Linking the Morphology of Sternal Glands to Rubbing Behavior by Vespa soror (Hymenoptera: Vespidae) Workers During Recruitment for Group Predation.

The activities of social insect colonies are supported by exocrine glands and the tremendous functional diversity of the compounds that they secrete. Many social wasps in the subfamilies Vespinae and Polistinae have two sternal glands-the van der Vecht and Richards' glands-that vary in their features and function across the species in which they are found. Field observations suggest that giant hornets use secretions from the van der Vecht gland to chemically mark targeted nests when workers initiate group attacks on social insect prey. However, descriptions of giant hornets' sternal glands and details about their recruitment behavior are lacking. We describe the morphology of the sternal glands of the giant hornet Vespa soror du Buysson and consider their potential to contribute to a marking pheromone. We also assess the gastral rubbing behavior of workers as they attacked Apis cerana F. (Hymenoptera: Apidae) colonies. V. soror workers have well-developed van der Vecht and Richards' glands on their terminal gastral sternites, with morphologies that robustly support the synthesis, storage, and dissemination of their secretory products. Observations confirm that the van der Vecht gland is exposed during gastral rubbing, but that the Richards' gland and glands associated with the sting apparatus may also contribute to a marking pheromone. Workers briefly but repeatedly rubbed their gasters around hive entrances and on overhead vegetation. Colonies were heavily marked over consecutive attacks. Our findings provide insight into the use of exocrine secretions by giant hornets as they recruit nestmates to prey colonies for group attacks.

A new species of Paracortina from a Vietnamese cave, with remarkable secondary sexual characters in males (Callipodida, Paracortinidae).

A new millipede species, Paracortinakyrangsp. nov., is described from a cave in Cao Bang Province, northern Vietnam. The new species is diagnosed by having an extraordinarily long projection on the head of males, reduced eyes, a gonocoxite with two processes, a long and slender gonotelopodite with two long, clavate prefemoroidal processes densely covered with long macrosetae apically, and with a distal, reverse, short spine on mesal side, and a rather sinuous distal part of the telopodite. This is the third species of the genus that is known from Vietnam. A brief comparison of some secondary sexual characters is made.

Biology of the southern giant hornet, Vespa soror: nest architecture, morphological differences among castes, and the genetic structure of colonies.

Giant hornets in the genus Vespa are apex predators that are known throughout Asia for their exceptional size and devastating group attacks on social insect colonies. The giant hornets include Vespa mandarinia, a well-studied and widespread temperate species, and Vespa soror, a poorly known sister species that is limited to subtropical and tropical regions of Southeast Asia. Both species have been recently documented on the west coast of North America, raising urgent questions about their potential impact in novel ecosystems. To better understand the biology of V. soror, we describe the nest architecture, caste morphology, and genetic structure of colonies collected in Vietnam. Comparisons of colony metrics between the two giant hornet species suggest important differences that are likely a consequence of the relatively warmer climate in which V. soror occurs. Like V. mandarinia, V. soror constructs large, underground nests of partially enveloped horizontal combs. However, compared to temperate V. mandarinia colonies, the longer nesting period of subtropical V. soror colonies likely resulted in relatively larger colony sizes and nests by the end of their annual cycle. Vespa soror workers and gynes were larger than males, distinguishable based on wing shape and body size (total length and measures of six body parts), and equivalent in size to female castes of V. mandarinia. We genotyped colony members from three mature nests, which revealed that males and females were offspring of singly mated queens. Two colonies were monogynous, but one colony was comprised of two unrelated matrilines. Polygyny has not been observed for V. mandarinia, but is more common in tropical hornet species. Our study sheds light on essential details about the biology of an understudied species of giant hornet, whose populous colonies and long nesting period suggest the potential for substantial ecological impact wherever they occur.

Comparison of the External Morphology of the Sternal Glands for Hornets in the Genus Vespa.

Many social wasps in the speciose subfamilies Polistinae and Vespinae have two sternal glands-the van der Vecht gland and the Richards gland-that are not found in other insects. The presence of these glands has been confirmed in only 6 of 22 hornet species (genus Vespa) and images of their fine structure have not been produced. Here; we characterize the external morphology associated with both glands for workers of nine Vespa species using scanning electron microscopy. All hornets had similar gland configurations; although gland-associated external features differed among species. Scaled for size, glands were equivalently sized for the giant hornets (V. mandarinia and V. soror) and their closest phylogenetic relatives (V. tropica and V. ducalis). Relative size of gland-associated structures was reduced by half for V. simillima; V. velutina; and V. affinis workers. The remaining species (V. crabro and V. analis) had intermediately sized features. Differences among species in external gland structure were best explained by selective pressures related to predatory behavior, rather than defense of nests against ants. However, a lack of information about how Vespa workers use their van der Vecht and Richards glands limits a comparative interpretation of the function of their external gland morphology.

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

Asian honeybees use an impressive array of strategies to protect nests from hornet attacks, although little is understood about how antipredator signals coordinate defences. We compared vibroacoustic signalling and defensive responses of Apis cerana colonies that were attacked by either the group-hunting giant hornet Vespa soror or the smaller, solitary-hunting hornet Vespa velutina. Apis cerana colonies produced hisses, brief stop signals and longer pipes under hornet-free conditions. However, hornet-attack stimuli-and V. soror workers in particular-triggered dramatic increases in signalling rates within colonies. Soundscapes were cacophonous when V. soror predators were directly outside of nests, in part because of frenetic production of antipredator pipes, a previously undescribed signal. Antipredator pipes share acoustic traits with alarm shrieks, fear screams and panic calls of primates, birds and meerkats. Workers making antipredator pipes exposed their Nasonov gland, suggesting the potential for multimodal alarm signalling that warns nestmates about the presence of dangerous hornets and assembles workers for defence. Concurrent observations of nest entrances showed an increase in worker activities that support effective defences against giant hornets. Apis cerana workers flexibly employ a diverse alarm repertoire in response to attack attributes, mirroring features of sophisticated alarm calling in socially complex vertebrates.

Honey bees (Apis cerana) use animal feces as a tool to defend colonies against group attack by giant hornets (Vespa soror).

Honey bees (genus Apis) are well known for the impressive suite of nest defenses they have evolved to protect their abundant stockpiles of food and the large colonies they sustain. In Asia, honey bees have evolved under tremendous predatory pressure from social wasps in the genus Vespa, the most formidable of which are the giant hornets that attack colonies in groups, kill adult defenders, and prey on brood. We document for the first time an extraordinary collective defense used by Apis cerana against the giant hornet Vespa soror. In response to attack by V. soror, A. cerana workers foraged for and applied spots of animal feces around their nest entrances. Fecal spotting increased after colonies were exposed either to naturally occurring attacks or to chemicals that scout hornets use to target colonies for mass attack. Spotting continued for days after attacks ceased and occurred in response to V. soror, which frequently landed at and chewed on entrances to breach nests, but not Vespa velutina, a smaller hornet that rarely landed at entrances. Moderate to heavy fecal spotting suppressed attempts by V. soror to penetrate nests by lowering the incidence of multiple-hornet attacks and substantially reducing the likelihood of them approaching and chewing on entrances. We argue that A. cerana forages for animal feces because it has properties that repel this deadly predator from nest entrances, providing the first report of tool use by honey bees and the first evidence that they forage for solids that are not derived from plants. Our study describes a remarkable weapon in the already sophisticated portfolio of defenses that honey bees have evolved in response to the predatory threats they face. It also highlights the strong selective pressure honey bees will encounter if giant hornets, recently detected in western North America, become established.

Species of the Polistes (Polistella) (Hymenoptera: Vespidae: Polistinae) from Vietnam, with description of a new species and a pictorial key.

Twenty seven species of the subgenus Polistella Ashmead, 1904 are recorded from Vietnam. Polistes chuyangsin Nguyen Nguyen sp. nov. and its nest are described and figured. A pictorial key to Vietnamese species of the subgenus is provided.

Polistes formosanus (Hymenoptera: Vespidae), a good species supported by both morphological and molecular phylogenetic analyses, and a key social wasp in understanding the historical biogeography of the Nansei Islands.

Polistes formosanus Sonan, 1927 is closely related to P. japonicus de Saussure, 1858, and has been treated variously as a good species or subspecies or synonym of P. japonicus. We designate the lectotype of P. formosanus. Detailed examination of morphological characters of specimens from continental Asia, Taiwan, the Nansei Islands and main islands of Japan showed that P. formosanus is a good species different from P. japonicus. Molecular phylogenetic analyses using mitochondrial genes also supported this conclusion. Polistes formosanus is distributed in northern and central Taiwan and in the Nansei Islands and extends northward to the Amami Islands, while P. japonicus occurs in continental Asia, central Taiwan, Korean Peninsula, Honshu to Kyushu of Japan and the Osumi Islands (Yakushima and Tanega-shima Island) of the Nansei Islands. The speciation and biogeography of P. formosanus are briefly discussed.

Taxonomic notes on the paper wasps of the genus Ropalidia in the Indian subcontinent (Hymenoptera: Vespidae).

The taxonomy of Ropalidia wasps in the Indian subcontinent is revised, recognizing 26 species in the subcontinent. Their diagnostic characteristics are summarized in a key to species. New synonymies proposed in the present study are: R. bicolorata shiva Das and Gupta, 1989 under R. bicolorata van der Vecht, 1962; R. colorata sordida van der Vecht, 1941 under R. colorata van der Vecht, 1941; R. rodialipa Lambert and Narendran, 2005 and R. anupama Lambert and Narendran, 2005, both under R. cyathiformis Fabricius, 1804; R. jacobsoni flavoscutellata Das and Gupta, 1989, and R. bangalorica Lambert and Narendran, 2005, both under R. jacobsoni du Buysson, 1908; R. travancorica Lambert and Narendran, 2005, under R. marginata Lepeletier, 1836; R. sridharani Lambert and Narendran, 2005, under R. rufocollaris Cameron, 1900; Ropalidia rufoplagiata nursei van der Vecht, 1941 under R. rufoplagiata Cameron, 1905; Icaria lugubris Smith, 1858, under R. sumatrae Weber, 1801; and a revised synonymy is Icaria pendula Smith, 1857, under R. variegata Smith, 1852. The new replacement name Ropalidia kasaragodensis Lambert and Narendran is proposed for R. indica Lambert and Narendran, 2005, non van der Vecht, 1941.

Vespidae of Viet Nam (Insecta: Hymenoptera) 2. Taxonomic notes on Vespinae.

The taxonomy of the Vietnamese species of the social wasp subfamily Vespinae is revised. Vespa auraria Smith, 1852, is synonymized under V. velutina Lepeletier, 1836. Vespula koreensis (Radoszkowski, 1887) is recorded as new for Viet Nam, and its color characters are described. A key to vespine species of Viet Nam based on morphological characters is provided.

Review of the Polistes (Polistella) "Stenopolistes" species-group (Hymenoptera: Vespidae: Polistinae) from Vietnam, with description of a new species and key to species.

The "Stenopolistes" species-group of the subgenus Polistella Ashmead, 1904 comprising in Vietnam by six species. Polistes adsimilis Nguyen & Carpenter sp. nov. is described and figured. Polistes khasianus Cameron, 1900 is confirmed to occur in Vietnam, P. pallidus Gusenleitner, 2011 is newly recorded from Vietnam. A key to Vietnamese species is provided. The nest of P. khasianus is described.

Review of the paper wasps of the Parapolybia indica species-group (Hymenoptera: Vespidae, Polistinae) in eastern parts of Asia.

Nine species of the Parapolybia indica species-group in eastern parts of Asia are reviewed. Four new species are described: P. flava sp. nov. (Vietnam), P. crocea sp. nov. (Japan), P. nana sp. nov. (Vietnam), and P. albida sp. nov. (Vietnam). Parapolybia indica (de Saussure, 1854), P. bioculata van der Vecht, 1966 and P. tinctipennis (Cameron, 1900) are redescribed. The status is reinstanted for P. fulvinerva (Cameron, 1900), stat. resurr. and P. tinctipennis (Cameron, 1900), stat. resurr. and new status is proposed for P. bioculata van der Vecht, 1966, stat. nov. Parapolybia tinctipennis (Cameron, 1900) is newly recorded from China, Vietnam and Laos. The key to species is given. The nests of P. indica, P. bioculata, P. tinctipennis, P. flava and P. crocea are remarked.