Are The Populations Of Bees & Butterflies Declining?
Dr. Chandre Dharmawardana
There are always intermittent reports and circulation of petitions about the loss of bee populations, butterfly populations, fire-fly populations etc and evident environmental damage. These reports are never accompanied by entomological surveys of insect populations and other relevant data.
Instead, it will claim that the reader in his/her childhood days saw many butterflies, bees and fireflies, while today this is not the case. Of course, many people who had a rural childhood live today in crowded urban jungles enmeshed with roads choked with traffic. Why would they expect to see butterflies in a concrete jungle?
According to a comprehensive review article by Prof. David Goulson (Fellow of the Royal Society and Professor at the University of Cambridge), and his colleagues, the honey bee populations in the world have INCREASED by 40% over the last decade.
See the research article in the famous journal “Science”, published by the American Association for the Advancement of Science: Science. 2015 Mar 27;347(6229):1255957.
What has decreased is the population of WILD BEES. Some species of butterflies (e.g., Monarch butterfly) have also decreased due to the removal of specific flowering plants (Milkweed or “Varaa” in Sinhala,) due to urbanization and cutting down of forest.
1. This loss of wild bees is mostly due to LOSS of HABITAT due to people felling forests and building houses and roads. This reduces the amount of forest and bush available for wild bees, butterflies and indeed all flora and fauna. Even the elephant population in the Sinharaja has now been reduced to just two elephants – this is NOT due to glyphosate or pesticide use.
Haphazard urbanization should be stopped, and the existing Forests must be preserved and forest cover MUST BE increased. Roads passing through forest reserves must NOT be build. Much of waste farmland should be returned to forest instead of dredging and building houses. But even the Wilpattu has been razed for building human habitations, ostensibly for “war-displaced Muslims”.
2. Furthermore, human populations and urbanization help the growth of parasites which harm bees. The noxious fumes from motor vehicules, diesel engines, farm tractors, electronic and mining industries, coal-power plants etc., burning of garbage, increased particulate dust are vital factors producing extreme environmental stress on bees and butterflies.
3. The excessive use of pesticides has also been mentioned, but The chief entomologist of the primary agricultural Research institute in Britain (Rothamstead Research Inst.) has stated that there is no clear evidence that
no-necotinoids are a cause of wild-bee decline.
Glyphosate acts on green plants, and have no direct impact on fauna, insects and other zoo-species. In fact it is known to encourage the growth of soil microbes, earthworms etc. Its impact is only on plant-species as the mode of action of glyphosate is to interfere with photosynthesis (i.e., living species having chlorophyll). Bees don’t have chlorophyll and are unaffected by glyphosate.
Such herbicides are used to control weeds and this may lead to a reduction of some weeds useful to wild bees. But usual planted species (e.g., tomatoes, tea bushes) also provide flowers that are valuable to wild bees and so there is a compensating effect as long as flowering plants are used in farmlands which often tend to be mono-cultures (e.g., vast extensions of corn fields).
