European honeybee defense against Japanese yellow hornet using heat generation by bee‐balling behavior

Abstract

The Japanese honeybee, Apis cerana japonica Radoszkowski, uses unique generation of heat by bee‐balling to defend against, overheat and kill predacious Japanese hornets. We have now observed the European honeybee, Apis mellifera Linnaeus, using similar bee‐balling behavior and heat generation against the Japanese yellow hornet, Vespa simillima xanthoptera Cameron. We monitored temperatures in the center of the bee‐ball and inside thoracic muscles of the captured hornet and found that the thoracic internal temperature (45.8 ± 2.32°C) was higher than that of the bee‐ball (44.0 ± 0.96°C). Although the thoracic temperature of captured hornets rose to the upper lethal level, defending European bees also showed some stinging attempts against the hornet, unlike the sympatric Japanese honeybee, which never stings during bee‐balling. The European honeybee bee‐balling behavior consists of three phases: (i) heating; (ii) heat‐retaining; and (iii) break up. Our results suggest that European honeybees kill hornets by raising the body temperature of hornets rapidly without stinging. The tactics of bee‐balling against hornets are complex and may be performed by extended division of labor.

Giants are coming? Predicting the potential spread and impacts of the giant Asian hornet (Vespa mandarinia, Hymenoptera:Vespidae) in the USA

“…In their native range, Apis cerana Fabricius 23 (a sympatric species) cope with the predatory pressure of V. mandarinia by generating a mass defensive action against the hornets, which are captured by defending bees that increase their thorax temperature to kill the engulfed hornet by heat 24 . Although this defensive behavior against predator wasps has been argued for European honey bees evidencing recent adaptative responses to attacks, 24,25 a potential strategy to reduce the impact of V. mandarinia on honey bees should consider the similarity in habitat and ecological niche requirements between both species. The abundance of V. mandarinia is positively associated with amounts of green spaces in urban landscapes, suggesting that the control of their populations should be focused on urban green areas 26 .…”

Giant hornet (Vespa soror) attacks trigger frenetic antipredator signalling in honeybee (Apis cerana) colonies

“…Nasonov volatiles from antipredator pipers may prompt receivers in A. cerana colonies to amass near nest entrances as a defensive reserve. Such entrance assemblies are often reported across cavity-dwelling species of honeybees when workers collectively defend their colonies against sympatric hornet predators [47,70,72,88,[90][91][92][93]118]. Thus, antipredator piping may be part of a multimodal signal that pairs vibrations, which have the advantage of speedily transmitting a pressing message ('predator attacking') [1,29], with a nonredundant chemical signal that orients defenders ('gather here') [20].…”

“…In the evolutionary arms race between predator and prey, A. cerana has evolved several colonylevel defences to fend off hornet attacks. They often aggregate at the nest entrance as a first step [70,88,89], referred to as a 'bee carpet' in A. mellifera [90][91][92][93]. Once amassed, workers can engulf an individual hornet in a ball of hundreds of bees, simultaneously overheating and asphyxiating it [89,[94][95][96].…”

Hornets and Honey Bees: A Coevolutionary Arms Race between Ancient Adaptations and New Invasive Threats

“…Similar to Asian honey bee species, A. mellifera also shows shaking displays and balling behavior to some extent, but both defense strategies achieve a lower efficacy against hornets [28,55,93,96,97]. The defensive reaction of A. cerana is, in fact, more efficient in terms of both the number of recruited workers and the increase in balling temperature [30,55,59,73,96].…”