Gender Specific Brood Cells in the Solitary Bee Colletes halophilus (Hymenoptera; Colletidae)

We studied the reproductive behaviour of the solitary bee Colletes halophilus based on the variation in cell size, larval food amount and larval sex in relation to the sexual size dimorphism in this bee. Brood cells with female larvae are larger and contain more larval food than cells with males. Occasionally males are reared in female-sized cells. We conclude that a female C. halophilus in principal anticipates the sex of her offspring at the moment brood cell construction is started. Additionally a female is able to ‘change her mind’ about the sex of her offspring during a single brood cell cycle. We present a model that can predict the sex of the larvae in an early stage of development

Production of sexuals in the stingless bee Trigona (Lepidotrigona) ventralis flavibasis Cockerell (Apidae, Meliponini) in northern Vietnam

In a two-year study on the stingless bee Trigona ventralis under field conditions in Vietnam, production of males and gynes was investigated in ten colonies. Male production in this species was found to be periodic. Typically, colonies produced a batch of males in a period of several weeks. At the population level, however, males were found throughout the year, since male production was not synchronized between colonies. Male production varied significantly among various months and between the rainy and the dry season. The number of males produced was positively correlated with numbers of brood cells, of food storage pots, and of emerging workers. Unlike the clumped male production in a certain colony, gynes were continuously produced in all colonies at low numbers, but seasonal effects on their numbers were found similar to effects on the numbers of males. In a previous study, the same periodical production of males in individual colonies without synchronization between colonies was found in a new world-species, Melipona favosa. This suggests that the mechanisms underlying allocation of resources between sexes may be general for a number of stingless bees

Larval food composition and food plants of the solitary bee Colletes halophilus (Hymenoptera: Colletidae)

Summary The pollen component of the larval food of Colletes halophilus, studied in four nature reserves in the Netherlands, was strongly dominated by Aster tripolium. The liquid component of the larval food contained high concentrations of sugars (glucose and fructose), far more than could be supplied by A. tripolium pollen present in the food. This indicates that in addition to pollen, considerable amounts of nectar were collected from this plant. The larval food showed hydrogen peroxide production. We did not, however, find this in pollen collected directly from A. tripolium flowers. We conclude that females of C. halophilus produce the enzyme glucose oxidase and add this to larval food. This is the first such finding for solitary bees. The apparent dependency of C. halophilus on A. tripolium has implications for the conservation management of this solitary bee. Composición del alimento larval y plantas alimenticias de la abeja solitaria Colletes halophilus (Hymenoptera: Colletidae) Resumen Se estudió la composición polínica del alimento larval de Colletes halophilus, en cuatro reservas naturales de los Países Bajos, encontrándose una fuerte dominancia de Aster tripolium. El líquido que compone el alimento larval contiene altas concentraciones de azúcares (glucosa y fructosa), mucho más de lo que podría ser suministrado por el polen de A. tripolium presente en el alimento. Esto indica que además de polen, una considerable cantidad de néctar fue recolectado de ésta planta. Además, el alimento larval demostró producción de peróxido de hidrógeno. Sin embargo, este componente no lo encontramos en el polen recolectado directamente de las flores de A. tripolium. Concluimos que las hembras de C. halophilus producen la enzima glucosa oxidasa y la adicionan al alimento larval, siendo éste el primer hallazgo en abejas solitarias. La aparente dependencia de C. halophilus por A. tripolium tiene implicaciones para el manejo y conservación de esta abeja solitaria

Water content of stingless bee honeys (Apidae, Meliponini): interspecific variation and comparison with honey of Apis mellifera

Honey samples were taken on both islands of the country of Trinidad and Tobago, from colonies of Melipona favosa, Melipona trinitatis, Plebeia tobagoensis, Trigona nigra and Apis mellifera. The Moisture Content (MC) of honeys of the various bee species differed significantly. The honey of the smaller species, P. tobagoensis and T. nigra, had higher MC values than that of the larger Melipona. The highest MC value was found in honey from P. tobagoensis (42.0%). The other MC values were 36.2% for T. nigra, 31.2% for M. favosa and 32.2% for M. trinitatis. The lowest MC was found in honey of A. mellifera (20.2%). There was little variation between colonies of the same species at the same site, but honey of M. favosa from Trinidad had a higher MC (35.1%) than that from Tobago (30.2%). The finding that the MC of honeys of stingless bee species varies according to the species and to the area where it is produced, complicates the establishment of a quality standard for these honeys

Patterns of male production in the stingless bee Melipona favosa (Apidae, Meliponini)

In many stingless bee species, laying workers oviposit trophic eggs that serve as a component of the queen's diet. Workers of some species also lay reproductive worker eggs that give rise to males. Male-producing workers can occur in queenright colonies. We studied male production by workers of Melipona favosa. In six colonies monitored under field conditions, we observed that males emerged during distinct “Male Emerging Periods”. Subsequently, we studied the laying of male eggs in laboratory observation hives with the use of video. We found that laying workers oviposited reproductive eggs in distinct “Reproductive Laying Worker Periods” and that this was followed by the clumped mergence of males afterwards. Behaviours of laying workers and of the ovipositing queen are preliminarily described