Comparison of arthropod communities between high and low input maize farms in Mexico

Abstract

BackgroundAnimal communities are vulnerable to agricultural practices. Intensive farming considerably reduces overall arthropod diversity, but not necessarily pest abundance. Natural control of herbivores in agroecosystems is accomplished by predators and parasitoids, but in intensified agricultural regimes, the chemical control used to reduce pest abundances also affects pests’ natural enemies. To achieve more sustainable agriculture, there is a need to better understand the susceptibility of predators to conventional management.MethodsIn order to quantify the arthropod diversity associated with different schemes of agricultural management of maize, we evaluated agricultural fields under two contrasting management regimens in Michoacán, México during the spring–summer cycle of 2011. Arthropod communities were evaluated in plots with conventional high-input versus low-input agriculture in two sites—one rainfed and one with irrigation. The experimental units consisted of twelve 1 ha agricultural plots. To sample arthropods, we used 9 pitfall traps per agricultural plot.ResultsDuring the sampling period, we detected a total of 14,315 arthropods belonging to 12 Orders and 253 morphospecies. Arthropod community composition was significantly different between the sites, and in the rain-fed site, we also found differences between management practices. Predators, particularly ants, were more abundant in low-input sites. Herbivory levels were similar in all fields, with an average of 18% of leaf area lost per plant.ConclusionsOur results suggest that conventional farming is not reducing herbivore abundances or damage inflicted to plants, but is affecting arthropod predators. We discuss repercussions for sustainable agriculture.