Field Diagnosis of Exotic Honey Bee Parasites and Pests in Bee Hives

Note Number: AG1076
Published: December 2002
Updated: September 2011

This Agriculture Note provides information for beekeepers about exotic honey bee parasites and pests that are a serious threat to Australian honey bee colonies kept by commercial and hobby beekeepers.

Introduction

If the parasites and pests described below were to establish in Australia, severe losses of colonies would occur, putting at risk the livelihoods of sideline and commercial beekeepers. For these notes, the term exotic means not occurring in Australia.

Early detection of these parasites and pests in Australia will be extremely important in limiting their spread and impact on beekeepers. Beekeepers are encouraged to study these notes so that they can recognise these parasites and pests.

It may be necessary to confirm a field diagnosis using laboratory tests. DPI apiary officers are able to provide advice on the correct procedures for this to be done.

Varroa mite

Description

The adult female Varroa mite (Varroa destructor) is reddish-brown and shaped like a scallop shell. It is about 1.1 mm long and 1.7 mm broad, and can be seen with the naked eye.

The mites spend most of their life inside sealed brood cells where they multiply and feed on developing pupa. In lightly infested colonies this is the most likely place to find them.

Female mites may also be found on adult bees. They often hide between the hardened abdominal segments closest to the throrax. The mites may be found on adult bees in overwintering colonies that have no honey bee brood.

Photo 1. Varroa on pupa of worker bee. Photo courtesy Denis Anderson, CSIRO Entomology, Canberra	Photo 2. Varroa mite on adult bee. Photo copyright NSW Agriculture

Mite numbers increase slowly within a hive and it may not be until several years of infestation that mite numbers are sufficiently high for bee larvae to be parasitised by several females.

When this occurs, newly emerged adult bees with deformed wings, legs and abdomens may be found at the hive entrance. Patchy brood patterns may also be evident in advanced infestations.

The females of another species, V. jacobsoni, are slightly smaller than females of V. destructor. This species was recently found reproducing on European honey bees in Papua New Guinea. A laboratory diagnosis is necessary to confirm the presence of these mites.

Field diagnosis

Beekeepers are encouraged to conduct field tests for Varroa on at least one hive in each apiary, every 3-6 months. We suggest that the following tests be conducted. If you normally wear reading glasses, wear them while looking for these mites.

Examination of honey bee brood

Varroa have a preference for drone pupae at the edge of the brood nest. If there are drone pupae, use a pair of tweezers or a hive tool to remove individual pupae from their cells. Examine 50-100 of these for reddish-brown mites. When removing a pupa, carefully examine inside the brood cell, especially the base, for any mites. This is important, because Varroa may remain in the cell when brood is removed. Worker pupae should be examined if there are no drone pupae present in the hive.

Photo 3. An open honey bee (Apis mellifera) brood cell showing adult Varroa and offspring. Photo courtesy Denis Anderson, CSIRO Entomology, Canberra	Photo 4. Varroa jacobsoni on emerging Eastern honey bee (Apis cerana javana) drones. Photo courtesy Denis Anderson, CSIRO Entomology, Canberra

Icing sugar dusting of adult bees

When Varroa are dusted with icing sugar, the fine granules stick to their pads (feet) and they are no longer able to grip the surface on which they cling. The dusting of adult bees with icing sugar causes mites to fall off the bee into the white sugar where they are more easily seen.

The following simple detection method is now used by many beekeepers throughout Australia:

Tropilaelaps mite

Description

This mite (sometimes known as the Asian mite) is a parasite of brood only and causes death of brood or reduced longevity of adult bees that survive the parasitised brood stage. It will breed and survive in bee colonies as long as brood is present. The adult female mite is light reddish-brown, with an oval shaped body about 0.96 mm in length and 0.55 mm in width.

Field diagnosis

Initial signs of infestation are an irregular pattern of sealed and unsealed brood; newly emerged adult bees with deformed wings, legs and abdomens at the hive entrance, and deformed pupal remains also at the hive entrance.

Examine 50-100 pupa for reddish mites. If you normally wear reading glasses, wear them while looking for these mites. Use a pair of tweezers or a hive tool to remove individual pupae from their cells and examine them carefully. A laboratory diagnosis is necessary to confirm the presence of this mite.

Braula fly

Description

This insect, a flattened wingless fly (Braula caeca), is often incorrectly called bee louse. It is found in Tasmania, but not on the Australian mainland.

Adult braula are reddish-brown and measure 1.2–1.5 mm long, and 0.75 mm wide. They are found on the head and thorax, and between the thorax and abdomen of adult bees of all castes.

Field diagnosis

Braula may be found on both honey bee workers and queen. They feed on nectar and pollen (and possibly saliva) at the host bee's mouth. Braula larvae are not found on brood combs, but tunnel under the cappings of honey combs producing raised lines which damages the appearance of the comb.

Other mites

The pollen mite (Mellitiphis alvearius) is also found in beehives in Australia. The mite is brown, smaller than Varroa, measuring 0.75 x 0.75 mm. It is not a parasite of honey bees. A laboratory diagnosis is necessary to confirm the presence of this mite.

Steps if you find or suspect presence of an exotic parasite or pest in your apiary

It is important that when an exotic parasite or pest is found or even suspected to be present in an apiary that it is not spread to another apiary.
 
The following steps will help to reduce the risk of spreading a parasite or pest:

Notifiable disease

If you see or suspect any of the parasites described in this agricultural note is present in your apiary, you must notify an Inspector of Livestock (DPI apiary officer, animal health officer or veterinary officer) without delay and by the quickest means possible. The easiest way to do this is to ring the Disease Watch Hotline 1800 675 888 (24 hours a day, every day of the year).

Notification is required by the Livestock Disease Control Act (1994). To not notify is to break the law.

Early reporting and recognition of these parasites is one of the most important factors influencing the chance of controlling them and reducing their economic and social impact on the whole community.

Further information

The Department of Primary Industries apiary officers listed below are available to provide advice on sample collection and diagnosis of exotic honey bee parasites and pests.

Rutherglen, Joe Riordan, Telephone (02) 6030 4516, Mobile 0417 348 457.
Bendigo, Daniel Martin, Telephone 5430 4621, Mobile 0428 752 449.
Knoxfield, Russell Goodman, Telephone 9210 9222.

Acknowledgements

This Agricultural Note was developed by Russell Goodman and Peter Kaczynski in 2002.
It was reviewed by:
Russell Goodman and Joe Riordan in July 2010.
Russell Goodman, Animal Biosecurity and Welfare, Biosecurity Victoria, Knoxfield and Joe Riordan, Animal Health Field Services. Biosecurity Victoria, Rutherglen, in September 2011.