Varroa

Question 1

Four key aspects of honeybee health and disease

Answer 1

Global food security and threats to major pollinators
Major vector for Honeybee disease - Varroa destructor
Role of Varroa in spreading honeybee viruses
The control of Varroa by traditional and novel techniques

Question 2

What does the varroa mite feed on?

Answer 2

Current research indicates that varroa feeds on haemolymph - but found research indicating that fed on fat bodies primarily (due to particular location on bee) (Ramsey et al., 2019).

Question 3

Where is varroa from?

Answer 3

Parasite of Apis cerana (Asian honeybee)

Question 4

How is varroa contracted?

Answer 4

Raids of neighbouring hives (infected), raiders carry mites back to hive on body, nurse bees become infected. Nurse bees pass on varroa mites to uncapped brood. Varroa develops in capped brood cells.

Question 5

How do the different types of bees (worker/drone) affect level of varroa parasitism?

Answer 5

Drone males emerge later than workers, so are more heavily parasitised.

Question 6

What is the phoretic stage of varroa on adult bees?

Answer 6

The non-reproductive stage of mite

Question 7

What damage does varroa cause on the individual level?

Answer 7

weakened brood - weight loss/ septicaemia/ impaired performance

Question 8

What damage does varroa cause on the colony level?

Answer 8

weak wintering stock/ less swarming/ “parasitic mite syndrome”/ drones less change to mate

Question 9

What is an indirect way that varroa affect bees?

Answer 9

Varroa mites are vectors for at least 5 major viruses associated with bees.
E.g.) Deformed Wing Virus (DWV)

Question 10

Ways to treat varroa (think treatment pyramid)

Answer 10

soft acarides
acarides
biological control 
cultural
mechanical intervention 
tolerant bees - more hygienic bees (long-term)

Question 11

methods for monitoring

Answer 11

alcohol/detergent wash (kills bees)
powdered sugar roll
sticky board (mites fall off randomly to bottom of hive)

Question 12

soft acarides

Answer 12

oxalic acid - broodless
formic acid - phoretic and brood/does not taint honey
essential oils - temp.-dependent/ taints honey

Question 13

acarides

Answer 13

Organophosphates
Pyrethroids
Formamidine

Question 14

Organophosphates - how do they work?

Answer 14

Acts on nervous system of mites

- acetylcholinesterase inhibitor

Question 15

Pyrethroids - how do they work?

Answer 15

Act on Voltage-gated Sodium Channel (VGSC)

e.g.) Apistan

Question 16

Formamidine - how does it work?

Answer 16

Alpha-anergenic agonist, octopamine receptors, prostaglandin, MOA
e.g.) Amitraz (Apilife)

Question 17

Problem with use of chemical treatments to stop varroa focused on one inhibitor, voltage gate…etc.

Answer 17

Development of resistance

Question 18

Way to combat varroa resistance to voltage-gated sodium channel attack

Answer 18

gene knockdown - constructed dsRNA coding for a Varroa enzyme
glutathione S-transferase (GST) -> reduced GST activity