Temporal Response of Foragers and Guards of Two Stingless Bee Species to Cephalic Compounds of the Robber Bee <Emphasis Type="Italic">Lestrimelitta niitkib</Emphasis> (Ayala) (Hymenoptera,Apidae)

Lestrimelitta spp. are stingless bees that steal food and nesting materials from other highly social bees to survive. Though most of their victim species respond, either aggressively or submissively, to cephalic components of Lestrimelitta, little is known about if such response changes at some point during extended periods of exposure. Moreover, potential synergistic effects due to a mixture of victim’s alarm/defense pheromones and Lestrimelitta mandibular pheromones, like in an actual attack, have not been examined so far. In this paper, we investigated the response of two species of non-robber stingless bees, Scaptotrigona mexicana (Guérin) and Tetragonisca angustula (Latreille), to (a) cephalic compounds from crushed heads of nestmates, (b) cephalic compounds of Lestrimelitta niitkib (Ayala), and (c) a mixture of (a) and (b). We found that even though T. angustula did not react to nestmates’ crushed head, its response towards L. niitkib cephalic compounds was stronger and lasted longer than that of S. mexicana. Interestingly, the addition of crushed heads of the non-robber species to L. niitkib crushed heads caused no significant increase in the alarm response of both species. It may be that the absence of an alarm pheromone in T. angustula made this species more receptive to extraneous odors, which is not the case for S. mexicana; however, more species must be studied to elucidate any pattern regarding the absence/presence of alarm pheromones and the corresponding response to intruders’ pheromones.     

Nest-specific composition of the trail pheromone of the stingless bee Trigona corvina within populations

Social insects have evolved highly developed communication systems, enabling them to coordinate complex interactions in their colonies. Pheromones play a major role in the coordination of many tasks. In Trigona corvina, a stingless bee that occurs in Central America, foragers use pheromones produced in their labial glands to scent mark solid substrates between a food source and their nest. Newly recruited bees subsequently follow these scent marks until they reach the food source. A recent study has revealed nest-specific differences in the composition of these trail pheromones in colonies of T.?corvina, suggesting that pheromone specificity may serve to avoid competition between foragers from different nests. However, the nests used in this study came from different populations and their foragers certainly never met in the field (Jarau et al., 2010). The aim of the present study was to investigate whether differences in the trail pheromones of foragers from different nests can also be found between neighbouring colonies within populations. We analysed the composition of trail pheromones from labial gland secretions extracted from workers from nine colonies collected at three different populations in Costa Rica. The differences in pheromone composition were even more distinct between neighbouring nests within a population than between nests of different populations. This finding corroborates the hypothesis that nest specificity of trail pheromones serves to communicate the location of a food source exclusively to nestmates, thereby avoiding intraspecific competition at resources. Resource partitioning by avoiding conspecific non-nestmates is particularly adaptive for aggressive bee species, such as T. corvina.     

The Behavior of <Emphasis Type="Italic">Acromyrmex crassispinus</Emphasis> (Hymenoptera: Formicidae) on Trail Bifurcations and the Influence of Ant Flow on Error Rates of Nestbound Laden Workers

Ants are ordinarily faced with a succession of bifurcations along their foraging networks. Given that there is no directionality in pheromone trails, each bifurcation is potentially an opportunity for error in the trajectory of laden workers to the nest, which could entail considerable inefficiencies in the transportation of food to the colony. Leaf-cutting ants (Atta and Acromyrmex) commonly show intense traffic and complex foraging trail systems, which make them ideal organisms to study worker behavior in trail bifurcations. The behavior of leaf-cutting ants of the genus Acromyrmex in trail bifurcations is still largely unexplored. Thus, this study aimed to assess the behavior of Acromyrmex crassispinus workers on trail bifurcations and to investigate whether differences in ant flow on foraging trails influence the error rate of nestbound laden workers at trail bifurcation. There was a negative relationship between ant flow and error rate of nestbound laden workers. Most workers walked in the central part of the foraging trails but occupied a broader area of the foraging trail when the ant flow was high. The results of this study provide valuable insight into the organization of traffic flow in A. crassispinus and its impacts on the foraging strategy of the species.     

Lack of field-based recruitment to carbohydrate food in the Korean yellowjacket, <Emphasis Type="Italic">Vespula koreensis</Emphasis>

We investigated field-based recruitment via visual, chemical and acoustic cues provided by conspecific wasps on carbohydrate feeders in Vespula koreensis. A wild colony nest was excavated and artificially installed in a field site. Naïve foragers were individually marked and trained to an experimental feeder. We conducted three separate experiments in which foragers were presented with feeder dishes with different cue intensities. For the first, a different number of decoys were posed as if feeding (visual cue). In the second, dishes had been previously visited by different numbers of individuals, thus presenting different concentrations of a possible food site marking substance (chemical cue). In the third, each dish was placed in front of a covered flask with a different number of nestmates inside (acoustic cue combined with body-odor cue). We observed no social facilitation or social inhibition due to any of the experimental cues. Previous studies in Vespula species have shown a variety of foraging strategies ranging from local enhancement to local inhibition. Field-based recruitment mechanisms in yellowjackets may have evolved independently in different lineages.     

Spatial and temporal variation in pheromone composition of ant foraging trails

Many social insects use pheromones to communicate and coordinatetheir activities. Investigation of intraspecific differencesin pheromone use is a new area of social insect research. Forexample, interindividual variation in alarm pheromone contenthas been found in physical castes of polymorphic ants. Manyant species use multiple trail pheromones. Here we present novelresearch into trail pheromone variations between behavioralsubcastes of pharaoh ants, Monomorium pharaonis. Monomoriumpharaonis is attracted to trail pheromones found in its poisonglands (monomorines) and Dufour's glands (faranal). We showthat the most abundant monomorines, I (M1) and III (M3), canbe readily detected in pheromone trails. A behaviorally distinctsubcaste known as "pathfinder" foragers can relocate long-livedpheromone trails. Chemical analysis showed that pathfinder foragershad low M3:M1 ratios (mean 3.09 ± 1.53, range 1.03–7.10).Nonpathfinder foragers had significantly greater M3:M1 ratios(38.3 ± 60.0, range 3.54–289). We found that M3:M1ratio did not differ between foragers of different age but wascorrelated with behavioral subcaste at all ages. The relativeabundance of M3:M1 on foraging trails ranged from 3.03–41.3over time during pheromone trail build-up. M3:M1 ratio alsovaried spatially throughout trail networks, being lowest ontrail sections closest to a food source (M3:M1 = 1.9–3.61)and highest near the nest (M3:M1 = 67–267). Our resultsindicate a functional role for differences in pheromone trailcomposition, whereby pathfinder foragers might preferentiallymark sections of pheromone trail networks for future exploration.     

More than royal food - <Emphasis Type="Italic">Major royal jelly protein</Emphasis> genes in sexuals and workers of the honeybee <Emphasis Type="Italic">Apis mellifera</Emphasis>

Background

In the honeybee Apis mellifera, female larvae destined to become a queen are fed with royal jelly, a secretion of the hypopharyngeal glands of young nurse bees that rear the brood. The protein moiety of royal jelly comprises mostly major royal jelly proteins (MRJPs) of which the coding genes (mrjp1-9) have been identified on chromosome 11 in the honeybee’s genome.

Results

We determined the expression of mrjp1-9 among the honeybee worker caste (nurses, foragers) and the sexuals (queens (unmated, mated) and drones) in various body parts (head, thorax, abdomen). Specific mrjp expression was not only found in brood rearing nurse bees, but also in foragers and the sexuals.

Conclusions

The expression of mrjp1 to 7 is characteristic for the heads of worker bees, with an elevated expression of mrjp1-4 and 7 in nurse bees compared to foragers. Mrjp5 and 6 were higher in foragers compared to nurses suggesting functions in addition to those of brood food proteins. Furthermore, the expression of mrjp9 was high in the heads, thoraces and abdomen of almost all female bees, suggesting a function irrespective of body section. This completely different expression profile suggests mrjp9 to code for the most ancestral major royal jelly protein of the honeybee.

     

Pupal experience and nestmate recognition in <Emphasis Type="Italic">Polistes dominula</Emphasis> wasps

Social insects can discriminate between nestmates and aliens by comparing the chemical phenotype of an individual with the neural representation of their own colony odor (template). For social paper wasps of the genus Polistes, a general recognition model has been proposed and tested on few North American species: wasps learn colonial recognition cues from the nest paper during the first hours after emergence as adults. However, a recent study revealed that workers of Polistes dominula do not necessarily use the nest paper for early post-emergence cue-learning, suggesting that cues used for the formation of the referent template in this species could be learned at different life stages. Pre-natal learning is a widespread phenomenon in animals and it can shape various behaviors in adults. Here, we investigated whether pre-imaginal learning affects later nestmate recognition in P. dominula wasps. We reared worker pupae in artificial conditions to test whether the absence of nest material, or the exposure to nest material taken from a foreign conspecific colony, during pupal development would alter the nestmate recognition ability in adult life. Our results show that wasps maintain their correct recognition ability regardless of the treatment, suggesting that wasps do not form their referent template during the pupal stage from the nest paper. Alternative hypotheses for template formation timing and source of recognition cues are discussed. Moreover, we investigated whether young wasps already possess, on their own body, reliable chemical cues to form a recognition template by self-referent phenotype matching.     

Review of bees as guests in termite nests,with a new record of the communal bee, <Emphasis Type="Italic">Gaesochira obscura</Emphasis> (Smith, 1879) (Hymenoptera,Apidae), in nests of <Emphasis Type="Italic">Anoplotermes banksi</Emphasis> Emerson, 1925 (Isoptera,Termitidae, Apicotermitinae)

Associations between bees and termites are documented infrequently, but records are available for bee species ranging in behavior from solitary to highly eusocial. The subtribe Meliponina (stingless bees) is the most common bee group reported in termite nests, and, for some species, the occupancy of termite nests may be obligatory. The records of solitary bees nesting within termite nests include species of the tribes Emphorini, Centridini, Megachilini, and Paracolletini. Most of these bees can probably nest in other substrates, and their relationships with termite nests are presumably opportunistic. This study provides a review of published records of bees as guests in termite nests, and also describes the aggregation of nests of Gaesochira obscura within one nest of Anoplotermes banksi in Brazilian Amazonia. One termite nest contained at least ten nest entrances of G. obscura, with burrows 4–6 mm in diameter and about 10 cm long. Each burrow ended in brood cells in different stages of food provisioning and larval development. As commonly reported for other associations of this nature, there was no connection between the tunnels of bees and those of termites. This record adds important data on the biology of A. banksi. Because this is a single record, it is impossible to classify G. obscura either as a termitophile or termitariophile; this species may be opportunistic in relation to nesting substrate.     

Ambush Predation of Stingless Bees (<Emphasis Type="Italic">Tetragonisca angustula</Emphasis>) by the Solitary-Foraging Ant <Emphasis Type="Italic">Ectatomma tuberculatum</Emphasis>

Social insect colonies are high-value foraging targets for insectivores, prompting the evolution of complex colony defensive adaptations as well as specialized foraging tactics in social insect predators. Predatory ants that forage on other social insects employ a diverse range of behaviors targeted at specific prey species. Here, we describe a solitary foraging strategy of the ant Ectatomma tuberculatum, on nest guards of the stingless bee Tetragonisca angustula. We observed multiple instances of E. tuberculatum ambushing and successfully capturing the hovering and standing guards of T. angustula near nest entrances. The unique hovering behavior of the guard caste of this bee species, an adaptation to frequent cleptoparasitism by other stingless bees, may make these guards particularly vulnerable to ground-based, ambush attacks by E. tuberculatum. Likewise, the behavior of the foraging ants appears to adaptively exploit the defensive formations and activity patterns of these bees. These observations suggest an adaptive and targeted predatory strategy aimed at gathering external guard bees as prey from these heavily fortified nests.     

Female Responses to Synthetic Pheromone and Plant Compounds in <Emphasis Type="Italic">Agriotes brevis</Emphasis> Candeze (Coleoptera: Elateridae)

Traps baited with synthetic pheromone components of Agriotes brevis [geranyl butanoate + (E,E)-farnesyl butanoate] captured significantly higher numbers of not only male, but also female beetles, compared to unbaited controls. Catches of both sexes showed a clear positive relationship with increasing doses. In electroantennogram tests, antennal responses of females and males to a number of known Agriotes pheromone components, identified from pheromone glands, showed a similar trend, with geranyl butanoate eliciting the strongest responses. This suggests that the female and male A. brevis antennae are similar with respect to the perception of pheromone compounds, and female beetles have the sensory capabilities to perceive the pheromone components which they produce. Addition of the plant-derived compounds (Z)-3-hexenyl acetate, methyl benzoate, (Z)-3-hexenol and methyl salicylate (identified earlier from foliage as attractive for A. brevis) to the synthetic pheromone significantly increased catches. All the above results suggest that geranyl butanoate and (E,E)-farnesyl butanoate are constituents of an aggregation pheromone of A. brevis, in contrast to the general view of click beetle pheromones being “classical” sex pheromones. These findings could be useful for more precise monitoring and forecasting of damage, based on female catches.     

High Concentrations of the Alarm Pheromone Component,Isopentyl Acetate,Reduces Foraging and Dancing in <Emphasis Type="Italic">Apis mellifera</Emphasis> Ligustica and <Emphasis Type="Italic">Apis cerana</Emphasis> Cerana

A honeybee colony is a superorganism that has evolved precise communication systems, which allow the colony to gather information from numerous individuals and coordinate its behavior. Alarm pheromones, such as isopentyl acetate (IPA), the main component of sting alarm pheromone, play a critical role in the coordination of individual behaviors as well as colony communication in honeybee colonies. In this study, honeybees (Apis mellifera ligustica and Apis cerana cerana) were exposed to relatively high levels of IPA at a foraging site (6–8 bee equivalents) and inside their colony (28–58 bee equivalents) to investigate the influence of alarm pheromones on foraging activity and hive flight activity. IPA reduced the number of bees that flew out the hive, foraged, and waggle danced. Under both contexts in the hive and at the food source, IPA can therefore inhibit honey bee foraging and foraging communication.     

Revealing hidden species distribution with pheromones: the case of <Emphasis Type="Italic">Synanthedon</Emphasis><Emphasis Type="Italic">vespiformis</Emphasis> (Lepidoptera: Sesiidae) in Sweden

Synanthedon vespiformis L. (Lepidoptera: Sesiidae) is considered a rare insect in Sweden, discovered in 1860, with only a few observations recorded until a sex pheromone attractant became available recently. This study details a national survey conducted using pheromones as a sampling method for this species. Through pheromone trapping we captured 439 specimens in Southern Sweden at 77 sites, almost tripling the number of previously reported records for this species. The results suggest that S. vespiformis is truly a rare species with a genuinely scattered distribution, but can be locally abundant. Habitat analyses were conducted in order to test the relationship between habitat quality and the number of individuals caught. In Sweden, S. vespiformis is thought to be associated with oak hosts, but our attempts to predict its occurrence by the abundance of oaks yielded no significant relationships. We therefore suggest that sampling bias and limited knowledge on distribution may have led to the assumption that this species is primarily reliant on oaks in the northern part of its range, whereas it may in fact be polyphagous, similar to S. vespiformis found as an agricultural pest in Central and Southern Europe. We conclude that pheromones can massively enhance sampling potential for this and other rare lepidopteran species. Large-scale pheromone-based surveys provide a snapshot of true presences and absences across a considerable part of a species national distribution range, and thus for the first time provide a viable means of systematically assessing changes in distribution over time with high spatiotemporal resolution.     

Effectiveness of recruitment behavior in stingless bees (Apidae,Meliponini)

Summary We examined the ability of stingless bees to recruit nest mates to a food source (i) in group foraging species laying pheromone trails from the food to the nest (Trigona recursa Smith, T. hypogea Silvestri, Scaptotrigona depilis Moure), (ii) in solitary foraging species with possible but still doubtful communication of food location inside the nest (Melipona seminigra Friese, M. favosa orbignyi Guérin), and (iii) in species with a less precise (Nannotrigona testaceicornis Lep., Tetragona clavipes Fab.) or no communication (Frieseomelitta varia Lep.). The bees were allowed to collect food (sugar solution or liver in the necrophageous species) ad libitum and the forager number to accumulate, as it would do under normal unrestrained conditions. The median number of bees collecting differed considerably among the species (1.0–1436.5). It was highest in the species employing scent trails. The time course of recruitment was characteristic for most of the species and largely independent of the number of foragers involved. The two Melipona species recruited other bees significantly faster than T. recursa, S. depilis, and N. testaceicornis during the first 10 to 30 minutes of an experiment. In species laying a scent trail to guide nestmates to a food source the first recruits appeared with a delay of several minutes followed by a quick increase in forager number. The median time required to recruit all foragers available differed among the species between 95.0 and 240.0 min. These differences can at least partly be explained by differences in the recruitment mechanisms and do not simply follow from differences in colony biomass.     

Nesting Behaviour of the Giant Honeybees <Emphasis Type="Italic">Apis</Emphasis><Emphasis Type="Italic">dorsata</Emphasis> Occurring in Jhargram,West Bengal,India

The giant honeybees Apis dorsata are habituated to construct combs in trees, houses, caves as well as in overhead water reservoir occurring in their nesting localities. To verify their preference for nesting sites if any, surveys were conducted in recent years (2013–16), during nesting seasons of these bees in Jhargram area of West Bengal, India. It is revealed that A. dorsata construct their combs in big, tall, aged simul (Bombax ceiba), bot (Ficus benghalensis) trees mostly, irrespective of localities. Also they were seen to construct nest at the underside of the overhead water reservoir ignoring nesting potential trees occurring nearby. Of course, nesting in the houses, and on the walls of culvert is not uncommon. As the bees constructed more than 100–200 nests at the same nesting site e.g., a tree or/and an overhead water reservoir, depending upon the availability of space for construction of nest it is concluded that these insects prefer colonial nesting.     

<Emphasis Type="Italic">Metschnikowia</Emphasis> mating genomics

Genes involved in mating type determination and recognition were examined in Metschnikowia and related species, to gather insights on factors affecting mating compatibility patterns among haplontic, heterothallic yeast species of the genus. We confirmed the universality of the special mating locus organisation found in Clavispora lusitaniae across and exclusive to the family Metschnikowiaceae (i.e., Metschnikowia and Clavispora). Timing of the divergence between idiomorphs was confirmed to coincide with the origin of the larger (CUG-ser) clade comprising the Debaryomycetaceae and the Metschnikowiaceae, exclusive of Cephaloascus fragrans. The sequence of the a mating pheromone is highly conserved within the large-spored Metschnikowia species, including Metschnikowia orientalis and Metschnikowia hawaiiana, but not Metschnikowia drosophilae or Metschnikowia torresii, which have a pattern of their own, as do other clades in the genus. In contrast, variation in α pheromones shows a more continuous, although imperfect correlation with phylogenetic distance as well as with in vivo mating compatibility.     

Trail Chemicals of the Convergens Ladybird Beetle, <Emphasis Type="Italic">Hippodamia convergens</Emphasis>, Reduce Feeding and Oviposition by <Emphasis Type="Italic">Diaphorina citri</Emphasis> (Hemiptera: Psyllidae) on Citrus Plants

We investigated feeding and oviposition behavior of the Asian citrus psyllid, Diaphorina citri, when exposed to the foraging trails of the convergens ladybird beetle, Hippodamia convergens. Diaphorina citri females feeding on citrus leaves directly exposed to the ladybird adults or treated with trail extract excreted significantly less honeydew droplets than controls. The trail chemicals of the ladybird beetle also decreased oviposition by D. citri females on citrus. In a no-choice experiment, D. citri females preferred to oviposit on control flush and plants than those with ladybird trail-extract treatments. In two-choice experiments, 68.0% of D. citri released into cages exhibited strong selection preference for settling and eventual oviposition on control plants than plants treated with ladybird trail extract. Diaphorina citri eggs were found on all new leaf flush of control plants, whereas only 29.5% of flush on treatment plants were selected for oviposition. The trail chemical deposited by the convergens ladybird beetle elicits repellency of D. citri feeding and oviposition. Therefore, the trail chemicals my contain components that could be useful for behavior-based management of D. citri and HLB disease by reducing psyllid feeding and oviposition.     

A geometric morphometric and microsatellite analyses of <Emphasis Type="Italic">Scaptotrigona mexicana</Emphasis> and <Emphasis Type="Italic">S. pectoralis</Emphasis> (Apidae: Meliponini) sheds light on the biodiversity of Mesoamerican stingless bees

Geometric morphometrics and molecular methods are effective tools to study the variability of stingless bee populations and species that merit protection given their worldwide decline. Based on previous evidence of cryptic lineages within the Scaptotrigona genus, we tested the existence of multiple evolutionary lineages within the species S. mexicana and we investigated the status of S. pectoralis. By analyzing their population structure, we found differences between the Pacific and Atlantic populations of each of these species, although geometric morphometrics of the wing only confirmed these results in S. mexicana. There was a tendency towards enhanced genetic differentiation over larger distances in the Atlantic populations of both species but not in the Pacific populations. These results revealed a pattern of differentiation among evolutionary units and a specific distribution of genetic diversity within these Scaptotrigona species in Mesoamerica, suggesting the need for future taxonomic revisions, as well as activities aimed at management and conservation.     

Phylogenetic relationships and taxonomy of <Emphasis Type="Italic">Luciobarbus barbulus</Emphasis> (Heckel, 1847) (Teleostei: Cyprinidae)

Luciobarbus barbulus (Heckel, 1847), a cyprinid fish of the Persian Gulf basin is re-described. Its identity is discussed and its phylogenetic relationship among the tribe Barbini is reconstructed. Luciobarbus barbulus can be distinguished from its close species, L. pectoralis by having thicker lower lip, stronger last unbranched dorsal fin ray and with stronger serration, longer barbels and posterior barbel passes the middle of the eye (vs. not reaching the middle of the eye in L. pectoralis), confirming the identity of both, as distinct species. Moreover, phylogenetic analysis based on the mtCOI sequences, placed the sequenced L. barbulus in a distinct clade corresponding to the tribe Barbini which includes Aulopyge, Barbus and Luciobarbus (three genera from Eurasia and North of Africa), sister to L. pectoralis from Orontes River with genetic distance of 1.7% applying the Kimura 2 Parameter (K2P) model.