Varroa Flashcards
Latin name for varroa species in the UK
Varroa destructor
How many legs does a varroa mite have
8
What are the tubes used by the varroa mites to breath called?
Peritremes
How large are varroa mites
1.5 x 1 mm
What are the impacts of varroa mites on larvae?
They feed on them and cause them to be smaller upon emergence
What effect does varroa have on the colony?
They weaken the bees and kill them causing dwindling. If these bees are not replaced over winter then the colony will die
What are the effect of varroa on individuals
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
Describe the life cycle of the varroa?
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
What do varroa mites feed on?
Fat bodies
How many varroa mites are produced per reproductive cycle
Worker brood: 1.7-2
Drone brood: 2-3
How do varroa mites spread?
- 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
Why are varroa mites so good at being ectoparasites?
- 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
What is Parasitic Mite Syndrome?
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.
Explain how an inspection board can be used for varroa monitoring?
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.
Explain how the sugar roll method can be used to estimate varroa numbers
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.
Explain how drone brood uncapping can be used to estimate varroa numbers
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
Explain how an alcohol wash can be used to estimate varroa numbers?
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
Explain how drone comb removal works for varroa control?
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
Explain how to carry out queen trapping for varroa control.
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.
Explain chemical treatments for varroa?
These give great amounts of choice to the beekeeper when dealing with varroa.
Apiguard, MAQs strips, oxalic acid all have benefits and downsides
What are the 3 main points focused on by all varroa treatments?
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.
Describe some varroa sensitive hygiene (VSH) traits
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
What is a beltsville test and how do you carry it out?
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
