Agnès Rortais

Defensive behaviour of Apis mellifera against Vespa velutina in France: Testing whether European honeybees can develop an effective collective defence against a new predator

We investigated the prey-predator interactions between the European honeybee, Apis mellifera, and the invasive yellow-legged hornet, Vespa velutina, which first invaded France in 2004 and thereafter spread to neighbouring European countries (Spain, Portugal and Italy). Our goal was to determine how successfully honeybees are able to defend their colonies against their new predator in Europe. Experiments were conducted in the southwest of France-the point of entry of the hornet in Europe-under natural and semi-controlled field conditions. We investigated a total of eight apiaries and 95 colonies subjected to either low or high levels of predation. We analyzed hornet predatory behaviour and collective response of colonies under attack. The results showed that A. mellifera in France exhibit an inefficient and unorganized defence against V. velutina, unlike in other regions of Europe and other areas around the globe where honeybees have co-evolved with their natural Vespa predators.

Observations on the colony activity of the Asian hornet Vespa velutina Lepeletier 1836 (Hymenoptera: Vespidae: Vespinae) in France

Abstract Observations were made in the south-west region of France on the activity and behaviour of Vespa velutina workers from a nest reared in captivity as well as from free-living colonies. Seasonal nest development, daily extranidal activity, daily time budget allocated to nest construction and carbohydrates, water, pulp or prey collection were determined from the captive colony. In the meantime, nestmate and non-nestmate interactions were assessed. The percentages of pulp pellets and prey collections brought back by foragers were also determined from the free-living colonies and showed a noticeable preference of the hornet for honey bees. These preliminary data allow further investigations on the biology and behaviour of this Asian invasive species in the view to better assess its impact on biodiversity in France.

Attack or retreat: Contrasted defensive tactics used by Cyprian honeybee colonies under attack from hornets

This study describes the tactics used by Cyprian honeybees (Apis mellifera cypria) to defend their colonies against hornet (Vespa orientalis orientalis) attacks. We use simulated hornet attacks and a combination of video recordings and image analysis to reveal, for the first time, contrasted intra-subspecies defensive tactics that operate at the colony level during predation. In some colonies, when attacked, the numbers of guards at the hive entrance increases rapidly to attack, engulf, and kill invading hornets. In other colonies, guards avoid conflicts with hornets by retreating gradually and by forming a defensive line of honeybees at the hive entrance. Retreater colonies have propolis walls at the hive entrances with small apertures that are too narrow to allow the hornet to access the hive and that therefore reinforces entrance protection. On the contrary, attacker colonies have propolis walls with large openings through which the hornet can pass; these bees block the hornets access by intensively guarding the hive entrance. We experimentally destroy propolis walls to test whether colonies consistently rebuild walls with the same intrinsic characteristics and we also monitor the survival rate of each anti-predator tactic after massive natural predation by hornets.

High frequency sounds produced by Cyprian honeybees Apis mellifera cypria when confronting their predator, the Oriental hornet Vespa orientalis

Honeybees face several predators and their ability to express collective defence behaviour is one of their major life traits that promote colony survival. We discovered that, while confronting attacks by the Oriental hornet Vespa orientalis, Apis mellifera cypria honeybees engage in a distinct acoustic behaviour: they produce a characteristic hissing sound of unexpectedly high frequency. When recording and analysing these hissing sounds during an extended sample of artificial attacks by hornets, we found that honeybees can produce sounds covering a wide frequency spectrum with a dominant frequency around 6 kHz. Notably, these acoustic emissions are distinct from the background noise of neighbouring flying bees. These results provide a detailed description of the sounds generated by A. m. cypria when defending their nest against hornets, and they could be used for future research to better understand the biological function of the acoustic behaviour in honeybees’ colony defence.ZusammenfassungWährend der Abwehr von Angriffen durch die orientalische Hornisse Vespa orientalis zeigen die zyprischen Honigbienen Apis mellifera cypria ein spezifisches akustisches Verhalten, bei dem sie einen charakteristischen Zischlaut von unerwartet hoher Frequenz erzeugen. Dieser charakteristische Ton wird während der Annäherung des Räubers und während der Auseinandersetzung mit verteidigenden Bienen am Eingang der Kolonie hervorgebracht. Wir nahmen diese Zischlaute während einer ausgedehnten Serie künstlicher Angriffe von Hornissen auf und analysierten sie. Für die Aufnahmen verwendeten wir ein mit einem Marantz PMD 670 Digitalrekorder verbundenes Sennheiser ME64 Mikrofon. Die Aufnahmen wurden unter Verwendung der Avisoft und Seewave Software untersucht. Wir ermittelten, dass die Bienen ein weites Frequenzspektrum mit einer dominanten Frequenz um 6 kHz erzeugen können. Die Zischlaute zeigten ein bis zu 16–17 kHz ausgedehntes Spektrum, das bis zu 30–35 harmonische Bänder einschloss. Die Untersuchung von 93 an 9 Kolonien aufgenommenen verschiedenen Zischlauten ergab keine Hinweise auf akustische Kennzeichen der unterschiedlichen Kolonien. Insbesondere waren die akustischen Emissionen deutlich von den durch benachbarte fliegende Bienen hervorgebrachten Hintergrundgeräuschen abgesetzt. Diese Ergebnisse beinhalten eine detaillierte Beschreibung der von A. m. cypria bei der Verteidigung gegen Hornissen hervorgebrachten Töne und können in zukünftigen Untersuchungen zu einem besseren Verständnis der biologischen Bedeutung des akustischen Verhaltens bei der Nestverteidigung der Honigbienen beitragen.

Establishment of a cross-European field site network in the ALARM project for assessing large-scale changes in biodiversity

The field site network (FSN) plays a central role in conducting joint research within all Assessing Large-scale Risks for biodiversity with tested Methods (ALARM) modules and provides a mechanism for integrating research on different topics in ALARM on the same site for measuring multiple impacts on biodiversity. The network covers most European climates and biogeographic regions, from Mediterranean through central European and boreal to subarctic. The project links databases with the European-wide field site network FSN, including geographic information system (GIS)-based information to characterise the test location for ALARM researchers for joint on-site research. Maps are provided in a standardised way and merged with other site-specific information. The application of GIS for these field sites and the information management promotes the use of the FSN for research and to disseminate the results. We conclude that ALARM FSN sites together with other research sites in Europe jointly could be used as a future backbone for research proposals.

Genetic characterization of the cyprian honey bee (Apis mellifera cypria) based on microsatell ites and mitochondrial DNA polymorphisms

Abstract Honey bee populations from the island of Cyprus were analyzed using microsatellite and mitochondrial DNA markers. A total of 268 colonies were sampled in Cyprus, at six different locations-Kyrenia, Katydata, Flassou, Alabra, Troulloi, and Alassa-covering a wide area of the island. Results showed that the Cyprian honey bee Apis mellifera cypria could be distinguished from other Apis mellifera subspecies based on a „double pattern“ of mitochondrial DNA belonging to the C1 lineage and microsatellite DNA belonging to the O lineage. All populations were homogeneous, except the population from Kyrenia, probably due to the introduction of queens or colonies belonging to the C2, C6, and M7 lineages.