The honeybee crisis: paradoxical findings deepen the mystery

Vita urges beekeepers to become more proactive to prevent bee deaths. Beekeeping practices must change to ensure that honeybees survive and thrive, says Dr Max Watkins of Vita (Europe) Ltd following one of the worst honey harvests in the UK and Northern Europe for many years. Although poor weather conditions may have badly affected the harvest an array of unexplained research findings indicates a more sinister and long-term challenge.

In recent decades, beekeeping has had to change radically to cope with the arrival of the varroa mite, a honeybee parasite. Minimalist or reactive management is no longer enough. Now with the threat of CCD (Colony Collapse Disorder) and other unexplained colony deaths, beekeepers must now become more vigilant and pro-active and use emerging pre-emptive bio-technologies from trusted sources to avert beekeeping catastrophe.

“Although the bad weather has had a significant impact on reducing this year’s UK honey harvest by something in the order of 30-50%, something more complex is afoot,” said Dr Max Watkins, Technical Director at Vita (Europe) Ltd. “I have never before seen so many paradoxical research findings and anecdotal reports in beekeeping.

“Although I firmly believe that varroa is at the core of the problem, the developing interplay of other factors while unsettling for beekeepers, is fascinating yet perplexing for researchers. The answers can only come from a thorough scientific approach. Investigations are underway across the globe and many suspects and accomplices are under suspicion – viruses once of little consequence are now becoming more prominent killers, but a clear pattern is elusive. One novel line of enquiry in Israel is focusing on “gene silencing” in an attempt to suppress the expression of bee viruses in the honeybee genome.

“Controlling varroa is now merely the first – and still absolutely essential – line of defence. Other action is also now necessary to keep colonies healthy. As a honeybee health company we are investing heavily in researching new bio-technologies and treatments. Already we have introduced two Vita Feeds to boost honeybee immune systems and all-round health, and we are now developing several new potential products which we expect will become vital weapons in the beekeeper’s armoury. One strand of our R&D is focusing on new alternative anti-varroa treatments and another is looking at ways of inhibiting microbes which are implicated in the death of colonies.”

The array of strange recent findings, many of them aired at the recent international conference of the Society of Invertebrate Pathology at the University of Warwick, UK, organised by Rothamsted IACR and sponsored by Vita, include:

Heavy bee losses are not new. They have been recorded several times during the history of beekeeping in the USA and Europe, with some symptoms similar to those attributed to what is currently termed Colony Collapse Disorder. Denis van Engelsdorp, Pennsylvania State Apiarist, USA recounted such experiences in American beekeeping history. Mike Brown of the National Bee Unit, UK, has also pointed out previously that largely unexplained heavy bee losses have occurred at intervals throughout Europe in the past. It may be that what is now termed Colony Collapse Disorder is not new at all, but is a variant of a recurring syndrome.

Viruses are implicated in CCD, but no single one has been identified as being “the cause”. Colonies with CCD apparently present with multiple viral infection, usually with four or more viruses: commonly Deformed Wing Virus (DMV), Israeli Acute Paralysis Virus (IAPV), Black Queen Cell Virus (BQCV), and Acute Paralysis Virus (APV) out of a total of 18 viruses discovered widely in US honeybee colony samples.

Varroa and nosema are also implicated in CCD and varroa saliva is now known to destabilise the immune system of honeybees. Dr Diana Cox-Foster of Penn State University, USA discussed this briefly in relation to the impact of viruses and other secondary infections where the bee’s immune system is already compromised.

Viruses can be found in almost all hive contents – and even in pollen on plants – before it enters the hive. Other pollinators, including wasps and bumble bees, have also been discovered to be infected with IAPV and DWV.

Viruses don’t always debilitate: infection can be covert – Dr Elke Genersh of the Institut for Bee Research, Hohen Neuendorf, Germany showed that it depends on the threshold and the presence of infected varroa.

Research by Dr Ilan Sela of the Hebrew University of Jerusalem concentrated on detecting viral RNA incorporated into the honeybee genome. Honeybee colonies with IAPV-specific dsRNA within their genes triple their honey production and grow in size. Bees fed with IAPV specific dsRNA have a longer lifespan and are protected against some other viruses. However, bees infected with live IAPV alone are rapidly killed, falling to the floor with spasms and paralytic seizures. Several stress factors can trigger the expression of the virus when it is incorporated into the honeybee genome; the main trigger is believed to be parasitisation by varroa, but nutritional and environmental stresses can all contribute.

There appears to be some repellent in hives after CCD episodes – in the following few weeks the usual expected invasions by pests and scavengers do not occur. When colonies collapse they are usually soon robbed out by wasps or infested by wax moths, beetles etc, but this does not happen for some time, suggesting there is a repellent factor in these dead and dying colonies. Researchers in the USA are trying to determine what is causing the repellency.

In CCD colonies, some pollen was quarantined or entombed behind wax cappings suggesting that the bees were putting this food beyond use. All such pollen was reported to be contaminated with chlorthalonil fungicide.

In CCD colonies unexpectedly high residues from varroa treatments, notably coumaphos, have been found in many hives in the US – indicating over-dosing and misuse of illegal treatments. All beekeepers want to keep their bees alive. While it is understandable that desperate measures are sometimes taken, with any available [and cheap] treatment being applied, the indiscriminate use of non-regulated substances and products can have a devastating and long-term effect on bee health.