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DISEASES OF HONEY BEES IN NEW ZEALAND

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					   DISEASES OF HONEY BEES IN NEW ZEALAND
                      T. PALMER-JONES
 Wallaceville Animal Research Centre, Department of Agriculture,
                           Wellington.

                             SUMMARY
     Diseases of honey bees a r e reviewed in relation t o their im-
portance t o t h e New Zealand beekeeping industry.
     Honey bees (Apis mellifica L.) were first brought t o New Zea-
land f r o m England in 1839. Beekeeping developed rapidly and
importation of varieties of the various races of bees f r o m European
countries, t h e United Kingdom, and the U.S.A. was f r e q u e n t until
controls were introduced recently. We would expect t o find the
main diseases of bees in this country and, with t h e noticeable ex-
ception of acarine disease and European foulbrood, such is indeed
the case.
     In what follows, organisms, and the disease they cause a r e
discussed i n relation to their potential o r actual occurrence and
importance a s entities in this country.
             ORGANISMS AFFECTING ADULT B E E S
Acarapis woodi Rennie (Internal acarine mites)
     These cause acarine disease.     They infest t h e prothoracic
spiracles of honey bees, producing weakness and inability to fly,
which often results i n rapid dwindling of colony strength. The
mites have not been found in New Zealand in spite of widespread
examination of bees over the last 20 years. The most effective
control of acarine disease depends upon treating t h e hive with the
miticide chlorobenzilate.
Acarapis externus Morgenthaler and Acarapis dorsalis Morgenthaler.
            (External acarine mites)
       These mites were found during 1960 on local honey bees
(Palmer-Jones, 1961).         Although generally considered harmless,
they feed directly on t h e bee and the author regards heavy infest-
ation a s possibly causing weakness. A study of t h e possible harm-
f u l effect of t h e external acarine mites on honey bees is planned.
Chlorobenzilate treatment should also control external mites.
Nosema apis Zander.
      Nosema, a protozoan intestinal parasite of a d u l t bees, is of
world wide distribution. Bees become weakened by t h e enormous
number of parasites in the cells lining their stomachs a n d often
fail t o r e t u r n from foraging flights. The disease is spread by spores
voided by infected bees. A New Zealand-wide outbreak of dwindling
of hive strength during 1946-47 was caused by Nosema (Palmer-
Jones, 1947). During the epidemic several commercial beekeepers
suffered economic loss because little surplus honey could be col-
lected. Nosema soon reverted t o the more usual endemic state and
no large scale epidemic has occurred since (Palmer-Jones a n d
Robinson, 1951). The disease can be controlled by treatment of
combs from infected hives with glacial acetic acid which kills t h e
spores, by feeding hives the antibiotic fumagillin in sugar syrup or
by a combination of both methods. However, under our conditions
of beekeeping i t is generally uneconomic to t r e a t the endemic form
of Nosema.
Malpighamoeba mellifica Prell.
      Malpighamoeba is caused by a n amoeba which infects and
damages t h e malpighian tubules. Spread by cysts the disease is
often associated with Nosema.
      I t was first identified in New Zealand by Cumber (1948) who
found i t in Nelson infecting a single hive which was also suffering
from Nosema. Although the present author has searched extensively
f o r Malpighamoeba i t has not been found elsewhere.

                           BROOD DISEASES
     Brood diseases a r e those affecting the larval or pupal stages.
European Foulbrood
      This disease, caused primarily by Streptococcus pluton White,
followed by the growth of secondary bacterial invaders, is regarded
overseas a s serious. On several occasions t h e author has found
hives apparently infected with European foulbrood b u t attempts to
isolate Streptococcus pluton have been unsuccessful.
American Foulbrood
      This disease is caused by Bacillus larvae White, which attacks
worker brood, usually in the pre-pupal stage. The dried-up brood
contains enormous numbers of spores formed when conditions be-
come suitable f o r bacterial growth. The disease is spread by the
robbing of diseased hives by bees from healthy ones, by the transfer
of infected equipment, and by exposure of honey containing spores
t o bees. American foulbrood has been recognised in New Zealand
since the earliest days of beekeeping. It is persistent and wide-
spread in occurrence, being regarded a s t h e most serious bee disease
in New Zealand. I t may be treated by feeding sulphathiazole or
terramycin in sugar syrup t o infected hives but this method of
control suffers from serious drawbacks. Firstly, the drugs d o not
aflect spores of t h e disease but only the vegetative stage, necessitat-
ing time-consuming and meticulous manipulations of equipment to
prevent t h e disease spreading during treatment. Secondly, there
is a risk t h a t drug-resistant strains of the organism may arise.
Finally, extracted honey may become contaminated with the drug
so contravening the Food and Drug Regulations. For these reasons
the Department of Agriculture strongly opposes treatment of t h e
disease. Apiary Instructors control i t by gassing t h e bees of in-
fected hives with a cyanide compound and burning them and t h e
infected honey and equipment. Infected hives a r e located by a
system of hive registration a n d inspection.
Sac Brood
    A disease caused by a virus, sac brood affects only larvae,
causing them t o die and assume a sac-like appearance. In New
Zealand i t was first recognised (in Canterbury, under outbreak
conditions) i n 1941 (Palmer-Jones, 1949). Though much reduction
in hive strength occurred in some apiaries t h e outbreak did n o t
cause serious economic loss. Sac brood, like Nosema, has now re-
turned t o t h e more usual endemic s t a t e and is of little importance.
Chalk Brood
     This disease, caused by t h e fungus Ascosphaera apis Maassen
e x Clausen, attacks only larvae causing them t o d r y up and be-
come chalky in appearance. Diseased larvae with a n appearance
typical of chalk brood were examined by the a u t h o r i n 1957 in New
Zealand. The larvae were permeated with t h e mycelium of a fungus
tentatively identified a s Ascosphaera apis. Although chalk brood is
promoted by damp conditions i t is seldom found in New Zealand
even in high rainfall districts such a s the West coast of t h e South
Island.

                             DISCUSSION
       Apiaries Regulations were passed in 1948 mainly a s a precau-
tion against t h e introduction of acarine disease.        Under their
authority t h e e n t r y of bees was prohibited, first from countries
known t o have acarine and l a t e r from virtually all countries.
Present control measures would appear adequate t o exclude acarine
disease but a r e not proof against deliberate evasion.        An a i r
traveller could easily bring out a queen bee and attendants in a
small cage and smuggle i t out of the airport in his pocket. One
such instance is known, the queen having been established in a hive
f o r some months before discovery and destruction. The recent de-
velopment of methods of transporting immature stages of bees
which do not harbour acarine mites (Smith, 1962) niay enable u s
t o import fresh stock in safety.
     Bailey (1958, 1959) re-assessed the affect of acarine disease
on bee colonies a n d concluded t h a t i t is not a s severe a s formerly
believed. However, the U.S.A. which like New Zealand is f r e e f r o m
acarine disease takes every precaution t o prevent its entry. The
effect which acarine disease could have on t h e New Zealand bee-
keeping industry is unpredictable and might be disastrous. Should
the disease be discovered every effort will be made t o contain and
eradicate i t by measures already planned.
                          REFERENCES
BAILEY, L., 1958: The epidemiology of the infestation of the honey
        bee, Apis mellifera L, by the mite Acarapis woodi Rennie
        and the mortality of infested bees. Parasitol. 48: 493-
        506.
    1959: Infectious diseases of the honey bee. Rep. Rothamst.
        exp. Sta. 204-215.
CUMBER, R. A., 1948: Malpighamoeba mellifica Prell, a disease of
        the adult honey bee previously unrecorded in New Zealand.
        N.Z. Sci. Rev. 6: 85.
PALMER-JONES, T., 1947: Nosema apis recognised a s the cause
        of spring dwindling in bee colonies. N.Z. J. Agric. 74: 48.
    1949: Diseases of bees in New Zealand. N.Z. J. Agric. 79: 483-
        86.
    1861 : Tarsonemid (Scutacarid) mites and honey bees.       N.Z.
        Entomol. 2: 50.
PALMER-JONES, T. and ROBINSON, D.S., 1951: Observations on
        the treatment of Nosema apis with drugs. N.Z. J. Sci.
        Tech. A32: 28-38.
SMITH, M. V., 1962: Establishment of honey bee stocks by trans-
        porting immature stages and semen. J. Apicultural Res.
        1: 19-23.
    1962: Importing acarine-free bees by transporting brood. Bee
        World 43: 42-44.

				
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