Herbivores
Domestic vertebrate herbivores, namely sheep, cows and goats were by far
the most studied herbivores (Figure 3). This trend likely reflects
funding and societal priorities to support global red meat production
(Lemaire et al., 2005). Invertebrates, and other native mammalian
herbivores, however, can also have huge impacts on grassland
productivity and consequential livestock production (Risch et al., 2013;
Saunders, 2018; Umina et al., 2021). Improving our understanding on how
these herbivores impact plant defence syndromes may benefit the pastoral
industry, while also providing a better overall understanding of how
herbivores affect grassland plant communities. Many invertebrate species
examined were also commercially important or very common species such as
the cotton worm (Spodoptera littoralis ) and cabbage moth
(Mamestra brassicae ). Ensuring future research focuses on both
agriculturally and ecologically important herbivore species is
important.
Most invertebrate studies were not focussed on particular invertebrate
species but examined the response and effect of invertebrate communities
to/on plant traits, usually by measuring total leaf damage (Effah et
al., 2020) or by excluding invertebrate with the use of insecticide
and/or exclosures (Carson & Root, 1999; Firn et al., 2017). These
studies are useful for examining the overall influence of invertebrate
herbivore on plants and can be easier than species focussed studies to
conduct in the field.