The chalcid wasp Leucospis affinis has been known to parasitize only megachilid bees. Its rare occurrence as a parasite of the eumenid wasp Ancistrocerus antilope indicates that eumenid wasps may be a large resource this chalcid is not exploiting

Cowan, David P

English

ValpoScholar

The Great Lakes Entomologist 
Volume 19 
Number 3 - Fall 1986 Number 3 - Fall 1986 Article 7 
October 1986 
Parasitism of Ancistrocerus Antilope (Hymenoptera: Eumenidae) 
by Leucospis Affinis (Hymenoptera: Leucospididae) 
David P. Cowan 
Western Michigan University 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Cowan, David P. 1986. "Parasitism of Ancistrocerus Antilope (Hymenoptera: Eumenidae) by Leucospis 
Affinis (Hymenoptera: Leucospididae)," The Great Lakes Entomologist, vol 19 (3) 
Available at: https://scholar.valpo.edu/tgle/vol19/iss3/7 
This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. 
It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. 
For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 
1986 THE GREAT LAKES ENTOMOLOGIST 177 
PARASITISM OF ANCISTROCERUS ANTILOPE 
(HYMENOPTERA:EUMENIDAE) BY LEUCOSPIS AFFlNIS 
(HYMENOPTERA: LEUCOSPIDIDAE) 
David P. Cowan' 
ABSTRACT 
The chalcid wasp Leucospis affinis has been known to parasitize only megachilid bees. 
Its rare occurrence as a parasite of the eumenid wasp Ancistrocerus anti/ope indicates that 
eumenid wasps may be a large resource this chalcid is not exploiting. 
Krombein et. al. (1979) recorded Leu.cospis affinis Say as parasitizing seven genera of 
bees in the family Megachilidae. In general, these bees nest in hollow twigs or vacant 
insect tunnels in wood. The female of L. ajfinis pierces the twig with her ovipositor and 
deposits an egg in the bee's cell. The egg hatches and the larva feeds externally on the host 
larva (Graenicher 1906). This parasite is often abundant and may exert considerable 
mortality on its hosts, killing up to 80% of a host bee's larvae (Medler 1958). 
Many solitary aculeate Hymenoptera nest in hollow twigs and these species are 
relatively well known (Krombein 1967). Even though megachilid bees and hunting wasps 
(especially Eumenidae) use the same type of nest site, and are often in close proximity, 
L. ajfinis has only been reported from the nests of bees. 
For a number of years, I have been studying eumenid wasps that occupy trap-nests 
(artificial nest sites made from sticks of wood with drilled holes) (Cowan 1981, 1984). I 
have examined thousands of nests of wasps and bees, and with the exceptions mentioned 
below, L. ajfinis has been associated only with megachilid bees. 
During the winter of 1983-1984, I examined a sample of 600 trap-nests that had been 
in 
the field during thc summer 
of 1983 in Kalamazoo County, Michigan. Table 1 indicates 
the hosts examined, number of nests, and rate of parasitism by L. ajjlnis for the most 
abundant bees and eumenid wasps in this sample. Leu.cospis affinis emerged from 44% 
(96/217) of the megachilid bee cells. In addition, 11 L. affi is developed in two eumenid 
wasp nests. Each wasp nest was composed of six cells. When opened during the winter, 
11 
cells contained full-grown 
L. affinis larvae and one cell contained a eumenid larva. The 
eumenid hosts were killed after they had spun their cocoons. Each of the 11 L. affinis 
prepupae transformed into an adult female. Unfortunately, the eumenid larva died. 
Because I did not rear any adult eumenids from these nests, the determination f 
Ancistrocerus ami/ope (Panzer) as the host is conjectural. The nesting materials and 
structure were typical of A. antilope and there was no evidence that either trap-nest had 
been previously occupied by another wasp or bee. The most convincing evidence that A. 
anti/ope served as host was the presence of dead adults of the mite Kennethiella trisetosa 
(Cooreman) in three cells of one nest and one cell of the other. This mite is only known 
to be associated with the wasps A. antilope and Ancisrrocerus spinolae (Saussure) 
(Krombein 1967, Cowan 1984). Although the nests of these wasps are virtually identical, 
A. spinolae is very rare in Michigan and I think it unlikely that this wasp was involved. 
'Department of Biology, Western Michigan University, Kalamazoo, MI49008. 
1
Cowan: Parasitism of Ancistrocerus Antilope (Hymenoptera: Eumenid
Published by ValpoScholar, 1986
178 THE GREAT LAKES ENTOMOLOGIST Vol. 19, No.3 
Table 1. The number of nests, cells, L affinis reared, hosts reared, and percent of parasitism by 
L affinis, for megachilid bees and eumenid wasps. 
No. No. Percent 
No. No. L. affinis hosts parasitized 
Host nests cells reared reared by L affinis 
Megachilidae 
Megachile sp. 16 87 27 44 31 
Osmia pumila Cresson 14 102 49 39 48 
Chalicodoma sp. 6 28 20 I 71 
Eumenidae 
Ancistrocerus anti/ope 23 112 11 74 10 
Euodynerus 
foraminatus (Saussure) 30 127 0 98 0 
There is some question as to the ability of this parasitoid to complete its life cycle on 
eumenid hosts. Normally, young adults of L. affinis chew through the partitions that 
separate the cells of a bee's nest and escape through the original nest entrance. Depending 
upon the genus of megachilid host involved, this means L. affinis chews through partitions 
made of leaves (Megachile), masticated plant material (some Osmia), or resins 
(Chalicodoma). Eumenid wasps, however, separate their cells with partitions of dried 
mud which apparently presents an impenetrable barrier to L. affinis. Only two thin, inner 
mud partitions of the eumenid nests in which the L. affinis developed were breached. The 
others showed no evidence of abrasion or other damage by the parasites, and all of the 
parasites perished inside the nests without escaping. However, all of the L. affinis had 
chewed at the wood of the trap-nest near the mud partition. In two cases, this gnawing was 
"directed and purposeful" in that the L. affinis excavated tunnels 2-3 mm in diameter at 
a right angle to the wall of the nests for a distance of 3 and 6 mm, respectively. The longer 
tunnel carne within 1 mm of the outside. However, both of these individuals apparently 
became exhausted and died before completing their exits. If L. affinis were parasitizing 
wasp nests in hollow sterns of plants such as sumac or elderberry, it seems likely that 
gnawing through the side of the nest would frequently be more successful. 
From my observations, it is apparent that eumenid wasps are perfectly adequate as food 
for the development of L. affinis. Because these wasps are abundant and commonly nest 
in 
the same places as the normal megachilid hosts 
of L. affinis, one might expect natural 
selection to expand the behavioral repertoire of L. affinis to regularly include eumenid 
hosts. Why this has not happened is a mystery, 
LITERATURE CITED 
Cowan, D. P. 1981. Parental investment in two solitary wasps, Ancistrocerus adiabatus 
and Euodynerus foraminatus (Eumenidae: Hymenoptera). Behav, EcoL SociobioL 
9:95-102. 
__
, 1984. Life history and male dimorphism 
in the mite Kennetheilla trisetosa 
(Acarina: Winterschmidtiidae) and its s mbiotic relationship with the wasp 
Ancistrocerus antilope (Hymenoptera: Eumenidae) Ann. Entomol. Soc. Allier. 
77:725-732. 
Graenicher, S. 1906. On the habits and life-history of Leucospis affinis (Say). A parasite 
of 
bees. Bull. Wisconsin Nat. Hist. Soc. 4:153-159, 
Krombein, K. 
V. 1967. Trap-nesting wasps and bees: Life histories, nests, and 
associates. Smithsonian Press, Washington, D.C. 
2
The Great Lakes Entomologist, Vol. 19, No. 3 [1986], Art. 7
https://scholar.valpo.edu/tgle/vol19/iss3/7
1986 THE GREAT LAKES ENTOMOLOGIST l79 
Krombein, K. V., P. D. Hurd, S. R. Smith, and B. D. Burks 1979. Catalog of 
Hymenoptera in America north of Mexico. Vol. 1. Smithsonian Inst. Press. Washing­
ton, D.C. 
Medler, J. T. 1958. Parasitism of bees in trap-nests by Leucospis affinis Say 
(Hymenoptera: Leucospidae). Entomol. News. 69:21-24. 
3
Cowan: Parasitism of Ancistrocerus Antilope (Hymenoptera: Eumenid
Published by ValpoScholar, 1986

Parasitism of \u3ci\u3eAncistrocerus Antilope\u3c/i\u3e (Hymenoptera: Eumenidae) by Leucospis Affinis (Hymenoptera: Leucospididae)

Valparaiso University

The Great Lakes Entomologist Volume 19 Number 3 - Fall 1986 Number 3 - Fall 1986 Article 7 October 1986 Parasitism of Ancistrocerus Antilope (Hymenoptera: Eumenidae) by Leucospis Affinis (Hymenoptera: Leucospididae) David P. Cowan Western Michigan University Follow this and additional works at: https://scholar.valpo.edu/tgle Part of the Entomology Commons Recommended Citation Cowan, David P. 1986. "Parasitism of Ancistrocerus Antilope (Hymenoptera: Eumenidae) by Leucospis Affinis (Hymenoptera: Leucospididae)," The Great Lakes Entomologist, vol 19 (3) Available at: https://scholar.valpo.edu/tgle/vol19/iss3/7 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1986 THE GREAT LAKES ENTOMOLOGIST 177 PARASITISM OF ANCISTROCERUS ANTILOPE (HYMENOPTERA:EUMENIDAE) BY LEUCOSPIS AFFlNIS (HYMENOPTERA: LEUCOSPIDIDAE) David P. Cowan' ABSTRACT The chalcid wasp Leucospis affinis has been known to parasitize only megachilid bees. Its rare occurrence as a parasite of the eumenid wasp Ancistrocerus anti/ope indicates that eumenid wasps may be a large resource this chalcid is not exploiting. Krombein et. al. (1979) recorded Leu.cospis affinis Say as parasitizing seven genera of bees in the family Megachilidae. In general, these bees nest in hollow twigs or vacant insect tunnels in wood. The female of L. ajfinis pierces the twig with her ovipositor and deposits an egg in the bee's cell. The egg hatches and the larva feeds externally on the host larva (Graenicher 1906). This parasite is often abundant and may exert considerable mortality on its hosts, killing up to 80% of a host bee's larvae (Medler 1958). Many solitary aculeate Hymenoptera nest in hollow twigs and these species are relatively well known (Krombein 1967). Even though megachilid bees and hunting wasps (especially Eumenidae) use the same type of nest site, and are often in close proximity, L. ajfinis has only been reported from the nests of bees. For a number of years, I have been studying eumenid wasps that occupy trap-nests (artificial nest sites made from sticks of wood with drilled holes) (Cowan 1981, 1984). I have examined thousands of nests of wasps and bees, and with the exceptions mentioned below, L. ajfinis has been associated only with megachilid bees. During the winter of 1983-1984, I examined a sample of 600 trap-nests that had been in the field during thc summer of 1983 in Kalamazoo County, Michigan. Table 1 indicates the hosts examined, number of nests, and rate of parasitism by L. ajjlnis for the most abundant bees and eumenid wasps in this sample. Leu.cospis affinis emerged from 44% (96/217) of the megachilid bee cells. In addition, 11 L. affi is developed in two eumenid wasp nests. Each wasp nest was composed of six cells. When opened during the winter, 11 cells contained full-grown L. affinis larvae and one cell contained a eumenid larva. The eumenid hosts were killed after they had spun their cocoons. Each of the 11 L. affinis prepupae transformed into an adult female. Unfortunately, the eumenid larva died. Because I did not rear any adult eumenids from these nests, the determination f Ancistrocerus ami/ope (Panzer) as the host is conjectural. The nesting materials and structure were typical of A. antilope and there was no evidence that either trap-nest had been previously occupied by another wasp or bee. The most convincing evidence that A. anti/ope served as host was the presence of dead adults of the mite Kennethiella trisetosa (Cooreman) in three cells of one nest and one cell of the other. This mite is only known to be associated with the wasps A. antilope and Ancisrrocerus spinolae (Saussure) (Krombein 1967, Cowan 1984). Although the nests of these wasps are virtually identical, A. spinolae is very rare in Michigan and I think it unlikely that this wasp was involved. 'Department of Biology, Western Michigan University, Kalamazoo, MI49008. 1Cowan: Parasitism of Ancistrocerus Antilope (Hymenoptera: EumenidPublished by ValpoScholar, 1986178 THE GREAT LAKES ENTOMOLOGIST Vol. 19, No.3 Table 1. The number of nests, cells, L affinis reared, hosts reared, and percent of parasitism by L affinis, for megachilid bees and eumenid wasps. No. No. Percent No. No. L. affinis hosts parasitized Host nests cells reared reared by L affinis Megachilidae Megachile sp. 16 87 27 44 31 Osmia pumila Cresson 14 102 49 39 48 Chalicodoma sp. 6 28 20 I 71 Eumenidae Ancistrocerus anti/ope 23 112 11 74 10 Euodynerus foraminatus (Saussure) 30 127 0 98 0 There is some question as to the ability of this parasitoid to complete its life cycle on eumenid hosts. Normally, young adults of L. affinis chew through the partitions that separate the cells of a bee's nest and escape through the original nest entrance. Depending upon the genus of megachilid host involved, this means L. affinis chews through partitions made of leaves (Megachile), masticated plant material (some Osmia), or resins (Chalicodoma). Eumenid wasps, however, separate their cells with partitions of dried mud which apparently presents an impenetrable barrier to L. affinis. Only two thin, inner mud partitions of the eumenid nests in which the L. affinis developed were breached. The others showed no evidence of abrasion or other damage by the parasites, and all of the parasites perished inside the nests without escaping. However, all of the L. affinis had chewed at the wood of the trap-nest near the mud partition. In two cases, this gnawing was "directed and purposeful" in that the L. affinis excavated tunnels 2-3 mm in diameter at a right angle to the wall of the nests for a distance of 3 and 6 mm, respectively. The longer tunnel carne within 1 mm of the outside. However, both of these individuals apparently became exhausted and died before completing their exits. If L. affinis were parasitizing wasp nests in hollow sterns of plants such as sumac or elderberry, it seems likely that gnawing through the side of the nest would frequently be more successful. From my observations, it is apparent that eumenid wasps are perfectly adequate as food for the development of L. affinis. Because these wasps are abundant and commonly nest in the same places as the normal megachilid hosts of L. affinis, one might expect natural selection to expand the behavioral repertoire of L. affinis to regularly include eumenid hosts. Why this has not happened is a mystery, LITERATURE CITED Cowan, D. P. 1981. Parental investment in two solitary wasps, Ancistrocerus adiabatus and Euodynerus foraminatus (Eumenidae: Hymenoptera). Behav, EcoL SociobioL 9:95-102. __, 1984. Life history and male dimorphism in the mite Kennetheilla trisetosa (Acarina: Winterschmidtiidae) and its s mbiotic relationship with the wasp Ancistrocerus antilope (Hymenoptera: Eumenidae) Ann. Entomol. Soc. Allier. 77:725-732. Graenicher, S. 1906. On the habits and life-history of Leucospis affinis (Say). A parasite of bees. Bull. Wisconsin Nat. Hist. Soc. 4:153-159, Krombein, K. V. 1967. Trap-nesting wasps and bees: Life histories, nests, and associates. Smithsonian Press, Washington, D.C. 2The Great Lakes Entomologist, Vol. 19, No. 3 [1986], Art. 7https://scholar.valpo.edu/tgle/vol19/iss3/71986 THE GREAT LAKES ENTOMOLOGIST l79 Krombein, K. V., P. D. Hurd, S. R. Smith, and B. D. Burks 1979. Catalog of Hymenoptera in America north of Mexico. Vol. 1. Smithsonian Inst. Press. Washing­ton, D.C. Medler, J. T. 1958. Parasitism of bees in trap-nests by Leucospis affinis Say (Hymenoptera: Leucospidae). Entomol. News. 69:21-24. 3Cowan: Parasitism of Ancistrocerus Antilope (Hymenoptera: EumenidPublished by ValpoScholar, 1986

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Parasitism of \u3ci\u3eAncistrocerus Antilope\u3c/i\u3e (Hymenoptera: Eumenidae) by Leucospis Affinis (Hymenoptera: Leucospididae)

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