How Farm Plants Can Call Carnivores To Kill Pests

Posted: Oct 5 2015, 8:39pm CDT | by , in News | Latest Science News


How Farm Plants can Call Carnivores to Kill Pests
This diagram shows how nectar can enhance the survival and efficiency of predators and thus allow the establishment of more stable populations of these biocontrol organisms. Credit: Stenberg et al./Trends in Plant Science 2015

Ladybugs are the insect helpers of hobby rose gardeners, but how can this organic way of killing pests scale to farming? Now scientists provide some solutions.

Hobby gardeners know how to leverage insects to protect their plants against pests. This works well at the small scales of a backyard garden, but how can this organic way of dealing with pests be industrialized?

Agricultural researchers in Sweden and Mexico argue that one way around the scalability problem is to bring back the odors and nectars found in wild plants that attract pest-eating predators. This could be done either through breeding programs or by using artificial devices.

"Wild plants commonly emit natural odors when they are damaged that attract natural enemies of pest insects--even as humans we smell it when our neighbor is mowing the lawn - odors can carry very precise information," says co-author Martin Heil of CINVESTAV-Irapuato in Mexico. "Agriculture has bred such defenses out of crops, and since these odors have no negative effects on human consumers, we want to replace what the plant would already be doing."

It's also not unusual for wild plants to produce nectar on their leaves to feed carnivores. While leaf-eating caterpillars or beetles are munching away on plant matter, predatory ants or wasps have a sugary substance to drink and a well-stocked spot to lay their eggs.

Heil and others theorize that the reason these rather helpful traits no longer exist in crops is because plant breeders and decision makers couldn't tell the difference between helpful insects and pests. 

Only in the past 30 years has it been recognized that plants use odors to communicate to one another and to other species. Such defenses involve multiple genes, however, and it won't be easy to simply bring them back.

This shows again that humans do not understand the full picture and scientific advances often have severe side effects.

One faster alternative would be to plant crops alongside other species that both attract carnivores and repel pests. 

The downside is that intercropping requires more work during harvesting and its success rate isn't 100%.

Another option is to create mechanical dispensers that could release carnivore-calling odors and fungicidal nectar, which is something Heil and his team are now developing and testing.

"New regulations and changing consumer demands are gradually improving the prospects for more sustainable agriculture," Heil says. "This provides a ready market if we can give crops back their own immune system, either by breeding, genetic engineering, or replacing the traits artificially." 

The results of the research have been published in Trends in Plant Science, Stenberg et al.: "Optimizing Crops for Biocontrol of Pests and Disease" 

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The Author

<a href="/latest_stories/all/all/2" rel="author">Luigi Lugmayr</a>
Luigi Lugmayr () is the founding chief Editor of I4U News and brings over 15 years experience in the technology field to the ever evolving and exciting world of gadgets. He started I4U News back in 2000 and evolved it into vibrant technology magazine.
Luigi can be contacted directly at




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