The economic consequences of biodiversity loss in agro-ecosystems: a case study of low strain pear production in Belgium

Abstract

An integral part of agricultural intensification at the plot level is the deliberate reduction of biodiversity (Bianchi et al., 2013; Swift et al., 2004). Biodiversity provides however a wide variety of ecological services and disservices in agro-ecosystems (Tschjarntke et al., 2005, De Meester et al., 2011, Kragt et al., 2014).

In this research, the consequences of human-induced changes in predator population dynamics for biological pest control of Cacopsylla pyri were analyzed for two pear orchard agro-ecosystems in Flanders (Belgium) (i) organic production and (ii) Integrated Pest Management. A stochastic ecological model was built with the use of stella simulation software. Predator-prey dynamics between a pest insect (Cacopsylla pyri) and its main natural enemies (e.g. Anthocoris nemoralis, Allothrombidium fuliginosum and Heterotoma planicornis) were simulated. Species-specific data on phenology and feeding behavior were employed to simulate species interaction, predation and reproductive behavior. After determination of equilibrium conditions, the use of insecticides was added as a shock to the system and the changes in both (i) species abundance and (ii) the potential for biological pest control were assessed.

This way, the cascading effect of insecticide use on higher trophic levels as compared to those species which are directly targeted could be analyzed. Using this approach, we are able to (i) assess the impact of a reduction in biodiversity at ecosystem level rather than at the level of individual species and in doing so (ii), analyze the effect of these biodiversity losses on ecological services. With this analysis, the researchers aim to contribute to the growing debate on the importance of biodiversity conservation.