Almost every pest organism, from weeds to rats, seems able to develop resistance to chemicals used to kill them. Yet honeybees seem unable to resist the chemicals said to be contributing to their decline. Why?
鈥� One reason why organisms are deemed to be pests is their rapid rate of reproduction. Big populations that reproduce quickly increase the likelihood of genetic mutations in their offspring and thus their capability of developing resistance. This is why bacteria are able to develop resistance to antibiotics.
Honeybees don鈥檛 share this feature. Only one female in a hive 鈥� the queen 鈥� reproduces, and the colony can be considered a functioning individual. In theory, resistance could evolve over decades with a large enough population of honeybee colonies, but that process would probably involve the death of well over 99 per cent of the hives. Better to ban the chemicals.
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David Muir, Edinburgh, UK
鈥� Some populations of flea beetle 鈥� an oilseed rape pest 鈥� to neonicotinoid chemicals. But unlike bees, every female flea beetle can breed.
Another difficulty is the relatively small number of gene lines in commercial honeybees, particularly in the US.
The genetic variation in honeybees in Europe is much broader, but the European Union took the view that banning the most disruptive and long-lasting pesticides was preferable to gambling that pollinators would develop resistance.
Paul Honigmann, Steeple Aston, Oxfordshire, UK
鈥� Most organisms eventually evolve adaptive strategies or structural changes to cope with an environmental challenge. But evolution operates over multiple generations. Introducing pesticides faster than bees can reproduce may cause population crashes or extinction.
Some hope can be found in 麻豆传媒 reports of neonicotinoid exposure. Despite impairments to things like navigational ability, bees aren鈥檛 always killed by these pesticides. They can even show a preference for flowers previously exposed to them. This could be evidence of adaptation.
Peter Holness, Bengeo, Hertfordshire, UK
鈥� This might be a case of selection bias. The honeybee is one kind of organism, whereas 鈥減est鈥� refers to a large collection of varied organisms. There will be pest species that died out unnoticed in response to pesticides and a few very noticeable ones that developed resistance. Bees are only one kind of organism, and a very useful one too, so stand out in not developing resistance.
Perry Bebbington, Kimberley, Nottinghamshire, UK
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