Molecular approach to describing a seed‐based food web: the post‐dispersal granivore community of an invasive plant

Abstract

Communities of post-dispersal granivores can shape the density and dispersion of exotic plants and invasive weeds, yet plant ecologists have a limited perception of the relative trophic linkages between a seed species and members of its granivore community. Dandelion seeds marked with Rabbit IgG were disseminated into replicated plots in the recipient habitat (South Dakota) and the native range (Czech Republic). Arthropods were collected in pitfall traps, and their guts were searched for the protein marker using enzyme-linked immunosorbent assay (ELISA). Seed dishes were placed in each plot, and dandelion seed removal rates were measured. The entire experiment was repeated five times over the dandelion flowering period. Gut analysis revealed that approximately 22% of specimens tested positive for the seed marker. A more diverse granivore community had trophic linkages to seeds than has been previously realized under field conditions. This community included taxa such as isopods, millipedes, weevils, rove beetles, and caterpillars, in addition to the traditionally recognized ants, crickets, and carabid beetles. Rarefaction and Chao analysis estimated approximately 16 and 27 species in the granivore communities of the Czech Republic and South Dakota, respectively. Synthesis: Generalist granivore communities are diverse and polyphagous, and are clearly important as a form of biotic resistance to invasive and weedy plants. These granivore communities can be managed to limit population growth of these pests.

Plant density can increase invertebrate postdispersal seed predation in an experimental grassland community

“…In temperate climates, postdispersal seed predation by invertebrates is less dependent on specialized consumers and generally driven by a diverse consumer community (Lundgren et al. 2013) of mostly omnivorous groups (Honěk et al. 2003; Saska 2008; Koprdová et al.…”

Accuracy of a prey‐specific DNA assay and a generic prey‐immunomarking assay for detecting predation

“…Immunomarkers have been used to tag immobile foodstuffs such as sentinel egg masses in the open field (Mansfield, Hagler & Whitehouse ). Also, Lundgren, Saska & Noněk () tracked granivory exhibited by an arthropod complex in the field by protein marking dandelion seeds with rabbit IgG. Zilnik & Hagler () showed that the technique has enormous potential to study predator scavenging activity and can be adapted to assess cannibalism.…”

“…While the prey immunomarking technique has many advantages over the prey‐specific ELISA and PCR approaches, it has one major limitation. Specifically, field cage studies (as opposed to open field studies) are almost always necessary for a prey immunomarking experiment [but see Mansfield, Hagler and Whitehouse () and Lundgren, Saska and Noněk ()]. Unfortunately, field cage experiments might have limited appeal because they do not exactly replicate what occurs in nature.…”

Administering and Detecting Protein Marks on Arthropods for Dispersal Research

“…This technique has recently gained popularity among gut analysis researchers because it is less tedious and costly than conducting prey-specific ELISA or polymerase chain reaction (PCR) type molecular gut content analyses (see Hagler 18 and Fournier et al 19 for reviews of the pros and cons of the various gut assay techniques). Within the past decade, the prey immunomarking technique has been used to identify feeding activity of cotton predators on rabbit IgG-marked pests 18,20,21 , trophallaxis and feeding relationships in termite colonies using a rabbit IgG-treated paper food source 22 , granivory of an arthropod assemblage on invasive dandelion weed seeds marked with rabbit IgG 23 , stink bug predation rates on IgG-marked tomato hornworms collected in plots subjected to various semiochemical treatments 24 , and predator scavenging activity on IgG/IgY-marked carrion 25 .…”