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dung beetle
HELPFUL INSECT: If you have pasture, the dung beetle is a beneficial insect that breaks down manure and makes positive changes within the upper soil structure.

Insects: Friend or foe?

Salute Soil Health: Don’t plan an application just because you see an insect. Some species are beneficial.

By Tony Bailey  

It’s crucial to scout to establish if economic treatment thresholds have been met prior to making insecticide applications. Developing long-term prevention, avoidance, monitoring and suppression control strategies, known as PAMS, and using these strategies reduces the potential of insect pests developing resistance to insecticides.

Insecticidal seed treatments are meant to suppress occasional pests, but often have negative effects on beneficial insects and organisms. If using insecticidal seed treatments, use the lowest rate to suppress anticipated insect pests and minimize effects on beneficial organisms. 

Insecticidal seed treatments don’t control slugs, and beneficial insects feeding on slugs can be killed inadvertently, leading to a slug population with few to no predators. Did you know lightning bug larvae eat slugs?

Properly identify all pest species. Scouting is key to any Integrated Pest Management program. If using cover crops, be on the lookout for species such as black cutworms, armyworms, stinkbugs and slugs. Also know that cover crops promote predators, parasites and pollinators. Is the insect you find in a field friend or foe?

Scouting thresholds

Use scouting of beneficial and problem insects to determine if economic thresholds have been met to warrant treatment. Crops can sustain visible damage without yield loss. There’s often a lag before beneficial organisms catch up with a pest outbreak. If beneficial insects can control the pest outbreak, the effects of the pests will only last for a short time. If insecticides are sprayed, damage to beneficial organisms is usually longer lasting and can affect populations for months.

Properly identify and consider all beneficial organisms. This will give you an idea of your natural defenses against pest outbreaks. Have you ever identified beneficial insects or noticed spiders in your fields? 

Encourage beneficial species such as ground beetles, minute pirate bugs and spiders with a soil health management system that uses conservation practices such as no-till and strip-till, cover crops and buffers.  Buffers provide habitat and a food source promoting beneficial organisms and pollinators.

During herbicide applications, don’t add insecticides unless economic thresholds have been met. This also applies if scouting determines that a foliar fungicide application is justified to treat a crop disease. If an economic threshold is reached, follow all pesticide label instructions.

Other beneficials

In pasture systems, the dung beetle is one of the most important beneficial insects. Horn flies and face flies impact cattle growth and production, but a good population of dung beetles quickly breaks down and dries up manure pats, removing sites for fly larvae to live. Some research has shown a 95% decrease in horn flies thanks to dung beetles. 

These little manure harvesters bury nuggets of manure underground to feed their own larvae. Their actions create tunnels underground for water infiltration, plus they’re storing and later releasing nitrogen into the soil and adding organic matter. Good grazing management with plenty of residue is crucial for maintaining and increasing dung beetle herds.

Scouting and proper identification of all organisms in both your crop fields and pastures, treatment of problematic pests, and IPM strategies using a PAMS approach can help to reduce damage from pests and from making unnecessary pesticide applications. Avoiding unneeded applications can also save you time and money.

IPM is important to maintain the gains that have been made in conservation agriculture and to improve all conservation cropping systems.

Bailey is Indiana’s state conservation agronomist for the Natural Resources Conservation Service. He writes on behalf of the Indiana Conservation Partnership.

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