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Natural Pest Control Effective and Balanced

Nobody works harder at the San Bernardo Greenhouse in Zarcero than the bumblebees. The rotund insects flit from one tomato plant to the next. Pollen sticks to their legs as they invade yellow flowers in search of nectar.

Milena Chinchilla plucks one of the tiny grape tomato flowers and inspects it for bites. These are her bumblebees, and she wants to make sure the buzzing bugs are getting the job done. She looks for tiny bite marks on the flower, a sign that the busy bees have been nibbling and, therefore, pollinating the plant. While searching for nectar, the pollen sticks to the legs of the bee and is carried to the next tomato flower, fertilizing the flowers.

Chinchilla works for a company known as Reflex, a distributor for Koppert, a Dutch company that breeds biological controls. These controls – bees or predatory insects – help fertilize plants or control outbreaks of pests in a manner that is more in tune with nature.

This type of natural fertilization performed by the bumblebees is having major benefits for the tomato farm.

“The pollination of the fruit causes the fruit to have a better taste, better weight and more seeds,” said Paulo Blanco, president of the Producers Association in Zarcero’s Protected Environment (Apromeco), which has 16 enormous greenhouses in Zarcero.

A higher number of seeds means larger, rounder tomatoes, Blanco explained. The heavier the tomato the more they can be sold for in the United States, where all of Apromeco’s tomatoes are sent.

Although not organic (pesticides that don’t harm the desired insects are sometimes used), Reflex and other biological control companies intend to limit pests by letting Mother Nature do most of the work. Pesticides can lead to bugs building up a resistance to chemicals throughout multiple life cycles. Biological controls eliminate that possibility.

“The word ‘resistance’ doesn’t exist in nature,” said Edwin Smit, who has run Reflex’s Central American branch for eight years. “Because you have a natural balance, like an insect that’s controlling another insect, there’s always a balance.”

The pest might not be eliminated completely, but the balance will keep the pest from ever reaching a population size that would overrun the crop. There would be no mutant pests with resistances to poisons. In fact, there would hardly be a need for poisons.

Chinchilla said one farm she worked with went from spraying 12 times a week to 14 weeks without spraying once. The approach also saves money. Reflex claims that farms see a 30 to 50 percent decrease in pesticide use once they begin using biological controls.

The biological controls offered by Reflex include predatory wasps and swirsky-mites.

The most common garden pests these creatures devour are spider mites, white flies, aphids and thrips. Biological controls work best in greenhouse environments, since many of the variables that could reduce their effectiveness can be regulated. As a result, the bugs have been used most often with ornamental plants.

However, it’s growing more common to see biological control companies use predatory wasps and other insects to fight pest outbreaks outdoors. Reflex is planning to push the use if its biological controls in melon, banana and pineapple fields. For example, the company has started working with a pineapple farm in San Carlos.

Due to the numerous variables, maintaining the predatory bugs or the bees can be tricky. Conditions that can affect the bugs include weather, incompatible pesticides being used and poor storage. Smit said in the past, Reflex has had troubles picking up the bugs once they’ve been imported from the Netherlands. Due to strict government rules about importing animals into the country and delays with customs in distributing permits, bugs have died in storage while waiting to be picked up, Smit said.

But using these products is also more complicated than squirting some pesticide, because the activities of the insects have to be programmed and monitored.

“We don’t just sell bugs,” said Francisco González of Reflex, “We have to sell our program. We provide technical assistance, we assign protocols and we assign the exact dates. We cannot just give out (the insects).”

On another Apromeco farm in Zarcero, Chinchilla does another round of technical assistance. She walks through rows and rows of the grape tomato crops. The leaves of the plants look crippled. They are streaked with brown stains, and the edges of the leaves are curled upwards. The greenhouse had used a pesticide to wipe out a bacterial invasion. Chinchilla was checking the yellow flower buds again. Is there nibbling? Check. On to the next flower.

But this time Chinchilla inquires about the pesticide with a farmer.

“We have to check that the chemicals  they are applying are compatible with our products,” Chinchilla said, “With bees and … with (predatory) insects.”

The bees come in square boxes. Since tomato flowers contain nectar, the boxes have nectar inside them to allow the bees to produce honey. A gate regulates when the bumblebees can enter and when they can leave. In the past, Chinchilla has seen dozens of dead bees piled up in the corner of a hive, a sign that an incompatible pesticide had poisoned the bees.

The bees have a routine where they will pollinate the same group of plants for 10 to 14 weeks. The queen will die after a little more than three months, and, after that, government regulations about foreign insects require that the hive be incinerated. Other pests also can start breeding inside an old hive. So far Blanco has little complaint about the bees. Other than occasional bee sting, the bumblebees are some of the most reasonable workers available.

“It is a job that the bumblebees do for free,” Blanco said. “And they work the entire week.”

For more on biological controls and natural pollination, Koppert is hosting an event in Sabanilla, east of San José, from 10 a.m. to 4 p.m. on Sunday, August 29. The interactive event will include a presentation on the bumblebees, a how-to demonstration on spotting pests like spider mites and mealy bugs in a local garden, movies, and games for kids. To register for the event, contact Maite Salinas: 22730981 or

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