Poisoning of bees

Bees are in quite a unique position as they cover a lot more area than the normal farmed animal. Their territory will take them through farm land, households and commercial land. They can therefore be exposed to a wide range of potentially toxic compounds from pollen of exotic plants to insecticides and pesticides.

The clinical signs of poisoning will vary depending on the toxin. The ones that are going to be noticed by the beekeeper are going to be:

Acute – typically colony collapse, neurological disorders or piles of dead bees.

Chronic – deformities of the young.

Poison	Stages affected	Adult	Brood	Colony
Toxic chemicals	Adult	Dead forages. Perhaps nurse bees affected. Queen may be ok.	Usually few	Colony collapse. Weakened colony. Lots of dead bees in entrance
Plant poisons
California buckweed Aesculus californica	Young brood Forage bees	Deformed workers hairless with neurological problems. Call look like Chronic paralysis. Queens may become infertile	Drone brood produced. Workers die after emergence. Brood becomes uncapped	Progressively weakened hive. Queen becomes superseded. Dead workers at entrance.
Yellow Jessamine Gelsemium semperviens	All	Young adults die. Older adults normal	Pupae die in cells and become mummified	Hive slightly weakened
Loco plants	Pupae, Adult – queen.	Forage bees die away from hive. Those return with neurological issues. Queen may die	Many cells contain dried pupae	Colony collapse. Dwindling colony
False Hellebore Veratrum californicum	Adult	Forage bees die away from hive. Adults die in a curled state. Queen normal	No effect	Forage bee loss – reduction in production
Southern Leatherwood Cyrilla racerniflora	Larvae	No effect	Many blue or purple larvae.	Slight to severe weakening of the hive.

Milkweed pollinia (Aslepias spp)

The pollen is coherent – in pairs connected by a slender filament (the pollinia) – which looks like a bird’s wishbone. When the forager collects the pollen they can become ensnared and cannot free themselves from the plant. Those that do can have difficulty getting back to the hive with the pollinia still attached to their bodies.