Biodiversity and pest management

Abstract

Maintaining biodiversity and the associated ecosystem services is an objective of the European Union, implemented through agri-environmental programmes. Biodiversity decline is occurring at a worldwide scale and has twofold implications. From a conservation point of view, the number of extinct and endangered species increases, and this impoverishment of natural ecosystems reduces their resilience. From an agronomical point of view, reduction of biodiversity affects processes that hamper crop productivity, such as pollination or pest management, being the consequence of this biodiversity decline a reduction in agroecosystem sustainability. But both, ecosystem resilience and agro ecosystem sustainability are not isolated. In the case of pest control, in many cases it is assumed that it depends on biodiversity. However, a positive relationship between biodiversity of natural enemies and pest suppression is not always the case. In fact, in some cases this relationship does not occur (Fig.1), and the success of biological control depends not on biodiversity, but on the presence of one or only few species of natural enemies. As an example, in the case of olive trees, a single species such as Anthocoris nemoralis or relatively simple predator assemblagesare associated with better biological control than complex assemblages (Paredes et al., 2015). However, it seems that the general rule in different agroecosystems is that biodiversity rather than abundance of natural enemies is linked to pest control, although this has been proven mainly in annual crops and in non-mediterranean environmental conditions (Dainese et al., 2019).