General behavioral patterns and life-cycle of the colonial spider, Eriophora bistriata (Araneida: Argiopidae)

Neste estudo, apresentamos observações preliminares do comportamento e biologia da aranha gregária Eriophora bistriata. O trabalho inclui aspectos da organização social, obtidos através de estudos de laboratório e campo. São inicialmente descritos, além do ciclo básico, algumas interações como: construção de teia comum de caça, ausência de hostilidade inter-individual, alimentação comunal, comportamento reprodutor etc. Os resultados obtidos permitiram comparar Eriophora bistriata, com outras espécies gregárias segundo o esquema evolutivo de Shear (1970: pag. 73)

On some structures in Nannotrigona (Scaptotrigona) postica Latreille (Hymenoptera, Meliponinae)

No presente trabalho, estudamos o ciclo de desenvolvimento das glândulas hipofaringeanas, glândulas de cera e ovários de operárias de Scaptotrigona postiça, em colônias normal e órfã. As glândulas hipofaringeanas de operárias da colônia normal apresentaram um ciclo de desenvolvimento e regressão bem definido. As glândulas hipofaringeanas das operárias da colónia órfã entraram num processo de regressão, a partir do quinto dia de vida das operárias, não apresentando seu ciclo normal, provavelmente, devido à falta da atividade de aprovisionadoras dos alvéolos de cria. Em condição normal, os ovários, as glândulas de cera e glândulas hipofaringeanas, encontraram-se desenvolvidos, na mesma época. Este fato indica que a atividade de todas essas estruturas estão intimamente correlacionadas. Em operárias da calônia órfã, a coincidência de funções foi observada somente em relação as glândulas de cera e ovários

Food profitability and recruitment behaviour in a scent trail laying stingless bee (Scaptotrigona aff. depilis)

Innerhalb der sozialen Insekten haben viele Gruppen die faszinierende Fähigkeit entwickelt, Nestgenossinnen zu rekrutieren. Rekrutierung beruht auf einer Kommunikation, die angewandt wird, um Mitglieder des Nestes zu einem bestimmten Ort zu bringen, wo Arbeit von Nöten ist (Wilson 1971). Daher beinhaltet die Rekrutierungskommunikation sowohl die Aktivierung von Nestgenossinnen innerhalb des Nestes, als auch die Orientierungshilfen für das Auffinden des Zielortes (Traniello & Robson 1995). Die stachellosen Bienen (Hymenoptera, Meliponini) sind unter den sozialen Insekten eine hoch diverse Tiergruppe (über 400 Arten, Michener 2000). Sie eignen sich ausgezeichnet für die Untersuchung der ebenso diversen Rekrutierungs- und Kommunikationsmechanismen. Bei stachellosen Bienen, wie bei anderen sozialen Insekten, beeinflusst die Güte der Futterquelle die Rekrutierung. Bisher wurde an Arten, die keinen Duftpfad legen, gezeigt, dass zu ertragreichen Futterquellen mehr Bienen rekrutiert werden als zu weniger ertragreichen (Biesmeijer & Ermers 1999). In der vorliegenden Arbeit wurde erstmals untersucht, wie die Zuckerkonzentration des Futters die Rekrutierung einer Art (Scaptotrigona aff. depilis) beeinflusst, welche Rekruten durch das Auslegen eines Duftpfades zur Futterquelle führt (Schmidt & al. 2006b).How does the sugar concentration of the food source affect the recruitment of the stingless bee Scaptotrigona aff. depilis (Hymenoptera, Meliponini)? We offered sugar water of either constant, increasing, or decreasing concentrations. Simultaneously, we recorded the number of recruits and the recruiters’ running speed, jostling contacts, and vibrations inside the nest. Neither the number of recruits nor the behavioural parameters depended on the actual sugar concentration but rather on the changes experienced over time. Concentration decreases resulted in significantly decreased numbers of recruits. Concentration increases neither led to increased numbers of recruits nor to increased recruitment activity. However, most parameters of intranidal activity changed significantly only when the concentration was reduced from 40% to 20% w/w and recruitment to the food source nearly ceased. These findings support the idea of a feedback mechanism reducing the colony’s effort to exploit food sources of decreasing profitability

Shape differences rather than size differences between castes in the Neotropical swarm-founding wasp Metapolybia docilis (Hymenoptera: Vespidae, Epiponini)

BACKGROUND: Swarm-founding epiponine wasps are an intriguing group of social insects in which colonies are polygynic (several queens share reproduction) and differentiation between castes is often not obvious. However, caste differences in some may be more pronounced in later phases of the colony cycle. RESULTS: Using morphometric analyses and multivariate statistics, it was found that caste differences in Metapolybia docilis are slight but more distinct in latter stages of the colony cycle. CONCLUSIONS: Because differences in body parts are so slight, it is proposed that such variation may be due to differential growth rates of body parts rather than to queens being larger in size, similar to other previously observed epiponines

The acceptance rate of young wasps by alien colonies depends on colony developmental stages in the swarm-founding wasp, Polybia paulista von ihering (Hymenoptera: Vespidae)

In social insects, newly emerged individuals learn the colony-specific chemical label from their natal comb shortly after their emergence. These labels help to identify each individual's colony of origin and are used as a recognition template against which individuals can discriminate nestmates from non-nestmates. Our previous studies with Polybia paulista von Ihering support this general pattern, and the acceptance rate of young female and male wasps decreased as a function of their age. Our study also showed in P. paulista that more than 90% of newly emerged female wasps might be accepted by conspecific unrelated colonies. However, it has not been investigated whether the acceptance rate of newly emerged female wasps depends on colony developmental stage of recipient colonies. We introduced newly emerged female wasps of P. paulista into different colony developmental stags of recipient colonies, i.e., worker-producing and male-producing colonies. We found that the acceptance rate of newly emerged female wasps by alien colonies was pretty lower by male-producing colonies than worker-producing colonies. This is the first study to show that the acceptance rate of young female wasps depends on stages of recipient colonies

Presence of Strepsiptera Parasites in the Independent-founding Wasp, Polistes satan

Although the paper wasp genus, Polistes, has been examined extensively, little is known about the occurrence of parasitism in this group. We detected the obligate parasitic insect group, Strepsiptera in the gaster of Polistes satan Bequaert adult females. By dissecting 161 adult females from 24 colonies, we identified a total of four stylopized wasps in three colonies during the wet season.

Nest thermoregulation in Polybia scutellaris (White) (Hymenoptera: Vespidae)

Polybia scutellaris (White) builds large nests characterized by numerous spiny projections on the surface. In order to determine whether or not the nest temperature is maintained because of homeothermic conditions of the nest individuals or otherwise, we investigated the thermal conditions within the nests built by P. scutellaris. We measured the temperature within active and abandoned nests. The temperature in the active nest was almost stable at 27°C during data collection, whereas the temperature in the abandoned nest varied with changes in ambient temperature. These results suggest that nest temperature was maintained by the thermogenesis of the individuals of the colony. This is the first report of nest incubation caused by thermogenesis of species of Polybia wasps

Polymorphic Microsatellite Loci in the Independent-founding Wasp Polists versicolor (Hymenoptera: Vespidae)

Microsatellite primers developed for a given species are sometimes useful for another in the same genus, making possible to search for pre-existing suitable primers in the data banks such as GenBank. We examined whether existing primers developed for Polistes wasps could be used for the independent-founding wasp Polistes versicolor. We tested 50 microsatellite primers from three Polistes species and found that five microsatellite loci show polymorphism in size in P. versicolor. These five loci were highly polymorphic, having four to 10 alleles in P. versicolor with an expected heterozygosity of 0.530–0.836. These loci can be used to study parameters concerning genetic relatedness such as social interactions in colonies and genetic conflicts of interest among nestmate individuals

Neutral Sterols of Cephalic Glands of Stingless Bees and Their Correlation with Sterols from Pollen

Sterols are essential molecules in the membrane lipid composition and precursors of important sterol hormones that regulate many developmental processes. Insects are unable to synthesize sterols de novo and, thus, all phytophagous insects depend on an exogenous source of sterols for growth, development, and reproduction. The sterol requirements of social bees are not fully known due to the fact that there is no well-defined diet available throughout the year with regard to floral resources. Our study aimed to characterize the sterols present in pollen stored in Melipona marginata and Melipona scutellaris colonies, as well as evaluating their presence in the mandibular, hypopharyngeal, and cephalic salivary gland secretions. We analyzed the chemical composition of pollen stored in the colonies and the composition of the cephalic glands of workers in three adult functional phases (newly emerged, nurses, and foragers) by gas chromatography and mass spectrometry. The results showed that the pollen analyzed contained campesterol, stigmasterol, sitosterol, isofucosterol, lanosterol, and small amounts of cholesterol. The glands showed the same compounds found in the pollen analyzed, except lanosterol that was not found in M. scutellaris glands. Surprisingly, cholesterol was found in some glands with relative ratios greater than those found in pollen

Castes in neotropical swarm-founding wasps

24 p. : ill. ; 26 cm.Electronic version available in portable document format (PDF).Includes bibliographical references (p. 21-24).Reproductive castes are compared in species of swarming wasps representing all currently recognized genera of Epiponini (Polistinae). New morphometric data for nine measures of body parts and ovarian data are presented for 13 species. These are integrated with all similarly conducted available studies, giving a total of 30 species. Analysis reveals several syndromes relating reproductive and nonreproductive individuals: no meaningful distinction, physiological differences only, reproductives larger than nonreproductives with intermediate individuals present, reproductives different in shape from nonreproductives with no intermediates, and reproductives smaller in some aspects than nonreproductives. Distribution of these syndromes among species is consistent with phylogenetic relationships derived from other data. Optimizing these syndromes on the cladogram indicates that the basal condition of Epiponini is a casteless society that is not comparable to the primitively social genus Polistes where dominant queens control reproduction. Castes originate several times in Epiponini, with different results in different lineages. The best documented evolutionary sequence passes from casteless societies, to those with reproductives larger, to those with reproductives differing in shape from nonreproductives, to those with reproductives smaller in some measures. This sequence is consistent with Wheeler's theory of the origin of caste through developmental switches, and represents the most thorough test of that theory to date