Here we go again: as has already happened in the last four years, the estimates made on 15% of American beekeepers speak of a death of bee colonies around 30% in the winter season just past. A fact that worries and keeps the debate on the hive depopulation syndrome high (in English Colony Collapse Disorder, CCD) but which, at the same time, sounds like a confirmation for those who attribute most of the responsibility to the use of neonicotinoid insecticides in tanning of corn seeds (where the practice has been suspended – as in Italy – the phenomenon has no longer assumed the dimensions of the serious crises of recent years).
The US study was conducted by the US Department of Agriculture together with the Apiary Inspectors of America. More than 5,500 beekeepers were interviewed who care for about 15% of the country’s total hives, where there are about 2.68 million colonies. 31% of those questioned replied that between October 2010 and April 2011, they had lost a very significant part of the colonies (with percentages reaching 60%) without having found dead bees in the hive, or that they had encountered the depopulation syndrome (CCD). The other hives had less losses equal to about 30% of the colonies. A loss of 13% of colonies is generally considered acceptable, but more than six out of ten beekeepers said they lost many more.
The figure appears even more dramatic if compared with those of recent years: in the winter of 2007/2008 the loss was, on average, 32%, in 2008/2009 by 29% and in 2009/2010 by 34%. The substantial stability, the authors commented, is a very small consolation: it demonstrates that the situation has not worsened further, but also that the solution to the problem is far away.
Numerous hypotheses have been called into question on the causes of the slaughter of bees in recent years: climate changes, genetic variations in parasites, bacteria, fungi affecting bees, the appearance of new viruses, magnetic fields, bee stress caused by displacements, hormonal shifts and much more.
But the only idea supported by the facts is the one proposed above all by Italian researchers, namely the advent of neonicotinoids in the tanning of seeds and, in particular, of those of corn.
To understand where Italy is at, Ilfattoalimentare.it asked a few questions to Andrea Tapparo, associate of chemistry at the University of Padua and author of important studies on the subject, two of which are forthcoming.
Professor Tapparo, first of all what is the state of health of Italian bees?
«Good, I would say, because since 2009, the year of the introduction of the suspension on the use of neonicotinoids, we have no longer had the spring death that we had recorded since the early 2000s. Today the situation is under control and the bees are doing well ».
What evidence is there to support the responsibility for neonicotinoids in CCD?
“There are some of a different nature. First of all due to the ways in which the death of bees occurs: it occurs suddenly, usually one or two days after it is sown with tanning, a fact incompatible with infections of any nature, which require several days before leading to death and are however detectable, while so far nothing infectious has emerged. Then there is the counter-proof obtained with the suspension: since the use of tanning neonicotinoids is no longer permitted, there have been no more mass mortality phenomena in Italy. In this sense, the data of Apenet are impressivein 2010: there was not even a report of impoverishment or death, compared to 185 in 2008. The same is happening in other countries that adopt similar measures, such as the Land of Bavaria and Slovenia: as soon as you stop using these compounds , the mortality rates of bees return to expected averages. That said, there is no doubt that factors such as those induced by climate change can also play a role, even if none of them seem as important as that of tanning with these substances ».
How is intoxication determined?
«According to various studies, some carried out by us, the neonicotinoids are dispersed in the air at the moment of sowing; the dust remains attached to the integument (the external covering fabric) of the bees and being soluble it is gradually absorbed and accumulates until it causes lethal intoxication within a few hours. This also explains why there are no dead bees in the hives, but there are many around the fields where it is sown in this way: the insects are unable to return to the hive, they die sooner. The idea that bees could drink the neonicotinoids from the small drops of sap secreted by specialized leaf openings, proposed some time ago, seems less plausible, first of all because the times do not coincide (the dying occurs at the same time as sowing, not a few weeks after,
In Italy for now there is only one suspension, which has already been extended and which is about to expire. What do you expect for the near future?
«It is not easy to understand, also because we are already the second minister after Luca Zaia, who had accepted the requests of beekeepers and invested in research projects, establishing Apenet and authorizing the suspension. The hope is that the temporary arrangement will result in a real ban, despite the very strong pressure to the contrary from the large chemical multinationals and corn farmers. We will see, but the American case – remember that California had to import bees from other countries because it was no longer able to have the necessary pollinations of almond and plum trees – should make us reflect on the fact that there is not only the production of honey at stake, but the whole ecosystem, and that the potential damages caused by impoverishment of the hives are enormous, much higher than those of the renunciation of tanning ».