Uncovering different parameters influencing florivory in a specialist herbivore

Abstract

1. It has become increasingly recognised that several herbivores switch from folivory (leaf-feeding) to florivory (flower-feeding) during larval development. Yet, it remains poorly understood which cues influence this behaviour, whether a switch to florivory is consistently shown on different hosts, and to what extent florivory could be hindered by plant traits.2. Using the sawfly Athalia rosae and two Brassicaceae differing in architecture and surface structure, the cues that influence larval movement to the flowers were investigated. A broad set of behavioural assays was employed and physical and chemical plant traits potentially affecting the larvae were analysed. Furthermore, the consequences of folivory versus florivory on insect performance were studied.3. The larvae preferred flowers over leaves. Consumption of particular flower parts correlated partly with measured plant traits such as glucosinolate distribution. Visual cues were of higher importance than volatile cues. The initial position of newly hatched larvae on plants influenced the probability of the larvae reaching the flowers during development. Trichomes and surface waxes hindered the larvae from moving upwards to the flowers. Larvae developed slower and gained less body mass when feeding on inflorescences of Brassica nigra than when feeding on leaves, in contrast to the patterns observed before on Sinapis alba, where florivory led to an improved performance.4. This study demonstrates that florivory depends on various host plant traits. It reveals new insights into different parameters influencing this multifaceted phenomenon and into the expected impact on the ecology and fitness of both the attacking herbivores and the plants.

A Promiscuous CYP706A3 Reduces Terpene Volatile Emission from Arabidopsis Flowers, Affecting Florivores and the Floral Microbiome

“…Indeed, flowers are vehicles of Darwinian fitness due to their involvement in pollen and seed production, and at the same time are particularly exposed to attack by insects and pathogens (Li et al, 2017). In addition, pollinators are often florivores at another stage of their life cycle (Abdalsamee and Müller, 2015). Surprisingly, however, flower defense mechanisms have rarely been investigated, especially at the metabolic level (Junker, 2016).…”

Density-Dependent Effects of Simultaneous Root and Floral Herbivory on Plant Fitness and Defense

“…RH decreased flower number and increased the GLS concentrations, both affecting FH caterpillar development time. Our GLS measurements were performed for leaves, but we assume that plants with high GLS concentrations in leaves also have high GLS concentrations in reproductive tissue, as was suggested for several defensive compounds and plant species [ 77 , 78 , 79 , 80 , 81 , 82 , 83 ]. The SEM shows that a longer caterpillar development time slightly increased seed production, and thereby shortening caterpillar development time enlarges the negative effect of the RH density on plant reproduction, although even that does not make the RH effect significant.…”

Flowers prepare thyselves: leaf and root herbivores induce specific changes in floral phytochemistry with consequences for plant interactions with florivores

“…First, vegetative‐to‐reproductive tissue induction may help plants deal with current attackers. Many herbivores start feeding on leaves but later move to flowers (Lucas‐Barbosa et al ., 2013 ; Abdalsamee & Müller, 2015 ; Tsuji et al ., 2018 ). Second, vegetative‐to‐reproductive tissue induction may be adaptive by affecting other community members (Poelman & Kessler, 2016 ; Rusman et al ., 2019a ).…”

“…Due to the systemic nature of herbivore‐induced plant responses, JA–SA crosstalk is expected to occur between leaves and flowers as well, although this has not been tested. Flowers differ from leaves and even vary among flower organs in the accumulation and regulation of JA and SA signalling pathway components (Hause et al ., 2000 ; Rusman et al ., 2019a ), concentrations of defence chemistry (Onodera et al ., 2014 ; Palmer‐Young et al ., 2019 ; Stegemann et al ., 2019 ) and primary metabolites (Abdalsamee & Müller, 2015 ), which might reduce JA–SA crosstalk. A mechanistic understanding of the consequences of herbivory on vegetative tissues for plant interactions with florivores, and more specifically whether flower tissues reflect local or systemic species‐specific induction patterns, will help us understand the evolution of integrated defence responses across plant tissues (Agrawal & Fishbein, 2006 ).…”