IPM in action

To reduce crop losses from pests and diseases, there is often not a single way to keep them under the ETL (Economic Threshold Level). Often underlooked, in the term “Integrated Pest Management”, “Integrated” means that a broad range of methods (mechanical, cultural, biological, and chemical) are all used in concert and are articulated to prevent key pests to affect farmer’s income. Each method or action against a particular pest can affect, in turn, other pests (or diseases) and beneficial insects. In addition, IPM envisions that pest prevention will be the first step before pest control. Prevention of pests makes sense in terms of the economic costs that growers would face due to repeated yet sometimes unnecessary pesticide applications. Preventing pests and diseases to grow above the ETL would remain by far the most economically viable solution in a long term and would save higher costs for pest control.

In the previous post, we presented how IPM has been conceived and why it is of great help when managing complex agricultural systems. IPM shall provide the “least possible disruption to agro-ecosystems” (Source: FAO/WHO 2014) – but what does it mean in practice? Summarized below are the four (4) main control methods that can be used in IPM:

1. Cultural: such as crop rotation, crop sanitation, water management (reduced irrigation), restoration of soil health (reduced tillage, increase of soil organic matter, enhanced microfauna, proper pH to support beneficial bacteria life), time of planting, use of resistant varieties, intercropping, agroforestry, use of repellents or trap crops, border crops. A number of cultural practices connect with the idea that the more diversified (and less uniform) the agricultural landscape is, the fewer chances are that a major pest outbreak would occur. For resistant varieties, physical or chemical (natural plant defense compounds) features can prevent the pest to feed or lay eggs. Limitations can relate to constraints in breaking down the uniformity of a monoculture cropping system. For example, logistic constraints with crop management or harvest can lessen the possibility of intercropping or practicing a mosaic of crops. The absence of resistant varieties and the unavoidable presence of refuge crops where the pest can thrive are also potential limits.
2. Mechanical & physical: physical destruction of pests (hand picking), barriers to pests, pest trapping (light traps, sticky and color traps, traps baited with attractants and/ or pheromones), soil mulches, heat treatment.  Such methods can be time-consuming and enhance labor costs, yet these costs can be significantly less than costs for pesticide applications or costs incurred due to resistance to insecticides.
3. Biological control: use of natural enemies (predators, parasitoids) or pathogens (bacteria, viruses, nematodes), that can be commercially produced or naturally present in the crop or the surrounding agroecosystems. Aside from the strictest sense of “biological control”, bio-based products like botanical extracts can be used to repel or deter pests (e.g. neem, garlic).  The main limitation is the local availability in several regions or the absence of homologation in Southeast Asia. This may likely change with crop certification for higher standards and the increasing food demand for environmentally safer agricultural products.
4. Chemical control: once all solutions above have been set, the use of synthetic pesticides will be enhanced by monitoring pests (thresholds), spraying on limited areas where the pest occurs, reduction and balanced use of pesticides (managing resistance to pesticides)

The occurrence of pests can be drastically reduced using mechanical, physical, and biological methods without using any chemically based strategy. And cultural practices, in some cases rather simple, can help prevent many efforts to control the pest later.

In conclusion, using insecticides for a particular pest should be the last step of a complex process of decisions, which are strategic and can save large unnecessary costs. Prevention would considerably reduce the need for chemical-based control options. It will provide additional long-term benefits (reduced pollution, maintenance of beneficial insects and soil organisms, and improvement of soil long-term potential).

In the next post, we will illustrate how insecticides can become ineffective and how IPM can address the issue of resistance to insecticides