Is Kangkuan insecticide harmful to bees? Can it kill bees?

Insecticides cause disaster, and large numbers of bees die from acute poisoning. Watching the Western honey bees, golden yellow all over and covered in fuzz, fall to the ground one by one, twitching and no longer able to fly up into the sky, the beekeeper surnamed Xiao, who keeps more than two hundred hives in Dashu, Kaohsiung, also appeared helpless.

Only after pressing further into the cause did the beekeeper surnamed Xiao point out with some agitation, "These are the typical symptoms of pesticide poisoning." After poisoning, the bee colonies not only became violent and prone to stinging the beekeeper, but their death toll also increased by thirty to forty percent compared with before, almost a "carpet-style death." And the reason such a "massacre" happened at his location may have been that the longan orchard nearby sprayed large amounts of insecticide to control the recently rampant lychee stink bug. Kangkuan insecticide is one of them.

Severe death disasters broke out repeatedly, triggering dissatisfaction among beekeepers, who then demanded that the Bureau of Animal and Plant Health Inspection and Quarantine, the agency chiefly responsible for pesticide management, take responsibility. After coordinating with the Miaoli District Agricultural Research and Extension Station to further send personnel to sample and test Western honey bee corpses, it was found that insecticides such as fipronil, fluvalinate, chlorpyrifos and carbaryl were indeed the cause. Bees that came into contact with or ate crops sprayed with excessive pesticides then died from "acute poisoning."

Unable to wait for the bees to come home, large numbers disappear and lose their way.Although the test results set the conclusion, at the same time the bee colonies displayed another abnormal behavior. Beekeeper Xiao Hongchi in Nantou found that at first nearly more than a quarter of his two hundred hives never returned to the nest after going out, and several weeks later the number of bee colonies inexplicably fell by half.

"In the evening, you really cannot wait for them to come home," said Pan Jianming, secretary-general of the Taiwan Beekeepers Association, after collecting the shared observational experience of dozens of beekeepers. He also pointed out that in recent years beekeepers have successively found that their bees go out in the morning to work and collect nectar, and by the time before sunset in the afternoon, inside a hive that originally had ten combs and housed more than thirty thousand Western honey bees, the number of bees had sharply dropped to about ten thousand. No corpses could be found outside the hive, and it was unknown where the bees had actually gone, as if they had been subjected to a "mass kidnapping."

National Taiwan University research found that the pesticide imidacloprid causes "chronic poisoning" and affects bee neural development.Not only do bee colonies disappear, Pan Jianming also said that among hundreds of hives of Western honey bees, a certain proportion of colonies will also "become stupid."

Western honey bees that originally could rely on the "waggle dance" to transmit information and survive and work according to specific behavioral patterns would instead forget how to collect nectar among the flowers, and their flight trajectories would also become crooked and askew, as if they had been "possessed" and lost their ability to survive. But beekeepers had been puzzling over the cause all along, until National Taiwan University scholar Yang Encheng's research on the pesticide "imidacloprid" was formally published, which made everyone suddenly "see the light."

Yang Encheng, a professor in the Department of Entomology at National Taiwan University who specializes in bee behavior research, confirmed in a 2014 study that "even if imidacloprid is at an ultra-low dose of only 1 microgram (ppb), it can affect bee neural development." Although the dose of imidacloprid ingested by larvae is not lethal, during the growth period the bees' learning and memory abilities are severely damaged, amounting to "chronic poisoning."

He further explained that during the experiment, bee larvae were fed imidacloprid, and after they emerged as adults they were dissected. The results found abnormalities in the "mushroom body," which governs memory and learning ability in the bee brain. Imidacloprid clearly affected the number of synapses connecting nerves beside the mushroom body, causing problems in the transmission of signals received by the compound eyes and antennae, and consequently affecting the formation of memory. "Although it cannot be seen during the larval stage, after emergence the memory and learning ability collapse."