There are risks involved in both biologically-based and non-biologically-based methods. Using insecticides may lead to resistance over time, causing growers to use harsher chemicals and decreasing the overall value of their crops. This also increases exposure to growers, labourers and applicators. There might be restrictions being placed by the government to discourage excessive use of chemicals due to their potentially harmful effects on the environment and consumers. Similarly, biocontrol has its own risks. It requires knowledgeable staff who has the expertise of the biocontrol agents applied against pests, as well as knowledge of the compatibility of chemical use with biocontrol agents. If staff do not have this knowledge, using biocontrol products will be ineffective and expensive. Understanding the costs associated with biocontrol is valuable for the grower. Knowledge of different pests of different crops allows the grower to put into context where, when and why the biocontrol dollar should be spent, and where to focus on cost reduction.
Looking at the bigger picture, market trends are moving towards biocontrol use over insecticide use. This is because the public is becoming more health conscious. Some prefer produce that is pesticide-free and are willing to pay a little extra for it. Some branches of government are also encouraging the use of biocontrol agents due to their positive effects on the environment.
Setting biological control on a firm economic foundation would help to broaden its utility and adoption. By adopting a well-economised biological control programme, growers can not only grow good quality produce with minimal use of chemicals, but can save money and provide a healthy environment to workers. Such a system can be applied by critically-reviewed, preventative and curative measures, including steps such as:
- Encouraging rhizosphere microbiome activity to strengthen the plants and ready them for a fight with pests and diseases.
- Introduction of ground-inhabiting predators like Dalotia (formerly Atheta) coriaria as a slow release system and Hypoaspis miles as a key component against important soil residing / hibernating crop pests such as spider mites, fungus gnats, thrips, root aphids, etc.
- Introduce generalist predatory mites (e.g. cucumeris, swirskii, californicus) and insects active on plant foliage by using the sachet system for predatory mites and the banker plant system to support Dicyphus, Orius and Aphidius. This will keep the population of different pests below economic thresholds.
- Use specialist predatory mite (persimilis) and insects (Encarsia, Eretmocerus, Aphidius) of specific pests, keeping in mind the predator-to-prey ratio. Release the biocontrol agent as soon as possible once the presence of the pest is marked by the scout. Enrich the hot spots with predators instead of a blanket application. The use of specialists is not suggested as a preventative measure, because specialists will not survive in the absence of its prey.
- If a pest population flares up in spite of all the above said efforts, use a selective pesticide for quick suppression of the pest.
- It is highly recommended that you consult your service provider for where, when and how much biological control agents should be applied to avoid over spending and to use natural enemies correctly.
Abida Nasreen, PhD, is director of research and development at GrowLiv Ltd.
