Parasitic Cape honey bee workers (Apis mellifera capensis) are not ...

Herr Schıberl

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Parasitic Cape honey bee workers (Apis mellifera capensis) are not ...

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• Arts

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• Publié par: ifydesut
• Nombre de lectures: 73
• Langue: Français

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Summary.

Workers of the Cape honey bee

Apis mellifera

capensis

started to parasitize the African honey bee

A. m

.

scutellata

after being introduced into Gauteng (former

Northern Transvaal Province) from its native territory, the

Cape Province. The

A. m. capensis

strain that is parasitic has

at least two traits that make it a serious pest of the native

African bee colonies: workers rapidly develop their ovaries

when in a non-

capensis

colony even when a queen is present,

and worker-laid eggs are not killed by worker policing. Here

we investigate whether

A. m. capensis

workers also have spe-

cial mechanisms to circumvent the guard bees of

A. m.

scutellata

thereby aiding their horizontal transmission

between infected and non-infected colonies

.

We studied the

acceptance of non-nestmate

A. m. capensis

and

A. m. scutel-

lata

bees by guards of African bee colonies by introducing

them to the hive entrance of

A. m. scutellata

colonies. We

used 2

A. m. scutellata

discriminator colonies that were both

split into a queenright and a queenless portion. Our results

suggest that invading workers of

A. m. capensis

have no

special mechanisms to circumvent the African guards. Nei-

ther race of the introduced bee nor presence or absence of the

queen in the guarding colony affected the proportion of intro-

duced workers accepted. When pooled, 15% of introduced

A. m. capensis

and 18% of

A. m. scutellata

non-nestmate

workers were accepted by African guards.

Key words: Apis mellifera capensis

;

A. m. scutellata

, para-

sitism, guard bees, mandibular gland pheromones (QMP).

Introduction

Since 1992, when the Cape honey bee,

Apis mellifera capen-

sis

, was moved out of its native range by beekeepers

and introduced into Gauteng (former Northern Transvaal

Province), its workers have been killing colonies of the

African honey bee,

A. m. scutellata

(Allsopp and Crewe,

1993). Before then the two subspecies were separated with

the Cape honey bee only present in the Cape Province and the

African honey bee in the rest of South Africa, the only con-

tact between the two being in the so-called hybrid zone.

Despite mixing of the two subspecies in the hybrid zone, this

zone has been stable for decades with none of the subspecies

increasing its territory (Hepburn and Crewe, 1991 and Hep-

burn and Jacot Guillarmod, 1991). Although colonies of the

Cape honey bee had been moved into African honey bee area

previously (in 1927 (Lundie, 1954) and 1977 (Johannes-

meier, 1983)) the Cape honey bees were eradicated within a

few years. Its last introduction however, has lead to devastat-

ing results with vast number of African bee colonies being

killed by invaded workers of the Cape honey bee (Allsopp

and Crewe, 1993).

Unlike other honey bee subspecies where worker-laid

eggs are normally haploid and develop into males, eggs laid

by Cape honey bee workers are diploid and develop into

females (Anderson, 1963). Recently, it has been shown that

the

A. m. capensis

workers that invade and kill colonies of

A. m. scutellata

, are a pseudo-clone (Kryger, 2001). That is,

they are of one automictic line all of very similar genotype.

They kill their host colonies by increasing in number until

only Cape honey bee workers are present. These bees do

little work and ultimately the colony dies of starvation. The

A. m. capensis

pseudo-clone workers have at least two traits

that facilitate their reproduction in an

A. m. scutellata

host

colony (Martin et al., 2002). They activate their ovaries even

in the presence of a laying queen and lay eggs that are not

policed. Worker ovary activation is normally very rare in

queenright colonies (Ratnieks, 1993) and eggs laid by work-

ers are normally policed by other workers (Ratnieks and

Visscher, 1989). Both traits show that pseudo-clone workers

of

A. m. capensis

behave as a true parasite of other honey

Insectes soc. 49 (2002) 216–220

0020-1812/02/030216-05

© Birkhäuser Verlag, Basel, 2002

Insectes Sociaux

Research article

Parasitic Cape honey bee workers (

Apis mellifera capensis

) are not given

differential treatment by African guards (

A. m. scutellata

)

M. Beekman

1, 2

, T.C. Wossler

3

,

S

.

J

.

M

a

r

t

i

n

1

and F.L.W. Ratnieks

1

1

Laboratory of Apiculture and Social Insects, Department of Animal and Plant Sciences, Sheffield University, Sheffield, United Kingdom

2

Schools of Biological Sciences & Mathematics and Statistics, University of Sydney, A12, Sydney, NSW 2006, Australia,

e-mail: [e-mail].

3

Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa

Received 4 September 2001; revised 6 March 2002; accepted 8 March 2002.