LABORATORY FEEDING OF VARROA JACOBSONI OUDEMANS ON NATURAL AND ARTIFICIAL DIETS (ACARI : VARROIDAE)

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LABORATORY FEEDING OF VARROA JACOBSONI

OUDEMANS ON NATURAL AND ARTIFICIAL

DIETS (ACARI : VARROIDAE)

W.A. Bruce, F. Chiesa, S. Marchetti, D.A. Griffiths

To cite this version:

LABORATORY

FEEDING

OF VARROA JACOBSONI

OUDEMANS ON

NATURAL AND ARTIFICIAL DIETS

(ACARI : VARROIDAE)

W.A. BRUCE F. CHIESA S. MARCHETTI D.A. GRIFFITHS 1. Stored-Product Insects Research and _{Development Laboratory,}

U.S. _{Department of Agriculture, Agricultural} Research Service, Savannah, GA 3141J3 2. Istituto di Difesa delle Piante, Universita _degli Studi di Udine, Udine, Italia

3. _Storage Pests Department, Ministry of Agriculture, Fisheries, and Food,

Slough Laboratory, Berks, England

SUMMARY

Varroa _jacobsoni, a mite _parasite of _honey bees, _pierced a _synthetic membrane of stretched

Parafilm" _{(approximately} 10 _wm thickness) and fed on a modified artificial diet _developed for the

stored-product mite, Pyemotes tritici. Under _laboratory conditions (35 ± 1 °C and 85 % RH) all feeding stages

of V. jacobsoni fed on the artificial diet and diet was _incorporated into eggs. Females oviposited successfully in the environment of an artificial cell- Eggs hatched but _protonymphs failed to molt to the

dcutonymphal stage, thus a _complete lifc _cyclc was not obtained.

INTRODUCTION

Varroa

_jacobsoni

Oudemans is a mite

_ectoparasite

of

_honey

bees that is

found

_{throughout Europe}

and Asia. Its

_{potentially devastating impact}

on

apiculture

should neither be

_ignored

nor underestimated in those countries

where infestations

_already

occur

(D

E

JONG et

_al.,

_1982).

Countries such as the

United

States,

Canada, Australia,

and New Zealand fortunate

_enough

to be free from infestation must not become

_complacent

but must

_{participate actively}

in

_cooperative

efforts for the

_study,

containment,

and elimination of this serious threat to world

_agriculture.

In this

_regard,

the

_European

Economic

Community

(EEC)

countries have taken the lead in a coordinated research

effort to

_study

both the basic and

_applied

_aspects

of this

_{problem (C}

_AVALLORO

_,

1983 ;

GRIFFITHS et

al.,

1983).

Because of the

_unique

_biology

of this

_parasite,

_adequate

_study

of its behavior has been

_{greatly impaired.}

It is

_extremely

difficult to

_{study feeding,}

mating,

and

_ovipositing

behavior when the

_organism

is sealed in an _opaque

cell

_sequestered

within a bee hive.

Therefore,

researchers worldwide would

*

Present address : _USDA-ARS, Beneficial Insects _Laboratory, BARC-East, Beltsville MD 20705

benefit if

_large

numbers of

_{standardized,}

_{laboratory-reared}

mites of all

_stages

could be

_produced.

The

_possibility

of

_rearing

V.

_jacobsoni

in the

_laboratory

on an artificial diet was

_suggested

to the senior author

_by

Dr. Donald Griffiths

following

the Third International

_Working

Conference on Stored-Product

Pro-tection, Manhattan,

Kansas,

USA,

1983. The

_presentation

that the senior author had

_given

at this

_meeting

concerned the

_{laboratory rearing}

of

_Pyemotes

tritici

_{(Lagrèze-Fossat}

and

_Montane),

a mite

_ectoparasite

of

_{stored-product}

insects. Both P. tritici and V.

_jacobsoni

_pierce

the

_integument

of their host insect and feed on its

_hemolymph.

The

possibility

that V.

jacobsoni

would also

feed

_through

the same

_synthetic

membrane and on the same artificial medium as that

_developed

for P. tritici seemed

_probable

and

_worthy

of

_study.

The discussions that followed resulted in a

_proposal

_being

submitted to and

accepted by

the

EEC,

Experts’

Group

on Varroatosis. The overall

_objective

was clear :

_develop

an artificial

_{rearing technique}

for V.

_{jacobsoni. Specific}

objectives

of this

_study

were to determine if :

₍₁₎

female V.

_jacobsoni

would

probe, pierce

and feed

_through

a

_synthetic

_{membrane ;}

₍₂₎

other life

_stages

would also feed

_through

the

membrane ;

(3)

V.

_jacobsoni

would feed on a

non-insect,

artificial diet and

_lay

_{eggs ;}

₍₄₎

V.

_jacobsoni

could

_complete

its life

cycle

when fed an artificial diet and reared under

_laboratory

conditions.

This paper

reports

the results of research conducted at the Institute for Plant

Protection,

University

of

_Udine,

_Udine,

_Italy

_during

a 4 month

_period

(May

I -

_August

31,

1986).

MATERIALS AND METHODS

All life _stages of V. _jacobsoni were obtained from colonics of honey bees derived from free-flying

crosses and rc-crosscs between Apis mellifera carnica and _{Apis meltifera ligustica,} maintained _by the Institute for Plant Protection, University of Udinc. All worker and drone brood as well as comb and wax

necessary for this study were collcctcd from these hives. _{Quality and age of brood used} in all tests were

determined by a _{qualified beekeeper.} All _laboratory reared mites were _kept in a chamber maintained at

35 ± I °C and 85 ± 2 %! RH. Membranes

Various mcmbrancs were _brought from the United States to be tested ; all were _rcadily av<tilablc and _inexpensive. Membranes tested were : _{Handi-wrap. Handi-wrap} II, Glad

_wrap

_TM

_,

_{Saran wrap, nitex} cloth, silk, and Parafilm4’ t’!. The first four were made into _{liquid-filled} sachets or sacs _{using heat-sealing}

techniques, the nitex (25 wm) and silk were _tightly woven and would hold _liquids, and the Parafilm could be stretched, molded, filled with liquid, and pressure scaled. Theses dict-fillcd sacs were then

incorpo-rated into various chambers for _feeding studies.

Test Chambers

All test or _rearing chambers used for mites were modified from _readily available laboratory items and included _{glass tubing,} ELISA blocks, and _honey bee queen rcaring cclls. A small hole was drilled

into the bottom of each cell of a micro ELISA block to _{allow easy placement} of mites and was _stoppered

with sponge to allow air exchange. The top opening of the cell was fitted with a _synthetic membrane

through which _feeding could take place. Qucen cells were modified in the _{following way : the hole in the} bottom of the _tapered cup was covered with 20 _{wm nylon} mesh and _placed in the _holding stand ; another cup, fitted into the first, provided a suitable opening in which to _place diet-filled containers. The _opening in the bottom of the _holding stand _provided for ventilation _{(Fig. 1).}

Test Procedure

Larvae and pupae of Apis mellifera were each ground separately in a test tube and the _resulting

homogenate filtered and _placed within a candidate membrane sac. Larval _hemolymph was also obtained and tested in _separate sacs. _Mcthylcnc blue _{(1 mg : 100 ml distilled H=O)} was added to each _sample as an indicator of _{feeding upon fluids. The presence of blue color in the} gut or _{in the feces would prove}

uptake. One to three gravid, adult female V. _jacobsoni were _placed either _directly on the sac or into a

cell _{containing homogenate} that had been fitted with a membrane.

Artificial diets _{(BRUCE i5! ;} HINK _unpublished) were also _{prepared, dyed} with _methylene blue, and

placed in similar chambers with either adult female mites or immature _stages for observation of _feeding. Brucc’s diet consisted basically of the _{following ingredients :} Yeast _hydrolysate, casein _hydrolysate, Wcsson’s salt mixture, Vandcrzant’s vitamin mixture, cholesterol, sucrose _gelatin, RNA solution, Tween 80 solution, chicken egg yolk and distilled water.

Mites were _given the free choice of either artificial diet or a 6-11 _{day old pupa in the base of the} queen cell. Mites were first _placed on _{the pupa, then the nitex barrier} was removed, allowing the mite to

move _{frccly between the pupa and} sac filled with artificial diet. Unless otherwise noted, all results are from tests conducted with Bruce’s artificial dict.

RESULTS AND DISCUSSION

Membrane Selection

Membrane

_suitability

tests showed that

_only

Parafilm was

_penetrable.

One

possible

explanation

for the lack of

_penetration

of the

_{plastics by}

these mites is

that,

unlike P.

tritici,

V.

_jacobsoni

does not _{possess cheliceral} extensor

mus-clers to move the chelicerae forward

_(A

_KIMOV

and

_Y

_ASTRESTSOV

_,

_1983).

Appa-rently,

this

_species

lacks the

_strength

or was unable to brace itself

_against

a

hard surface to

_penetrate

the

_plastics

even

_{though they}

are of the

_appropriate

thickness

_{(10-15 p.m).}

In

_addition,

the chelicerae of V.

_jacot

oni are

_larger

and more blunt at the

_tip

than the

_stylet-like

structures of P.

tritici,

even

_though

both are

_{approximately}

the same effective

_length

(approximately

15

!,m).

Also,

the Parafilm sheets could be stretched

_consistently

to

_{approximately}

10 p-m in

thickness

_(verified

_by

_scanning

electron

_{microscopy) by pulling}

in both direc-tions until tension

_stopped

the

_pull.

Test Chambers

The modified micro ELISA blocks were somewhat

unsatisfactory.

This was because the cover sheet of Parafilm did not seal well to the

_diet-holding

sheet when the micro ELISA was turned over to observe the results of

feeding.

However,

of the 45 adult females set _{up in} tests No. 1 and

2,

all cells showed evidence

_{(blue feces)}

within 3

_days

of

_feeding

_through

a

_synthetic

membrane.

However,

all but 6 females died after 3.5

_days.

In a third test,

44 out of 48 females drowned within 1

_day

because

_hemolymph

leaked into the cells.

Results of

_feeding

tests in which

_glass-tube

chambers were used were also unsuccessful because of leaks

_along

the uneven

_edges

at the end of the tubes. Modified queen cells were used for the remainder of the tests

_(beginning

July 1)

because few leaks occurred and observation was

_simplified.

_Also,

from this

_point

onward further tests

_employed

artificial diets

_only,

because it had been

_clearly

demonstrated that adult females of V.

_jacobsoni

would feed

through

a

synthetic

membrane on

_honey

bee

_{hemolymph dyed}

with

_methylene

blue.

Results of the first test

_using

artificial diet

_(V.

_jacobsoni

adult female mites removed from drone

_pupae)

indicated

_feeding

within 24 hr in all cells

(gut

of female stained blue - blue feces in

_cell).

In

addition,

four eggs, one

hatched.

However,

three very

significant

events occurred

_during

this test :

(1)

females of V.

_jacobsorci

fed on an artificial

_diet,

(2)

females laid eggs on

synthetic

surfaces,

and

₍₃₎

both these results occurred under

_laboratory

condi-tions.

This test, when

_repeated

₍₅

cells,

3

_mites/cell)

with a

_slight

modification

in the artificial diet

_(chicken

_egg

_yolk

_removed),

resulted in

_feeding

in all cells and 7 eggs laid within the first 24 hr. After 48 hr all females were alive and had

_{fed ;}

four more _{eggs had been}

laid,

three of which had

hatched,

and two

protonymphs

were alive. One egg laid

_during

this second 24 hr

period

contained

_methylene

blue

_dye.

This

_suggested

_{that the egg} was formed after

feeding

had

_begun

and that

_perhaps

some

_components

_(protein

_?)

of the diet were

_incorporated

into the egg

(T

EWARSON

and

J

ANY

,

1982).

After 72 hr 12

females were

_alive,

three more _eggs were laid

(two blue),

and four more _eggs

had hatched. After 120 hr 6 females were

_alive,

one more blue egg was

_laid,

and one

_protonymph

had fed on the died as indicated

_by

the presence of

methylene

blue in the

_gut.

This

_procedure

was

repeated

three times and the results are combined and

presented

in Table l. About 75 % _{of the eggs} were laid within the first 24

hr,

with the remainder on

_days

two and three.

_Egg

hatch

_began

on

_day

two and

was

_{completed by day}

four.

_Only

a small

_percentage

(28 %)

of the eggs

hatched. Adult female survival remained

_high

until

_day

four and

_dropped

rapidly

thereafter. The Hink artificial _{diet gave somewhat similar results in} that all

_feeding

_stages

fed on the diet but no adult females lived

_longer

than two

_days

and all

_stages

that fed

_appeared

_slightly

distended. In

addition,

while

over half the _eggs were blue

(15

_eggs laid - 9

blue), only

one hatched. The

preliminary

results indicate the likelihood of

_developing

an artificial diet that

provides

the nutritional

_requirements

of V.

_jacobsoni

is

_{quite promising.}

days.

In another

_study

conducted

_{concurrently,}

adult females of V.

_jacobsoni

reared on

_honey

bee larvae and pupae under similar conditions of

_temperature

and

_humidity,

in various

_{environments,}

_{gave similar results for the} immature

stages.

Adult

_{females, however,}

survived several

_days

_longer

when

_compared

to the artificial diet

_(C

_HIESA

and

_M

_ILANI

_,

_1986).

Both studies used the

temperature

and

_{humidity regime}

described

_by

SAKAI et al.

_(1979).

_{It appears} that some combination of

_temperature,

_humidity

_{and air flow may also be} critical.

Results of

_feeding

tests with

_protonymphs

and

_deutonymphs

indicated that both instars could

_pierce

the Parafilm sac and

_ingest

the artificial diet.

However,

only

4 to 16

_protonymphs

and 2 of 8

_deutonymphs

_actually

_fed,

and

only

one of the

_deutonymphs

molted. All

_appeared

to be _{in the process of}

desiccating

within 24 hr.

Results of the food choice selection were

_{quite interesting.}

Of the 11 cells set _{up, 4 had} to be discarded because the _pupae were

_damaged.

_However,

feeding

on both pupae and artificial diet occurred in 4 of the

_remaining

_{7 cells} as evidenced

_by

_{the presence of both white and blue feces. This kind of} behavior may indicate that few stimuli are

_required

to initiate

_feeding,

and that V.

_jacobsoni,

because of its

_{biology, indiscriminately}

_probes

whatever is within its

_environment,

_feeding

on that which is

_{acceptable. Normally}

this environment is the brood cell with

_only

a larva or _pupa

_being

available as the food source.

During

these

studies,

no

_attempt

was made to use

_aseptic

_techniques

either

_{during preparation}

of the artificial diet or

_{during testing,}

and as a

consequence, mold

frequently

was a

_problem.

It is not known what effect mold had on the results but

_clearly

if an artificial diet is to be used in the

mass-rearing

of these

_mites,

_appropriate

measures will need to be taken. While not _every

_objective

was met, the

_following

was

_clearly

demons-trated :

(1)

All

_feeding

_stages

of V.

_jacobsoni

were able to feed

_through

a

synthetic

membrane on an artificial diet.

(2)

Females

_oviposited

within the environment of an artificial or

_plastic

cell.

(3) Components

of the artificial diet were observed to be

_incorporated

into eggs.

(4)

Eggs

hatched to

_larvae,

and larvae to

_protonymphs.

_Protonymphs

did not

_{complete development}

to the

_deutonymphal

_stage,

and thus a

complete life-cycle

was not achieved.

Further studies to

_accomplish

a

_complete

life

_cycle

and

_develop

the

University

of

Udine,

Udine,

Italy

and the Institute for Animal

Health,

Freiburg,

FR

_{Germany, respectively. Hopefully}

these results will stimulate the continued

_cooperation

of the EEC with the various research

_{organizations,}

including

U.S.

_Department

of

_Agriculture,

to

_{provide appropriate}

solutions to

a _{very real threat} to world

_agriculture.

Received _{for publication} in _July 1987.

Accepted for publication in October 1987.

ACKNOWLEDGEMENTS

The authors thank Professor F. FRILLI for his _{outstanding support} and activity in helping to set _up

the multinational team which made this _{project possible.} Also, the _project could not have succeeded without the _expertise of M. _{D’AGARO, beekeeping specialist,} and the technical support of Dr. N. MILANI,

both of the University of Udine, nor without the _{gracious provision by} Dr. F. Hirrx of his artificial diet. We also thank Dr. R. BARBA111NI and M. G. ZUGOLO for their administrative assistance. Finally, we extend _special thanks to Professor R. CAVALLORO and the EC Committee on varroatosis for _supporting the _project.

RÉSUMÉ

ÉLEVAGE EN LABORATOIRE DE VARROA JACOBSONI OUDEMANS (ACARI, VARROIDAE) SUR RÉGIMES ALIMENTAIRES NATUREL ET ARTIFICIEL

La _possibilité d’élever Varroa _jacobsoni Oudemans en laboratoire sur un _régime artificiel a été

suggérée par Donald Griffiths à la suite de la 3‘ Conférence Internationale sur la Protection des Denrées

Entreposées, qui s’est tenue à Manhattan (Kansas, USA) en 1983, où il a _présenté une communication sur la mise au _point d’un _régime artificiel et sur une méthode d’élevage en laboratoire de _Pyemotes tritici

(Lagrèze-Fossot and _{Montané), cctoparasite} des insectes des denrées entreposées. Bien que P. tritici et

V. jacobsoni percent tous deux le _tégument de leur hôte et se nourrissent de leur hémolymphc, il est

difficile de comparer plus avant leur biologie. Il nous est _{néanmoins paru probable que V. jacob.soni} soit

également susceptible de se nourrir sur _{le même milicu artificiel que celui mis} au _{point pour P. tritici} et

qu’il le fasse à travers la même membrane _{synthétiquc.} La recherche a été menée à l’Institut de Protection des Plantes de l’Université d’Udine à Udinc (Italie) sur une _période de 4 mois (I&dquo; mai-31 août 1986). Elle avait pour but de déterminer si :

1) la femelle adulte de V. jacobsoni pourrait explorer et percer une membrane _{synthétique,} non vivante et se nourrir à travers cllc ;

2) d’autres stades de _{développement pourraient également} se nourrir à travers cette membranc ; 3) V. _{jacob.soni pourrait} se nourrir sur un _régime artificiel ne _{provenant pas d’un insecte} et _pondre

des oeufs ;

4) V. _{jacobsoni pourrait accomplir} son _cycle de _{développement} sur ce _régime artificicl et être ainsi élevé en laboratoirc.

On a _prélevé dans des colonies d’abeilles, Apis mellifica, tous les stades de développement de V.

On a choisi et testé un certain nombre de membranes _{synthétiques.} Les tests _{initiaux pour déterminer la}

capacité de l’acarien à se nourrir à travers la membrane ont utilisé un _homogénat filtré _{d’hémolymphe} larvaire et nymphale, coloré au bleu de méthylène. Par la suite un _régime artificiel _(BRUCE. non _publié) a

été mis au _point et testé dans les mêmes conditions.

La membrane _synthétique choisie comme étant la mieux _adaptée est la membrane Parafilm@+ ;

toutes les autrcs membranes testées ont donné des résultats _{négatifs. Parafilm, étirée pour avoir} une

épaisseur d’environ 10 _u.m. s’est montrée très efficace. Les tests initiaux _qui utilisaient le bloc ELISA modifié et _{l’hémolymphc homogénéisée} et colorée ont _{prouvé, par la présence} de fèces colorés, la

capacité de la femelle de V. jacob.soni à se nourrir à travers la membrane. Néanmoins on abandonna le bloc de test ELISA en raison de la _perte de nourri turc due n des _problèmes de fuite.

Pour la suite des tests on a donc _adaptc des cellules de reine modifiées et le _régime artificiel a

remplacé l’hémolymphe homogénéisé. Avec cette _technique, les femelles se sont nourries à travers la

membrane, ont _pondu des oeufs à sa surface ou sur les côtés de la cellule, tout ceci dans des conditions de laboratoirc (35 ± 1 &dquo;C et 85 ’%! d’HR). La _présence de bleu de méthylène il l’intérieur de certains &oelig;ufs

montre _{que l’oeuf s’est formé après} le début de J’alimentation et _{que certains composants} du régime ont

pu être incorporés à )’&oelig;uf. Environ 30 % de ces oeufs ont éclos au stade de _{protonymphe (Tahl. 1). ¡.} Parmi celles-ci, on a pu en observer _qui se nourrissaient mais aucune n’a subi la mue _{pour passer} au stade de _deutonymphe. De même, de nombreuses _{deutonymphes prélevées} directement dans les ccllulcs de couvain se sont nourries mais aucune n’a réussi à atteindre le stade adulte. Il est à noter _{également que}

des femelles, _auxquelles on donnait le libre choix de se nourrir naturellement sur une _nymphe ou à

travers une membrane _{synthétique,} se sont _réparties de _façon aléatoire sur les deux, comme l’a _prouvé la

présence de fèces blancs et bleus dans la cellule de test.

ZUSAMMENFASSUNG

LABORAUFZUCHT VON VARROA JACOBSONI OUDEMANS

MIT NATÜRLICHER UND KÜNSTLICHER NAHRUNG _{(ACARI : VARROIDAE)} Die _{Möglichkeit,} Varroa jacobsoni Oudemans im Labor auf künstlicher Diät aufzuziehen, wurde von Dr. Donald Griffiths auf der 3. Intern. Arbeitskonferenz über den Schutz von Lebensmittelvorräten in Manhattan. Kansas. USA, vorgetragen. Er _{präsentierte} auf dieser Konferenz eine _{Veröffentlichung} über die Laboraufzucht von fycmfff.! tritici (Lagr!ze-Fossot und Montane), einem Ektoparasitcn von

Vorrats-schädlingen, und über dessen Entwicklung bei künstlicher Diät. Obwohl beide Milben, P. tritici und V.

jacabsoni das _Integument ihres Wirtes durchbohren und sich von dessen _Hämoiymphe ernähren, sind weitere _Vergleiche ihrer _{Biologie schwierig.} Trotzdem erschienen uns _{Spekulationen} darübcr annehmbar,

da&szlig; sich V. _jacobsoni von der _gleichen künstlichen Diät wie P. tritici und ebenfalls durch eine

synthetische Membran ernähren könnte.

Die _{Untersuchungen} wurden am Institut für Pflanzenschutz der Universität Udinc, in Udinc, Italien, während einer Periode von 4 Monaten _(1. Mai - 31. _{August 1986) durchgeführt.} Als _{Ziclvorstcllung galt}

die _{Beantwortung folgender Fragen :}

(1) Würden adulte V. jacobsoni-Weibchcn die tote, synthetische Membran untersuchen, durchbohren und Nahrung aufnehmen ?

(2) Würden andere Lebensstadien sich auch durch die Membran crnährcn 1’

(3) Würde sich V. _jacob.soni von einer nicht von Insekten stammenden, künstlichen Diät ernähren und Eier _Icgcn ’?

(4) Würde V. _jacob.soni ihren _Lebenszyklus mit der künstlichen Diät beenden und somit unter

Laborbcdingungen aufgezogen werden können ?

umgearbeiteten Königinncnzellen (Fig. 1) oder aus einem Mikro-ELISA-Testblock _hergestellt. Eine Reihe von _{synthetischen} Membranen wurde _ausgewählt und getestet. Anfängliche Tests zur _Bestimmung der

Fähigkeit der Milbe, sich durch die Membran hindurch zu ernähren, wurden mit einem _gefilteren

Homogcnisat von larvaler und _{pupaler Hämolymphe, angefärbt} mit _{Methylenblau, durchgeführt.} Anschlic&beta;end wurde eine künstliche Diät (BaucF, unveröffentlich) hergestellt und unter den _gleichen

Bedingungen getestet.

Die am besten geeignete synthetische Membran war Parafilm@+ ; alle anderen _getesten Membranen

ergaben negative Ergebnisse. Parafilm, der auf _{ungefähr 10 wm Dicke ausgczogcn} wurde, ergab eine hohe Effektivität. _Anfängliche Tests mit dem modifizierten ELISA-Block und _angefärbtem

Hämolymphe-Homogcnisat zeigten durch das Vorhandensein _angefärbten Kots die _Fähigkeit von V.

jacobsoni-Weibchen sich durch eine künstliche Membran hindurch zu ernähren. Der ELISA-Tcstblock wurde

jedoch später aufgegeben, da infolge von undichten Stellen _Nahrung verloren _ging.

Daher wurden die umgebauten Königinnenzcllcn für die rcstlichcn Tests verwendet und anstelle von

homogenisierter Hämolymphe die künstliche Diät. Mit dieser Technik konnten sich die Weibchen unter

Laborbcdingungen (35 ± I °C und 85 % rF) durch die Membran hindurch ernähren und _legten Eier auf der Membran oder an den Zellwändcn ab. Der Nachweis von _Methylenblau in _einigen Eiern wies darauf hin, da&szlig; die Eier _{gebildet wurden,} nachdem die Fütterung begonnen hatte und wahrscheinlich _einige

Komponenten des künstlichen Futters in die Eier _inkorporiert wurden. Etwa 30 % dieser Eier

entwickel-ten sich zum _{Protonymphenstadium (Tab. 1).} Von diesen wurden _einige bei der _{Nahrungsaufnahme}

beobachtet, aber keine entwickelte sich zur _Deutonymphe. In gleicher Weise crnährtcn sich viele

Deutonymphen, die aus Brutzellen entnommen wurden, von der künstlichen Diät, aber keine cntwick-kelte sich weiter zum adultcn Stadium. Es sollte weiterhin vermerkt werden, da&szlig; Weibchen, denen eine freie Wahl zwischen der natürlichen Ernährung auf der _Bienenpuppe oder der künstlichen durch die Membran hindurch geboten wurde, sich eher _zufällig von bcidem Futter ernährten, wie das Vorhanden-scin von wei&szlig;em und blauem Kot in der Testzclle bewies.

REFERENCES A

KIMOV LA. and YASTREBTSOV _A.V., 1983. -

[The muscular system of the mite Varroa jacobsoni (Parasitiformes, Varroidae) : A _parasite of the _honey bee. I. Muscles of the _gnathosoma]. Vestn. Zool.

(2), 68-72 _{(in Russian).} C

AVALLOROR., 1983. -

Varroa _jacobsoni Oud. _{affecting honey} bees : _present status and needs. _Proceedings.

European Experts’ Group Meeting on _Varroatosis, R. Cavalloro cd., Wageningen, Netherlands. Ctttssn F. and MILANI N., 1986. - Some

preliminary observations on the behaviour of Varroa _jacobsoni Oud. on its natural host under _laboratory conditions. In _{« Europcan} Research on Varroatosis

control » Proceedings of a _Meeting of the EC _{Experts’ Group.} Bad _Homburg, 15-17 October 1986

(In press). D

E JoNC D., MORSE R.A. and EICKWORI G.C.. 1982. - Mite

pests of _honey bees. Annu. Rev. Entomol., 27, 229-252.

GeitF!THS D.A., GRAY J. and PEGAZZANO F., 1983. -

Varroa - The _{acarologists’} view. In : _Proceedings

European Experts’ Group Meeting on Varroatosis, R. Cavalloro cd., Wageningen, Nctherlands,

107 p.

Sntcnt T., Tnxt:ucttt K. and HARA A., 1979. -

[Studies on the life _history of a _{honeybee mite,} Varroa

jacobsoni Oudemans, in _{laboratory rearing].} Bull. Fac. _{Agric. Tamagawa} Univ. _{(19), 95-103 (in Japanese).}

T

EWARSON N.C. and JANY K., 1982. - Determination of