Honeybees Get Lost After Eating Pesticides: How to Detect It? National Taiwan University Pioneers Tattoo Technique
Human tattoos are nothing new, but tattooing a bee less than one centimeter long is high-level technical work, and the world's first tattooed bee is in Taiwan, China!
In recent years the world has been troubled by the mysterious disappearance of bees, and many scientists believe pesticides are the culprit. To study the link between the two, National Taiwan University entomology professor Yang En-cheng pioneered a bee "tattoo" technique, combining the infrared and network transmission systems commonly used by the military to track bees fed the pesticide imidacloprid, and found that they actually became "lost," unable to find their way home, and did not even know how to feed on sugar water, overturning the previous thinking of using lethal doses to measure pesticide toxicity.
Worker bees exposed to pesticides cannot find their way home
Bees are humanity's good partners; one third of the world's crops rely on them for pollination, and in the United States alone the annual value of crops pollinated by bees exceeds 15 billion US dollars. But since 2006, mysterious bee disappearances have been reported one after another in North America and Europe, raising fears of a food crisis. Amid global shock, several scientists have pointed out in their research that after long-term exposure to neonicotinoid pesticides, bees show abnormal behavior and even cannot find their way home, which may be the main cause of this wave of colony collapse disorder (CCD), and Public Television Service also took this as its subject and produced the documentary "The Mad Bee."
A typical phenomenon of CCD is the disappearance of worker bees carrying honey, leaving only the queen and immature young bees in the hive, and the entire colony system falls into disorder and collapses. Although Taiwan, China has not seen typical CCD, cases of mass bee deaths have also been reported in recent years.
To unravel the mystery, National Taiwan University entomology professor Yang En-cheng began four years ago the study "Effects of Non-lethal Doses of Imidacloprid on the Olfactory Behavior of Honeybee Workers," setting up 30 hives at National Taiwan University's Ankang Farm and feeding the bees the pesticide imidacloprid at concentrations of 10 to 50 parts per billion. The result was that the bees actually became "lost": whereas the round trip between the feeder and the hive box originally took only 5 minutes, 15% of bees that had eaten 50 ppb imidacloprid took longer for the round trip; when the concentration increased to 600 ppb, 34% of the bees could not find their way home; some bees even "forgot" the instinct to extend their mouthparts when they smelled sugar water.
Imidacloprid is a new neonicotinoid pesticide, a systemic pesticide usually used by farmers to soak seeds or sprayed directly on the soil, so the entire plant absorbs it, effectively controlling pests; it has risen in the market in recent years, but experiments including Yang En-cheng's, along with many international studies, have confirmed that imidacloprid makes bee colonies dumber, causing them to lose their sense of direction and communication ability, and it is listed alongside two other neonicotinoid pesticides on the EU's banned list.
Yang En-cheng said with even greater concern that even if worker bees do not die after collecting pollen containing pesticides, the pollen they carry back may still affect the more fragile young bees in the colony. "In the past people always thought about pesticide toxicity in terms of lethal doses, but more and more scientific evidence shows that pesticides considered low-toxicity, although they will not directly kill bees, will have long-term effects on bee colonies."
Nearly 90% of pollen samples test positive for pesticides
Besides the chronic effects of pesticides, acute poisoning is also a major crisis for bees in Taiwan, China. A beekeeper in Yilan who had been in business for more than 60 years saw his bees plummet by more than 90% last year, with more than 3 million dying. Chen Yu-wen, director of the Department of Biotechnology and Animal Science at National Ilan University, performed dissections and found that pollen remaining in the bees' midguts contained pesticides, and inferred that they likely died of pesticide poisoning.
In a research project funded by the Bureau of Animal and Plant Health Inspection and Quarantine of the Council of Agriculture in 2012, Chen Yu-wen collected 41 pollen samples from across Taiwan, China, and only 5 tested free of pesticides; a pollen sample from Lugu Township in Nantou even tested positive for 14 pesticides at once. Among them, fluvalinate, a pesticide farmers use against the bee parasite "Varroa mite," had the highest detection rate at 65.9%, and the insecticide chlorpyrifos ranked second at 61.0%, clearly showing that contamination does not come only from external pesticides; the fluvalinate sprayed by beekeepers on the combs may also poison the bees.
However, Chen Yu-wen said that honey is water-soluble while pesticides tend to be oil-soluble, and the doses of these pesticides are not high, so they do not remain in the honey.
Although the link between pesticides and bee disappearance is extremely high, it is not a single factor. Chen Yu-wen said that climate change, rampaging Varroa mites, and pesticides weakening the bees' constitution combine to cause the sharp decline in bees, and unlike other countries Taiwan, China does not use helicopters for large-area sowing and pesticide spraying, so what form bee poisoning takes still awaits further research.