Why are bees disappearing? This conundrum has continued to baffle scientists for decades, and there is still no adequate explanation regarding the matter.
The honeybee industry makes up NT$2.3 billion of Taiwan's annual output value, and bee pollination indirectly contributes NT$20 - 30 billion to the nation's overall agricultural production each year. This is just in Taiwan, so imagine the widespread threat that the decline in bees poses globally.

To address the problem, researchers from the Department of Entomology, Department of Bio-industrial Mechatronics Engineering, Department of Electrical Engineering, and the College Bioresources and Agriculture formed an interdisciplinary research team, which after seven years of collaborative effort, announced its important findings at a press conference on April 14.

Previous studies have confirmed that the use of insecticides has led to the mass disappearance of bees, a phenomenon known as Colony Collapse Disorder. Building on this premise, Prof. En-Cheng Yang of the Department of Entomology led the research team in focusing on the relation between bee behavior and an insect neurotoxin known as imidacloprid, a common substance in nicotine insecticide. According to the findings, neurological changes in the insect's learning ability, rather than its high fatality rate, which had been the focus of previous studies, are the main cause for this large-scale disintegration of the ecosystem.

Aiming to gain a fuller understanding of how imidacloprid influences bees, the team found that when a worker bee ingests 50 ppb (parts-per-billion) of the neurotoxin, it instantly loses its ability to return to its hive, affecting the colony's ability to reproduce. As the dosage increases, the number of affected bees also grows.

However, when the same experimental model is applied to the larvae, an astonishing result occurs. According to Prof. Yang, imidacloprid has little effect on a larva's fatality rate, even when dosages that are fatal to imago (adult) bees are applied. Although the larva is still able to go through capping, pupa, and metamorphosis, dosages of as little as 10 ppb can affect the larva's learning ability after metamorphosis. In other words, Prof. Yang's research shows that the affected bees have not mysteriously disappeared; they have simply gotten lost as a result of neurological degeneration of their learning abilities and cognitive capacities.

This conclusion is of great significance as it offers the first proof that imidacloprid has a detrimental effect not only on bees but also on larvae. Additionally, the research further substantiates how imidacloprid residue of as little as 10 ppb can damage a bee's neurological system, which in turn, is the likely cause behind the bees’ mass and rapid decline.

A special tracking device was created for the experiment, and interdisciplinary efforts were put into the design, construction, and operation of the equipment. Prof. Ta-Te Lin of the Department of Bio-Industrial Mechatronics Engineering combined laser track-mark technology with an image recognition system to help track the bees' activities, while Prof. Huei Wang of the Department of Electrical Engineering provided his expertise in radar and other advanced tracking technologies.

Prof. Joe-Air Jiang, also from the Department of Bio-industrial Mechatronics Engineering, used infrared technology to monitor the colony's activities and the bees' locations in order to maintain accurate experimental records. Prof. Yuan-Tay Shyu of the College Bioresources and Agriculture also played an essential role over the course of the research project.

The team's findings, which confirm that non-lethal doses of insecticide also affect adult bees, have garnered widespread attention in the international community. The team's reliance on interdisciplinary collaboration and cutting-edge technology also offers a novel approach to the study of bees around the globe. NTU will continue to investigate this problem in order to contribute to the maintenance of ecological balance.