Chronic Bee Paralysis : 7 THE HISTORY AND BIOLOGY OF A HONEY BEE DISEASE
aralysis has an ancient association with honey bees, with a diverse array of wonderfully descriptive names littering the literature.
Chronic Bee Paralysis P
Giles Budge and Kirsty Stainton
These include ‘black robbers’ and ‘little blacks’ in Britain; ‘Schwarzsucht’ (black addiction), ‘maladie noire’ and ‘mal nero’ (black disease) in continental Europe; and ‘hairless black syndrome’ in the United States. It was in the 1960s that one of our personal heroes, Leslie Bailey, first identified the causative organism as a virus and named it chronic bee paralysis virus (CBPV, Figure 1).
Symptoms
In a valiant attempt to unite disparate malaises from across the literature, Bailey classified symptoms of individual bees into two ‘types’. Type 1 syndrome was described as the most commonly observed in Britain(1) and included an abnormal trembling motion with paralysis of the wings and bodies. Affected bees are unable to fly and sometimes crawl on the ground. They are often misplaced in the hive, appearing on top bars and lugs, leading some researchers to deem them to be ‘stupid’. Abdomens can be bloated and the bees may suffer from dysentery and dislocated wings. Type 2 syndrome united observations such as hairless
September 2016 Vol 98 No 9
Figure 1. Electron micrograph of chronic bee paralysis virus (CBPV). Particles vary in length between 30 nm and 60 nm, with a diameter of approximately 20 nm
bees, appearing almost black, and shiny, greasy bees suffering from nibbling attacks by healthy bees. This gives them the appearance of robber bees (Figure 2, page 9). After a few days, these individuals also suffer from paralysis and die. Given our modern acceptance that CBPV can cause both types, there seems little benefit in continuing to distinguish between them – symptoms are not mutually exclusive to a honey bee colony and frequently occur in tandem. The symptoms of a severely affected colony can be startling, with dead bees on the floor, inches deep, and thousands piled up just outside the hive entrance,
producing a rancid smell as the bees decompose. These colonies can sometimes recover but, more often, the colony will lose so many adult bees that it will enter terminal decline. A recent example of a severe outbreak of chronic bee paralysis led to the loss of 150 out of 400 colonies in a single bee-farm operation.
Diagnosis and Cases of Mistaken Identity
Individually, many of the symptoms can be confused with other afflictions. Nosema can cause dysentery; acarine may cause bees to become flightless; deformed wing virus may cause dislocated wings; and there are at least four other paralysis
Apimondia Gold Medal for Popular Beekeeping Journals, 2007, 2013 and 2015
viruses of the honey bee. However, taken together, the symptoms are most frequently confused with pesticide poisoning. Andy Wattam, the national bee inspector, kindly highlighted two important differences between pesticide poisonings and CBPV infections. First, adult bees afflicted with chronic bee paralysis virus never do the ‘dying fly’ act – where individuals spin in circles on their backs seemingly unable to fly. This symptom is found exclusively with pesticide poisonings. Second, chronic bee paralysis is associated with piles of dead bees directly outside the front of the hives, whereas pesticide poisonings sometimes show a carpet of dead bees more evenly spread across the apiary, perhaps caused by bees not quite making it back to the colony. It is worth noting that there is help at hand if you suspect a pesticide poisoning. Simply contact your local National Bee Unit (NBU) inspector and, if they also suspect pesticides, your samples could be entered into a national monitoring scheme known as the Wildlife Incident Investigation Scheme (for more details see www.
nationalbeeunit.com/index. cfm?sectionid=33). Diagnosis in the field requires several of the above mentioned symptoms to be observed together. However, given the opportunity for misidentification, the only definitive diagnosis
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Photographs courtesy The Animal and Plant Health Agency (APHA), Crown Copyright
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