Reproductive escape: annual plant responds to butterfly eggs by accelerating seed production

Abstract

Summary1. Plants respond to insect herbivores with changes in physical and chemical traits, both locally and systemically, in leaves and flowers. Such phenotypic changes may influence the behaviour of every community member that interacts with the plant. Here, we address effects of plant responses to eggs and subsequent herbivory by caterpillars on plant-mediated interactions with pollinators and consequences for plant fitness. 2. Using a common garden set-up, we have investigated responses of Brassica nigra plants to herbivore exposure from egg deposition onwards throughout larval development. We quantified effects of infestation by the specialist Pieris brassicae on: 1. behaviour of pollinators; 2. volatile emission and 3. timing and number of seeds produced. 3. Egg deposition and folivory did not influence visitation by pollinators to plots of infested or control plants. Effects of herbivore infestation on both pollinator visitation and volatile emission were observed only at a later stage, when caterpillars were feeding on the flowers. 4. Remarkably, before eggs had hatched, infested plants accelerated seed production. The caterpillars that developed from the eggs fed on flowers but not on seeds and thus seed production prior to herbivory on flowers safeguarded reproductive output. 5. The results of this study show that early plant investments in reproduction can successfully prevent consumption of expensive reproductive tissues. By accelerating seed production, plants prevented consumption of flowers and effectively defended themselves against the herbivores.

Herbivory Increases Fruit Set in Silene latifolia: A Consequence of Induced Pollinator-Attracting Floral Volatiles?

“…Volatiles with significant differences are given in bold. For statistical analysis, both sexes were analysed together using a GLM; significant effects of Btreatment^(β-ocimene) or Btreatment * sex^((Z)-3-hexenyl acetate) were found accordance with earlier studies in Brassica (Lucas- Barbosa et al 2013;Poveda et al 2003), we found that herbivory increased fruit production (Figs. 2 and 3).…”

“…a trade-off between defense and reproduction often has been found in studies that have jointly investigated herbivory and reproductive performance (e.g., Belsky 1986;Bergelson and Crawley 1992;Bergelson et al 1996;Freeman et al 2003;Lohman et al 1996;Marquis 1992;Strauss et al 1996Strauss et al , 2002. Although herbivory usually triggers defense at the cost of reproduction (Strauss et al 2002), in a few other cases herbivory has been shown to increase reproductive output (Lucas-Barbosa et al 2013;Poveda et al 2003). In addition to direct trade-offs, however, herbivory also may indirectly impact on plant reproduction, namely through ecological trade-offs (Strauss et al 2002).…”

Herbivory-induced changes in the olfactory and visual display of flowers and extrafloral nectaries affect pollinator behavior

“…Disentangling the relative contribution of herbivory-induced changes in olfactory and visual traits and associated nectar rewards of both nectaries to the observed pollinator behavior would be an interesting field for future studies. So far most studies have focused on flower traits to assess the effect of herbivory on flower visitor behavior, and showed either increased or decreased flower visitation rates depending on the animal and plant species (Lucas-Barbosa et al 2013;Hoffmeister et al 2015). Our study investigating herbivory-induced changes in flowers and EFNs thus adds another aspect to plant-mediated interactions of herbivores and pollinators.…”

“…in floral scent, morphology and nectar, have been shown to alter flower visitor behavior (Schiestl et al 2014;Bruinsma et al 2014;Hoffmeister et al 2015). Depending on the animal and plant species this resulted in either increased or decreased visitation frequencies (Lucas-Barbosa et al 2013;Hoffmeister et al 2015). The effects of herbivory on interactions between EFNs and nectar-consumers and on flowervisitor interactions have mostly been studied separately (but see Hernández-Cumplido et al 2010).…”

Plants under dual attack : consequences for plant chemistry and parasitoid behavior

“…While this controlled approach has yielded valuable information and insights, if we are to truly understand the ecological and evolutionary context of plant volatiles as foraging cues, it is necessary to step out of the laboratory and take research out in the field, in the plants' and insects' natural environment. Plants out in the field may produce very different volatile blends (Kigathi et al, 2009), though behavioral responses of foraging insects seem robust and persist out in the field (Poelman et al, 2009;Lucas-Barbosa et al, 2013).…”