Invasion of the Nest of Polistes dominulus by the Social Parasite Sulcopolistes sulcifer (Hymenoptera, Vespidae)1

Ethology 84, 47-59 (1990) 0 1990 Paul Parey Scientific Publishers, Berlin and Hamburg ISSN 0179.1613

Dipartimento di Biologia Animale e Genetica, Universita di Firenze, Firenze

Invasion of the Nest of Polistes dominulus by the Social Parasite Sufcopofistessufcifer (Hymenoptera, Vespidae)') S. TURILLAZZI, R. CERVO & I. CAVALLARI TIJRILLAZZI, S., CLRVO, R. & CAVALLARI, I. 1990: Invasion of the nest of Polrstes dominulus by the social parasitc Sulcopolistes sulcifer (Hymenoptera, Vespidae). Ethology 84, 47-59.

Abstract The main characteristics of invasion of a Polistes dominulus Christ colony by a female of Sulcopolistes sulczfer Zimmermann can be summarized as follows: the parasite is usually attacked by Polistes while still approaching the nest. The parasite fights all opponents on the ground, both foundresses and workers, some of which can be very aggressive even off the nest. Others succumb to the parasite immediately o n the very first encounter. Sulcopolistes' strategy is to fight one adversary at a time and then return rapidly to the nest. In this way it is easier for her to defeat the hosts one after another, and to usurp nests with a high number of workers. While fighting on the ground the parasite never used its sting, but tried to bite the legs off its victims. The alpha foundress is the one which attacks the parasite most aggressively, which in turn is particularly aggressive towards her. Beta females o n bigynic and gamma females o n trigynic foundations are less aggressive than their nestmates of higher hierarchical status. After nest conquest, dominance activity of the parasite increases, and she offers drops of liquid to nest occupants during encounters. When not interacting with the hosts, Sulcopolistes performs an intense nest inspection and carefully strokes the nest surface and internal parts of some cells with her abdominal sterna. Dipart. Biologia Animale e Genetica, Universita di Corresponding author: D r . S. TURILLAZZI, Firenze, via Romana 17, 1-50125 Florence.

Introduction Sulcopolistes, which live almost exclusively around the Mediterranean basin (see GUIGLIA 1972), usurp the nest of some species of Polistes towards the end of the pre-emergence period. These parasites lack a worker caste and rely on the workers of the host to rear their brood. The genus consists of the only three known examples of obligate social parasites of Polistes wasps (and as far as we ') Studies supported by the Italian Ministry of Education (funds M.P.I. 60 % and 40 "10) U S Copvright ~ l e ~ r a Center n ~ e Code Srarernent

0179-1613/90/8401-0047$02.50/0

48

S. TURILLAZZI, R. CERVO & I.

ChvhLi A K I

know, of all the polistine wasps, cf. WILSON1971), but this is far from established. The only extensive study is that of SCHEVEN (1958), which treated the biology and behaviour of the three described species (5. utvimundibufuvis Zimmermann, S. semenowi Morawitz and S. sulcifev). Prior to this paper, scattered information on the behaviour and social biology of some species had been furnished by WEYRAUCH (1937), DE BEAUMONT & MATTHEY(1945), and DE BEAUMONT (1955). After SCHEVEN(1958) only DISTEFANO (1969) published some observations o n two colonies of P. dominufus Christ (= P. gulficus L. of the previous literature: DAY1979) which had been usurped by females of S. sulcifev, while DEMOLIN & MARTIN(1980) reported an infestation of S. semenowi o n a bigynic nest of P. nimphu Christ. Despite the small attention they have received, these parasites are of great importance for the study of the evolution of social parasitism in vespids for their uniqueness in the subfamily Polistinae. Recently, we had the opportunity to study the biology and social behaviour of S. sufcifer. In this paper w e report on the behaviour of the parasite females during the invasion of colonies of P. dominulus performed in cages kept in the laboratory, and try to quantify the occurrence of various behavioural patterns during the initial stage of invasion and responses of the hosts. Methods Females of S.sulcifer were found o n usurped colonies of P. dominulus or netted in flight at the beginning of June 1986, 1987 and 1988 in various localities of northern and central Italy. The wasps were transferred in small glass containers to the Zoological Laboratory of the Dept. of Animal Biology of the University of Florence. The parasites were kept singly in small cages with water and honey ad lib. for a period n o longer than a fortnight, until their utilization in the experiments. Usurpation experiments in the laboratory used pre- and post-emergence colonies of P. domindus with varying numbers of adult females. These colonies were maintained in glass boxes (15 x 15 x 15 cm) and had either been collected in the field some days before or founded in captivity by foundresses captured approximately one month earlier. The condition (number of cells, eggs, larvae and pupae) of each nest was noted before the experiment. Females founding nests in groups of two or more were marked individually with enamel paint, and observed before the experiment to ascertain their dominance hierarchy. The parasites were introduced in small containers into the boxes with the host colonies. The container was opened a t the beginning of the experiment. If the parasite did not take possession of the nest within 45 min we considered the usurpation as failed. In this case, the same parasite was eventually used for other experiments with different host colonies, and the same colony was later presented to other parasites. 22 successful usurpations by different animals were recorded with a videocamera for a time varying from 10 to 45 min after the parasite first landed o n the nest. Of the 22 usurpations 18 occurred the first time the parasite was tested, three the second, and one the third. The behaviour of the parasites was then analyzed by reviewing the video tapes to compute the frequencies of particular behavioural patterns.

Results Attack and Fighting

Soon after their introduction into the experimental cage, the parasites began to antennate in the air with their heads raised. For a while they walked along the

walls, then reached the host nest, sometimes walking there, other times in flight.

Invasion of Host Nest by Su/copo/rstes rulcrfcr

49

Fig. I : Antenna1 duel near host nest. Sulcopolistes sulclfer (right) and an alpha Polrstes dorninuluj female

The time from introduction into the cage and the first contact with the host varied from 10 s to 20 rnin (mean = 4 rnin 20 s; n = 19). More often (14 out of 22 cases) the Polistes attacked the parasite while it was still approaching the nest. The parasite was never observed to attack a Polistes female first. The parasite fighting tactic consisted of confronting one host after the other. She challenged the Polistes, and a more o r less prolonged antenna1 duel (a skirmish using the antennae only) followed. During the fight, the wasps sometimes rose up o n their middle and hind legs, the Pofistes held her front legs wide apart and the parasite kept hers lower (Fig. 1). The Polistes usually kept her mandibles open, while the parasite more often held them closed. The two wasps then grasped each other and fell to the ground together. This is where the most fierce combats took place when the contenders grappled with each other for some time. In one case this “wrestling match” lasted for 21 min. Usually the Sulcopolistes was on the top with the Polistes trying to sting her in the abdomen from below. The parasite, on the other hand, usually kept her abdomen to the outside of her adversary’s, which was bent ventrally, with her mandibles aimed at the coxae of the host’s legs. We never observed the Polistes kill a parasite or, on the other hand, the Sulcopolistes kill her host with her sting. However, in 4 out of 38 ground duels, observed before nest conquest (we define with this term the first time the parasite remained for at least 1 min continuously on the nest), the parasite bit off a leg of the defender at the coxa. This was also the result of some ground fights after nest conquest. At the end of each fight the parasite usually returned to the nest quicker than her adversary and there she took on another Pofistes. Often, depending also on the number of hosts present on the nest, the parasite remained alone. In o u r experiments, the time between the parasite’s introduction into the cage and “nest conquest” varied from 1 min to 30 rnin (average 9 min). Defeated Polistes might return to the nest after a variable length of time and engage in fighting the parasite. This combat usually ended in the two females falling to the ground where they continued fighting. In this case the parasite was usually the first to return to the nest. Dominance-subordinance interactions included the parasite’s looming over the host, akinesis of the Polistes, fluid regurgitation and its offering to the

50

S. TLKIL I A Z Z I , R. CLKVO 8( I. CAVALL AKI

Fzg. 2: S. sulctfrr mouthing body of a P. dominulus host female after nest conquest

parasite, trophallaxis, biting and mouthing of the body of the host (Fig. 2 ) by the Sulcopolistes. They often became evident some time after invasion and depended on the kind of individuals present o n the nest. Usually subordinate foundresses and newly emerged workers were not very aggressive and were dominated from the very first moment. Fluid offerings were not only made by the host but also by the parasite. The parasite was not solicited when she made these offerings, nor did her dominant position seem to be challenged. Sometimes the offerings were reciprocal and simultaneous; in some cases we noted that the parasite attached its d r o p of fluid to that of Polistes, so that the host sucked up the parasite’s liquid as well as its own. From the moment of “nest conquest” the parasite began to inspect the nest and cells carefully. During this activity she usually rubbed the last abdominal sterna over the nest surface, on the cell opercula, and inside the cells (Fig. 3 ) . Permanence on the Nest by the Parasite

The parasite rarely left the nest once this had been conquered. Average permanence of the parasite on the nest appeared high and constant on the different types of colonies. The parasite seemed to stay slightly less on monogynic

Fzg. 3: Parasite stroking nest surface with gastral sterna after conquest

51

Invasion of H o s t Nest by .Sulcopolistes S I I I C L ~ E ~ 3

1

300280260240220200n 180W 160140120100-

.-E

+

80-

6040200-

0-5

5-1 0

10-15

15-20

20-25

min from nes t conquest

= monogynic nests EI trigynic nests

bigynic nests EECd nests with workers

Fig. 4: Av. presence of SuIcopolistes o n various nest types: first 35 rnin after conquest Sample sizes above bars

nests, but the time difference compared with the other nests was not significant. Fig. 4 gives the average number of seconds spent on the nest, every 5 min and up to 25 min after the “nest conquest” during the 22 experimental invasions. Distribution in Time of Particular Activities of the Parasite The average distributions in time of various activities of the parasite measured in the 22 experimental invasions after nest conquest are reported in Fig. 5 for 8 o r 9 periods of 5 min each (up to 40 and 45 rnin after nest conquest respectively). While the dominance activity of the parasite increases significantly (Spearman rank correlation test, n = 9; r = 0.9; p < O.OI), the fighting (n = 9; r = -0.73; p < 0.05) and abdominal stroking (n = 7; r = -0.92; p < 0.01) decrease. Behaviour of the Parasite towards Host Females of Different Caste and Hierarchical Status Table 1 shows the number and caste of the females present on 20 out of 22 colonies which were usurped in the experiments. In the remaining t w o colonies we were not able to discover the caste o r social status of the females present at the moment of invasion, and they were excluded from the computation. Monogynic Nests (n = 4) After the first fight and once the parasite had climbed o n t o the nest, foundresses of the monogynic nests did not return at all during the study period (10, 30, 30 and 30 min respectively) except for very rare and very brief visits o n one nest only. 4:.

52

S. TURILLAZZI, R. CERVO & I. CAVALLARI

Table I :

Conditions of 20 out of 22 nests of P. dominulus usurped by Sulcopolistes sulcifer in the laboratory

Nest

Foundress

A B C D E F G H I

S

1 1 1 1 2 2 2 3 3 3 3 3 3 2 2 3 3 1 1

T

-

J K L M N 0

P

Q R

Workers

Cells

Opercula

Larvae

Eggs

26 35 32 27 88 20 40 30 64 58 60 49 16 22 23 25 47 59 39 48

1 0 3 2 23 5 9 5 4 13 9 10 2 0 4 3 3 4 1 9

9

11 4 9 7 24 7 8 7 14 20 22 14 7 6 9 15 25

5 7 10 33 8 9 13 25 23 28 19 6 12 9 9 14 22 14 21

14

17 16

Bigynic Nests (n = 3)

Before nest conquest, the Sulcopolistes first fought with the alpha female which attacked the parasite while she was still approaching the nest in 3 cases out of 3. The duels continued on the ground, and when the parasite arrived on the nest again, in two cases she started fighting with the beta female. After nest conquest the alpha females rarely returned to the nest, while the average presence of the beta females increased, reaching 100 % after 30 min (Fig. 6 a). The average amount of time that beta spent on the nest (742 s ) was significantly higher than that of the alpha (30 s) (t-test; t = 4.38; p < 0.01). The parasite only directed the dominance activity towards beta females sometime after “nest conquest” (5 min) (Fig. 6 b). The parasite offered fluid to beta on 22 occasions and only once to the alpha. If we consider the time of co-presence of the parasite with each of the two foundresses on the nest, offerings to beta worked out at an average of 0.008 offers/s and those to alpha 0.01 1 offers/s; differences are not significant. Trigynic Nests (n = 6)

Before nest conquest all the host females attacked the parasite approaching the nest regardless of their social status and all fought with her on the ground. After nest conquest, the gamma females remained on the nest the longest (246 s ) [significantly more than alpha (23 s) and beta (9 s); t = 2.29; p < 0.05 and

53

Invasion of Host Nest by Sulcopolistes sulcifer

< 0.02; respectively] (Fig. 7a). Trigynic beta females remained on the nest significantly less than beta females on bigynic nests (t = 3.14; p < O.O2), while the permanence of the alpha females did not significantly differ from alphas' on bigynic nests. Parasites mostly directed dominance towards the gamma females and only in one case towards the beta (Fig. 7b). Dominance activity increased from the first min up to 25 min after nest conquest. The parasite offered fluid to the gamma in 6 cases, in 4 to the alpha and 1 to the beta (in 2 other cases we could not establish which was the partner). Taking the co-presence on the nest

t = 2.85; p

c

10

P)

C P)

5 C

I

I

7

I

.-i

22

c

''TT

17

i

3

TI II : I

\

._ E c

m

.c c

0,

G

-5

-5 -10-15-20-25-30-35-40

-10-15-20-25-30-35-40-45

min from nest conquest

-45

min from nest conquest

A c

O.9

22

01 C

0

5 C

.-E c

\

.-E c

m

C .Y

e

c c

m C

Fig. 5: A) Quotient of av. time Sulcopolistes fought -5-10-15-20-25-30-35-40

min from nest conquest

C

host foundresses and workers, first 45 min after nest k SD). B) As A), but for conquest, and time on nest dominance activities, and time of co-presence on nest f SD). C) As A), but for nest stroking (first 40 min) k SD). Sample sizes above bars and time on nest

(x

(x

(x

54

S. TUKII LAZZI, R. CI KVO & I. CAVAI IA K I

of the parasite with each of the foundresses, we obtained average values of 0.0057 offers per second to the alpha, 0.0087 to the beta and 0.002to the gamma, which do not differ significantly. 300

3

200]

50 -

I i Ii iI 3

00 -

50 -

0-

A

3

rn 3 0-5

5-10

10-15

15-20

20-25

min from nest conquest 30-1

20-

3

10-

0-

3 0-5

10-15

5-10

i

15-20

20-25

B

25-30

min from nest conquest

alpha

beta

Fig. 6: A) Av. presence of a and p foundresses o n bigynic nests for first 25 min after conquest by Sulcopolistes. B) Av. % of time Sulcopolistes dominated a and p females from bigynic nests, first 30 min after conquest. Sample sizes above bars

55

Invasion of H o s t Ncst b) Sdcopolistcs sulcifrr

2 300

250

A

100

6

50

6

0-5

10-15

15-20

B

30 -

20 6

10-

0-

20-25

25-30

I

35-40

40-45

min from nest conquest

50 -

40 -

l 30-35

5-10

6 0-5

5-10

10-15

I-

15-20

20-25

25-30

30-35

2

35-40

40-45

min f r o m nest conquest

E E Z E l alpha beta Ugamma I,'ig. 7: A) Av. presence of (I, /j and y foundresses on trigynic nests, first 45 min after conquest by Sulcopolistes. €3) Av. time Sulcopolistes dominated a , /3 and y females of trigynic nests: 45 min after conquest. Sample sizes above bars

Nests with Workers (n = 7)

Before nest conquest both workers and foundresses attacked the parasite. Sometimes the workers even attacked the parasite when they were away from the nest. After nest conquest the average presence of the workers remained almost constant; foundresses returned only after 5 min, and their average presence

56

S. TURILI AZZI, R. CERVO & I. CAVALLARI

increased in time (Fig. 8). Workers were, on average, more subjected to dominance by the parasite than foundresses (only 6 nests were considered because one lacked the foundress), although the difference is not statistically significant. The parasite offered fluid to foundresses in 6 cases and to workers in 4. If we consider the average time of co-presence of the parasite with the workers and the foundresses, we obtain values of 0.0039 for the foundresses and 0.001 for the workers. Differences are not statistically significant.

150

300 n

v,

W

Q)

.-E

100

1

2 6

6

4

-

4

2 50

-

0 0-5

5-10

10-15

15-20

20-25

25-30

30-35

min from nest conquest average presence per foundress Fzg. 8:

average presence per workers

Av. presence per host foundress (all ranks) and worker o n nests with workers, first 40 min after nest conquest. Sample sizes above bars

Discussion Previous authors have already documented some characteristics of the invasion of the nest of P. dominufus by S. sufcifer. SCHEVEN (1958) described the fighting behaviour of the parasite and its dominance activity over the host foundresses; DISTEFANO (1 969) observed a different response of Polistes females to the invasion of the parasite depending o n their hierarchical status. SCHEVEN compared 'the behaviour of the parasite to that of the alpha female of an associative foundation of the host species (PARDI1942); he did not think that the

Invasion of Host Nest by Sulcopolistes sulczfer

57

large mandibles of the Sulcopolistes had any function during the fight (contrary to DE BEAUMONT & MATTHEY 1945) but reported the use of the sting both by the host and the parasite. DISTEFANO (1969), on the contrary, observed that the mandibles were used to cut the legs off the Polistes and that after a time the foundresses abandoned the usurped colony one after the other. O u r observations on usurpation behaviour were limited to the moment of invasion and to a brief period afterwards, as the captivity conditions could have influenced the later behaviour of both parasite and host. The most fierce and decisive fights occurred on the ground and thus away from the nest. The strategy of the parasite seemed to be to fight one adversary at a time and then to quickly return to the nest. In this way she more easily defeated the hosts in succession and succeeded in usurping nests where even 11 workers were present (on one nest with 20 workers the parasite was defeated because too many workers attacked her from different sides at the same time). Both foundresses and workers attack the parasite, but, as DISTEFANO (1969) noted, aggressive interactions between the parasite and her hosts differ in intensity. While fierce duels were the rule when the parasite met the alpha female, a lower degree of aggressiveness distinguished the encounters with other foundresses and workers. O n bigynic foundations the beta females were observed to soon return to the nest and to submit themselves to the parasite; this also occurred in gamma females on trigynic colonies. Thus lower ranking females were more usually found on the nest, at least in the very first period after invasion, while alpha females rarely returned, even in the restricted space in the box. Some newly emerged workers never abandoned the nest and accepted the intruder from the start, while others often engaged in violent duels with her before being dominated. The cases in which we observed the parasite to attack first were very rare, thus it is possible that she waited for a sign of aggression from the host before entering into combat. From her point of view, besides recognizing the more dominant individuals in this way, this tactic would avoid useless and dangerous contests both for the parasite herself and for the possible host worker-force she will exploit later. A serious problem for all the submissive individuals is that their fitness is extremely compromised by the unrelated parasite. Unless they can try to reproduce in some way in the future, they will only remain on the nest to rear unrelated brood if they are deceived by the parasite. Thus it is highly probable that the parasite employs some other mechanism to keep the colony under control besides the purely behavioural one. The offering of fluid to the host by the parasite has not been described by any previous author. Actually in Polistes a minor passage of regurgitated fluid from dominant to subordinate individuals does occur but it is much lower than in the opposite direction (see MARINOPICCIOLI & PARDI1980, who measured the passage of radioactive tracers in foundresses of P.dominulus but pointed out that transfer of salivary fluid could not be detected with their method). In the case of Sulcopolistes - Polistes interactions, we observed that the offering by the parasite is made without any apparent solicitation from her host and could be explained as a pacificatory behaviour. Another explanation could be that the drop contains substances (allomones) with special inhibitory effects on the aggressivity and/or

58

S. TURILLAZZI, R. CERVO & I. CAVALLAKI

the reproductivity of the hosts. This could also explain the apparent interest the parasite has in her partner accepting the “gift.” The mouthing of the body of the host, sometimes performed by the parasite and already described by SCHEVEN (1958), could implicate the topical application of substances which could have some function in controlling the hosts. Another behaviour that leads us to think that the parasite uses allomones to control the host colony is the intense nest stroking she performs with her abdominal sterna from the first moment she arrives on the nest and when she is not interacting with her hosts. Such a behaviour has been only recently observed in Sulcopolistes (TURILLAZZI & ROW 1989) but has been reported (nest dragging) in other vespid social parasites, e.g. Dolichovespula urctica Rohwer (JEANNE 1977; GREENE et a]. 1978) and Vespula austriaca Panzer (REED& AKRE1983), and has been interpreted as the release of secretions which may signal to other parasites that the nest has already been usurped (JEANNE1977) or serve to inhibit the aggressivity of the host (GREENEet al. 1978) or to partially suppress worker oogenesis (REED& AKRE1983). In Polistes, this behaviour belongs to the repertoire of the species (see WEST EBERHARD 1986). It seems probable, as suggested by other authors, that during this behaviour the females apply secretions produced in the sternal glands of the abdomen (LANDOLT & AKRE1979; TURILLAZZI 1979; POST& J E A N N E 1980) over the nest surface. The functions of these secretions are, for the moment, only speculative. They could be allomones directed at adults, pupae and larvae of the host. As foundresses of Polistes gallicus L. (= P. foederatus Kohl of previous authors: DAY1979), which have been experimentally found to adopt a nest, show this type of behaviour particularly (CERVO& TURILLAZZI 1989), it could serve to apply a secretion which covers the previous colony odour, and so deceive the larvae as to their relatedness with the queen they will find on emerging. Sulcopolistes sulcifer apparently adopts a technique in its aggressive usurpation of the nest that differs from that of 5. semenowi (see the description of DEMOLIN & MARTIN 1980, of the usurpation of a bygynic foundation of Polzstes nimpha) and S. atrimandibularis (CERVOet al. 1989). It conquers Polistes dominulus colonies counting on behavioural and probably pheromonal components. Its large mandibles serve to injure the more aggressive individuals which are hard to control, especially the dominant females, while it dominates and controls the other hosts using behaviour patterns similar to that found in the host repertoire and with the probable emission of chemicals. The existence and the function of these are, at present, only hypothetical, as the only proofs of their possible application are purely behavioural. Moreover, it reopens the very neglected problem of whether pheromonal components play a role in the dominance system of Polistes wasps (DOWNING &JEANNE1983). Acknowledgements We wish to thank Mr. W. BOKSATOfor his help in determining the specimens studied, Mr. D. ROW and Mr. D. MELOTTIwho helped us in the field, Prof. L. PARD](Firenze) who revised the manuscript and Mrs. C. Coster LONGMANfor the revision of the English text.

Invasion of Host Nest by Sulcopolistes sulctfev

59

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I)E 1955: Hyminopteres ricoltes par une mission suisse au Maroc. Vespinac, PoLstinac. Bull. Soc. Sc. nat. phys. Maroc 35, 217-221. - - & MATTIII‘Y, R. 1945: Observations s u r les Polistes parasites de la Suisse. Bull. Soc. vaudoisc Sci. nat. 62, 441-454. CI-KVO,R. & T U K I L L A Z ZS.I ,1989: Nest exchange experiments in P. gallicus (L.). Ethol. Ecol. Evol. 1, in press. _ - , I.OKFNZI,M. C. & TLKII.LAZZI, S. 1989: Different srrategics of host nest invasion in t w o species of Sulcopolistes (Hymenoptera, Vespidae). Ethol. Ecol. Evol. 1, in press. D A Y , M . 1979: T h e species of Hymenoptera described by Linnaeus in the genera Sphex, Chrysrs, Vespa. Apzs and MutilLt. Biol. J. Linn. Soc. 12, 45-84. U I M O II N , G. & MAKTIN,J. C. 1980: Biologie de Sulcopolistes semenowi (Morawitz) parasite d e Polistes nimphu (Christ), Hymenoptera Vespidae. Biologie Ecol. medit. 7, 181-1 82. DISTIIANO, S. L. 1969: Ricerche sulla fauna e s u l l ~zoogeografia della Sicilia 42. Osservazioni \ u Sulcopolistes siilctfer parassita sociale di Polzstcs g d i c u s . Boll. sed. accad. gioenia sci. nat. (4) 9, 662-678. D O W N I N GH. , A. & J I A N N I ,K. L. 1983: Correlation of season and dominance status with activity of exocrine glands in Polistes /uscatus (Hymenoptera: Vcspidae). J. Kansas Entomol. Soc. 56, 387-397. GKLI..NI,,A,, AhRF., K. D. & LANL)OI.T,P. J . 1978: Bchaviour of the yellowjacket social parasite, Dolichovespula i l i c t i u (Kohwer) (Hymenoptera Vespidae). Mclandcria 29, 1-28. GUIGII A , D. 1972: Les guepes sociales (Hymenoptera Vespidae) d’Europe Occidentale et Septentrionale. F’aune de I’Europe et d u Bassin Meditcrraneen. 6. Masson Paris. J E A N N I , K. L. 1977: Behavior of the obligate social parasite \’espu/a arcricu (Hymenoptera: Vespidae). J. Kansas Entomol. Soc. 50, 541-557. LANDOIT,P. J . & A K K EK. , I). 1979: Occurrence and location of exocrine glands in some social Vespidae (Hymenoptera). Ann. Entomol. Soc. A m . 72, 141-148. MAKINOPIC:CIOI I , M. T . & PAKUI,L. 1980: Social dominance and irophallaxis in bigynic societies of Polzstes gallzcus. Rend. sc. fis. mat. nat. Acc. Lincei 68, 443-448. P A K U II.. , 1942: Ricerche sui polistini. V. La poliginia iniziale in Poltstes gullicus. Boll. 1st. Ent. Univ. Bologna 14, 4-106. POST, D. C. & JEANNE, R. L.. 1980: Morphology of the sternal glands of Po/zstes fuscatus and P. canadensis (Hymenoptera: Vespidae). Psyche 87, 49-58. KEFI), H. C . & AKKI:, K. D. 1983: Colony behavior of the obligatc social parasite Vespulu austnaca (Panzer) (Hymenoptera, Vespidae). Insectes Soc. 30, 259-273. SCHEVIN,J . 1958: Beitrag zur Biologie der Schmarotzerfeldwespen. Insectes SOC.5, 409-438. TURII I AZZI, S. 1979: Tegumental glands in the abdomen of some European Polistes (Hymenoptera Vespidae). Monitore zool. ital. (N. S.) 13, 67-70. _ _ & ROW, D. 1989: Recent studies on the behaviour of Sulcopolistes sulcifer Zimm. (Hymenoptera Vespidae). Monitore zool. ital. ( N . S.) 22, 552. WEST EBEKIIAKL), M. J. 1986: Dominance relations in Polistes canadensis a tropical social wasp. Monitore zool. ital. 20, 263-281. WEYKAUCH, W. 1937: Zur Systematik und Biologie der Kuckuckswespen Pseudovespa, Pseudovespula and Pseudopoltstes. Zool. Jahrb. (Syst.) 70, 243-290. WII.SON,E. 0. 1971: T h e Insect Societies. Belknap Press, Harvard Univ., Cambridge.

Received: j u n e 30, 1989 Accepted: October 5 , 1989 (W. Pflumm)