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The European beewolf (''Philanthus triangulum''), also known as the bee-killer wasp or the bee-eating philanthus (from the now obsolete synonym ''Philanthus apivorus''), is a solitary
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...
that lives in the Western Palearctic and
Afrotropic The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopi ...
s. Although the adults of the species are herbivores (feeding on nectar and pollen), the species derives its name from the behaviour of the inseminated females, who hunt
Western honey bee The western honey bee or European honey bee (''Apis mellifera'') is the most common of the 7–12 species of honey bees worldwide. The genus name ''Apis'' is Latin for 'bee', and ''mellifera'' is the Latin for 'honey-bearing' or 'honey-carrying', ...
s. The female places several of its paralysed prey together with an egg in a small underground chamber, to serve as food for the wasp larvae. All members of the genus '' Philanthus'' hunt various species of bees, but ''P. triangulum'' is apparently the only one that specialises in Western honey bees.


Identification

The European beewolf is a species of solitary wasp with bold yellow and black markings on the abdomen, males have trident-shaped markings between their bluish eyes while the larger females have a reddish stripe behind the eyes and a pale face.


Habitat

The European beewolf is found mainly in areas of open sandy ground in areas such as lowland heathland and coastal dunes. They are infrequently found in clay areas and in Britain have been recorded digging burrows in coal dust and ash and have been found on spoil heaps from coal mining.


Subspecies and distribution

The European beewolf has a wide distribution in the
Afrotropical The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopi ...
and Western Palearctic zoogeographical regions from
Scandinavia Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also ...
to
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
. In Europe its distribution has been moving northwards as summers have longer periods of warm weather. There are currently five recognised subspecies: *''Philanthus triangulum abdelcader'' Lepeletier, 1845; northern Africa and the
Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...
from
Iraq Iraq, officially the Republic of Iraq, is a country in West Asia. It is bordered by Saudi Arabia to Iraq–Saudi Arabia border, the south, Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq border, the east, the Persian Gulf and ...
westwards to the Atlantic and the
Canary Islands The Canary Islands (; ) or Canaries are an archipelago in the Atlantic Ocean and the southernmost Autonomous communities of Spain, Autonomous Community of Spain. They are located in the northwest of Africa, with the closest point to the cont ...
this subspecies also occurs on the
Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...
island of Lampedusa; *''Philanthus triangulum bimaculatus'' Magretti, 1908;
Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
; *''Philanthus triangulum diadema'' ( Fabricius 1781); the Afrotopics; *''Philanthus triangulum obliteratus'' Pic 1917;
Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...
and
Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...
: *''Philanthus triangulum triangulum'' (Fabricius, 1775); Europe.


Biology

In the more northerly parts of its distribution, the European beewolf is univoltine and the flight period is between mid-July and September. In the warmer areas in which it occurs there can be more than one generation per year, for example, in Central Europe, there may be two broods in the summer. Female European beewolves excavate their burrows in sandy soil or in vertical soil faces in open sunny places and these can be up to a metre in length with no less than three and as many as 34 short side tunnels at the end, each of which contains a brood cell. The material displaced by the burrowing wasp is flicked behind it as it excavates the nest. They nest in aggregations which may have as many as 15,000 burrows. The females hunt honey bees ''
Apis mellifera The western honey bee or European honey bee (''Apis mellifera'') is the most common of the 7–12 species of honey bees worldwide. The genus name ''Apis'' is Latin for 'bee', and ''mellifera'' is the Latin for 'honey-bearing' or 'honey-carrying', ...
'', which are paralysed with the stinger, the female stings the prey through the articular membranes which are situated behind the front legs, the female then carries the immobilised bee to the nest in flight between the wasp's legs. On reaching the nest she often hovers over the entrance before slowly descending into the burrow. Each brood cell is provisioned with between one and five honey bees for the larva. After the larva has fed sufficiently it spins a cocoon, the cocoon is attached to the wall of the brood cell at its base. In cooler regions the larva overwinters and the adults emerge the following summer. Other species of bee, other than honey bees, have been reported as prey including '' Andrena flavipes'', '' Lasioglossum zonulus'' and '' Nomada sp'' in Britain as well as bees of the genera '' Dasypoda'', '' Halictus'' and ''
Megachile The genus ''Megachile'' is a cosmopolitan group of solitary bees, often called leafcutter bees or leafcutting bees; it also includes the resin bees and mortar bees. While other genera within the family Megachilidae may chew leaves or petals ...
'' in continental Europe. Each female may collect up to 100 bees during its flight period. The humid and warm conditions in the brood cells provide good growth conditions a number of species of mould fungi which can colonise the cells opportunistically from the surrounding soil, especially ''
Aspergillus flavus ''Aspergillus flavus'' is a saprotrophic and pathogenic fungus with a cosmopolitan distribution. It is best known for its colonization of cereal grains, legumes, and tree nuts. Postharvest rot typically develops during harvest, storage, and/or ...
'', which can either infect the larva or the stored immobilised bees and this normally causes the larva to die. Female beewolves protect their offspring against pathogens, and they have evolved strategies to reduce the mortality of their offspring in the brood cell. The first strategy is to apply copious amounts of an anti-condensation secretion from a cephalic gland onto the paralysed bees to reduce water condensation on those bees and thereby delay fungal germination. The second strategy consists of a concentrated release of nitric oxide from the beewolf egg itself once the brood cells are closed by the mother that sterilises the deposited bees by killing actively growing fungi. The third strategy is that the female wasp secretes a whitish substance from specialised glands in its antennae into the brood cell, this secretion contains symbiotic bacteria of the genus ''
Streptomyces ''Streptomyces'', from στρεπτός (''streptós''), meaning "twisted", and μύκης (''múkés''), meaning "fungus", is the largest genus of Actinomycetota, and the type genus of the family Streptomycetaceae. Over 700 species of ''St ...
'', which are ingested by the larva and before the larva pupates the bacteria are applied to the cocoon to protect the larva from fungal infection. The males set up territories in vegetation near to the females' nesting aggregations, these territories do not hold any resources to interest the females. The territories are around a quarter of a square metre in extent and are marked with a
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
from the male's cephalic glands. The males defend these territories from intruding males but the defence does not involve physical contact between the antagonists. Males may have territories which are often close to one another, constituting a form of lek, which allows the females to choose their mates from among the males. The males do not appear to attract the females by using any form of visual display and it is thought that the females choose the males to copulate with based on the quality of the pheromones the male produces. The amount of time the male occupies a territory is dependent on the number of female nests near that territory. The adult wasps feed on nectar and have been recorded as feeding on nectar from
bramble ''Rubus'' is a large and diverse genus of flowering plants in the rose family, Rosaceae, subfamily Rosoideae, most commonly known as brambles. Fruits of various species are known as raspberries, blackberries, dewberries, and bristleberries. I ...
, sea-holly, ''
Erica Erica or ERICA may refer to: * Erica (given name) * Erica (plant), ''Erica'' (plant), a flowering plant genus * Erica (chatbot), a service of Bank of America * Erica (video game), ''Erica'' (video game), a 2019 FMV video game * Erica (spider), ' ...
'', thrift, pale toadflax '' Linaria repens'', common ragwort, hemp-agrimony and creeping thistle.


Nests

Niko Tinbergen Nikolaas "Niko" Tinbergen ( , ; 15 April 1907 – 21 December 1988) was a Dutch biologist and ornithologist who shared the 1973 Nobel Prize in Physiology or Medicine with Karl von Frisch and Konrad Lorenz for their discoveries concerning th ...
made a series of carefully designed experiments demonstrating ''Philanthus'' identifies its nest by sight.


Status in the UK

This wasp was previously considered to be one of the great aculeate rarities in Britain, with colonies only in sandy habitats on the
Isle of Wight The Isle of Wight (Help:IPA/English, /waɪt/ Help:Pronunciation respelling key, ''WYTE'') is an island off the south coast of England which, together with its surrounding uninhabited islets and Skerry, skerries, is also a ceremonial county. T ...
and
Suffolk Suffolk ( ) is a ceremonial county in the East of England and East Anglia. It is bordered by Norfolk to the north, the North Sea to the east, Essex to the south, and Cambridgeshire to the west. Ipswich is the largest settlement and the county ...
. It has undergone an expansion in range, with the wasp now locally common in a steadily increasing number of sites as far north as
Yorkshire Yorkshire ( ) is an area of Northern England which was History of Yorkshire, historically a county. Despite no longer being used for administration, Yorkshire retains a strong regional identity. The county was named after its county town, the ...
(2002). The species has RDB2 status (vulnerable) but, if revised, it is now likely that this status will be removed because of its increase in range and population.


See also

* Philanthotoxin


References


External links


Semiochemicals of ''Philanthus triangulum'', the European beewolves
{{Taxonbar, from=Q301297 Philanthidae Hymenoptera of Europe Hymenoptera of Africa Insects described in 1775