25 research outputs found
Bee guards detect foreign foragers with cuticular chemical profiles altered by phoretic varroa mites
<p>Detection of diseased individuals in a social group is a critical step of social immunity, to prevent the spread of parasites or pathogens. Parasite-induced alterations of the host phenotype might be used by healthy conspecific to identify an individual bearing a threat to the social group, and to prevent it from entering the colony. The ecto-parasitic varroa mite (<i>Varroa destructor</i>) is a crucial driver for the extensive worldwide honey bee losses, and the parasite is currently considered one of the major threats for apiculture. Here, we first investigated the alterations induced by phoretic varroa mites on the cuticular hydrocarbons profile of adult honey bees. Our gas chromatography–mass spectrometry analyses showed an increase in cuticular methyl-branched compounds of parasitized bees. Then, we used lure presentation experiments to evaluate the response of guard honey bees at the hive entrance towards foreign foragers with a parasite-altered cuticular profile. We found an increase in the aggressive responses of guard bees towards bee-lures with a parasite-altered cuticular profile, highlighting the ability of <i>Apis mellifera</i> guard bees to recognize the alterations induced by varroa in the cuticular profile of alien bees.</p
PLS-DA plots on chemical distances.
<p>Plots for genetic clusters (a, b) and nests (c,d) are described by the first two pairs of components (Comp). Scores were normalized between -1 and 1 and plotted in the same graph with the loadings of variables. Scores of individual ants of the same group are represented by the same number (14 genetic clusters and 29 nests). Loadings of variables are indicated by compound names (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0137919#pone.0137919.g002" target="_blank">Fig 2</a>). According to biplot theory, proximity among cases (individuals) and variables (compounds) represents a tendency of individual ants to have a higher abundance of the studied compounds.</p
The Rules of Aggression: How Genetic, Chemical and Spatial Factors Affect Intercolony Fights in a Dominant Species, the Mediterranean Acrobat Ant <i>Crematogaster scutellaris</i>
<div><p>Nest-mate recognition plays a key role in the biology of ants. Although individuals coming from a foreign nest are, in most cases, promptly rejected, the degree of aggressiveness towards non nest-mates may be highly variable among species and relies on genetic, chemical and environmental factors. We analyzed intraspecific relationships among neighboring colonies of the dominant Mediterranean acrobat ant <i>Crematogaster scutellaris</i> integrating genetic, chemical and behavioral analyses. Colony structure, parental relationships between nests, cuticular hydrocarbons profiles (CHCs) and aggressive behavior against non nest-mates were studied in 34 nests located in olive tree trunks. Bayesian clustering analysis of allelic variation at nine species-specific microsatellite DNA markers pooled nests into 14 distinct clusters, each representing a single colony, confirming a polydomous arrangement of nests in this species. A marked genetic separation among colonies was also detected, probably due to long distance dispersion of queens and males during nuptial flights. CHCs profiles varied significantly among colonies and between nests of the same colony. No relationship between CHCs profiles and genetic distances was detected. The level of aggressiveness between colonies was inversely related to chemical and spatial distance, suggesting a ‘nasty neighbor’ effect. Our findings also suggest that CHCs profiles in <i>C</i>. <i>scutellaris</i> may be linked to external environmental factors rather than genetic relationships.</p></div
Example of a Gas chromatography-Mass spectrography (GS-MS) chromatogram of hydrocarbon molecules in <i>C</i>. <i>scutellaris</i>.
<p>The <i>x</i>-axis is the time (in minutes) elapsed from injection of the compound mixture to the elution of chemicals (retention time). The <i>y</i>-axis represents absolute abundance, which is related to the number of times each ion reported in the chromatogram struck the GS-MS detector. Chemical compounds are 1) c27_1, 2) c27, 3) M11c27, 4) DM11yc27, 5) M3c27, 6) c28, 7) CeMc28, 8) M2c28, 9) c29_1, 10) c29, 11) CeMc29, 12) M5c29, 13) DM11yc29, 14) M3c29, 15) c30, 16) CeMc30, 17) M4c30, 18) c31, 19) CeMc31, 20) DM11yc31, 21) DM7yc31, 22) DM5yc31. Compounds abbreviations: M: methyl; CeM: central-methyl; DM: dimethyl.</p
Spatial distribution of nest clusters in the study area.
<p>Dots are olive trees. Ovals represent nest clusters. A) spatial clusters (S1–S10); B) clusters resolved by genetic analysis (G1–G14).</p
Estimated coefficient values of model-averaging for the first two models listed in Table 2.
<p>Estimated coefficient values of model-averaging for the first two models listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0137919#pone.0137919.t002" target="_blank">Table 2</a>.</p
Schematic map of aggressive interactions between all possible pairs of nest clusters.
<p>Clusters are sorted according to the number of aggressive interactions they were involved in, clockwise from the most (G11) to the least aggressive (G4) one. Dark grey clusters showed aggressive behavior in more than half of staged tests. Light grey and white clusters showed signs of aggressions in half of the encounters and less than half of staged tests, respectively. Lines connecting nest clusters show levels of aggressions between each pair of clusters: no aggression (score 0, no line), aggressive display (score 1, dotted line), direct aggression (score 2, dashed line) and strong aggression (score 3, solid line).</p
Results of GLM models assessing the relationship between the number of aggressive individuals and genetic, chemical and spatial divergences.
<p>Models are listed in order of increasing AICc value. Explanatory variables are chemical distance (chem), genetic <i>θ</i> values and spatial distance (spat) between each pair of nests. The difference between the AICc value of a specific model and the AICc of the best model (ΔAICc) is reported for each model considered in the regression analysis. W<sub>i</sub> is the Akaike weight.</p
Table_2_Antennal Protein Profile in Honeybees: Caste and Task Matter More Than Age.XLSX
<p>Reproductive and task partitioning in large colonies of social insects suggest that colony members belonging to different castes or performing different tasks during their life (polyethism) may produce specific semiochemicals and be differently sensitive to the variety of pheromones involved in intraspecific chemical communication. The main peripheral olfactory organs are the antennal chemosensilla, where the early olfactory processes take place. At this stage, members of two different families of soluble chemosensory proteins [odorant-binding proteins (OBPs) and chemosensory proteins (CSPs)] show a remarkable affinity for different odorants and act as carriers while a further family, the Niemann-Pick type C2 proteins (NPC2) may have a similar function, although this has not been fully demonstrated. Sensillar lymph also contains Odorant degrading enzymes (ODEs) which are involved in inactivation through degradation of the chemical signals, once the message is conveyed. Despite their importance in chemical communication, little is known about how proteins involved in peripheral olfaction and, more generally antennal proteins, differ in honeybees of different caste, task and age. Here, we investigate for the first time, using a shotgun proteomic approach, the antennal profile of honeybees of different castes (queens and workers) and workers performing different tasks (nurses, guards, and foragers) by controlling for the potential confounding effect of age. Regarding olfactory proteins, major differences were observed between queens and workers, some of which were found to be more abundant in queens (OBP3, OBP18, and NPC2-1) and others to be more abundant in workers (OBP15, OBP21, CSP1, and CSP3); while between workers performing different tasks, OBP14 was more abundant in nurses with respect to guards and foragers. Apart from proteins involved in olfaction, we have found that the antennal proteomes are mainly characterized by castes and tasks, while age has no effect on antennal protein profile. Among the main differences, the strong decrease in vitellogenins found in guards and foragers is not associated with age.</p
Results of non-parametric Manova on chemical distances among nests of different clusters and among nests within clusters.
<p>Results of non-parametric Manova on chemical distances among nests of different clusters and among nests within clusters.</p