Monthly Archives: September 2016

Are there tipping points in pest management?

Tipping points are common in nature. When systems are disturbed beyond a certain point – a tipping point – they may undergo irreversible or hardly reversible changes that provoke shifts towards undesirable system states. It is often difficult to get systems back from this new ‘stable’ yet undesirable situation. Examples are many. A classical one comes from the work of Marten Scheffer in The Netherlands. He studied the dynamics of shallow lakes as they undergo phases of turbidity as influenced by nutrient loads or pollution. You can find out more about his work here.

Screen Shot 2016-09-05 at 10.02.21

 

How about agricultural systems subject to high pesticide pressure? 

Synthetic pesticide applications are standard practice in conventional farming systems because they are simple to use, cheap, and usually effective in providing short-term reduction in pest densities. Yet, their effectiveness as a long-term sustainable pest management strategy is debated. This debate has been fuelled by the introduction of recent technologies, such as neonicotinoids seed coatings and herbicide tolerant GMO crops, with uncertain outcomes for biodiversity and resistance development.

Historic cases show that the use of pesticides can set off a positive feedback process whereby natural enemy populations are decimated and pesticides become the only pest management option left. The positive feedback between pesticide use and natural enemy mortality suggests the possibility of tipping point dynamics where the system can “tip” from a biocontrol dominated state to a pesticide dominated state. Tipping the system back from the pesticide dominated state to the biological control state could be challenging and require persistent efforts to allow a recovery process of natural enemy populations. Such transition may depend on landscape context and involve complex interactions between human actors and the agro-ecological environment.

The question remains: is there evidence for such tipping points? This will be the central question to be addressed during the debate that will bring Felix Bianchi, Dave Mortensen, Doug Landis and me together at a workshop organised by the PE&RC Graduate School of Wageningen University.

MORE INFORMATION: Poster-Tipping points in pest management