for decadal drought, thermal buffering and amplification effects and host plant dynamics

“…Notably, drought and phenology should produce qualitatively different effects on the studied nitrogen-related traits (%N, C/N). In contrast, in the case of drought-induced effects on plant ecophysiology, an increase in the quantity of nitrogen in the leaves could be expected (e.g., Bauerfeind & Fischer, 2013b;Grant et al, 2014;Valim, Teixeira, Santos, Oliveira, & Campos, 2016). Overall, phenology should promote a progressive reduction of leaf %N and an increase in leaf C/N over the late spring and early summer period.…”

Combined effects of soil silicon and drought stress on host plant chemical and ultrastructural quality for leaf‐chewing and sap‐sucking insects

“…However, acclimatization with decreased photosynthesis or productivity apparently imposes a trade‐off in resource allocation among fundamental processes such as growth, reproduction, energy storage and defence metabolites against herbivorous insects (Valim, Teixeira, Oliveira, & Campos, ). The prediction of a lower concentration of defence compounds in drought‐stressed plants, in which both growth and secondary metabolism are impaired, has been supported in some cases (Gutbrodt, Mody, & Dorn, ; Khan, Ulrichs, & Mewis, , ; Valim et al, ; Walter et al, ). Primary metabolism related to nitrogen compounds (Martinelli et al, ; Mattson & Haack, ; Vaseva et al, ), lipids and leaf surface waxes (Bernard & Joubès, ; Gigon, Matos, Laffray, Zuily‐Fodil, & Pham‐Thi, ; Kim, Park, & Jenks, ; Kosma et al, ), and fibre content (cellulose, hemicellulose and lignin) (Küchenmeister, Küchenmeister, Kayser, Wrage‐Mönnig, & Isselstein, ) is also affected during acclimatization to drought.…”

“…Along with secondary metabolites, combinations of plant nutritional and structural traits determine food quality for herbivores (Awmack & Leather, ; Mitchell et al, ) and thus, by means of such traits, water status or drought condition may mediate plant resistance to herbivory (Valim et al, ). The indirect effect of water stress on herbivores may depend on the type of plant (e.g.…”

“…Thus, whether plant acclimatization to drought stress benefits or impairs herbivorous insects remains unclear and there is still limited evidence for generalization. Studies have generated conflicting results, but host‐specific leaf‐chewing and sap‐sucking insects have shown lower performance in severely and continuously drought‐stressed, fast‐growing plants (Valim et al, ).…”

Roles of C1A peptidases during barley leaf senescence mediated by abiotic stresses

“…Detrimental effects may be even amplified due to synergistic events during the prevalence of biotic factors (Gupta et al, 2016;Valim et al, 2016). Plants respond to water deprivation by activating specific molecular and physiological changes to minimize damage.…”