Fig 1.
Outdoor formicarium of Lasius fuliginosus.
The carton nest is housed in three darkened terraria; foragers moved through three arenas to reach the food sources provided in two foraging chambers.
Fig 2.
Bridge placement in arena A of the outdoor formicarium.
In arena A, a brass ditch that was coated with mineral oil was inserted in the middle and the bridge crossing the ditch was placed either in the middle (A1), on the left side (A2), or the right side of arena A (A3). The black bars numbered 1 to 19 represent the locations of Balsa wood shelters.
Fig 3.
Design of formicarium used in the isotope laboratory.
Foragers on their way back to the carton nest, moved from the food chambers through two arenas, one of which housed Amphotis beetles.
Fig 4.
Amphotis marginata beetles resting under old bark in the ground litter.
The picture above shows a total 12 beetles clustered together during daytime. The image below is a close-up of resting beetles taken at a different locality (photo courtesy Konrad Fiedler).
Fig 5.
The abundance of beetles on one L. fuliginosus trail.
Columns represent the average abundance of beetles associated with one L. fuliginosus foraging trail from May–August, 1969 (n = 6 sample dates, bars represent the standard error of the mean). Beetles were most abundant near the nest entrance, and at a second Robinia pseudoacacia tree located 25 m away. Beetles were not removed from their original location during the censuses.
Fig 6.
Beetle abundance at five L. fuliginosus nests.
Beetles were collected exhaustively on foraging trails up to 30 meters away from 5 nests (June of 1969 and June of 1972). Columns represent the total number of beetles on all trails at each distance.
Fig 7.
Distribution of Amphotis beetles in the arenas of the outdoor formicarium.
Significantly more beetles assembled in the arena closest to the carton nest terraria (bars represent the standard error the mean)
Fig 8.
Results of choice tests designed to investigate the preference of Amphotis beetles in selecting resting shelters.
The beetles preferred to take shelters close to L. fuliginosus ants, hindgut (HGE) or head extracts, respectively, of L. fuliginosus, but show no preferences for other ant species tested.
Table 1.
Beetles were attracted to head and hindgut extracts of L. fuliginosus workers.
Table 2.
Beetles were not attracted to live F. sanguinea in a choice test that also included L. fuliginosus.
Table 3.
Beetles were not attracted to live Myrmica rubra in a choice tests that also included L. fuliginosus.
Table 4.
Beetles were not attracted to live L. niger in a choice test that also included L. fuliginosus.
Fig 9.
Behavioral sequence of food solicitation by A. marginata beetles from L. fuliginosus foragers.
(a) Food exchange between two L. fuliginosus workers. The donor ant has its mandibles opened widely, with the labium extended and the antennae folded backwards. The receiving ant antennates the head of the donor. (b to f) Behavioral sequence that leads to regurgitation of a drop of crop content by the ant (g and h). For detailed description see text.
Fig 10.
The relationship between begging time and food transfer between A. marginata and its host, L. fuliginosus.
There was a significant positive association between begging time and the amount of food transferred to beetles (binomial GLM, z = 35.04, p< 0.0000).
Fig 11.
The accumulation of food by beetles over time.
Beetle impulse rate increased over time when beetles were restricted to a foraging area associated with one L. fuliginosus colony (bars represent the standard error of the mean).
Fig 12.
Amphotis marginata soliciting regurgitation from a worker ant of M. rubra.
(Above) The beetle approaches the ant. (Below) The ant antennates and licks the beetle’s mouthparts.
Fig 13.
Myrmica rubra worker feeding A. marginata.
(Above) The beetle stimulates the ant’s labium. (Below) A food droplet is regurgitated by the ant.
Fig 14.
Amphotis marginata soliciting food from a worker of F. pratensis.
(Above) The beetle thrusts its head toward the ant’s head. The ant briefly licks the beetle’s mouthparts. (Below) The beetle stimulates the ant’s labium. The ant opens the mandibles, folds the antennae backwards and regurgitates a food droplet.
Fig 15.
Amphotis marginata soliciting food from a worker of F. sanguinea.
(Above) The beetle thrusts its head towards the ant’s head. The ant licks the beetles head. (Below) The beetle stimulates the ant’s extended labium.
Fig 16.
Amphotis marginata soliciting food from workers of C. ligniperdus.
Although there is a considerable size difference between beetle and ant, the beetle is able to elicit regurgitations in these carpenter ants.
Fig 17.
Two A. marginata individuals attempt to solicit food from each other.
These occasional attempts soliciting food from conspecifics were never successful.
Fig 18.
Scanning electron microscopic images of a front leg of A. marginata.
The powerful claws and tarsal setae my serve to attach the beetle tightly to the ground.
Fig 19.
Antagonistic interactions between L. fuliginosus workers and A. marginata.
(a) The beetle attacked by an ant worker retreats head and antennae under its carapace and attaches itself tightly to the ground. (b) Occasionally the ant is able to lift the beetle off the ground and flip it over. (c) A beetle on its back is very vulnerable. Usually the ants bite off the legs of the beetle.
Fig 20.
Scanning electron microscopic dorsal view of the head of A. marginata.
Above: Head and part of the thorax; (M) mandible: (Sc) scapus of antenna. (Below) Close up of mandibles (M), clypeus (C) labrum (Lr) and (MS) mecahosensilla.
Fig 21.
Scanning electron microscopic close up image of clypeus and labrum.
The pores (P) on clypeus (C) and labrum (Lr) are clearly visible.
Fig 22.
Scanning electron microscopic images of the mandible of A. marginata.
(a) Entire mandible; one of the apical teeth is partly broken off; the inner edge of the mandible with densely packed setae forming a brush-like structure (Br). (b)A close-up of the mandibular brush, with glandular pores (P) also visible. (c) Close-up of the surface of the mandible showing the pore openings (P).
Fig 23.
Frontal section of the head of A. marginata.
(Right) Overview of the entire head; “lateral head gland” (LG); “labial gland” (LbG); Labium (Lb); mandible (M). (Left) Close-up of the section through the “labial gland” (LbG), the ducts (GD) open between glossa and paraglossa.
Fig 24.
Frontal section through the head of A.marginata showing one side of the “lateral gland”.
(Left) The “lateral gland cells” (LG) appear to open through ducts (GD) near the lateral base of the mandibles (M). (Right) Close-up of the cells of the “lateral gland.”
Fig 25.
Single glandular cells in the head of A. marginata.
The glandular cells (GC) presumably drain their secretion through duct cells (DC) and cuticular pores.
Fig 26.
Club-shaped antenna of A. marginata.
The long mechanosensory setae (MS) are a striking feature of these antennae.
Fig 27.
Scanning electron microscopic images of last antennal segment of A. marginata.
(Above) Overview of the tip of the antenna; (MH) mechanosensory hair. (Below) Close-up view showing sensilla and glandular pores (P).
Fig 28.
Scanning electron microscopic close-up view of glandular pores in the last antennal segment of A. marginata.
(Above) Secretion (Scr) oozing out of the pores. (Below) Single pore (P) with secretion (Scr).
Fig 29.
Longitudinal section through the last three antennal segments of A. marginata.
(Above) The last three antennal segments are densely packed with olfactory sensilla (OS) and mechanosensilla (base of mechanosensilla MS); sensory neuron (SN). Below: Glandular cells (GC) at the base of the last antennal segment.
Fig 30.
Scanning electron microscopic images of the mouthparts of A. marginata.
(a) Mouthparts; mandibles (M), maxillary palps (MxP), labial palps (LbP). (b) Sensilla on tip of maxillary palps. (c) Sensilla on tip of labial palps. (d) Close-up of special sensilla on labial palps, see white box in (c).