IPM: Trials showing bugs achieving results where pesticides fail

IPM: Trials showing bugs achieving results where pesticides fail

Each adult lacewing has an acute ability to detect aphids and can eat up to 100 per day.

Farmers are getting a new insight into the law of the jungle in their crop foliage, as they turn to integrated pest management (IPM).

Now they are more and more likely to release a predator, which turns the crop into a graveyard for unwanted pests. They were able to keep insect murder at a distance by applying sprays, but IPM uses natural killing methods whenever possible, with chemical pesticides as a last resort.

Some of the latest IPM methods were on show at the SIVAL crop production trade show in France.

For example, there was an innovation silver medal for the Micromus-System marketed by Biobest France. It's a typical IPM product, said to be the only one commercially available in France which delivers brown lacewing insects (Hemerobiidae) into a crop.

Each adult lacewing has an acute ability to detect aphids and can eat up to 100 per day. Even the larvae eat aphids; with each consuming an average of 130 aphids before it enters pupation.

It's a bit like letting a terrier loose in a rat-infested field. Except that the female lacewing is extremely fertile, each laying up to 1,000 eggs to hatch into an army of aphid hunters. Low rates of cannibalism are another advantage for this aphid killer.

Even though a lacewing lives only 70 to 90 days, it is active at low temperatures, completing its development in temperatures as low as 10°C.

The lacewing can also prey upon other soft-bodied arthropods, such as mealybugs.

Users of the system buy a 240ml carton (100% biodegradable) containing 250 adult lacewings, in buckwheat hulls and honeycomb paper to protect the insects during transport. This is left in the crop in whatever quantity is needed, recommended for use very early in the season, and if aphids return in the autumn.

Target crops include strawberries, sweet pepper and hot pepper, roses, aubergine, cucumber, gherkin, and medicinal cannabis.

The farmer can go for maximum aphid slaughter by combining lacewings with parasitoids (which attach to or within the aphid and ultimately sterilise or kill it), hoverflies (the larvae can consume between 70 and 100% of the aphid population in their vicinity), aphidoletes (the larvae prey on many aphid species), or Chrysopidae (green lacewing).

Killer insects are only one of several principles of IPM. Others include crop rotation; adequate cultivation techniques (such as stale seedbed technique, sowing dates and densities, under-sowing, conservation tillage, pruning and direct sowing); using pest-resistant or tolerant crop varieties and certified seed and planting material; balanced fertilisation, liming, and irrigation or drainage; and hygiene measures to stop spreading of harmful organisms (regular cleansing of machinery and equipment, etc).

IPM is an important way to protect pollinators in both agricultural and non-agricultural areas, such as public parks.

Farmers will have to rely more and more on IPM, because the EU wants a 50% reduction by 2030 in the use and risk of chemical pesticides.

The aim is to minimise pesticide risks to people and the environment while controlling pests that damage crops and plants, which is necessary for food security and viable farmer income..

Some IPM products have even been successful where pesticides didn't work.

That is the claim for Nezapar, made by the Koppert company in France, and the innovation gold medal winner at the SIVAL show in France.

It offers growers new help against the southern green stink bug, currently considered a major pest in vegetable crops. Conventional products are ineffective, and there is currently no solution to fight it in organic farming.

The Nezara stink bug causes severe damage when it pierces flowers or fruit, causing stains and deformations, flower drop, and losses of up to 40% of the yield.

Koppert has come to the rescue with Trissolcus basalis, a small Hymenoptera that parasitises the eggs of Nezara viridulais.

The Nezapar product formulation contains 5,000 bug eggs parasitised by Trissolcus basalis. These eggs are placed in the crop, ready to hatch within a week, giving birth to parasitoids that take action on Nezara viridula populations after one week.

Trials carried out over the last five years showed that repeated releases of Trissolcus basalis every week, starting as early as possible, prevent the spread of Nezara viridula and limit populations. The parasite does not completely eliminate the pest, but significantly reduces the damage caused in crops.

Nurspray, another silver medal winner at SIVAL, comes under the IPM heading of biostimulants that promote or augment natural processes within the plant.

It is designed to activate plants’ natural mechanisms of tolerance to water stress.

Foliar application of the product sends the plant the message that it is in a state of stress, and the plant responds with overproduction of proline, which helps plants exposed to stress. In the absence of real stress, this proline is recycled by the plant and, when real stress occurs, the plant will help itself by naturally overproducing proline more rapidly.

The plant remembers this means of defence, and can trigger it in the event of stress, which it then withstands more effectively.

The effects of Nurspray on crops include better use of available water, greater resilience to water stress, and better post-stress recovery, demonstrated in a large number of crops.

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Karen Walsh

Karen Walsh

Law of the Land


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