The production, consumption, and sale of Melipona bee honey (as well as of other stingless bees) make them both culturally and economically significant. These bees are eusocial and are important pollinators of crops and natural flora in the tropics. Melipona Illiger is a species-rich genus of stingless bees in the Neotropics, currently comprising 74 species classified into five subgenera. Herein we provide an illustrated identification key to the five species of the subgenus Melipona (Meliponiella) Melo, a table displaying important characters for each species, an occurrence map with new geographical records and we describe Melipona rasmusseni, new species, from Peru and Bolivia for this subgenus.

The abundant members of the Meliponini (stingless bees) are restricted to the tropics and subtropics worldwide. Because past studies of the anatomy of their mature larvae are limited, revealing little anatomical variation in the tribe, the current investigation attempts to examine this topic more thoroughly. Herein we describe the mature larvae of 30 species representing 16 genera of a total world fauna of perhaps 32 genera. Although the larvae of most taxa show little anatomical diversity, two species, Trigona (Duckeola) ghilianii Spinola and Trigona (Frieseomelitta) varia (Lepeletier), have mature larvae that differ remarkably in anatomical structure from those of other known stingless bees, and, further, their individual anatomies suggest a close evolutionary relationship. Larval evidence is presented indicating that Trichotrigona extranea (Camargo and Moure) is also related to these two taxa. Because eggs are often included in collections of bee larvae, this study adds descriptions of the eggs of 11 species of the Meliponini not previously characterized as well as a list of those that had been treated earlier.

Long-distance migration of insects impacts food security, public health, and conservation–issues that are especially significant in Africa. Windborne migration is a key strategy enabling exploitation of ephemeral havens such as the Sahel, however, its knowledge remains sparse. In this first cross-season investigation (3 years) of the aerial fauna over Africa, we sampled insects flying 40–290 m above ground in Mali, using nets mounted on tethered helium-filled balloons. Nearly half a million insects were caught, representing at least 100 families from thirteen orders. Control nets confirmed that the insects were captured at altitude. Thirteen ecologically and phylogenetically diverse species were studied in detail. Migration of all species peaked during the wet season every year across localities, suggesting regular migrations. Species differed in flight altitude, seasonality, and associated weather conditions. All taxa exhibited frequent flights on southerly winds, accounting for the recolonization of the Sahel from southern source populations. “Return” southward movement occurred in most taxa. Estimates of the seasonal number of migrants per species crossing Mali at latitude 14°N were in the trillions, and the nightly distances traversed reached hundreds of kilometers. The magnitude and diversity of windborne insect migration highlight its importance and impacts on Sahelian and neighboring ecosystems.

Knowledge on long-distance migration of insects is especially important for food security, public health, and conservation–issues that are especially significant in Africa. During the wet season, the Sahel nourishes diverse life forms which are soon purged by the long dry season. Windborne migration is a key strategy enabling exploitation of such ephemeral havens. However, our knowledge of these large-scale movements remains sparse due to the virtual invisibility of insects flying at altitude. In this first cross-season investigation (3 years) of the aerial insect fauna over Africa, we sampled crepuscular and nocturnal insects flying 40–290 m above ground in four Sahelian villages in Mali, using sticky nets mounted on tethered helium-filled balloons. Nearly half a million insects were caught, representing at least thirteen insect orders following preliminary sorting of the collections. At least 100 insect families were determined to have been captured at altitude in samples collected on 222 nets, obtained in 125 collections over 96 nights. Control nets (raised momentarily to >40 m during system launch and retrieval) confirmed that the insects were captured at altitude, not near the ground. Thirteen ecologically and phylogenetically diverse species were studied in detail. The flight activity of all species peaked during the wet season every year across localities up to ~100 km apart, and occurred over multiple nights, suggesting regular migrations. Species differed in flight altitude, seasonality, and correlations with aerial temperatures, humidity, and wind speed. All taxa exhibited frequent migrations on southerly winds, accounting for the recolonization of the Sahel from southern source populations. “Return” southward movement at the end of the wet season occurred in most taxa but no selectivity for such winds was detected. Extrapolation of aerial density to estimate the seasonal number of migrants crossing Mali at latitude 14°N suggested numbers in the trillions, even for the modestly abundant taxa. Assuming 2–10 hours of flight, the nightly distances traversed exceed tens and even hundreds of kilometers. Two migration strategies were proposed: “residential Sahelian migration” and “round trip migration”. The unprecedented magnitude and diversity of long-range windborne insect migrations highlight the importance of this life strategy in their impact on Sahelian and neighboring ecosystems.

Abstract Eusocial insects offer a unique opportunity to analyze the evolution of body size differences between sexes in relation to social environment. The workers, being sterile females, are not subject to selection for reproductive function providing a natural control for parsing the effects of selection on reproductive function (i.e., sexual and fecundity selection) from other kinds of natural selection. Patterns of sexual size dimorphism (SSD) and testing of Rensch's rule controlling for phylogenetic effects were analyzed in the Meliponini or stingless bees. Theory predicts that queens may exhibit higher selection for fecundity in eusocial taxa, but contrary to this, we found mixed patterns of SSD in Meliponini. Non‐Melipona species generally have a female‐biased SSD, while all analyzed species of Melipona showed a male‐biased SSD, indicating that the direction and magnitude of the selective pressures do not operate in the same way for all members of this taxon. The phylogenetic regressions revealed that the rate of divergence has not differed between the two castes of females and the males, that is, stingless bees do not seem to follow Rensch's rule (a slope >1), adding this highly eusocial taxon to the various solitary insect taxa not conforming with it. Noteworthy, when Melipona was removed from the analysis, the phylogenetic regressions for the thorax width of males on queens had a slope significantly smaller than 1, suggesting that the evolutionary divergence has been larger in queens than males, and could be explained by stronger selection on female fecundity only in non‐Melipona species. Our results in the stingless bees question the classical explanation of female‐biased SSD via fecundity and provide a first evidence of a more complex determination of SSD in highly eusocial species. We suggest that in highly eusocial taxa, additional selection mechanisms, possibly related to individual and colonial interests, could influence the evolution of environmentally determined traits such as body size.

The egg and mature larva of a presently unnamed species of the bee genus Plebeia are anatomically described, illustrated, and compared with those of other known Meliponini, based on abundant specimens collected from two nests recovered from a tree at the Yasuni Scientific Station, Orellana Province, Ecuador. A key to the four tribes (Apini, Bombini, Euglossini, and Meliponini) of known mature corbiculate larvae is then presented. It, in turn, is followed by a preliminary larval description of the Meliponini based on those taxa the mature larvae of which are known so far. The main feature distinguishing the mature larva of the Meliponini is in its having a tapering slender elongate mandibular apex, which contrasts with the much shorter, robust mandibular apex of the other three tribes. Furthermore, unlike in the other tribes, late stage larval Meliponini possess paired dorsolateral tubercles on most abdominal segments.

The first part of this publication, written by a group of participants in Bee Course 2018, results from the discovery of three nests of Caupolicana yarrowi (Cresson, 1875) at the base of the Chiricahua Mountains in southeastern Arizona. The nests are deep with branching laterals that usually connect to large vertical brood cells by an upward turn before curving downward and attaching to the top of the chambers. This loop of the lateral thus seems to serve as a "sink trap: excluding rainwater from reaching open cells during provisioning. Although mature larvae had not yet developed, an egg of C. yarrowi was discovered floating on the provisions allowing an SEM examination of its chorion, the first such study for any egg of the Diphaglossinae. Larval food for this species at this site came from Solanum elaeagnifolium Cay. (Solanaceae). Nests were parasitized by Triepeolus grandis (Friese, 1917) (Epeolini), which previously was known to attack only Pliloglossa (Diphaglossinae: Caupolicanini). The subterranean nest cells of the desert bee Caupolicana yarrowi (Colletidae), which are enveloped by a casing of hardened soil that easily separates from the surrounding matrix, are discussed in a separate appendix. Chemical analysis revealed the casing to be rich in reducing sugars, indicating that the mother bee had regurgitated floral nectar onto the rough interior walls of the cell cavity before smoothing and waterproofing them. This novel use of nectar in nest construction is compared with that of other bee species that bring water to a nest site to soften soil for excavation.

20 pages : illustrations (some color), color maps ; 26 cm. Appendix: Use of nectar by the desert bee Caupolicana yarrowi (Colletidae) in cell construction / James H. Cane and Jerome G. Rozen, Jr.

The small (length less than 6 mm) postdefecating larva of Tetragonula (Tetragonula) sapiens Cockerell) from the Huon Peninsula, Papua New Guinea is described and illustrated, the first representation of the immature stage for any member of this genus of stingless bees. A reexamination of the recently described larva of Melipona fallax Camargo and Pedro using a new technique reveals valuable insights regarding its integumental microstructures. On the basis of these findings and previously published accounts of larval representatives of five other genera (Melipona, Nogueirapis, Partamona, Plebeia, and Trigonisca), a preliminary description of the mature larva of the tribe Meliponini is presented. Multipronged spicules, recently discovered in meliponines, are investigated.

This paper describes the eggs and last larval instars of certain species of bees belonging to the tribe Meliponini, one of the four related tribes that comprise the corbiculate bees in the subfamily Apinae. The four taxa analyzed include some whose immature stages have previously been described. Our purpose is to identify what is known about the anatomy of immature stages and suggest what needs to be studied to better understand the developmental anatomy of eggs and mature larvae in this group of highly eusocial bees.

13 pages : illustrations ; 26 cm. Specimens of Tetragonula sapiens collected by Hobart M. van Deusen on 12 May 1964 during the seventh Archbold Expedition to New Guinea.

ABSTRACT Stingless bees (Apinae: Corbiculata: Meliponini) are biologically and culturally important pollinators within the tropical and subtropical areas of the world. However, limited information is available for the majority of the species. Biological and systematic data are presented for a new species of Trigonisca Moure, from the arid region of La Guajira, Colombia. The genus is part of the distinctive Trigonisca genus group, noteworthy for its position as the earliest diverging extant lineage of neotropical stingless bees. We briefly diagnose the genus group and provide a key to the genera and subgenera of the Trigonisca genus group, along with the description of Exochotrigona Engel, new subgenus. We also outline the species occurring in Colombia and present a description for Trigonisca (Trigonisca) mepecheu Engel and Gonzalez, new species, including accounts of all three castes. A single, poorly preserved egg is noteworthy because of its extremely small size. Its chorion is extensively covered by a surface pattern of elevated geometric figures, as seems to be characteristic of the Meliponini. The robust mature larva, though remarkably small, exhibits extensive spiculation of dorsal body surfaces and most body segments with small, paired dorsolateral tubercles. In addition, the labral apex exhibits an apical patch of recently discovered multipronged spicules intermixed with various sensory sensilla. These morphological features of immature stages, where known, are similar to those previously reported for other Meliponini. We document the internal architecture of nests of T. mepecheu, which we found in trunks of Stenocereus griseus (Haw.) Buxb. (Cactaceae) and more commonly in Libidibia coriaria (Jacq.) Schltdl. (Fabaceae), along with nests of the only other stingless bee from La Guajira, Melipona favosa (Fabricius). Nests were also found in the sides of manufactured structures. The indigenous Wayúu harvest stingless-bee honey and have specific names in Wayuunaiki for the two species occurring in the region, although there is apparently an oral tradition in which the honey of T. mepecheu causes blindness. Trigonisca (Trigonisca) ameliae Penney from Colombian copal is a new junior synonym of T. (T.) schulthessi (Friese).

This contribution results from an investigation of four commercially obtained colonies of Bombus (Pyrobombus) impatiens Cresson in an attempt to understand the functional anatomy and behavior of its immature stages. Eggs are described in detail, and their chorionic micro- structure is contrasted with that of Bombus (Cullumanobombus) griseocollis (De Geer). They are deposited in groups consisting of a few to more than nine eggs into a single chamber. The study confirms that larvae pass through four instars. Although increasing in size dramatically from one instar to the next, larval anatomy and behavior change little during the first three instars. The last instar is the one that commences defecation and production of silk resulting in cocoon construction. In contrast to most bees, its larval activities result in substantial changes in size and shape of its brood chamber, whereas brood chambers of most bees are constructed by the female and modified little by the offspring. This study is a part of a series of investigations into the similarities and differences in the developmental biologies among corbiculate bees.

This paper describes and illustrates the egg, fifth, first, and fourth larval instars, as well as the female pupa of Bombus (Cullumanobombus) griseocollis (DeGeer), all collected from a single nest in June 2017 in Wisconsin. In so doing, attempts are made to understand the biological significance of the anatomical and behavioral features of these various life stages.

This article explores the occurrence of hatching spines among bee taxa and how these structures enable a larva on hatching to extricate itself from the egg chorion. These spines, arranged in a linear sequence along the sides of the first instar just dorsal to the spiracles, have been observed and recorded in certain groups of solitary and cleptoparasitic bee taxa. After eclosion, the first instar remains loosely covered by the egg chorion. The fact that this form of eclosion has been detected in five families (Table 1 identifies four of the families. The fifth family is the Andrenidae for which the presence of hatching spines in the Oxaeinae will soon be announced.) of bees invites speculation as to whether it is a fundamental characteristic of bees, or at least of solitary and some cleptoparasitic bees. The wide occurrence of these spines has prompted the authors to explore and discover their presence in the highly eusocial Apis mellifera L. Hatching spines were indeed discovered on first instar A. mellifera. The honey bee hatching process appears to differ in that the spines are displayed somewhat differently though still along the sides of the body, and the chorion, instead of splitting along the sides of the elongate egg, seems to quickly disintegrate from the emerging first instar in association with the nearly simultaneous removal of the serosa that covers and separates the first instar from the chorion. Unexpected observations of spherical bodies of various sizes perhaps containing dissolving enzymes being discharged from spiracular openings during hatching may shed future light on the process of how A. mellifera effects chorion removal during eclosion. Whereas hatching spines occur among many groups of bees, they appear to be entirely absent in the Nomadinae and parasitic Apinae, an indication of a different eclosion process.