Using lasers, Legos and an algorithm based on a classic spy trick, scientists have created a sensor that can instantaneously classify the insects that fly past it.
The invention offers a powerful and cheap new strategy for quickly identifying infestations that threaten agriculture and human health. Among other applications, the technique could lead to more targeted attacks that would reduce the load of pesticides needed to squelch invasions.
Encouraged by good results in the lab, entomologists are now beginning to test the system in places like Mali, where a massive search has yet to determine exactly where malaria-carrying mosquitoes hide out during the dry season.
"This has the potential to save lives and crops," said Eamonn Keogh, a computer scientist at the University of California, Riverside. "My feeling is that in the next year or two, there will be a lot of applications for this."
Every year, insects kill millions of people by transmitting diseases, and they destroy more than $40 billion of food crops. For nearly 70 years, scientists have been looking for efficient ways to detect infestations as soon as possible to mitigate the damage, but they've repeatedly run up against roadblocks.
Many previous attempts to create automated insect detectors have attempted to use sound to identify insects, but acoustic microphones are limited by distance. The farther away a flying critter is, the less volume a mic will pic up, making the technique useless unless insects fly right in front of the system.
Instead, current methods for surveying insects have remained inefficient and laborious. Scientists often set out sticky-paper traps and then send someone out every week to check and identify what has landed on the paper. Some insects only live for a week or two, so by the time the technician arrives, it may already be too late to beat the infestation. It's also easy for human eyes to make mistakes because so many species look extremely similar to each other.
In search of a better system, Keogh and colleagues turned to a classic James Bond-style spy trick. When a person standing near a glass window speaks, he explained, the glass vibrates. If you want to eavesdrop, you can shine a light on that glass and use the vibrating reflections to interpret what is being said.
Like a spy detector, the new bug-sensing device shines a laser-thin line of light against a board that converts light fluctuations into sounds. These sounds get recorded as MP3 files, which can then be analyzed by a computer program.