Cascading effects of livestock grazing on insect functional groups associated to flowers in arid lands

M. TADEY

AGRICULTURAL AND FOREST ENTOMOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2023

1461-9555

Abstract1.Disturbances affect plant diversity with consequences on other trophic levels, like the associated insect communities. Domestic livestock is a major disturbance affecting flowering plant abundance at the bottom of insect food webs with unpredicted consequences on ecosystem functioning. 2.This work evaluated livestock effect on flower-associated insect functional groups (i.e. predators, herbivores and pollinators) hypothesizing that plant damage produced by grazing exerts bottom up effects on insect populations, affecting their interactions. Contrary, livestock might supply food resources for several dipteran pests (e. g. scavengers, parasites or bloodsucking) or benefit predator species by increasing habitat transparency with grazing. 3.Seven independent rangelands within the same arid environment and increasing livestock density, were used to test these hypotheses using a regression approach. 4.Insect, herbivore and pollinator diversity decreased with increasing livestock density, and increased with increasing vegetation. Bare soil affected solitary bees (but not all the pollinators) and habitat transparency benefited predators, as expected. Dipteran pests quadratically decreased with increasing livestock density, rejecting the hypothesis of food supply. Apparently, predators reduced the abundance of almost all insect groups. 5.Grazing reduce vegetation positively affecting predators, which negatively affect other insect groups (top-down), potentially altering species complex interactions and ecosystem functioning.