The Benefits of Maintaining Biodiversity in Rice Fields

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white waterbird in watery field

Nature has an incredible knack for regulating itself. A hungry insect devours a plant. Another hungry insect devours that pest. In an ideal state, the populations of both species are naturally balanced.

In practice, however, maintaining this kind of balance is extremely challenging, especially at the farm level. Farmers must protect their crops from all sorts of pests—diseases, weeds and insects—that threaten their harvests. Farmers have to act in order to protect harvests, but they want to choose interventions that are minimally disruptive to the beneficial organisms that help make the land healthier and more productive.

In rice production, natural enemies play a particularly vital role in protecting crops. Planthoppers are the most important insect pest threat in rice, capable of destroying entire harvests. When planthoppers appear, so do natural enemies like spiders, lady beetles, predatory mirid bugs and wasps, which prey on planthoppers. But when these natural predators aren’t enough to keep pest populations under control, farmers also need to use insecticides to protect their harvests. If farmers choose an insecticide that controls planthoppers and negatively impacts beneficial insects, they lose an important natural method of control that can work alongside the insecticide. When the insecticide’s effect wears off, planthopper populations can come roaring back, now with no natural predators to help reduce their numbers. In this case, the farmer’s efforts to control a pest have only made the problem worse.

Insecticide products that effectively control planthoppers while allowing beneficial insects to thrive help farmers maintain balance in their fields and benefit from natural control of planthoppers. Pexalon™ insecticide with Pyraxalt™ active from Corteva Agriscience is one such option for farmers. It has a very low use rate, so when used at the earliest signs of planthopper infestation*, Pexalon provides fast and long-lasting pest control with minimal impact on beneficial organisms.

Researching planthopper control and beneficials

To better understand how Pexalon™ insecticide controls planthoppers while preserving beneficials, scientists conducted a study in rice fields in the Telangana state of India. The study looked at how several factors worked together in the field, including:

  • Planting marigolds to conserve planthopper predators
  • Applying organic manure to help with early colonization of spiders and aquatic planthopper predators
  • Using different insecticide products, including Pexalon

In the study, all of the insecticide treatments reduced the populations of planthoppers. The treatment groups that included Pexalon showed the best planthopper control performance, but this was not the only benefit researchers uncovered.

Researchers also examined populations of beneficial organisms in all of the treatment groups. Pexalon-treated fields maintained the highest levels of spider populations, with a mean of 1.28 spiders per hill. This population was higher than the untreated group, demonstrating no negative effect from Pexalon on spiders. In the other insecticide treatment groups, spider populations fell to less than one spider per hill on average. Similar results were seen in populations of predatory mirid bugs, which feed on planthoppers. Pexalon-treated fields maintained populations of these beneficials, while areas treated with other insecticides saw mirid populations fall, sometimes by more than half versus pre-treatment numbers. Fields treated with Pexalon also maintained populations of dryinid, which are parasites of planthoppers. With use of other insecticides, dryinid populations were almost 70% less on average compared with Pexalon-treated areas.

The researchers also noted a wide diversity of beneficial insects in the treated fields, including multiple species of dragonflies, wasps and parasites of planthoppers. They found that Pexalon-treated areas which also utilized marigolds and organic manure maintained a level of biodiversity closest to the untreated control areas. In other words, use of Pexalon did not disrupt the balance of beneficial organisms in these fields and was compatible with practices (such as planting marigolds) that preserve natural planthopper enemies.

Controlling pests, maintaining natural balance

With the right tools and practices, farmers can protect their crops from destructive pests and maintain balance in the environment. Pexalon™ insecticide enables farmers to control planthopper infestations quickly without depleting populations of beneficial organisms. When innovative crop protection products like Pexalon are combined with other beneficial-friendly practices, like planting selected flower species, farmers can maintain healthy and productive farms where nature can do its best work and rice can yield to its fullest potential.

close up of dragon fly on orange flower
close up of dragon fly on orange flower

Researchers in Telangana, India found that using a combination of marigold plantings, organic manure and Pexalon in rice fields enabled effective control of planthoppers while maintaining biodiverse populations of beneficial organisms.

Learn more about Pyraxalt active

*5-10 planthoppers per hill in transplanted paddy rice and 200-250 per 0.25m2 in direct-seeded rice

Pexalon™ insecticide is not registered for sale or use in all states or countries. Contact your local regulatory agency to determine if a product is registered for sale or use in your area. Always read and follow label directions.