Bryophytes as food: comparative consumption and utilization of mosses by a generalist insect herbivore

Abstract

Compared with angiosperms, bryophytes are seldom fed upon by insects, despite being commonly used for shelter. Bryophytes are assumed to be unpalatable, and three classes of mechanisms have been suggested as possible barriers to bryophagy: chemical defenses, low digestibility, and low nutrient content. However, very few studies have tested these hypotheses. The present study examines pre‐ and post‐ingestive defenses of mosses. The acceptability and quality of four species of moss –Bryum argenteum Hedw. (Bryales: Bryaceae), Climacium americanum Brid. (Leucodontales: Climaciaceae), Leucobryum glaucum (Hedw.) (Dicranales: Leucobryaceae), and Sphagnum warnstorfii Russ. (Sphagnales: Sphagnaceae) – were compared with two control diets using the generalist caterpillar, Trichoplusia ni Hübner (Lepidoptera: Noctuidae: Plusiinae). In no‐choice trials, caterpillars consumed much less of any of the mosses than lettuce or wheat germ. The only moss consumed in sufficient quantities to evaluate post‐ingestive responses was C. americanum. Digestibility, assimilation, and overall utilization efficiency of C. americanum did not differ from that of lettuce, although C. americanum and lettuce were both less digestible than artificial diet. Choice assays using leaf discs showed that ethanol extract of L. glaucum, the least consumed moss, was deterrent, implying that chemical defenses play a major role in deterring feeding on L. glaucum. This study suggested that pre‐ingestive mechanisms are more important than post‐ingestive mechanisms in discouraging herbivory on mosses, and offered evidence that mosses are not simply nutrient poor.

Valuable Fatty Acids in Bryophytes—Production, Biosynthesis, Analysis and Applications

“…Humans de novo synthesize LA and ALA with very low synthetic efficiency, therefore we must obtain these essential fatty acids from food [74]. Although bryophytes are not an ideal source for food consumption due to the poor nutrient content [9], this unique metabolism of bryophytes can still indirectly benefit human by optimizing ω-3 oil production in seed crops by a transgenic approach [37].…”

“…Unlike higher plants, bryophytes do not have a vascular system and lack thick waxy cutin protection on the cell walls [8], they defend themselves by producing several specialized metabolites instead. This can explain why bryophytes are rarely consumed by insects and herbivores, not only because bryophytes have low caloric content but also for the diversity of “chemical weapons” they produce [9,10]. Besides, bryophytes have a high desiccation tolerance and freezing tolerance, which allow them to survive in dry surroundings or in cold temperatures and recover rapidly afterwards [11].…”

Middle Devonian liverwort herbivory and antiherbivore defence

“…Historically liverworts have been consumed by a variety of herbivores, given the extent that invertebrates, especially arthropods, consume or otherwise alter modern liverwort tissues (Gerson, 1982;Glime, 2006;Haines & Renwick, 2009). Generalized herbivory, usually in the form of external foliage feeding, has been recognized on epiphyllous liverworts from several tropical sites (Olarinmoye, 1974;Lawrey, 1987;Monge-Najera, 1989;Coley et al, 1993).…”

Novel Acetylenic Oxylipins from the Moss Dicranum scoparium with Antifeeding Activity against Herbivorous Slugs

“…But even more than 100 years after the first investigations of Ernst Stahl on the chemical defense of plants and mosses against slugs and snails [1] we know very little about the nature and biosynthesis of metabolites responsible for moss chemical defense. [2,3] Dicranum scoparium is an example of a well-defended moss; it is globally distributed in temperate and arctic forests and often occurs in dense patches that show no sign of herbivory. In a recent survey of the volatile oxylipins (products of the oxidative transformation of polyunsaturated fatty acids) from mosses, we identified D. scoparium as a prolific producer of such metabolites.…”