Beneficial insects support agriculture, protect environments

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There are an estimated 10 quintillion insects (that’s 10 plus 17 zeroes) on planet earth and, with the exception of our beloved pollinators, they get mostly bad press: Mosquitoes that spread malaria, ticks that cause Lyme disease, and invasive pests that devastate forests, gardens and crops. But it’s not just the bees we couldn’t live without. In addition to pollinating flowers and farmlands, beneficial insects help control agricultural pests and are critical in maintaining balanced natural ecosystems. Roughly 80 percent of the world’s species are insects, making them the most diverse group of animals in our world.

“Certainly, those of us who work in agriculture and agricultural research spend considerable time trying to control and manage pests, but the truth is that without insects, our global food systems and ecosystems would collapse,” said Margaret Smith, professor of plant breeding and genetics and director of the Cornell University Agricultural Experiment Station (Cornell AES). “Most bird and amphibian species would go extinct without insects to eat, leading to food web consequences that would harm ecosystems and agriculture. More immediately, without birds and insects, many of our food crops that rely on external pollination would disappear. Cornell AES supports a growing body of research focused on how beneficial insects bolster environmental resources and human wellbeing, and on understanding how we can better use their ‘services’ to enhance our agricultural systems.”

Every Wednesday afternoon, about 500 Cryptolaemus montrouzieri beetles are released into the Liberty Hyde Bailey Conservatory on Ithaca’s campus. The conservatory growers’ job is to maintain and protect Cornell’s internationally recognized plant collection, and C. montrouzieri – better known as the mealybug destroyer – helps them do that.

As the name suggests, mealybug destroyers are avid pest controllers, whose voracious appetite for mealybugs is channeled to protect vineyards, orchards and greenhouses worldwide. Mealybugs suck the sap from a host of plants, stealing nutrients, stunting growth and eventually killing plants. Adult destroyers eat some mealybugs directly, but what really gets them is the larva: the beetles lay their eggs in patches of mealybug eggs, and when the destroyers hatch, the larva eat the young mealybugs.

The Cornell AES professional greenhouse staff have been using biocontrols – the term for actively encouraging one living thing to control another, problematic living thing – for at least 20 years. They do also use pesticides to combat other harmful species, but the biocontrols let them minimize these chemicals. The conservatory is used by students, staff and faculty, and is open to the public. If visitors see insects in the conservatory, they may well be seeing a piece of the integrated pest management approach used to maintain a balanced and healthy environment.

Scientists began intentionally introducing beneficial insects to control pest species in the 1930s, but with the invention of DDT and other pesticides in the 1940s, commercial and scientific interest in biocontrols dropped off. It wasn’t until 30 years later, when some bugs began to develop resistance to pesticides, that inquiry into natural controls reemerged.

“Over the past 20 years, commercial use of biocontrols has become far more common”, said Elizabeth Lamb, coordinator for ornamental plants, greenhouses and nurseries for the New York State Integrated Pest Management Program. When she began doing this work 18 years ago, only about 10% of growers used any kind of biocontrol. Now, she estimates, more than half do, with some growers using biocontrols near-exclusively. “Almost all of the Cornell AES greenhouse complexes on campus and on Long Island use some biocontrols, where their use doesn’t interfere with research”, she said. Beetles, nematodes and wasps are among the species being commercially bred and sold to control pests.

“There’s a little faith involved in using these bugs because you release them and you may never see them again,” Lamb said. “But if you give them a chance to work, they can do wonders for your greenhouse.”

“The growing interest in beneficial insects has been driven by several factors,” Lamb said, “including consumer preferences for less pesticide use and decreasing effectiveness of pesticides as bugs develop resistance to them. She expects such interest to continue growing, especially in New York state, where legislation signed in December 2023 will gradually phase out use of neonicotinoid pesticides. Neonicotinoids are believed to harm honeybees and other pollinator species.”

“People can sometimes be insect-averse, but beneficial insects are really very important for our food supply,” Lamb said. “In field situations, the biocontrol is going on for free and helping limit pest damage. In greenhouse production, it’s important for us to study how to replicate that benefit, and it’s important for us to tell growers and consumers why we’re doing it. These bugs are one more tool in our toolbox. They’ve been doing this kind of work for us for centuries, we just need to help them do it.”


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