Pairs Of Colonies Research Articles

The usefulness of unmanned aerial vehicles (UAV) in white stork censusing

Unmanned aerial vehicles (UAV) are effective and often noninvasive tools successfully used in bird monitoring. However, when handling long-term data in the context of population changes, the consistency of methods over time is essential as the method-related bias may lead to wrong conclusions. In two distinct populations of white stork Ciconia ciconia, in Poland and Spain, we compared two censusing methods: traditional observation by a human from the ground and using UAV. We recorded the number of recorded fledglings, the time needed to obtain this information, and the number of detected breeding pairs in colonies. We investigated 57 and 117 nests in Poland and Spain, respectively. In Poland and Spain, the number of fledglings was significantly lower when recorded by human observer than by UAV, i.e., 2.21 vs. 2.60 and 1.35 vs. 1.55. The probability of mistakenly recording the number of fledglings by the observer was significantly lower in colonial white storks in Spain than in solitary nesting in Poland. The mean time needed to record the number of fledglings was significantly longer when using a UAV than by a human observer in both populations. The mean number of detected nests in colonies in Spain differed significantly between the human observer and UAV, 13.1 vs. 7.4, respectively. The difference between human and UAV in recorded pairs was higher when colonies were on trees than on human-made structures. We conclude that introducing UAVs in long-term studies may affect the results and should be performed cautiously.

Behavioral assays reveal mechanisms of supercolony formation in odorous house ants

The formation of expansive multi-nest and multi-queen supercolonies is perhaps the most important factor responsible for the ecological success of invasive ants. The odorous house ant, Tapinoma sessile, is a widespread ant native to North America. T. sessile is a challenging urban pest, but also serves as an interesting system to study ant social organization and invasion biology. This is due to its remarkable dichotomy in colony social and spatial structure between natural and urban environments. Natural colonies typically consist of a small number of workers, inhabit a single nest, and are monogyne whereas urban colonies show extreme polygyny and polydomy and form large supercolonies. The current study examined the extent to which T. sessile colonies from different habitats (natural vs. urban) and social structures (monogynous vs. polygynous) exhibit aggression toward alien conspecifics. Additionally, interactions between mutually aggressive colonies were examined in colony fusion experiments to assess the potential role of colony fusion as a mechanism leading to supercolony formation. Aggression assays demonstrated high levels of aggression in pairings involving workers from different urban colonies and workers from different natural colonies, but low aggression in pairings involving queens from different urban colonies. Colony merging tests demonstrated that urban T. sessile colonies are highly aggressive to each other, but capable of fusing under laboratory conditions when competing for limited nesting and food resources. Despite highly aggressive interactions and relatively high worker and queen mortality, all colony pairs merged in 3–5 days. Fusion occurred after most workers died and the survivors merged. This result suggests that the success of T. sessile in urban areas may be driven, at least in part, by successful colony mergers of unrelated colonies which may be determined by ecological constraints such as seasonal shortages in nest and/or food availability. In summary, two independent factors including the growth of a single colony and/or the merger of multiple colonies may be responsible for the evolution of supercolonies in invasive ants. Both processes may be happening simultaneously and may act synergistically to produce supercolonies.

Initial compatibility during a "Speed-Dating" test predicts postpairing affiliation in titi monkeys (Plecturocebus cupreus).

Behavioral compatibility plays a critical role in shaping how potential mates interact with and evaluate each other and whether they choose to pursue a relationship. Compatibility is especially important for mate choice and relationship quality in pair-bonding species that form long-term attachments between mates. Although this process has been studied in humans and birds, relatively few studies have investigated it in non-human primates. In this study, we investigated whether pairing titi monkeys (Plecturocebus cupreus) based on initial compatibility increased postpairing affiliation between mates. Subjects were 12 unpaired adult titi monkeys (two cohorts of three males and three females). We determined each subject's initial interest in each opposite-sex potential mate in their cohort across a series of six 30-min interaction periods (i.e., "speed-dates"). To determine initial compatibility, we used the Social Relations Model to calculate relationship effects in initial interest (how much each subject uniquely preferred each potential mate beyond their own affiliative disposition and their partner's popularity). We then paired monkeys in a way that maximized net relationship effects between pairs, and measured longitudinal pair affiliation (Proximity, Contact, Tail Twining, and Combined Affiliation) for 6 months postpairing using daily scan-sample observations and monthly home-cage video recordings. Multilevel models showed that, on average, the six speed-dating pairs exhibited higher levels of Tail Twining (determined from scan-sample observations; β = 0.31) compared to a group of 13 age-matched colony pairs that were determined quasi-randomly without quantifying compatibility. The degree of initial compatibility within speed-dating pairs also predicted higher levels of Combined Affiliation (determined from video recordings) at earlier post-pairing time points, with the association peaking at 2 months postpairing (β = 0.57). These findings suggest that initial compatibility facilitates pair bonding in titi monkeys. We conclude by discussing how the speed-dating design can be used for colony management to inform pair-housing decisions.

A Two-Layer Heterogeneous Ant Colony System With Applications in Part-Picking Planning

Abstract The tape carrier packaging machine with multiple sucking discs is designed for modern, high-speed packaging production line, which is an important part of the electronic manufacturing process. The efficiency of the part-picking can directly affect the efficiency of the packaging production line. The problem involves at least three coupled sub-problems: the number of picking rounds, the matching relationship between the parts and sucking discs, and the picking order. Because the actual industrial production requires real-time or soft real-time scheduling, the challenge is how to efficiently solve this multi-dimensional combinatorial optimization problem within a fairly limited time. The existing advanced algorithms such as the genetic algorithm and the simulated annealing algorithm usually require complex and time-consuming encoding and decoding while solving this problem. In contrast, the ant colony algorithm has advantages in the convergence rate and parallel computing, especially for searching high dimensional paths in dynamic environments. In order to further improve the comprehensive performance of the ant colony algorithm in solving multi-dimensional coupled optimization problems in extremely limited time, we propose a novel two-layer heterogeneous ant colony system based on three strategies: (1) a bottom-up two-layer solution framework to decouple the original tightly coupled problem into a loosely coupled problem composed of two sub-problems; (2) a candidate cluster augmentation strategy based on the Delaunay triangulation to improve the diversity and quality of the clusters; (3) a co-evolution between a pair of heterogeneous colonies by mixing the high-quality pheromone properly as well as a co-evolution based on the prior knowledge. Finally, through a large set of comparisons, the average picking efficiency of Two-layer Heterogeneous Ant Colony System improved by the three proposed strategies is 13–16% higher than that of other popular heuristic algorithms.

An experimental test of Lanchester's models of combat in the neotropical termite Nasutitermes corniger (Blattodea: Termitidae).

Lanchester's models of combat have been invoked to explain the mechanics of group fighting in social animals. Specifically, Lanchester's square law posits that the fighting ability of the group is proportional to the square of the number of combatants. Although used to explain a variety of ecological phenomena, the models have not been thoroughly tested. We tested the Lanchester models using group battles between colonies of the termite Nasutitermes corniger. Our main goals were to determine if mortality rates fit the Lanchester models, and if so, whether the behavioural mechanisms underlying a group's success match those used in deriving the model. We initiated battles between pairs of colonies with different ratios of fighters and recorded deaths over time. We found that the numerically larger army has an advantage, but that the advantage is not as pronounced as predicted by Lanchester's square law. We also video-recorded battles to analyse individual behaviour, which did not support the mechanisms invoked by Lanchester. Instead, the killing power of an individual is increased by the presence of nest-mates, giving the larger group a disproportionate advantage. Although the behavioural mechanisms leading to the advantage may differ, our results still support some of the proposed ecological phenomena.

The Life Span and Levels of Oxidative Stress in Foragers Between Feral and Managed Honey Bee Colonies.

Molecular damage caused by oxidative stress may lead to organismal aging and result in acute mortality to organisms. Thus, oxidative stress resistance and longevity are closely linked. Honey bees (Apis mellifera) are the most important managed pollinator in agriculture, but the long-term survival of honey bees is seriously threatened. Feral honey bee colonies can be used as natural resources to improve honey bee health. One question we ask here is whether feral honey bees are stress resistant or survive longer than managed bee populations. More work is needed to determine the impact of oxidative stress on honey bee health and survival. In this study, we used paired colony designs to compare the life span of worker bees (foragers) between feral and managed colonies and their levels of oxidative stress. Each pair of colonies shared similar foraging resources. The results indicated that foragers in feral colonies had longer survival times and life spans than those in managed colonies. The levels of oxidative stress from lipid damage content in feral colonies were higher than those in managed colonies, indicating that they used a tolerance mechanism rather than a repair mechanism to survive. Our study provides new insights into a colony difference in the physiology and oxidative stress resistance of feral honey bees compared with managed colony stocks.

201. Frequency of Pseudomonas aeruginosa (PA) Discrete Inner Colonies and Comparison of Minimal Inhibitory Concentration (MIC) Values between Parent and Inner Colony Isolates Following Fosfomycin Disk Diffusion (DD) Testing

BackgroundFosfomycin combination therapy is a potential approach for treatment of multidrug-resistant (MDR) PA infections despite a lack of approved susceptibility breakpoints for this organism. While DD testing is commonly used for fosfomycin, growth of discrete inner colonies (IC) within the zone of inhibition has been observed for multiple organisms following DD. Criteria recommended by CLSI and EUCAST are contradictory for interpreting these inner colonies. We therefore sought to determine the frequency of inner colonies and MIC differences between PA parent-inner colony pairs from an international isolate collection.MethodsA convenience collection of 198 clinical PA isolates from three U.S institutions (n = 82), two Australian institutions (n = 72), and the CDC & FDA Antibiotic Resistance Isolate Bank (n = 44) were included. Fosfomycin MIC values were determined in duplicate on separate days by DD and broth microdilution (BMD) testing. For parent isolates with discrete IC observed during DD, IC isolates were subcultured and MIC values were determined and then compared to their corresponding parent isolates. MIC values were interpreted using CLSI Escherichia coli (EC) breakpoints (susceptible: MIC ≤ 64 μg/mL, intermediate: MIC = 128, resistant: MIC ≥ 256 μg/mL).ResultsParent isolate BMD MIC values ranged from < 4 to > 256 μg/mL while IC isolate BMD MIC values ranged from 128 to > 1024 μg/mL. MIC50/90 values were 128/256 μg/mL and > 1024/ > 1024 μg/mL for the parent and IC isolates, respectively. A high frequency of 45% (89/198) of parent isolates displayed discrete IC which also demonstrated a higher frequency of resistance (97.8%) compared to the parent isolates (23.7%).ConclusionIC MIC values were higher overall compared to parent MIC values, with an average fold difference of ~18 between the parent-inner colony pairs. The frequency of IC found in this study (45%) is considerably higher than previously observed in EC clinical isolates. These data highlight the need to further investigate the importance of these IC and warrant caution for extrapolation of EC breakpoints for fosfomycin susceptibility testing against PA.Disclosures All Authors: No reported disclosures

Effects of decolonization on bilateral trade: Evidence from natural experiments

This paper estimates the effects of decolonization on bilateral trade by exploiting the end of colonial linkages between the United Kingdom and Hong Kong in 1997 and between Portugal and Macau in 1999. The two-year gap between these two historical events creates an exogenous time variation in colonial separations across colonial pairs to implement the differences-in-differences strategy. The results show that if a colonial relationship breaks up, then the imports from the former colonial counterpart increases by 42 percent and the post-colonial trade share increases by 0.29 percentage points. Further investigations suggest that the large and positive effects of decolonization on the post-colonial imports are largely operated through mechanisms of income and exchange rate.

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Abstract

Solitary breeding barn swallows pay a higher nest defense cost

Successful reproduction depends on the ability of parents to defend from nest predators. Breeding birds often put their life at risk to defend their offspring from predators. Communal nest defense has been proposed as an individual benefit of group living. We tested this by experimentally exposing a short-lived avian species to a potential risk of predation. We presented decoys of both a diurnal and a nocturnal predator to barn swallows Hirundo rustica breeding solitarily and in large colonies in South-western Spain. We found clear benefits of group living compared to solitary pairs in relation to investment in individual nest defense and the capacity to deter a challenging predator. Although we did not find differences in the time needed to detect the predator, we found that the number of individuals recruited to participate in nest defense was greater for colonial breeding pairs, leading to fewer attacks per individual in comparison to solitary breeding pairs. We also found that barn swallows defended their nests more vigorously against a nocturnal predator than against a diurnal predator. Therefore, barn swallows living in groups obtained clear benefits in communal nest defense by reducing the risk, energy and time dedicated to nest defense. Colonial breeding is thus a more effective strategy for decreasing nest predation rates.

Gut microbial pulse provides nutrition for parental provisioning in incipient termite colonies

Success in aerial dispersal involves a trade-off between propagule size and dispersal ability, such that reducing weight may increase dispersal capability. Therefore, dispersing propagules such as plant seeds, fungal spores, and insect alates need to settle in new habitats with very limited resources. In termites, the time from alate dispersal to colony foundation is the most critical period in their life cycle, because a male and female pair establishes a new colony without help from others. In addition, termites depend largely on gut microbes for their nutrition. However, little is known about how termite founding pairs with limited resources establish new colonies and raise their first brood in association with their gut symbionts. Here, we provide an integrated analysis of the reproduction schedule, gut microbial fluctuations, and resource allocation of founding pairs in incipient colonies of the subterranean termite Reticulitermes speratus. There was a steep increase followed by a rapid decrease in the numbers of intestinal protozoa (hereafter, gut microbial pulse) at the time of larval hatching. Besides the monogamous pairs, same-sex (male-male and female-female) pairs also form tentative colonies in this species. Comparisons of changes in the amounts of protein and lipids in the different pair types revealed that the gut microbial pulse played an essential role in the parental feeding of the first-brood larvae. It was also observed that founders utilized stored protein and lipids for brood production. Our study highlights a significant role for intestinal symbionts during the early stage of the termite life cycle. Propagules of most animals and plants encounter resource limitations after dispersal. This is especially true for termite alates; monogamous pairs found new colonies without help from workers. How do they manage the limited resources, including their nutritional reserves and gut microbes, during colony foundation? To gain a better understanding, we analyzed time-series data of reproduction schedules, gut microbial fluctuations, and resource allocation patterns in the founders of incipient termite colonies. We identified a “gut microbial pulse”, i.e., a steep increase followed by a rapid decrease in the number of intestinal protozoa, that occurred at the time of larval hatching. Our data imply that resources derived from the pulse play an essential role in parental provisioning to larvae. This study highlights a novel strategy of termites to overcome resource-limited situations and successfully establish a new colony.

Synchronization of alate emergence among colonies and dispersal strategy in the Ryukyu dry-wood termite Neotermes sugioi (Isoptera: Kalotermitidae)

The synchronized dispersal of colonies is an important strategy among social insects in terms of both successful mating and the avoidance of inbreeding. Although several studies have focused on these processes in the most common termite species characterized by pulsed dispersal, only a few studies have reported on termite species characterized by continuous dispersal. Here, we describe the phenology and biological characters of the dispersal flight of Neotermes sugioi, a dry-wood termite native to the Ryukyus Islands of Japan, using five colonies isolated under semi-field conditions over a period of 183 days. We obtained evidence for the synchronicity of alate emergence among colonies of N. sugioi based on observations of synchronous patterns on the major flight and non-flight days, which showed positive correlations in alate emergence between all colony pairs. However, due to the occurrence of months with small correlation coefficients, and inconsistent alate emergence peaks among colonies on a single day, N. sugioi showed less synchronization than subterranean termites characterized by pulsed dispersal flights. Environmental conditions of temperatures and humidities greater than 22 °C and 70% were found to be necessary for high flight activity during both high and low flight seasons. In all colonies, the sex ratio of emerging alates during the observation period was significantly biased toward males. Given that adjustment of synchronous and asynchronous alate release among neighboring colonies could reduce the risk of sibling pair mating and inbreeding, the characteristic alate emergence in N. sugioi may indirectly minimize the potential for inbreeding.

Spatial synchrony of breeding success in the blacklegged kittiwake Rissa tridactyla reflects the spatial dynamics of its sandeel prey

Synchrony in demographic rates between spatially disjunct populations is a widespread phenomenon, although the underlying mechanisms are often not known. This synchrony and its spatial patterns can have important consequences for the long-term persistence of metapopulations and can also be used to infer drivers of population dynamics. Here, we examined spatial patterns of synchrony in the breeding success of black-legged kittiwakesRissa tridactylain the UK, using an extensive dataset on kittiwake breeding success and 2 different ways of measuring synchrony: one reflecting synchrony in inter-annual fluctuations only (rdiff) and one reflecting synchrony in both inter-annual fluctuations and long-term trends (r). We found that between-colony synchrony in breeding success decreased with distance up to just over 200 km but that some colony pairs showed stronger or weaker synchrony than expected based on distance. This was also reflected in the configuration of spatially coherent clusters of kittiwake colonies with synchronous breeding success. Further, we compared the support for different drivers of these spatial patterns, including trophic interactions and weather conditions. We found that the spatial dynamics of the kittiwakes’ main prey in this region, the lesser sandeelAmmodytes marinus, appeared to play some role in generating synchrony in long-term patterns, but their role in generating synchrony in inter-annual fluctuations was less clear. The study shows that examining spatial patterns in synchrony can provide useful information for inferring potential drivers and the spatial scale over which they are acting.

At-sea movements of wedge-tailed shearwaters during and outside the breeding season from four colonies in New Caledonia

The wedge-tailed shearwater (WTS) population of New Caledonia is one of the largest in the world, yet its biology and foraging ecology are poorly known. We studied WTS from 4 colonies in New Caledonia. We examined foraging behaviour and habitats using GPS receivers and light sensors during and outside the breeding season, respectively, and compared our findings with those from other WTS populations worldwide. During breeding, New Caledonian WTS alternated short foraging trips close to the colony over the lagoon, or off the reef edge, with longer trips over distant, deep waters. Whereas neighboring colonies overlapped at sea, especially during short trips, there was a clear separation of foraging zones between the pairs of colonies located in the southern versus northwestern parts of New Caledonia. Although WTS actively foraged and commuted to foraging zones during the day, they mainly returned to the colony or rested at night, indicating that they feed mainly during the day. Active foraging did not take place in more productive areas, suggesting that it may instead be related to the presence of sub-surface predators. Outside the breeding season, birds from 3 colonies had similar trans-equatorial migratory behaviour. All left New Caledonia at the same time of the year with a fast, northeasterly movement and wintered over deep waters in the same sector of the northwestern tropical Pacific Ocean. At overwintering sites, they spent most of their non-foraging time presumably sitting on the water, especially at night, making a slow westward movement before returning to New Caledonia. WTS from New Caledonia forage over warm, oligotrophic deep waters throughout their life cycle, and the species appears to have a flexible foraging strategy adapted to the various environmental conditions encountered across its wide tropical range.

A biodiversity-friendly method to mitigate the invasive Asian hornet’s impact on European honey bees

The Asian hornet is an invasive predator of honey bees in Western Europe. The Asian hornet-related risk of bee colony mortality has motivated the development of biological and physical control methods over the past years. Although the technical cost–benefit ratio has been established for most of these control methods, it is still unclear whether such methods can reduce the detrimental effects of the Asian hornet on European honey bees. In this study, we investigated the potential benefits of a biodiversity-friendly control method, the beehive muzzle. We observed the flight activity of bees and the predation behaviour of the Asian hornets at the beehive entrance of 22 pairs of honey bee colonies, each with one muzzle-equipped colony and one control colony without muzzle, in France. We measured HF (bee homing failure due to hornet predation of bees) and FP (foraging paralysis: the stop of flight activity in beehives due to hovering hornets), and estimated the mortality probability of the colonies using a mechanistic modelling approach. The beehive muzzle did not reduce the hornet-related HF, but drastically reduced FP. Moreover, the muzzle increased the survival probability of hornet-stressed colonies up to 51% in context of high abundance of Asian hornets based on theoretical simulations. These results suggest that installing beehive muzzles can mitigate the detrimental effect of the Asian hornet on European honey bees. This low-cost technique does not lead to any environmental impacts and could therefore be recommended to beekeepers as an effective biodiversity-friendly method of Asian hornet control.

Dear Enemy Phenomenon in the Ant Ectatomma brunneum (Formicidae: Ectatomminae): Chemical Signals Mediate Intraspecific Agressive Interactions

The integrity of ant colonies depends exclusively on social relationships between their individuals, especially the ability of communication between group members, which is mainly mediated through chemical signals. Another important feature of ant behavior is territory defense, since they need to gather large amounts of food to feed their larvae, males and breeding females. Thereby, ants might display behavioral strategies to defend their territories from intruders. Here we investigated whether Ectatomma brunneum displays the Dear Enemy Phenomenon, what is the relationship between Cuticular Hydrocarbon composition and levels of aggression during their intraspecific interactions and which compounds and/or classes of compounds might be the most important to modulate the level of aggression. To test our hypothesis, we evaluated the levels of aggression through behavioral observations during interactions between 23 pairs of colonies nested in two distinct sites at varied distances. Then, we analyzed the cuticular chemical profile of the individuals involved in the interactions, and compared these results with the levels of aggression displayed between colonies tested. The results allow us to confirm our hypothesis that the DEP occurs in E. brunneum. The higher tolerance between closer colonies can be explained due to their kinship level in addition to sharing the same microhabitats. The results also showed there are significant differences in CHCs profiles, especially between colonies nested at relatively greater distances, and it is likely that differences in content of some branched alkanes are the most important to establish these differences and, therefore, the levels of aggression during the interactions.

Nest characteristics and breeding success of Black Kites (Milvus migrans migrans) in the High Plateau (Algeria)

The breeding ecology of the Black Kite Milvus migrans migrans in Algeria was first studied in 2014 and 2015 on Tarf Mountain in the semi-arid High Plateaus region. The nearest-neighbour nest distance was found to range from 130 to 550 m for colonial pairs and from 1,730 to 2,390 m for the solitary ones. All 12 monitored nests were placed on cliffs at different heights ranging from 149 to 155 m. The mean egg laying period was 15 days, and the mean clutch size was 2.83 ± 0.31 and 3 ± 00 eggs per nest in 2014 and 2015, respectively. The mean hatching success was 83% and that of fledging 75%. Only 2 nests were predated. Our results disagree with those of the previous studies that were carried out mainly in the Mediterranean basin and Asia, differing in such nest characteristics as the nearest - neighbour nest distance, cliff and nesting heights, egg laying period and hatching success. Otherwise, no consistent differences in clutch size and fledging success were revealed. Finally, we determined that Black Kites tend to build their nest on the eastern side of cliffs. However, our analysis showed no effect of nest placement on breeding parameters and success.

Effects of hot-pack rolling process on microstructure, high-temperature tensile properties, and deformation mechanisms in hot-pack rolled thin Ti–44Al–5Nb-(Mo, V, B) sheets

Thin Ti–44Al–5Nb–1Mo–2V-0.2B alloy sheets were processed under different pack-rolling process directly from HIPed ingot in (α+β) phase region. The corresponding microstructure evolution, deformation mechanisms, and high-temperature tensile properties were systematically studied. As the pack-rolling progressed and thickness of plates is reduced, the microstructure was characterized by elongated lamellar colonies with B2+equiaxed γ grains at colony boundaries, that transformed into nano-lamella colonies along with γ platelets within B2 grains. The nano-lamella colonies were divided by a number of α mechanical twins and deformation bands. During the initial stage of rolling, mechanical twins, continuous, and discontinuous dynamic recrystallization of γ were the primary deformation mechanisms in the multi-phase microstructure. When the total rolling reduction was 74%, α2 phase dominated the deformation instead of γ. Two kinds of straight HAGBs with ~60.6° - 65.5° and ~71.0° - 72.7° formed in pairs in α2 colonies indicating the presence of twin boundaries and shear bands, respectively. While both the as-rolled alloys were produced via 4 and 6 rolling passes, exhibited high performance at 800 °C with ultimate tensile stress and ductility of ~600 MPa and 60%–70%, respectively. Nano-lamellae, nanoscale DRX grains, and ω precipitation in B2 grains at colony boundaries contributed positively to the high-temperature tensile properties.

Is the Brood Pattern within a Honey Bee Colony a Reliable Indicator of Queen Quality?

Failure of the queen is often identified as a leading cause of honey bee colony mortality. However, the factors that can contribute to “queen failure” are poorly defined and often misunderstood. We studied one specific sign attributed to queen failure: poor brood pattern. In 2016 and 2017, we identified pairs of colonies with “good” and “poor” brood patterns in commercial beekeeping operations and used standard metrics to assess queen and colony health. We found no queen quality measures reliably associated with poor-brood colonies. In the second year (2017), we exchanged queens between colony pairs (n = 21): a queen from a poor-brood colony was introduced into a good-brood colony and vice versa. We observed that brood patterns of queens originally from poor-brood colonies significantly improved after placement into a good-brood colony after 21 days, suggesting factors other than the queen contributed to brood pattern. Our study challenges the notion that brood pattern alone is sufficient to judge queen quality. Our results emphasize the challenges in determining the root source for problems related to the queen when assessing honey bee colony health.

Do roads act as a barrier to gene flow of subterranean small mammals? A case study with Ctenomys minutus

Road-barrier effects can lead to population isolation, with consequent negative outcomes for individuals and populations. Small mammals have been identified as particularly vulnerable to barrier effects, yet few studies have focused on subterranean species. Given the burrowing habit of these species, we hypothesized that roads block their movement and therefore the gene flow between roadside populations. The tiny tuco-tuco (Ctenomys minutus), a small subterranean rodent that inhabits the coastal plains of southern Brazil, was used as a model species to test this hypothesis. We used 14 microsatellites to genotype 80 individuals from four colonies (n = 20 per colony). We compared the population differentiation (FST, G″ST and DEST) and population structuring (STRUCTURE and GENELAND, and discriminant analysis of principal components) of two colony pairs, one pair divided by a road, and the other with no road or other potential barrier between the colonies (control). The results indicated higher genetic differentiation and structuring between the roadside colonies than in the control sites, although less evident than initially predicted. We concluded that the road reduced but did not halt the gene flow of C. minutus. Nevertheless, in view of the rapid economic development of the region, measures to ensure long-term gene flow, i.e., installation or retrofitting of crossing structures, should be considered. This study complements previous analyses of road-barrier effects on small mammals, suggesting that subterranean species such as C. minutus can cope with these barriers, at least in conditions similar to our study area.