The European beewolf is a solitary digger wasp of the genus Philanthus that comprises about 140 species worldwide. Female beewolves construct nest burrows in sandy soil, hunt honeybees (Apis mellifera),
paralyze them by stinging and carry the prey to the nest in flight. One
to five honeybees are provisioned as larval food in each brood cell.
The larva feeds on the prey and spins a cocoon that is attached with
its basal part to the wall of the brood cell. Larvae mostly overwinter
and emerge next summer.
Since the conditions in the brood cell are humid
and warm, there is a continuous threat that pathogenic microorganisms, in particular mold fungi,
infest the larva or the provisioned honeybees, which usually results
in the death of the larva. Therefore, there is a high selection
pressure on female beewolves to protect their offspring against
pathogens, and beewolves evolved at least two different ways to
reduce offspring mortality in the brood cell:
(1) They apply large
amounts of a secretion from a cephalic
gland to the provisioned honeybees, which significantly delays
fungal growth on the bees.
(2) The beewolf female secretes a whitish
subtance from its specialized antennal
glands to the brood cell that contains symbiotic
bacteria of the genus Streptomyces. The bacteria are
later taken up by the larva and applied to its cocoon, where they
significantly reduce fungal infestation and thereby protect the
(3) Beewolf eggs emit gaseous nitric oxide (NO) to fumigate their brood cell. NO is spontaneously oxidized to NO2 with the latter causing a pungent smell of the brood cells. Both are radicals and more or less toxic. As a consequence, most fungi in the brood cell are killed. Thus the paralyzed bees can be consumed by the larva without competition by mold fungi. However, it is a puzzle how the eggs themselves but also the symbiotic Streptoymces bacteria can survive the toxic atmosphere in the brood cell.
Male beewolves establish territories consisting
of about 0.25 m2 of vegetation, mostly in the vicinity of the females’
nest aggregations. They mark their territories with a pheromone
from cephalic glands and defend them against intruding males in
combat flights without physical contact of the opponents. Territories
of different males are often found close together, thereby constituting
a lek situation in which the females have an ideal opportunity to
choose among males. Since the copulation is not preceded by any
kind of visual display, female choice could, at least predominately,
be based on information obtained from the male
Strohm E, Herzner G, Ruther J, Kaltenpoth M, Engl T (2019 in press) eLife 2019;8:e43718. Nitric oxide radicals are emitted by wasp eggs to kill mold fungi. DOI: https://doi.org/10.7554/eLife.43718.
Kaltenpoth M, Kroiss J, Strohm E (2007) The odor
of origin: kinship and geographical distance are reflected in the
marking pheromone of male beewolves (Philanthus triangulum
F., Hymenoptera, Crabronidae). BMC
Herzner G, Schmitt T, Peschke K, Hilpert A, Strohm
E (2007). Food wrapping with the post pharyngeal gland secretion
by females of the european beewolf Philanthus triangulum.
Journal of Chemical Ecology 33 (4): 849-859.
Herzner G, Goettler W, Kroiss J, Purea A, Webb
A, Jakob PM., Rössler W, Strohm E (2007). Males of a solitary wasp
possess a postpharyngeal gland. Arthropod Structure & Development
Strohm E, Herzner G, Goettler W (2007). A "social"
gland in a solitary wasp? The postpharyngeal gland of female European
beewolves (Hymenoptera, Crabronidae). Arthropod Structure &
Development 36: 113-122.
Herzner G, Strohm E (2007). Fighting fungi with
physics: food wrapping by a solitary wasp prevents water condensation.
Current Biology 17: R46-R47.
Goettler, W., Kaltenpoth, M., Herzner, G., Strohm,
E. (2007) Morphology and ultrastructure of a bacteria cultivation
organ: The antennal glands of female European beewolves, Philanthus
triangulum (Hymenoptera, Crabronidae). Arthropod
Structure & Development 36: 1-9.
Kroiss J, Schmitt T, Schreier P, Strohm E, Herzner
G (2006). A selfish function of a social gland? A postpharyngeal
gland functions as sex pheromone reservoir in males of a solitary
wasp. Journal of Chemical Ecology 32: 2763-2776.
Kaltenpoth, M. (2006) Symbiotische Streptomyces-Bakterien
in Grabwespen. Naturwissenschaftliche Rundschau 59 (11): 618-619.
Kaltenpoth, M., Strohm, E. (2006). The scent
of senescence: Age-dependent changes in the composition of the marking
pheromone of the male European beewolf (Philanthus triangulum,
Hymenoptera, Crabronidae). Journal
of Insect Science 6:20.
Herzner, G., Schmitt, T., Heckel, F., Schreier,
P. and Strohm, E. (2006). Brothers smell similar: Variation in the
sex pherome of male European Beewolves and its implications for
inbreeding avoidance. Biological Journal of the Linnean Society.
Kaltenpoth, M., Göttler, W., Dale, C., Stubblefield,
J.W., Herzner, G., Roeser-Mueller, K., and Strohm, E. (2006) 'Candidatus
Streptomyces philanthi', an endosymbiotic streptomycete in the antennae
of Philanthus digger wasps. International
Journal of Systematic and Evolutionary Microbiology 56 (6): 1403-1411.
Herzner, G., Schmitt, T., Linsenmair, K. E. and
Strohm, E. (2005). Prey recognition by females of the European beewolf
and its potential for a sensory trap. Animal Behaviour 70, 1411-1418.
Kaltenpoth, M. (2005). Bakterien schützen Wespen-Nachwuchs
vor Pilzbefall. Naturwissenschaftliche
Rundschau 58: 329-330.
Kaltenpoth, M., Göttler, W., Herzner, G. and Strohm, E. (2005).
Symbiotic bacteria protect wasp larvae from fungal infestation.
Biology 15: 475-479.
Kaltenpoth, M., Strohm, E. and Gadau, J. (2004). Polymorphic
microsatellite markers for a solitary digger wasp, the European
beewolf (Philanthus triangulum; Hymenoptera, Sphecidae).
Ecology Notes 4: 589-592.
Strohm, E. and Daniels, W. (2003). Ultrastructure
meets reproductive success: performance of a sphecid wasp is correlated
with the fine structure of the flight-muscle mitochondria, Proc. R.
Soc. Lond. Ser. B-Biol. Sci. 270, 749-754.
Schmitt, T., Strohm, E., Herzner, G., Bicchi, C.,
Krammer, G., Heckel, F. and Schreier, P. (2003).
(S)-2,3-dihydrofarnesoic acid, a new component in cephalic glands of
male european beewolves Philanthus triangulum, J. Chem. Ecol. 29,
Herzner, G., Schmitt, T., Linsenmair, K. E. and
Strohm, E. (2003). Flagellar sensilla in male and female European
beewolves, Philanthus triangulum F. (Hymenoptera : Sphecidae), Entomol.
Fenn. 14, 237-247.
Strohm, E. and Marliani, A. (2002). The cost of parental care: Prey hunting in a digger wasp, Behavioral Ecology 13, 52-58.
Strohm, E., Schmitt, T., Herzner, G. and Schreier,
P. (2002a). Wolves in sheep's fur? Chemical camouflage in the European
beewolf and its major brood parasitoid, Zoology Jena 105, 30.
Strohm, E. and Linsenmair, K. E. (2001). Females of
the European beewolf preserve their honeybee prey against competing
fungi, Ecological Entomology 26, 198-203.
Strohm, E. (2001). Females of the European beewolf
preserve their larval provisions against competing fungi, Zoology Jena
Strohm, E., Laurien, K. C. and Bordon, S. (2001).
Escape from parasitism: Spatial and temporal strategies of a sphecid
wasp against a specialised cuckoo wasp, Oecologia Berlin 129, 50-57.
Strohm, E. and Lechner, K. (2000). Male size does
not affect territorial behaviour and life history traits in a sphecid
wasp, Animal Behaviour 59, 183-191.
Strohm, E. and Linsenmair, K. E. (2000). Allocation
of parental investment among individual offspring in the European
beewolf Philanthus triangulum F. (Hymenoptera: Sphecidae), Biological
Journal of the Linnean Society 69, 173-192.
Strohm, E. (2000). Factors affecting body size and fat content in a digger wasp, Oecologia Berlin 123, 184-191.
Strohm, E. and Linsenmair, K. E. (1999).
Measurement of parental investment and sex allocation in the European
beewolf Philanthus triangulum F. (Hymenoptera: Sphecidae), Behavioral
Ecology and Sociobiology 47, 76-88.
Strohm, E. and Linsenmair, K. E. (1998).
Temperature dependence of provisioning behaviour and investment
allocation in the European beewolf Philanthus triangulum F, Ecological
Entomology 23, 330-339.
Strohm, E. and Linsenmair, K. E. (1997). Low
resource availability causes extremely male-biased investment ratios in
the European beewolf, Philanthus triangulum F. (Hymenoptera,
Sphecidae), Proceedings of the Royal Society of London Series B
Biological Sciences 264, 423-429.
Strohm, E. and Linsemair, K. E. (1997). Female size
affects provisioning and sex allocation in a digger wasp, Animal
Behaviour 54, 23-34.
Strohm, E. (1995). Allokation elterlicher
Investitionen beim Europäischen Bienenwolf Philanthus triangulum
Fabricius (Hymenoptera: Sphecidae). Berlin: Verlag Dr. Köster.
Strohm, E. and Linsenmair, K. E. (1994/95). Leaving
the cradle: How beewolves (Philanthus triangulum F.) obtain the
necessary spatial information for emergence, Zoology Jena 98, 137-146.