Are pests adapting to the push-pull system?

The idea of ecological intensification is to utilize biodiversity to maintain agricultural yields while reducing negative environmental impacts. Anthropogenic inputs such as pesticides and synthetic fertilizers are replaced using carefully managed biodiversity to maintain or improve ecosystem services, including productivity. But how do these systems develop over longer time scales?

– While pest management is a common goal of ecological intensification, studies examining ecologically intensified pest management systems over longer time scales are rare, says Mattias Jonsson.

Pests decline over time

Using the push-pull system in Western Kenya, Mattias Jonsson, together with colleagues from Kenya, USA and South Africa, examined whether the abundance of insect pest and weeds and crop yield vary with time.

With data from 476 unique farmers and 24 cropping seasons, the researchers found that pests declined with time since establishment in both push-pull and nearby control fields. In addition, yield improved with time since establishment in push-pull fields.

– Our study suggest that ecologically intensified agriculture is resilient against pest adaptation, maintaining consistently high yields over time, concludes Mattias.

Encouraging results

The results of the study are encouraging for the resilience of ecological intensification more broadly.  Over a large number of farms and several growing seasons, the benefits of an ecologically intensified agricultural system do not degrade with time since establishment, and in fact improve slightly over time.

– Interestingly, we also found possible benefits of ecologically intensified fields to other fields nearby, whether or not they were under the same management scheme. Now, we need to investigate different mechanisms within the system and how the system is developing in the presence of fall armyworm, an invasive pest that cause big economic losses in agriculture in Kenya.