Anne Murray: Chocolate flies, honey bees, and the not-so-sweet story of pesticides
Did you know that a small fly, the size of a pin head, is responsible for the existence of chocolate? By pollinating cacao plants, tropical Ceratopogonidae midges ensure seeds are set and chocolate can be produced. These midges live their entire life cycle in less than a month, yet without them we would be denied a lifetime of the most delectable taste sensation ever discovered. Food, fibre, and spice crops need insect pollinators to set seed, and pollination is worth billions of dollars to the world’s economy. But we seldom pay attention to insects, until bitten by a mosquito or stung by a wasp.
For farmers growing crops on a commercial scale, doctors fighting malaria in the tropics, or gardeners irritated by aphids, insect control is big business. Because of this, the 20th century saw the start of a universal war on insect life, with disastrous results for the natural environment. Insects make up 80 percent of animal life (the remaining 20 percent is mostly other invertebrates) and the Earth’s biosphere cannot function without them. From honey bees to monarch butterflies, many insects and the food chains they support are in trouble. It is time for us to pay attention.
Neonicotinoid insecticides (also known as “neonics”) are hitting the headlines for their suspected impact on bee populations. The latest study shows that honey bees affected by neonics fail to return to their hives. As reported in the journal Functional Ecology, researchers Nigel Raine and Richard Gil used tiny bee tracking devices, each weighing just two micrograms, to determine that neonicotinoids inhibited the bees’ ability to learn navigation, an essential skill for these pollinator insects. Any disruption to their directional abilities could ultimately lead to colony collapse. The study augments previous scientific findings that neonics are bad news for the ecosystem as a whole, even as they are lauded by industry as a much safer alternative to the previously popular carbamate and organophosphate insecticides.
Canada’s federal Pest Management Regulatory Agency is reviewing neonics’ regulation but conclusions may take until 2018. This is troubling given the new information that is emerging. Only 20 years after they were first approved, neonics have become the most widely used pesticides in the world. They are pre-applied to North American agricultural seeds, such as soy, corn, and canola. Their effect may be much more detrimental to other wildlife than originally thought. The State of Canada’s Birds report showed that many insectivorous birds breeding or migrating through the agricultural heartlands of North America have declined dramatically in the last decades.
The global history of pesticide use is one of wild optimism on the part of inventors, manufacturers, and users, often followed by doubts, denial, and bans. DDT, the most famous organochlorine pesticide, was hailed as a miracle and sprayed on crops and suburbs. Paul Muller was even awarded the Nobel prize in 1948 for its discovery. DDT’s role in killing mosquitoes, the transmitters of many serious diseases, was particularly welcomed. So much so, that trucks sprayed urban streets with a DDT fog in the 1950s, and children ran along behind the cool jets of water. Rachel Carson’s book, Silent Spring, sounded the alarm in 1962. A biologist, she recognized the widespread impact the death of insects was having on birds and the ecosystem. An unrealized aspect of DDT, its concentration up the food chain, was also being noticed, as were its effects on human health. Birds, fish, and crabs were all accumulating the organochlorine in their bodies, and DDE, a breakdown of DDT, even showed up in human breast milk, miles from the application areas. Ten years after Silent Spring was published, DDT was banned for use in North America.
The next generations of insecticides through the 1970s and 80s were carbamates, organophosphates, and synthetic pyrethroids. Carbofuran, a carbamate, was widely used on potatoes, corn, and soybeans, but it too is now widely banned. This compound not only killed insects but was also highly toxic to birds and mammals. A single grain could kill a bird, and prior to 1991, it caused many millions of bird deaths, directly and indirectly. Bald eagles died through eating affected carcasses. Furthermore, the pesticide acted by disrupting the endocrine system and hormones. One effect was to lower sperm counts in mammals, another red flag for human health.
Organophosphates, including malathion, parathion, and diazinon, were used for mosquito eradication, and agricultural and home garden herbicides and insecticides. Because they degrade faster on exposure to air than did DDT, they became a popular choice and were seen, for a while to be more environmentally friendly. However, these highly toxic substances inactivate nerve function in all animals, including humans, and they were proven too dangerous for continued use. Eventually many jurisdictions, including the U.S. Environmental Protection Agency, banned or limited their application.
Synthetic pyrethroids were introduced in the early 1970s. These insecticides have a very high lethality for bugs and also entered water courses where they wiped out all invertebrate life for miles around. They may have played a key role in the widespread decline of insect-eating birds, such as flycatchers and barn swallows, populations of which have plummeted in the last 40 years.
Neonics are the latest great hope for eliminating insect pests, yet they too carry the spectre of environmental destruction. What can we do? In B.C. we are less impacted than many intensively agricultural areas. Only three percent of our province is arable, and Lower Mainland farmers are relatively light users of pesticides. Many Delta vegetable farmers, for example, use integrated pest management as a means of controlling unwelcome insects on their farms. Natural alternatives, such as the use of beneficial insects, are encouraged in hedgerow planting programs by the Delta Farmland and Wildlife Trust. Organic vegetable and berry growing is on the rise throughout B.C. and consumers have many more choices in the supermarket.
We are often inspired to conservation action for large, dramatic animals. Now it is time to extend that care of nature to the world of insects which, though small, are absolutely vital to life on Earth. Insects are pollinators, garbage disposers, recyclers, and food for many other species. While some spread diseases, many more spread life. The implications of pesticide use are profound for humans and the world’s ecosystems.
We can make our voices heard in many ways: buying organic produce, eliminating home pesticide use, and supporting local initiatives to enact cosmetic pesticide bylaws. Many progressive municipalities around Canada have eliminated unnecessary, non-agricultural use of insecticides and stopped hazardous spraying in suburban parks and gardens. We can also request action from politicians and agencies, to protect our health and that of the environment. As well, it is worth taking time to really look at some of our local insects: they are pretty marvellous creatures. I am doing that this summer: pictures of a few of them are in my latest blog post at www.natureguidesbc.wordpress.com.