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.