Varroa

Question 1

Latin name for varroa species in the UK

Answer 1

Varroa destructor

Question 2

How many legs does a varroa mite have

Answer 2

8

Question 3

What are the tubes used by the varroa mites to breath called?

Answer 3

Peritremes

Question 4

How large are varroa mites

Answer 4

1.5 x 1 mm

Question 5

What are the impacts of varroa mites on larvae?

Answer 5

They feed on them and cause them to be smaller upon emergence

Question 6

What effect does varroa have on the colony?

Answer 6

They weaken the bees and kill them causing dwindling. If these bees are not replaced over winter then the colony will die

Question 7

What are the effect of varroa on individuals

Answer 7

They can reduce the tolerance of pesticides.

They can weaken the immune system so are more susceptible to disasters.

Alters navigation skills in foragers and reproductive fitness in drones

Vector for viruses

Question 8

Describe the life cycle of the varroa?

Answer 8

1) female enters cell, cell capped over.
2) 1 egg laid 60 hours after capping. This turns into a male
3) eggs laid 1 every 30 hours
4) protonymphs turn into deytonympphs
5) females and males mate and emerge with the bee

Question 9

What do varroa mites feed on?

Answer 9

Fat bodies

Question 10

How many varroa mites are produced per reproductive cycle

Answer 10

Worker brood: 1.7-2
Drone brood: 2-3

Question 11

How do varroa mites spread?

Answer 11

• if two foragers are on the same flower they can spread
• drifting drones at DCAs
• colony manipulations by the beekeeper where they move bees/equipment with varroa
• robbing of a colony where varroa move onto robbers
• drifting between colonies

Question 12

Why are varroa mites so good at being ectoparasites?

Answer 12

• it feeds on both adults and larvae so can survive broodless period
• it’s flattened shape means that it can fit beneath the abdominal scales and avoid being dislodged
• coating on the varroa body makes them smell like the hive (chemical camouflage)
• a high reproduction rate
• a mouth part that penetrates the bees cuticle. Anticoagulants in varroa saliva
• spreading diseases to weaken the colony and allow for greater infection

Question 13

What is Parasitic Mite Syndrome?

Answer 13

This is a condition where bees are severely impacted by varroa. The number of varroa disrupts normal colony operations and the signs include: mites visible on bees, emerged adults with deformed wings, dead brood with proboscis protruding, poor brood pattern.

Question 14

Explain how an inspection board can be used for varroa monitoring?

Answer 14

1) Insert a white inspection board beneath the mesh floor. Cover it in petroleum jelly to avoid mites falling off.
2) Leave for 7 days
3) Divide the mite drop by 7 to get daily mite drop

This accuracy is low but does sample the entire colony.

Question 15

Explain how the sugar roll method can be used to estimate varroa numbers

Answer 15

1) Obtain a sample of 300 bees by shaking a brood frame into a bucket.
2) tip the bees into a jar with a mesh lid. Swirl jar to keep bees at the bottom
3) add 2 heaped tbsps of icing sugar
4) roll the jar a few times and leave for 2 minutes
5) shake the jar over a plate for 90 seconds and count the mites

Not fatal to the bees but only gets 70% of the mites off so it usually an underestimate.

Question 16

Explain how drone brood uncapping can be used to estimate varroa numbers

Answer 16

1) Use an uncapping fork to uncap 100 drone dells in the purple eye stage (18 days old)
2) Count the percentage of infected pupae rather than the number of mites

Drones are preferred by varroa so there is selective bias, does kill drones

Question 17

Explain how an alcohol wash can be used to estimate varroa numbers?

Answer 17

1) Prepare the alchohol mix which is 1:4 isoporoppnal to water.
2) Shake bees into a large bucket and spray with fine mist so they clump together
3) Get 300 bees into test container.
4) Shake the container to wet the bees with the alcohol which kills them. Shake for 1 minute.
5) Count the mites .

Kills the bees and has a small sampling size as only 1 frame is used

Question 18

Explain how drone comb removal works for varroa control?

Answer 18

Varroa prefer drone brood so this works well. You need to remove the sealed cells.

Have a frame divided into 3 parts. Label them A, B & C. Allow the bees to draw comb in all 3. Then cut out B and C, come back a week later and cut out C. Then the week after remove A and subsequent weeks just remove the sealed section

Question 19

Explain how to carry out queen trapping for varroa control.

Answer 19

This method takes 36 days to complete and causes a brood break. Place the queen in her frame cage on frame A. 9 days later remove her and place her and a new frame into the cage. On day 18, remove the first frame as it will now be sealed. And move the queen onto a new caged frame (C). 9 days later remove frame B and destroy it.

Question 20

Explain chemical treatments for varroa?

Answer 20

These give great amounts of choice to the beekeeper when dealing with varroa.

Apiguard, MAQs strips, oxalic acid all have benefits and downsides

Question 21

What are the 3 main points focused on by all varroa treatments?

Answer 21

1) They are vulnerable and exposed during the phoretic phase
2) They prefer drone brood
3) When there is limited brood the mites are forced to use it.

Question 22

Describe some varroa sensitive hygiene (VSH) traits

Answer 22

Honey bees may increase the grooming they carry out on one another to dislodge mites on their abodmen.

They will remove infected pupae with two or more foundresses

They may temporarily uncap the brood which doesn’t impact the worker developing but does stop the varroa from reproducing

Question 23

What is a beltsville test and how do you carry it out?

Answer 23

This is used to determine mite resistance to chemical treatment (in particular Apiatan).

1) Gather 200 workers and place them in a ventilated container with medicated strip (apiatan) for 4 hours
2) Turn the container upside down over a piece of white paper and knock the bottom of the container to dislodge the mites
3) Count the mites and record the number as these are the susptible mites
4) Submerge the bees in soapy water to kill them
5) Straij the bees through a small mesh and count the notes present. These are your resistant mites
6) If the number of mites that were susceptible was less than 50% then you should not use pyretheorids such as Apistan