Cascade effects of crop species richness on the diversity of pest insects and their natural enemies

Abstract

Understanding how plant species richness influences the diversity of herbivorous and predatory/parasitic arthropods is central to community ecology. We explore the effects of crop species richness on the diversity of pest insects and their natural enemies. Using data from a four-year experiment with five levels of crop species richness, we found that crop species richness significantly affected the pest species richness, but there were no significant effects on richness of the pests' natural enemies. In contrast, the species richness of pest insects significantly affected their natural enemies. These findings suggest a cascade effect where trophic interactions are strong between adjacent trophic levels, while the interactions between connected but nonadjacent trophic levels are weakened by the intermediate trophic level. High crop species richness resulted in a more stable arthropod community compared with communities in monoculture crops. Our results highlight the complicated cross-trophic interactions and the crucial role of crop diversity in the food webs of agro-ecosystems. trophic level, stability, generalized additive model, monoculture, polyculture Citation:

Effects of seed mixture sowing with transgenic Bt rice and its parental line on the population dynamics of target stemborers and leafrollers, and non‐target planthoppers

“…Reasonable mixtures of different crop cultivars can alleviate the limitations triggered by monoculture and low biodiversity (Van & Harfington, ) and enhance the natural enemy species richness (Shi et al ., ). It has been suggested that the increase in crop diversity in agricultural landscape configuration contributes to a general decrease in pest damage on crops (Chaplin‐Kramer et al ., ; Gagic et al ., ); the effect may range from localized reduction of pest abundance to a lower general equilibrium of pest populations at the landscape level (Jonsson et al ., ).…”

“…Therefore, we focused on an examination of an ecological approach (habitat diversity through cultivar mixture) toward enhancing vegetation diversity and its associated functional biodiversity in transgenic rice production systems, which could potentially narrow the gap between sustainable agriculture and biodiversity conservation (Tscharntke et al, 2012). Reasonable mixtures of different crop cultivars can alleviate the limitations triggered by monoculture and low biodiversity (Van & Harfington, 2007) and enhance the natural enemy species richness (Shi et al, 2014). It has been suggested that the increase in crop diversity in agricultural landscape configuration contributes to a general decrease in pest damage on crops (Chaplin-Kramer et al, 2011;Gagic et al, 2011); the effect may range from localized reduction of pest abundance to a lower general equilibrium of pest populations at the landscape level (Jonsson et al, 2012).…”

Crop dominance exerts specific effects on foliage-dwelling arthropods inBacillus thuringiensiscotton

“…As reported in previous studies, herbivores are influenced primarily by vegetation composition within habitats, whereas predators and parasitoids may be more sensitive to changes in field size and habitat arrangement (Stoner & Joern, ; Tscharntke & Brandl, ). In addition, crop species richness significantly affected the pest species richness, although there were no significant effects of the pests' natural enemies on richness (Shi et al , ). In general, herbivores are generally dominated by insects with a relatively lower migration capability, whereas most of the predators show higher mobility.…”

An optimal proportion of mixing broad‐leaved forest for enhancing the effective productivity of moso bamboo

“…1996; Lehman and Tilman 2000; Shi et al. 2014a). Indeed, plant diversity has been shown to affect the water cycle in forest ecosystems by differentiating water consumption and recharging groundwater (Sprenger et al.…”

“…Mixing different plant species in managed habitats not only can increase the species diversity of other taxa, but also can potentially enhance the stability and productivity of the entire ecosystem (Tilman et al 1996;Lehman and Tilman 2000;Shi et al 2014a). Indeed, plant diversity has been shown to affect the water cycle in forest ecosystems by differentiating water consumption and recharging groundwater (Sprenger et al 2013).…”