NTU says insecticide residue contributing to bee disappearance
By Joy Lee ,The China Post
April 15, 2014, 12:01 am TWN
TAIPEI, Taiwan -- Research shows that imidacloprid (益達胺) residue is a major contributor to colony collapse disorder in which worker bees from a beehive abruptly disappear, National Taiwan University (NTU) announced yesterday.
After seven years of research, NTU said, it finally discovered that imidacloprid, a type of insecticide that acts on the central nervous system of insects with much lower toxicity to mammals, damages worker bees' abilities to fly back to the beehive.
According to NTU's research, once bee larvae are affected by imidacloprid, even just low doses of it, they will lose the ability to learn and memorize, which results in colony collapse.
NTU entomology professor Yang En-cheng (楊恩誠) said that imidacloprid works by interfering with the transmission of stimuli in the insect nervous system.
"Through the experiences, we discovered that worker bees fly back to the beehive within 300 seconds after harvesting nectar," said Yang. "However, after feeding the bees sugar water containing 40 ppb of imidacloprid, bees stopped flying and they kept using their antennas to scratch their eyes, acting as if they are uncomfortable."
Yang said that according to many international research papers, the more imidacloprid that the bees consume, and the more bees will be affected by it.
According to the NTU's research, Yang said, if the dose of the imidacloprid is increased to 2,000 ppb, the bee larvae can at least survive. However, Yang said, after they are affected by 10 ppb of the imidacloprid, they lose the ability to harvest nectar or to fly back to the beehive.
"Even just a small amount of imidacloprid will contribute to colony collapse disorder," said Yang. "Therefore, it will require cooperation between different academic fields to do more research on colony collapse disorder by tracking and monitoring bees' activities."
Yang said that except for imidacloprid, all types of insecticides can result in poisoning of the bees.
"In the 1980s, imidacloprid began to be considered as a safe insecticide that brought no harm to mammals," said Yang. "However, imidacloprid acts on the central nervous system of insects and invertebrates."
Bureau of Animal and Plant Health Inspection and Quarantine Deputy Director Feng Hai-tung (馮海東) said that over 500 tons of imidacloprid is used annually on rice crops, fruit trees and vegetables.
Even though the European Union banned the usage of imidacloprid last year, Feng said Taiwan has no plan on taking the same action to ban the usage of imidacloprid at present.