Septicaemia

Septicaemia is a rarely seen disease caused by bacteria entering the haemolymph (blood fluid) of adult bees and multiplying there. Its most typical sign is that freshly dead bees come apart easily into head, thorax, abdomen, legs and wings when touched. No medicine is needed; the disease is usually a sign that the apiary is too damp and poorly kept.

What is it and how is it transmitted?

The agent most often reported is Pseudomonas aeruginosa (formerly P. apiseptica); other opportunistic bacteria such as Serratia marcescens can produce a similar picture. These bacteria live in soil and in stagnant, dirty water.

The bacteria cannot easily enter a healthy bee. They usually get into the body through the tracheal openings (spiracles) or through wounds in the exoskeleton. They multiply rapidly in the haemolymph and kill the bee within a short time; because the bacteria also break down muscle and connective tissue, the dead bee quickly falls apart.

Conditions that favour the disease:

• Permanently damp, marshy, shady and airless apiary sites
• Condensation and a wet floor inside the hive
• Bees taking water from dirty, stagnant water
• Weak, stressed colonies

How to recognise it

• The bee falls apart: When a freshly dead bee is picked up, the body segments, legs and wings break off easily. This is the most distinctive sign.
• Milky white haemolymph: The normally clear haemolymph looks cloudy and milky white. It can be seen in a live or freshly dead bee when a leg is pulled off.
• Foul smell: The dead bees may give off a sharp, putrid smell.
• Sluggish bees: Before dying the bees are listless and cannot fly; dead bees accumulate in front of the hive and on the floor.

How it differs from similar conditions

How to confirm it at the hive

1. Take a few freshly dead bees from in front of the hive or from the floor.
2. Hold the bee gently between two fingers: if the head, thorax and abdomen come apart easily and the legs and wings drop off, suspect septicaemia.
3. Pull a leg off a live but listless bee and look at the drop that comes out: if it is milky white and cloudy, the suspicion is strengthened.
4. For a definitive diagnosis, send the bees to a laboratory in a closed container under refrigeration; the bacterium is identified by culturing it from the haemolymph.

If you suspect poisoning (spraying nearby, sudden deaths in many hives), freeze and keep the bees and report it to the local agriculture authority; this situation requires a different procedure.

What to do

There is no medicinal treatment for septicaemia and none is needed; do not use antibiotics. Once conditions improve, the disease recedes on its own.

• Move the apiary to a dry, airy place. Marshes, stream beds, permanently shaded spots and windless hollows are not suitable.
• Raise the hives off the ground. A sturdy stand cuts off moisture from the ground and splashing mud.
• Reduce humidity inside the hive. Improve ventilation, fix covers that cause condensation, and clean and dry a wet floor.
• Provide clean water. Put a regularly refreshed water source near the apiary, so that the bees do not turn to dirty puddles.
• Clear away dead bees. Remove the dead bees accumulating in front of the hive and on the floor.
• Keep the colony strong. A strong colony manages the climate inside the hive better; consider uniting weak ones.

Prevention

On its own, septicaemia is rarely a serious threat. When it appears, the real message concerns the apiary site: humidity, ventilation, the water source and the height of the hives should be reviewed. If it recurs in the same apiary, moving the apiary is the most lasting solution.