Richard C. Miller and Frank E. Kurczewski.
A Review of Nesting Behavior in the Genus Entomognathus, with Notes on E. memorialis Banks (Hymenoptera: Sphecidae).
Psyche 79:61-78, 1972.

Full text (searchable PDF, 2944K)
Durable link: http://psyche.entclub.org/79/79-061.html

The following unprocessed text is extracted from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.

A REVIEW OF NESTING BEHAVIOR IN THE
GENUS ENTOMOGNATHUS, WITH NOTES ON
E. MEMORIALIS BANKS
(HYMENOPTERA: SPHECIDAE)
The genus Enton~o~nathus contains at least 40 species, half in the Ethiopian and in the Palaearctic, Nearctic, Oriental, and Neo- tropical regions (Leclercq, 1954, 1955, 1961, 1963 ; Nouvel and Ribaut,
I 956 ; Krombein, 1963). Relatively little is known about the nesting behaviors, host preferences, or life histories of members of this genus. Only the Palaearctic E. (Entonzognathus) brevis van der Linden has been studied in any detail, and almost nothing is known about the four U. S, species belonging to the subgenus Toncahua.
One of the purposes of the present paper is, therefore, to amalgamate information on the host preferences, nesting behaviors, life histories, and immature stages of the species of Entomognathus, based upon a review of the world literature. The maior portion of
- -
this paper details the components of the nesting behavior of E. (Ton- cahua)
memorialis Banks, describes the mature larva and cocoon, and compares this species and related crabronine and larrine wasps in nesting ethology and larval and cocoon morphology. The adult
wasps and prey beetles have been placed in the S. U. N. Y. 'College of Forestry Insect Museum, and the mature larva has been deposited in the Museum of Comparative Zoology, Harvard University. Entomognathus (Mashona) mimicus Arnold
One female from Bekily, Madagascar was observed by Arnold ( 1944) preying upon a small chrysornelid beetle. Entomognathus (Mashona) patricius Arnold Arnold (1932) reported several females nesting in a clay bank beside a stream in Bulawayo, S. Rhodesia. The wasps were preying upon a species near Ootheca modesta Gahan (Chrysomelidae: Gale- rucinae) .
Entonzognathus (Entomognathus) brewis v. d. Lind, This widely distributed Palaearctic species has been reported to nest in sand, gravel, clay, and chalky-loam, and to burrow in hori- 'Department of Forest Entomology, State University College of Forestry, Syracuse, New York 13210.
Manuscript received by the editor July 5, 1972. Pswhe 7961-78 (1972). hup //psyche cntclub ai-gffW79-Oei.htinl



================================================================================

62 Psyche [March-June
zontal and vertical situations as well as in depressions (Chambers, 1949). E. brews has been known to nest in or near woodlands (Grandi, 1927 ; Chambers, 1949), and to aggregate ( Benoist, I 9 I 5). According to Adlerz ( 1912), females were observed to enter the burrows of other wasps, remain for only a moment, and exit, but it was not ascertained whether the wasps used pre-existing burrows for nest-sites.
The females have been noted to construct earthen, chimney-like extensions of the burrows, 10-25-mm-long, above the ground surface (Benoist,
1915 ; Grandi,
1927, 1931), or to make no such exten-
sions (Maneval, I 928, 1937 ; Abrahamsen, I 95 I ) . Grandi ( 193 I ) found nests with and without turrets in the same area. The main burrow, 2-3 mm in diameter, plunged obliquely downward, some- times circumventing subterranean obstacles, and at depths of 6-12 cm branched into side burrows leading to the cells; the oval cells, 4 X 8 mm, were located at depths of 6-12 cm beneath the surface ( Grandi 1927 ; Maneval, 1928 ; Abrahamsen, 195 I ) , the maximum number per nest being ten (Benoist, 1915). The wasps transported their prey in flight, holding it with the middle legs, and hovered back and forth in front of the entrance before diving inside ( Adlerz, I 9 I 2). Seven genera and seventeen species of 'Chrysomelidae have been reported as prey of E. brevis (Table I). All are members of the subfamily Alticinae except Cryptocephalus labiatus L. (Crypto- cephalinae). In one of the earliest reports on this species, Sick- mann ( I 893) recorded small flies as prey; however, this record was probably based upon a misidentification of the wasp. The prey are never killed by the wasp but invariably paralyzed (Benoist, 1915 ; Grandi, I 927, I 93 I ; Maneval, I 928 ; Abrahamsen, 195 I ) . Both Maneval ( 1928) and Grandi ( 1931 ) noted that large and small chrysomelids were captured by the wasps. The number of prey stored per cell ranged from 14 to 24. From one to four genera and species were stored in a single cell, and at least two and usually three or four species were captured at all but one of the several localities where more than one prey was collected (Benoist, 1915; Hamm and Richards, 1926; Grandi, 1927, 1931 ; Maneval, 1928, 1937 ; Richards, 1944; Abrahamsen, 195 I ) . According to Grandi ( 1927) and Maneval ( 1928), the wasp did not lay her egg until the full complement of prey had been put in the cell. Maneval ( 1937)
found prey near the bottom of the nest
in a section of the burrow, 3-4-crn-long, but he did not note an egg attached to any of the beetles. In fully-provisioned cells, the beetles



================================================================================

19721 Miller &? Kurczewski - Entomognathus 63 TABLE I.
Species of prey of Entomognathus brevis. Genus and species of prey
Source
Aphthona euphorbiae Schrank Grandi, 1931 Aphthona herbigrada Curtis
Grandi, 1927 ; Maneval, 1937
Aphthona pygmaea nigella Kutsch. Grandi, 193 I Chaetocnema arida Foudras Maneval, I 937 ChJaetocnema concinna Marsham Richards, 1944 Chaetocnema hortensis Geoff roy Grandi, I 93 I ; Richards, I 944 ; (= aridella Paykull)
Abrahamsen, I 95 I
Chalcoides aurata Marsham Richards, 1944 Crepidodera ferruginea Scopoli
Maneval, I 928 ; Bouwman, I 930 ;
Grandi, I 93 I ; Chambers, I 949 ;
Abrahamsen, 195 I
Cryptocephalus Zabiatus Linnaeus Hamm and Richards, 1926 Longitarsus jacobaeae Waterhouse Hamm and Richards, I 926 Longitarsus luridus Scopoli Adlerz, 1912 Longitarsus nasturtii Fabricius Abraharnsen, 195 I Longitarms pellucidus Foudras Grandi, 1927 Longitarsus firatensis Panzer Grandi, I 92 7, I 93 I ; Maneval, I 93 7
Longitarsus succ'meus Foudras
Maneval, I 928 ; Grandi, I 93 I
Longitarsus suturalis Marsham Maneval, I 937 Phyllotreta nigripes Fabricius
Grandi, 193 I
Phyllotreta sp.
Benoist, I 9 I 5
were piled indiscriminately with the egg-bearer, ventral-side-upward, on top of the pile; the wasp's egg was attached to the venter of the beetle at the mesa1 base of the forecoxa, and extended transversely beyond the side of the beetle (Grandi, 1927). It was elongate, subcylindrical, curved, and measured 2 X mm. The cocoon of E. brevis has been reported to be thin-walled and to measure 4.5-6 X 2-3 mm (Benoist, 1915). According to this author, the mature larva pushed the uneaten prey fragments to one end of the cell rather than distributing them over the surface of the cocoon. The larva pupated in June of the following year and the adult appeared during the second half of July. Adult wasps have been collected in Europe from the second week in June (Chambers, I 949) to the second week in September (Grandi, I 927). Entomognathus ( Tonc,ahua) texana Cresson Cazier and Mortenson ( 1965) collected one female flying above



================================================================================

Psyche [March-June
Fig. I.
Nesting-site of F., memorialis Backs at Chittenango, N. Y. Indi- vidual nests occupied the upper portion of cliff, among roots. a sandy river bed in New Mexico with a Diabrotica tricincta Say ( Chrysomelidae : Galerucinae) .
Entwtognathus ( Toncahua) me~noridis Banks Ecology. Krombein (1963) characterized this species as a sylvi- colous form which nests in rather heavy soil. He recorded specimens from Connecticut, New Jersey, Maryland, District of Columbia, Virginia, and Kansas. We observed small aggregations of this species flying near the tops of I-6-ft-high sand cliffs at Chittenango, Madison Co., N. Y. ( Fig. I ) during 19-28 August 1970 and I 2 July 1971, and at Presque Isle St. Pk., Erie Co., Pa. from 4 to 9 July 1971. Both sites bordered bulldozed sandy fields near stands of deciduous northern hardwoods. At Chittenango, other sphecids nesting in the cliff included Philanthus poKtus Say, Oxybelus hi- @actatus Oh., 0. entarginatus Say, and Xylocelia sp. Cliff-nesting sphecids at Presque Isle comprised Miscophus mnericanus Fox, Philmthus gibbosus ( F. ) , and Xylocel'w franclemonti Krm. Mating Behdr. Ten males and three females were observed flying in front of the sand cliff at Presque Isle during the 6-day observation period The males continuously circled a small Rubus plant at the base of the cliff and attempted to mate with small



================================================================================

19721 Miller å£ Kurczewski - Entomognathus 6 5 wasps, flies, and beetles as they landed on the leaves. They pursued females in flight and pounced upon them as they rested on the vegetation. One "mating ball" of three males and a female was seen tumbling over the sand until only one male remained whereupon the pair flew, still coupled, into the dense vegetation behind the cliff. Nest-Site Selection. Although both males and females spent the night in preexisting holes in the cliff, facing head-outward, these burrows were not utilized by the wasps for nest-sites. The females emerged from the holes between 10 and 11 a.m. and reentered them for the night between 2 :30 and 3 :30 p.m. The males were seen outside earlier in the morning and later in the afternoon than this. During the day females flew from one preexisting cavity to another, searching longest in root-shrouded areas near the top olf the cliff. Occasionally, they climbed up the rootlets and sampled the soil with their mandibles. The males, on the other hand, investigated holes in the cliff only during late afternoon when they were looking for places to spend the night.
At Presque Isle females were out for nearly a week without one of them selecting a permanent nest-site or bringing in provisions. Seven males and three females observed at Chittenango on 12 July 1971 behaved similar to the wasps at Presque Isle, except for one female which entered a nest with prey.
Nest Structure. Seven nests of E. memorialis were excavated and studied at Chittenango. The entrances, 4.0-4.5 mm in diameter, were located among dense rootlets, 9.5-24.0 (mean 13.3) cm below the top of the cliff. A narrow, rather inconspicuous streak of sand extended down the slope beneath each entrance, indicating evidence of recent soil removal. The burrows, 3 mm in diameter, entered the outer sandy-loam at about right angles to the cliff and usually arched upward before descending into hard-packed sand in one or more undulations (Fig. 2a-d). The mean length of unobstructed burrow from the entrance was 16.8 (9.5-27.0) cm. The distance from the entrance to the farthest cell in the nest via the burrow ranged from 9.5 to 29.0 (mean 21.2) cm.
The four nests containing the largest number of cells (9-20) exhibited branching of the main burrow. The cells were arranged either singly, in fan-shaped clusters, or in series, with cells in tandem especially common. Tunnels from the main burrow to cells in clusters were not traceable, but those leading to and adjoining the cells in tandem were often loosely filled with sand and easily fol- lowed. The broadly oval cells averaged 4.4 X 8.5 mm and ranged from 4 X 6 to 5 X 13 mm (N=29). They were located 13.5-25.0



================================================================================

Psyche
[March- June
Fig. 2a-d. Side (S) and top (T) views of four nests of E. memonalis Banks;
x indicates burrow storage, numbers in (c) the sequence in which cells were provisioned. Stippling refers to sand fill. Scale for nest (d) applies to all nests.




================================================================================

19721 Miller &? Kurczewski - Entomognathus 67 (mean 18.8, N=74) cm below the top of the cliff. Relative to the entrance, the cells were found from 2.5 cm above its level to 13.5 cm below it, averaging 5.5 cm below. The horizontal distance from the cliff face to a cell averaged 12.2 (4.5-21.5, N==:66) cm. The number of cells per nest ranged from 3 to 20 (mean 10.7). Except for cells in tandem, there was no correlation between the age of the cell and its position in the nest. In each tandem series, the cell farthest from the entrance in terms of total burrow length was the oldest. Because cells in series occasionally curved back toward the entrance, an older cell was sometimes closer to the entrance than a newer one in absolute distance (Fig. 2b, c). In nests I and 2 (Fig. 2a, b), the female moved farther away from the entrance as she constructed new series of cells. In nest 3 (Fig. 2c), worked on by two females in succession, the first wasp apparently constructed tandem series toward the entrance whereas the second one built a series of three cells near the front and then a fan-shaped cluster of four cells at the back.
Transport and Storage of Prey. A provisioning female returned to her nest in flight, holding the beetle head-forward and venter-up with the middle legs. She usually hovered briefly in front of the cliff face before diving into the open entrance. The myriad of root- lets frequently made entry difficult and may have been responsible for many of the abandoned prey found beneath the entrances. The single hunting time recorded was 3 min. 15 sec. The same female twice took 2 min. to store a prey and return to the entrance. Temporary storage of beetles in the burrow at some distance from the entrance was recorded for three of the seven nests (Fig. 2c, d) . Such prey were placed head-inward and were loosely covered with sand particles. All of the beetles were partially paralyzed and moved their antennae and legs or flexed their elytra. Nest provisions. Prey taken from the Chittenango nests in 1970 were determined as Altica ulmi Woods (Chrysomelidae : Alticinae) . Two specimens collected from nests at this. locality in July and August 1971 proved also to be this species. E. J. Kurczewski (corre- spondence) took a memorialis female with A. marevagans Horn at Presque Isle in August 1971. Of the 220 A. ulmi preserved for identification, 46.8 % were females and 53.2% males. The mean number of prey per cell was 5.1 (3-9, N~42). The total weight of the beetles per cell in
13 fully-provisioned cells
ranged from 16.8 to 54.5 (mean 27.0) mg. Individual beetles weighed from 3.7 to 8.0 (mean 5.4, N=68) mg, whereas one female wasp weighed 7.0 mg. The beetles in the cells were positioned head-



================================================================================

68 Psyche
[March-June
Fig. 3.
(above). 8 Altwa dmi Woods bearing egg of E. memorialis Banks in typical position.
Fig. 4. (below). Cocoon of E, memorialis Banks.



================================================================================

19 721 Miller ^3" Kurczewski - Entomognathus 69 inward and ventral-side-upward or, less commonly, dorsal-side- upward or on the side. The egg-bearing beetle was located at the back end of the cell and was placed venter-up or pressed obliquely against the wall.
In several nests, cells contained fresh 01- moldy prey but no egg, larva, or parasites. In three cases, abandoned prey were found buried in the sand plug which sealed off a fully-provisioned cell. Four beetles were entombed in single file in the loose sand in front of a cell containing six prey and an egg. The elytra of one beetle served as a wall-like 'barrier to the cell. Egg and Inzmature St,ages. The curved, hyaline egg, 1.5-mm-long, was attached by the cephalic end to the anterolateral mesosternum near one of the procoxae
(Fig. 3). It extended transversely but
somewhat obliquely across the mesosternum, the free end lying above one of the anterolateral corners of the metasternum. Several mature larvae were reared and are described later in this paper. The brown, ellipsoidal cocoons averaged 2.5 X 5.5 mm and consisted of silk, saliva, and sand grains (Fig. 4). The uneaten prey fragments were not embedded in the cocoon but were pushed to one end of the cell by the larva.
Nest Repossession and Renovation. During I 9-28 August 1970, several females were provisioning nests at Chittenango but no males were seen. Other females were observed searching in holes and crevices rather than bringing in prey. Two of the wasps persisted in entering, backing out of, hovering in front of, and reentering certain burrows. Providing an appropriate site is found, such wasps may repossess and add to nests used earlier in the season by other females. In fact, nest 3 (Fig. 2c) with recently-captured beetles in the burrow also contained a dead memorialis female sealed off by loose sand at the end of the main burrow. Cells 1-13 housing cocoons or nearly mature larvae were probably made by the first female before she died, whereas cells 14-20 with recently-captured prey and eggs were probably made by the new occupant. In another nest, containing mostly old cells, a dead menzorial'is female was found deep in the burrow but she was not sealed off with sand. This nest, now being occupied by another female, held some recently completed cells and three beetles in burrow storage. Six mature larvae from Chittenango which were preserved in Kahle's solution and later transferred to 70% alcohol were utilized in the following description. None of the larvae had begun to spin



================================================================================

Psyche
[March- June
Figs. 5-12.
Mature larva of E. memorialis Banks. 5. Lateral view of entire larva. 6. Thoracic spiracle. 7. Head in frontal view. 8. Clypeus and labrum (right), epipharynx (left). 9. Dorsal view of right mandible. I'O. Ventral view of right mandible. 11. Dorsal view of right maxilla. 12. Dorsal view of prementum of labium.




================================================================================

19721 Miller ‰â Kurczewski - Entomognathus 71 cocoons. Specific parts examined under the microscope were boiled briefly in KOH and then mounted in glycerine. Body (Fig. 5).
Length 7 mm; maximum width 2.5 mm. Stout, slightly curved, fusiform to subclavate, greatest width somewhat beyond middle ; pleural lobes prominent, broadly rounded, those on meso- and metathorax oblique and more protuberant; penultimate abdominal segment with small pleural lobe; anus ventral, preapical and directed ventrad, anal segment rounded smoothly beyond anus; integument clothed with abundant minute spinules and sparse setae confined mainly to dorsum and pleural lobes; pronotum, mesonotum and metanotum with transverse series of 12 or 13 setae along dorsal ridge which is free of spinules, thoracic pleural lobes without spinules but with 2 or 3 setae, longest seta on thorax about 58 p; first abdominal tergite with transverse row of 10 setae, the longest 35 p; other tergites without conspicuous setae; sternites uniformly and thoroughly clothed with minute spinules; spiracles (Fig. 6) small, weakly pigmented, posterior ones slightly smaller than anterior ones ; thoracic spiracular atrium 55 p in diameter, weakly lined with anastomosing non-spinose ridges to form irregular polygons, opening into atrium surrounded by circular, non-sculptured area, entrance to subatrium simple and unarmed.
Head (Fig. 7). Height 30 mm, excluding labrum; width .82 mm. Coronal suture and parietal bands apparently lacking; front with two oval longitudinal impressions between antennal orbits; epistomal suture indistinct, indicated by a weak transverse impres- sion; antennal orbits subcircular, 45-50 p in diameter, antenna1 papillae lacking, three sensilla in equilateral triangle arising from membrane at lateral margin of orbit. Setae on head numerous, 40 of them
distributed rather uniformly on sides and top and above bases of mandibles, only 4 setae on frons between antennal orbits, the longest 49 p; clypeus (Fig. 8) with transverse row of 4 setae and basal transverse series of 7 or 8 minute "sensory" convexities; head weakly pigmented except for anterior tentorial arms and mandibles.
Mouthparts. Labrum (Fig. 8) .39 mm wide, truncate, with about 18 setae 28 p long, distributed laterally and anteriorly, several smaller setae extending from apical margin medially ; apical margin bristly except in center; apex of oral surface with median pair of minute sensory pegs arising from circular pores; epipharynx papillose on basal lateral areas but spinulose elsewhere, center with stout, somewhat raised spinules arranged in semicircular pattern; apical



================================================================================

72 Psyche
[March- June
spinules more slender and appressed; small oval area apparently free of pores or sensory structures at each side of central patch of spinules. Mandible (Figs. 9, 10) .41 mm long, .20 mm wide near base, with single basal seta; inner margin with four distinct rounded teeth in about the same plane and decreasing in size from apex to base; basal tooth blunt and transverse; conspicuous, broadly-rounded laminar protuberance between and ventral to second and third teeth; dorsal surface with polygonal sculpturing near teeth. Maxilla (Fig. I I) strongly and broadly produced mesally, but not angulately so, inner margin densely spinulose, spinules moderately long and appressed; lacinial area with conspicuous tuft of long slender erect spinules; outer margin with four or five strong lateral setae of maximum length 46 p; palpus 50 p long, stouter than galea which is 28 p long. Hypopharynx a broad lobe with strong dense spinules.
Labium ( Fig. I 2) with oral surf ace of prementum completely clothed with moderately long spinules of maximum length 19 p,
spinules not separated into patches; base of prementum strongly sclerotized on oral side and separated from remainder of labium by distinct suture; palpi 43 p long, exceeded by paired spinnerets which are 73 p long, spinnerets slender and truncate apically. Entomognathus can be categorized as a genus of chrysomelid- hunters, based upon the prey records presented in this paper. Thus far there is no species overlap in the genera of Chrysomelidae preyed upon. The European E. brevis is the most polyphagous species which has been studied, preying upon no less than 17 species of Alticinae and Cryptocephalinae (Table I ) . The North American E. (Toncahua) tex~anus captures galerucine leaf-beetles, whereas E. (Toncahua) memorial'is preys upon alticine leaf-beetles. One prey species of the latter, A. ulnzi, has been reported to feed in the field only on Ulmus americana, the American elm (Woods, 191 8). Nevertheless, we were unable to discover where hunting and prey capture took place. A second prey species, A. marezfagans, has been collected on Oenothera biennis, the evening primrose (J. A. Wilcox, correspondence). The fact that slightly more males - -
than females were taken by E. ??zemoriali,c is puzzling in view of Blatchley's (1910) statment that males of Altica are "much less abundant than the females."
The prey of E. memorialis is relatively large compared to that of some other crabronine wasps. For example, mean prey/wasp



================================================================================

19721 Miller &' Kurczewski - Entomognathus 73 weight ratios, expressed as decimals, for E. memoriak Crossocerus maculiclypeus (Fox), and Lindenius columbianus errans (Fox) were 0.77, 0.22, and 0.07, respectively. This point should not be stressed, however, because the weight of the female wasp may vary depending upon her physical condition (see Iwata, 1942). We caught a female of Cerceris fumipennis Say (Sphecidae) at Auburn, N. Y., weighed, released, and recaptured her 12 days later, and found that her body weight had decreased from 95 to 74 mg, or 22%!
Many fully-provisioned cells of E. memlorialis lacked an egg, larva, or parasites, and we believe this may also be related to the physiological state of the female. Because they were excavated late in the nesting season, such cells were possibly made by females which had already exhausted their egg supplies. The rather small mean number of prey per cell recorded for E. memorialis (5. I ) is undoubtedly related to the relatively large mean sizes of the beetles. E. brevis constructs a cell of similar size