Grazing and Orthoptera: a review

Abstract

Orthoptera are an important biological component of grasslands as a crucial link in the food chain. Grazing, either by wild animals or livestock for human food production, exerts considerable influence on the Orthoptera of grasslands. For example, grazing prevents succession of open grasslands to scrub and forest, creates heterogeneity in sward height, and provides patches of bare earth through the action of livestock hooves breaking the vegetative cover. Grazing may also interact with other forms of grassland management such as burning to produce quite complex interactions which vary greatly between regions and Orthoptera species. Threats to grassland Orthoptera include overgrazing; conversely, abandonment of grazing can lead to the loss of open habitats vital to many species. It is important to have ungrazed areas to provide refuges for species negatively affected by grazing. Rotational management -moving domestic livestock between different pastures -will also allow a range of sward structures to develop over a landscape. The over-arching principle for grazing management should be to establish a heterogeneous sward with a range of sward heights and bare earth for oviposition/basking. In more extensive systems, patches of scrub can form habitat of woody vegetation for species such as bush crickets. The greatest diversity of habitats should provide the highest species richness.

The response of Orthoptera to grazing on flood defense embankments in Europe

“…A study in the Netherlands found that canopy height is affected by two variables: livestock species and livestock density (Nolte et al 2014). The livestock species (including wild herbivores like rabbits) can also affect plant abundance and assemblage diversity, which are correlated with Orthoptera conservation and pest management (Gardiner 2018). Herbivore species and densities should therefore be chosen depending on their impacts.…”

“…The effect of grazing is usually species-specific because the response of species and assemblages differs in accordance with the region and the grassland type (Gardiner 2018). Both phytophagous and entomophagous insects are affected by grazing intensity (Kruess and Tscharntke 2002).…”

“…Sometimes, mowing may be the only solution in areas hardly accessible to domestic livestock such as remote sea walls. A rotational management strategy produces complex effects on orthopteran assemblages and develops a diverse range of vegetation structures (Gardiner 2018). A combination of grazing and mowing is possible on dikes and sea walls.…”

“…9), locally scarce species such as T. viridissima can be abundant. Ungrazed pastures with tall grassland provide important refuges, like latrines, for Orthoptera (Gardiner 2018). Indeed, an experiment showed that C. parallelus nymphs and adults released in a heavily grazed area dispersed to tall grass (Gardiner and Hill 2004).…”

“…Grazing can also occur naturally, for example where rabbits Oryctolagus cuniculus L., 1758 (Lagomorpha: Leporidae) and hares Lepus europaeus Pallas, 1778 (Lagomorpha: Leporidae) occur (Gardiner et al 2015). According to Gardiner (2018), 'grazing prevents succession of open grasslands to scrub and forest, creates heterogeneity in sward height, and provides patches of bare earth through the action of livestock hooves breaking the vegetative cover. ' In European semi-natural grasslands, livestock grazing is a common practice which maintains a high floristic species richness (van Klink et al 2016).…”