Effects of Indole Glucosinolates on Performance and Sequestration by the Sawfly Athalia rosae and Consequences of Feeding on the Plant Defense System

Abstract

In this study, the performance and sequestration specificity of the sawfly Athalia rosae L. (Hymenoptera: Tenthredinidae) reared on two wild Brassica oleracea L. (Brassicaceae) populations (KIM and WIN), which express indole glucosinolates (GSs) in very high concentrations, were investigated. The local and systemic plant responses to larval feeding also were analyzed. Indole GSs predominated in KIM plants, whereas aliphatic GSs prevailed in the WIN population, which had several times higher total GS concentrations than KIM plants. Plants of the KIM population had lower specific leaf areas, and higher carbon/nitrogen ratios than WIN plants. The insects reared on WIN plants performed better for most traits than insects reared on the KIM population. The larvae preferentially sequestered aliphatic GSs but when feeding on KIM plants, indole GSs were also concentrated in the hemolymph. In response to feeding by A. rosae larvae, indole GSs were induced locally and systemically, whereas aliphatic GSs were reduced only in systemic leaves of the WIN population. Soluble myrosinase activities were constitutively higher in WIN than in KIM plants, and feeding damage led to a significant reduction of this glucosinolate-degrading enzyme in WIN plants only. The data suggest that the sawfly is well adapted to high concentrations of aliphatic GSs, which are sequestered by the larvae. In contrast, the larvae may be less adapted to plants dominated by indole GSs. Selective induction of indole GSs by the plants in response to larval feeding may be adaptive as accumulation of indole GSs may lower the performance of the larvae.

Seasonal and herbivore-induced dynamics of foliar glucosinolates in wild cabbage (Brassica oleracea)

“…The increase of indole GSLs from May to August in the field-grown plants may reflect herbivore pressure which is also highest during this period (Bustos-Segura et al 2017). In nature, levels of inducible indole GSLs in wild B. oleracea , which are much higher than has been thus far reported in any other brassicaceous species, may play an important role against specialist herbivores such as P. rapae, Plutella xylostella and Athalia rosae (Gols et al 2008; Harvey et al 2011; Abdalsamee and Müller 2012). These herbivore species are specialist feeders on plants containing GSLs and are able to effectively circumvent exposure to toxic aliphatic and aromatic GSL breakdown products (Müller et al 2001; Ratzka et al 2002; Wittstock et al 2004).…”

Phyllotreta striolataflea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system

“…For example, larvae of Athalia spp. sawflies show species-specific sequestration patterns in the hemolymph that were suggested to reflect adaptations to different host plants (16,38). In the crucifer aphid, B. brassicae, glucosinolate accumulation in the hemolymph differs quantitatively between wingless and winged morphs feeding on the same diet, which indicates regulated transport between the gut and hemolymph (17).…”

Aphids Pick Their Poison: Selective Sequestration of Plant Chemicals Affects Host Plant Use in a Specialist Herbivore

“…Several specialist species have been shown to selectively sequester at the level of glucosinolate group. For example, the crucifer flea beetle Phyllotreta striolata and the sawfly Athalia rosae both exhibit a preference for host plant glucosinolates belonging to the aliphatic group over indoles (Abdalsamee and Müller 2012;Beran et al 2014). Our study reports a similar result.…”