Viruses, the main cause of bee mortality

“Bee mortality has never been higher than last winter, says Philippe Lecompte, professional beekeeper of the Marne and president of the Biodiversity Network for Bees (RBA). Contrary to popular belief, plant protection products, and in particular neonicotinoids (NNI), are not responsible for this unparalleled mortality. The development of virus populations is the main cause. »

60 lethal viruses are permanently present in a hive. Beyond a certain threshold, the bees’ immune defenses are no longer sufficient to deal with it. They develop pathologies and weaken until they die. Philippe Lecompte does not understand. «For more than 10 years, scientists have been warning of developing viral populations and their devastating consequences, but no one wants to hear it.

The beekeeper believes that scientific knowledge is difficult to disseminate to beekeepers. Only 12% of them think viruses are a problem for hives, according to ANSES. “Unfortunately it is too little, complains Philippe Lecompte. We are in denial. We need to change our reasoning and have another vision of beekeeping and its problems.”

Warnings about hives that are not new

Since the 1980s, several exotic parasites have colonized France, including the varroa mite. They represent real doors open to viruses. In France, bees have not evolved with these parasites, which explains their difficulty in protecting themselves from them. “A virus multiplies intensely, which undeniably leads to genetic multiplication errors and the development of new strains”, explains the beekeeper. Direct and indirect transmitter, varroa recombines viruses and amplifies their pathogenicity. This creates competition between viruses and the hosts that fight them.

“We are witnessing a real viral problem that deserves to be explained to beekeepers and fought by them”, warns Philippe Lecompte. He is offended to note that in the last two years many publications have focused on the deformed wing virus (DWV virus), transmitted by the varroa mite. At low levels, this causes severe disturbances in the bees’ spatial orientation and nervous system. “We still have little knowledge yet the alert on this topic of virology has existed since the 80s and has been amplified since the 2000s! Today, almost 30% of the beekeeping research budget goes to varroa control. But nothing is planned to study the consequences of viruses and their devastating effects on bee health.

The remaining 70% of the budget is intended to finance studies on the impact of plant protection products on bee mortality. “This research is highly publicized. It is therefore easy to understand why plant protection products (NNI, SDHI and even glyphosate) cause such discontent among beekeepers, protests Philippe Lecompte. Plant protection products are the scapegoat of beekeeping when there is no scientific evidence that they are responsible for the massive and recurrent mortality of bees. Sure, laboratories are capable of measuring a tiny concentration of plant protection products in beehives. But what about its effect on the health of the hive?

For the professional beekeeper, the use of techniques such as mass spectrometry would allow the presence and impact of viral attacks and other stressors to be determined, in order to anticipate problems related to the health of the hive. “We need to invest in this extremely promising new technology, explains the beekeeper. This is one of the conditions to get out of the conflicting debates between agriculture and beekeeping”.