PESTICIDES TOXIC TO HONEY BEES





Anyone growing edible produce in their garden will know how important our native bees are in maximizing yields through cross pollination. However using systemic insecticides on any flowering plants can have catastrophic effects on local bee populations. Over the years the government has removed licensing for many of these indiscriminate products, but one that still remains is ‘Provado’ which notably contains the active ingredient Imidacloprid.

Provado is predominately marketed as a vine weevil killer, but will kill most insects that ingests it. What makes it worse is that it can remain active within the plant for up to three months at a time on a single application. However, when applied as a soil drench, Provado 'Vine weevil Killer 2' is an even bigger threat by remaining viable in the plant for up to four months.

This lethal chemical is believed to be one of the factors in Colony Collapse Disorder in bee hives as it can be absorbed into both the nectar and pollen. Once collected, the contaminated nectar and pollen is taken back to the hives and passed on through the food chain killing yet more bees. With this kind of chemical progression and length of viability, it doesn't take long to exterminate an entire hive.

If the chances of a bee collecting pollen from a contaminated plant were the result of random searching, then perhaps there wouldn't be so much concern. Unfortunately research from both Greenwich University and University College London show that bees have a far more complex system of identifying and locking on to local nectar producing flowers than previously thought. Like humans, bees are sensitive to light at three different wavelengths (trichromatic). Also like humans, they can recognise the colour of objects such as flowers even when their illumination changes (so-called colour constancy).

Dr Beau Lotto and Dr Martina Wicklein at the Institute of Ophthalmology have also shown that bees can identify a particular flower among a grid of 64 flowers when each is set on a black background. This is even possible when they are illuminated under four spatially distinct lights. This shows us that bees' colour constancy abilities seem to hold true even in situations more complex then they would expect to encounter under normal field conditions. This enables bees' to easily identify a specific plant species solely from its particular colour shade. Combined with their unique 'waggle dance' which is used to inform other worker bees the direction and distance of nectar rich grounds, you can easily end up with many worker bees from the same hive visiting the same patch of contaminated flowers day after day after day.

With disturbing research such as this becoming ever more common place, the practice of gardening organically has never been so important. But more significantly, it carries strong evidence as to why the licences for Imidaclprid and any other similar product should be revoked.
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