Beewolf Females (beewolf + female)

Distribution by Scientific Domains


Selected Abstracts


Females of the European beewolf preserve their honeybee prey against competing fungi

ECOLOGICAL ENTOMOLOGY, Issue 2 2001
Erhard Strohm
Summary 1. Females of the European beewolf Philanthus triangulum (Hymenoptera, Sphecidae) provision brood cells with paralysed honeybees as larval food. Because brood cells are located in warm, humid locations there is a high risk of microbial decomposition of the provisions. Low incidence of fungus infestation (Aspergillus sp.) in nests in the field suggested the presence of an anti-fungal adaptation. 2. To test whether the paralysis caused the protection from fungus infestation, the timing of fungus growth on bees that were freeze-killed, paralysed but not provisioned, and provisioned regularly by beewolf females was determined. Fungus growth was first detected on freeze-killed bees, followed by paralysed but not provisioned bees. By contrast, fungus growth on provisioned bees was delayed greatly or even absent. Thus, paralysis alone is much less efficient in delaying fungus growth than is regular provisioning. 3. Observations of beewolves in their nests revealed that females lick the body surface of their prey very thoroughly during the period of excavation of the brood cell. 4. To separate the effect of a possible anti-fungal property of the brood cell and the licking of the bees, a second experiment was conducted. Timing of fungus growth on paralysed bees did not differ between artificial and original brood cells. By contrast, fungus growth on bees that had been provisioned by a female but were transferred to artificial brood cells was delayed significantly. Thus, the treatment of the bees by the female wasp but not the brood cell caused the delay in fungus growth. 5. Beewolf females most probably apply anti-fungal chemicals to the cuticle of their prey. This is the first demonstration of the mechanism involved in the preservation of provisions in a hunting wasp. Some kind of preservation of prey as a component of parental care is probably widespread among hunting wasps and might have been a prerequisite for the evolution of mass provisioning. [source]


Low level of cuticular hydrocarbons in a parasitoid of a solitary digger wasp and its potential for concealment

ENTOMOLOGICAL SCIENCE, Issue 1 2009
Johannes KROISS
Abstract Insect cuticular hydrocarbons (CHC) play a role as semiochemicals in many host,parasite systems and chemical mimicry or camouflage is a well-known mechanism of parasites to evade detection by the host. The cuckoo wasp Hedychrum rutilans (Hymenoptera, Chrysididae) is a parasitoid of larvae of the European beewolf Philanthus triangulum (Hymenoptera, Crabronidae). Females chemically mimic the cuticular hydrocarbons of their hosts to avoid detection and countermeasures when entering the host nest for oviposition. Here we report on a possible second mechanism of the chrysidid wasp H. rutilans to evade detection: the amount of CHC/mm2 of cuticle is only approximately one-fifth compared to its beewolf host. Furthermore, we show that surprisingly large amounts of CHC of beewolf females can be found on the walls of the underground nest. Potentially, these hydrocarbons might constitute a background odor against which the cuckoo wasps or their chemical traces have to be perceived by the beewolf. The reduction in the amount of CHC of the cuckoo wasps might be equivalent to a dilution of recognition cues, especially against the background odor of the nest walls, and might provide a means to escape detection within the nest due to "chemical insignificance". [source]


Food wrapping by females of the European Beewolf, Philanthus triangulum, retards water loss of larval provisions

PHYSIOLOGICAL ENTOMOLOGY, Issue 2 2008
GUDRUN HERZNER
Abstract Females of the European beewolf, Philanthus triangulum F. (Hymenoptera, Crabronidae), embalm the provisions of their larvae, paralyzed honeybees, with a secretion from a postpharyngeal gland prior to oviposition. This food wrapping is known to delay fungus infestation of the prey. In the present study, the hypothesis that the food wrapping has an additional function, namely the prevention of prey desiccation, is tested. Water loss of paralyzed but unembalmed honeybees and embalmed honeybees is measured and the composition and quantity of their cuticular hydrocarbons analyzed by coupled gas chromatography,mass spectrometry. Water loss is significantly lower in embalmed compared with unembalmed bees. This might have important advantages for the larvae under the warm and dry conditions that prevail in some brood cells. The embalming by beewolf females increases the total amount of hydrocarbons on the surface of the bees by almost ten-fold. Moreover, the proportion of unsaturated and short-chained hydrocarbons is significantly increased. Unsaturated and short-chain hydrocarbons are usually less effective against water loss, so the increased protection against water loss appears to be mediated mainly by the thickness of the hydrocarbon layer. [source]