Reduced plant fitness by pre-dispersal seed predation in the threatened plant species Cirsium decussatum

Abstract

Seed predation has been suggested to play a crucial role in plant population dynamics and could act as a strong selective force in the evolution of plant traits such as plant phenology, size and number of flowers. The loss of seeds could be particularly threatening for population maintenance of rare plant species. We investigated the influence of seed predators on plant fitness of the rare monocarpic thistle Cirsium decussatum. We tested the following hypotheses: (1) pre-dispersal seed predators reduce the number of dispersed propagules; (2) seed predators select larger inflorescences as oviposition sites; (3) the size of the capitulum is correlated with seed productivity; and (4) seed predators compete for the oviposition sites. We identified ten insect taxa from different taxonomic groups in the capitula of C. decussatum. Terellia longicauda larvae (Diptera: Tephritidae) were the most common. The presence of the flies’ larvae was positively correlated with the predation level in the capitula. Females of T. longicauda selected larger inflorescences for laying eggs that may increase offspring fitness as larger inflorescences promise more food resources. We could not prove the presence of competition between insect species inhabiting the capitula. Our data suggest, however, that T. longicauda, a specialized seminophagous dipteran, is one of the factors that negatively influence the fitness of threatened C. decussatum, lowering significantly the seed pool. Terellia longicauda potentially acts as a strong selective force in the evolution of C. decussatum inflorescence size.

Seed size of co‐occurring forb species predicts rates of predispersal seed loss from insects

“…More typical, however, are more moderate levels of seed loss (Kolb et al, 2007; Leimu et al, 2002; Preisser & Bastow, 2005, but see Aguirrebengoa et al, 2021). Yet, even 20%–50% mortality of seeds can impose major reductions in recruitment (Weppler & Stöcklin, 2006), plant fitness (Herrera et al, 2002; Louda & Potvin, 1995; Root, 1996), target plant abundance (Katz, 2016; Maron & Crone, 2006), and even distribution (Baer & Maron, 2018; Louda, 1982; Stachurska‐Swakoń et al, 2018).…”

“…Plants are frequently attacked by insects that consume flower embryos and developing seeds. Though inconspicuous, predispersal seed loss imposed by insect herbivores is common and occurs in many ecosystems and species (Ehrlén et al, 2002; Janzen, 1971; Kolb et al, 2007; Kurkjian et al, 2016; Louda & Potvin, 1995; Stachurska‐Swakoń et al, 2018). Interspecific variation in predispersal seed predation, however, can be substantial.…”

The Relationships of Habitat Conditions, Height Level, and Geographical Position with Fruit and Seed Traits in Populations of Invasive Vine Echinocystis lobata (Cucurbitaceae) in Central and Eastern Europe

“…Our results suggest that the defence against seed-eating animals might be the strongest in semi-natural habitats, as well as on banks and shores of inland surface waters, as E. lobata produces the highest number of seeds in these habitats. In general, seed predation is an important factor reducing seed availability and could be an evolutionary driver [77][78][79][80][81]. On the other hand, rodents and birds can serve as vectors of seed dispersal [32,75], and mutualism involving animal-mediated seed dispersal facilitates plant invasions [82].…”

Allelopathic influence of medicinal plant Filipendula vulgaris Moench on germination process

“…Allelochemical substances increase the vacuolization of cells, which is accompanied by a reduction in the number of mitochondria, the density of ribosomes, and dictiosomes (Burgos et al, 2004). The seed coat can also play an important role, as it protects the seed against harmful external factors and mechanical damage (Rzepka and Stachurska-Swakoń et al, 2018;Mazur, 2019).…”