New research suggests that dogs might be able to help save diseased citrus trees.

A group of scientists trained dogs to use their sense of smell to detect a crop disease called citrus-greening. The disease has affected orange, lemon and grapefruit trees in the American states of Florida, California and Texas.

The dogs can detect the disease weeks to years before it appears on tree leaves and roots, the researchers report. A study on their findings was published recently in the Proceedings of the National Academy of Sciences. The report says using dogs is also faster, less costly and more exact than having people collect hundreds of leaves for lab analysis.

Timothy Gottwald is a researcher with the U. S. Department of Agriculture and a co-writer of the study. He told The Associated Press, “This technology is thousands of years old-the dog’s nose. We’ve just trained dogs to hunt new prey.”

Citrus-greening is caused by a bacteria (细菌) that is spread by a tiny insect that feeds on the leaves and stems of citrus trees. Once a tree is infected (感染), there is no cure. The disease has also hurt citrus crops in Central and South America and Asia. In one experiment involving grapefruit trees in Texas, trained dogs were correct 95 percent of the time in telling the difference between newly infected trees and healthy ones. “The earlier you detect a disease, the better chance you have at stopping an epidemic (流行病) by removing infected trees,” Gottwald said.

Matteo Garbelotto studies plants at the University of California, Berkeley. He says the new research shows that dogs can detect an infection well before current methods. Garbelotto has been involved in similar research but had no part in the new study.

Laura Sims is a plant scientist with Louisiana Tech University. She praised the steps taken to find out if the dogs were detecting the bacteria itself or a plant’s reaction to an infection. To do that, the researchers infected different kinds of unrelated plants with the bacteria in a laboratory. The dogs were still able to pick out the infected plants.

Gottwald said, “You’ve seen dogs working in airports, detecting drugs and explosives. Maybe soon you will see them working on more farms. ”

GPS has completely transformed how we get around. But other animals have long had their navigation (领航) systems built right in.

“We know their eyes are quite sensitive to polarized (偏振的) light and the sky has a particular pattern of polarized light relative to the position of the sun,” Barbara Webb, a researcher at the University of Edinburgh, says.

You can see polarized light firsthand if you take a pair of polarized sunglasses and spin them against the sky-the light passing through the glasses changes. Webb says the insects have polarization like that built into their many eyes. “You can think of it as having lots of sunglasses pointing in different directions.”

But Webb was curious whether there’s really enough information in the sky to give insects an accurate sense of direction. So her team built a sensor (传感器) modeled after a desert ant eye and put it under artificial light meant to simulate the sky. They then put that sensor into a model meant to model the brains of desert ants and other insects. And they found that with the insects’ sensing and processing equipment, they can likely sense direction down to just a couple degrees of error.

A system based on that of insects could someday be a cheap, low-energy choice to GPS. Insects have very tiny brains. A brain the size of a pinhead that’s using hardly any energy. And yet they’re still able to navigate better than we can with GPS, which is surprising. Webb is now working on building a robot that can use light to get its directions.

Individual innovation is considered one sign of intelligence within species, and elephants are among the animals that researchers have long taken an interest in because of their approach to problem solving. A newly published study in the journal Animal Behaviour details findings from a six-month-long study documenting the abilities of individual wild Asian elephants to access food by solving puzzles that unlocked storage boxes.

“This is the first research study to show that individual wild elephants have different willingness and abilities to solve problems in order to get food,” said the study’s lead author Sarah Jacobson. “This is important knowledge, because how animals think and innovate may influence their ability to survive in environments that are rapidly changing due to human presence.”

Conducted at the Salakpra Wildlife Sanctuary in Kanchanaburi, Thailand, the study used motion-activated cameras to observe 77 wild Asian elephants who approached and decided whether to attempt opening puzzle boxes with three different compartments (隔间) that contained their favorite fruit—jackfruit. Depending on the compartments with which the elephant interacted, the jackfruit could be accessed by pulling on a chain so the door opened toward the elephant, pushing the door so that it swung open into the box, or sliding the door open to the right. The elephants had to independently interact with the puzzle boxes to discover how the compartments could be opened.

Over time, 44 of the elephants who approached the puzzle boxes interacted with them, but there were individual differences in how innovative the elephants were. The researchers found that elephants who interacted with the puzzle boxes more frequently and with greater persistence were more successful in getting food from all three different compartments.

“Conflict involving humans and elephants is increasing due to loss of natural habitat and agricultural encroachment into what is left of it, ” said the study’s principal investigator Dr. Joshua Plotnik, a psychology professor with the CUNY Graduate Center and Hunter College, and Sarah Jacobson’s dissertation advisor. “Investigating innovation and problem solving in elephants can inform our understanding of wild elephants’ cognitive flexibility and its potential impact on conservation management and human-elephant conflict mitigation.”