Search

Simple Summary: Locusts can be at a state called the solitarious phase, associated with harmless populations, or at the gregarious phase, associated with outbreaks. Given the importance of the phenomenon, researchers are trying to reveal its molecular basis and find ways to tackle it. For this, assessing the phase state and comparing locusts is essential, and researchers have thus far used different formulae. To address the problem presented by the lack of standardised tools for such an essential task, we previously suggested two models as tools for standardising the method for assessing the main pest locust, Schistocerca gregaria. However, a theoretical work later cast doubts on the validity of such models and predicted that they would not work as well on future samples as in their initial application. Here, we use additional, different S. gregaria samples to test and assess the performance of these models. The results reaffirm the validity of the results of our previous work, since the models performed just as well on the present samples as they did in the previous ones. The models are thus reinstated as potential tools for standardising the way solitarious and gregarious S. gregaria samples are assessed and compared. Outbreaks of the desert locust Schistocerca gregaria affect some of the poorest parts of Africa, with devastating outcomes. The key to understanding and dealing with this problematic adaptation to environmental changes is comparing gregarious and solitarious locusts, either in nature or in laboratories. Categorising locusts and detecting changes in their phase status is key to such comparisons, which have been hitherto based on applying mathematical models that use behavioural parameters and that each laboratory has to build anew for each experiment. All the models used thus far are different from one another. This implies differences in the tools used for the different experiments and by the different laboratories and, thus, potential noise in the results and interpretations. Standardising the way locusts are categorised is necessary if we want to reduce noise and errors. It is crucial if we seek to make the results and interpretations transferable and comparable between experiments and laboratories for such an important research area. To tackle this problem, we suggested two models as possible standardising tools. However, the problem of a lack of standardised tools re-emerged due to the doubts cast on the validity of those models. Here, we use samples from independent S. gregaria populations in order to test and validate those models. We discuss how successful the two models were at categorising solitarious, intermediate (transient), and gregarious nymph and adult S. gregaria samples. We highlight shortcomings and make more specific recommendations on the use of those models based on the precision differences they show when categorising solitarious and gregarious S. gregaria nymph and adult samples. Overall, both models have proven to be valid since their results were largely replicated and seem reproducible. [ABSTRACT FROM AUTHOR]

Abstract Background Song performed in flocks by European starlings (Sturnus vulgaris), referred to here as gregarious song, is a non-sexual, social behavior performed by adult birds. Gregarious song is thought to be an intrinsically reinforced behavior facilitated by a low-stress, positive affective state that increases social cohesion within a flock. The medial preoptic area (mPOA) is a region known to have a role in the production of gregarious song. However, the neurochemical systems that potentially act within this region to regulate song remain largely unexplored. In this study, we used RNA sequencing to characterize patterns of gene expression in the mPOA of male and female starlings singing gregarious song to identify possibly novel neurotransmitter, neuromodulator, and hormonal pathways that may be involved in the production of gregarious song. Results Differential gene expression analysis and rank rank hypergeometric analysis indicated that dopaminergic, cholinergic, and GABAergic systems were associated with the production of gregarious song, with multiple receptor genes (e.g., DRD2, DRD5, CHRM4, GABRD) upregulated in the mPOA of starlings who sang at high rates. Additionally, co-expression network analyses identified co-expressing gene clusters of glutamate signaling-related genes associated with song. One of these clusters contained five glutamate receptor genes and two glutamate scaffolding genes and was significantly enriched for genetic pathways involved in neurodevelopmental disorders associated with social deficits in humans. Two of these genes, GRIN1 and SHANK2, were positively correlated with performance of gregarious song. Conclusions This work provides new insights into the role of the mPOA in non-sexual, gregarious song in starlings and highlights candidate genes that may play a role in gregarious social interactions across vertebrates. The provided data will also allow other researchers to compare across species to identify conserved systems that regulate social behavior.

Background: Song performed in flocks by European starlings (Sturnus vulgaris), referred to here as gregarious song, is a non-sexual, social behavior performed by adult birds. Gregarious song is thought to be an intrinsically reinforced behavior facilitated by a low-stress, positive affective state that increases social cohesion within a flock. The medial preoptic area (mPOA) is a region known to have a role in the production of gregarious song. However, the neurochemical systems that potentially act within this region to regulate song remain largely unexplored. In this study, we used RNA sequencing to characterize patterns of gene expression in the mPOA of male and female starlings singing gregarious song to identify possibly novel neurotransmitter, neuromodulator, and hormonal pathways that may be involved in the production of gregarious song. Results: Differential gene expression analysis and rank rank hypergeometric analysis indicated that dopaminergic, cholinergic, and GABAergic systems were associated with the production of gregarious song, with multiple receptor genes (e.g., DRD2, DRD5, CHRM4, GABRD) upregulated in the mPOA of starlings who sang at high rates. Additionally, co-expression network analyses identified co-expressing gene clusters of glutamate signaling-related genes associated with song. One of these clusters contained five glutamate receptor genes and two glutamate scaffolding genes and was significantly enriched for genetic pathways involved in neurodevelopmental disorders associated with social deficits in humans. Two of these genes, GRIN1 and SHANK2, were positively correlated with performance of gregarious song. Conclusions: This work provides new insights into the role of the mPOA in non-sexual, gregarious song in starlings and highlights candidate genes that may play a role in gregarious social interactions across vertebrates. The provided data will also allow other researchers to compare across species to identify conserved systems that regulate social behavior. [ABSTRACT FROM AUTHOR]

Outbreaks of the desert locust Schistocerca gregaria affect some of the poorest parts of Africa, with devastating outcomes. The key to understanding and dealing with this problematic adaptation to environmental changes is comparing gregarious and solitarious locusts, either in nature or in laboratories. Categorising locusts and detecting changes in their phase status is key to such comparisons, which have been hitherto based on applying mathematical models that use behavioural parameters and that each laboratory has to build anew for each experiment. All the models used thus far are different from one another. This implies differences in the tools used for the different experiments and by the different laboratories and, thus, potential noise in the results and interpretations. Standardising the way locusts are categorised is necessary if we want to reduce noise and errors. It is crucial if we seek to make the results and interpretations transferable and comparable between experiments and laboratories for such an important research area. To tackle this problem, we suggested two models as possible standardising tools. However, the problem of a lack of standardised tools re-emerged due to the doubts cast on the validity of those models. Here, we use samples from independent S. gregaria populations in order to test and validate those models. We discuss how successful the two models were at categorising solitarious, intermediate (transient), and gregarious nymph and adult S. gregaria samples. We highlight shortcomings and make more specific recommendations on the use of those models based on the precision differences they show when categorising solitarious and gregarious S. gregaria nymph and adult samples. Overall, both models have proven to be valid since their results were largely replicated and seem reproducible.

The elite group of Indian English Poetry today congregates into a house where there is an excess of precariously good-humored diversity addressing on or after a peer pedestal the chronicles of an exceptional unity. The multiplicity explicit in the craftsmanship of creative potentates likewise is inimitably one of its own kind. The rhythmic patterns also appear to boost up larger than life profiles. Verbal skill and phraseology ebbs and flows as per native milieu. Indigenous ecology and strong sense of cultural/traditional ethos appear in a flux. However, everywhere and in everybody the theme of national integration appears affably lofty in spite of being cantankerous. Anil K. Sharma based at Chandigarh eruditely edits (Now no more with us) CONTEMPORARY VIBES, a quarterly devoted to literary pursuits besides being a well-known poet, critic and author of genuine-feelings. That is why his poetry is a greater challenge to contemporary peers, scholars, poets and avid readers of our post-millennium era bubbling in multi-media and globalization. The linguistic, social, political, economic and environmental aspects along with other salient features find a leading place in this study. The democratic, philanthropic and humanitarian standpoints are amply discussed alongside the lines cited from the poems. Above all what enhances the dignity of his poised and self-assured poetic output is the incorporation of great souls and creative visionaries of India whose ever-widening mystique, charismatic imagination and forethoughts have not only inspired the contemporary humanity but also will continue to do so in the days yet to dawn. Thus his poetry creates a revolutionary stream that flows gracefully to sanitize our age-old edifice of ritualistic and sacramental settlement historically known as Bharat, Hindustan or India. Alas! this affectionate soul of exceptional caliber untimely bereaved and left us bewailed on 15 October 2021, just a day before Vijayadasami, all of a sudden, unexpectedly to meet his sad demise. A true pilgrimage to heavenly abode! Adieu to dear departed poet [ABSTRACT FROM AUTHOR]

The first natural history data is reported for the tortoise beetle, Cyrtonota serinus (Erichson, 1847) (Chrysomelidae: Cassidinae: Mesomphaliini). An Ipomoea sp. (Convolvulaceae) is recorded as the host plant. Larvae and adults feed on the leaves. Larvae retain an exuvio-fecal shield and are gregarious. Adults are sexually dimorphic and polymorphic in sizes and coloration.

Herding behavior is widespread among herbivorous insect larvae across several orders. These larval societies represent one of several different forms of insect sociality that have historically received less attention than the well-known eusocial model but are showing us that social diversity in insects is broader than originally imagined. These alternative forms of sociality often focus attention on the ecology, rather than the genetics, of sociality. Indeed, mutually beneficial cooperation among individuals is increasingly recognized as important relative to relatedness in the evolution of sociality, and I will explore its role in larval insect herds. Larval herds vary in in the complexity of their social behavior but what they have in common includes exhibiting specialized social behaviors that are ineffective in isolated individuals but mutually beneficial in groups. They hence constitute cooperation with direct advantages that doesn’t require kinship between cooperators to be adaptive. Examples include: trail following, head-to-tail processions and other behaviors that keep groups together, huddling tightly to bask, synchronized biting and edge-feeding to overwhelm plant defenses, silk production for shelter building or covering plant trichomes and collective defensive behaviors like head-swaying. Various selective advantages to group living have been suggested and I propose that different benefits are at play in different taxa where herding has evolved independently. Proposed benefits include those relative to selection pressure from abiotic factors (e.g., thermoregulation), to bottom-up pressures from plants or to top-down pressures from natural enemies. The adaptive value of herding cooperation must be understood in the context of the organism’s niche and suite of traits. I propose several such suites in herbivorous larvae that occupy different niches. First, some herds aggregate to thermoregulate collectively, particularly in early spring feeders of the temperate zone. Second, other species aggregate to overwhelm host plant defenses, frequently observed in tropical species. Third, species that feed on toxic plants can aggregate to enhance the warning signal produced by aposematic coloration or stereotyped defensive behaviors. Finally, the combination of traits including gregariousness, conspicuous behavior and warning signals can be favored by a synergy between bottom-up and top-down selective forces. When larvae on toxic plants aggregate to overcome plant defenses, this grouping makes them conspicuous to predators and favors warning signals. I thus conclude that a single explanation is not sufficient for the broad range of herding behaviors that occurs in phylogenetically diverse insect larvae in different environments.

A new species of Aprostocetus (Hymenoptera: Eulophidae), gall inducer on Astragalus alpinus (Fabaceae), is described from Norway. The eulophid causes an irregular round or spindle-shaped gall on stem, which shows a single internal cavity for the gregarious larvae. One generation is developed from spring to spring. The parasitoids Macroneura vesicularis (Retzius) and Eurytoma sp. emerged from the gall.

Space availability is a key factor linked to the settlement success of marine invertebrates. Settlement space on coral reefs is predicted to become increasingly fragmented and occupied by competitors under future disturbance regimes, yet how this impacts coral settlement remains largely unknown. We test the effects of space limitation on larval settlement in three common Indo-Pacific corals (Acropora valida, Acropora digitifera and Anacropora spinosa) by manipulating substrate area while maintaining a constant larval supply. Settlement success was highly variable among coral species, with reduced space leading to an up to four-fold increase in settlement of A. valida larvae, a two-fold decrease in settlement of An. spinosa larvae and no significant effect for A. digitifera. All species displayed similar spatial settlement patterns, whereby larvae settled gregariously irrespective of how much space was available. At the same time, settlers were found to increasingly occur in aggregates (in direct contact with each other) as space decreased. We propose that increased settler aggregations, coupled with settlement intensification for some species, facilitates the formation of chimeras as space becomes limiting. In colonial organisms, the formation of aggregates and particularly chimeric individuals may offset the negative effects of increased competition for space by allowing settlers to rapidly exceed size-escape thresholds, thereby increasing the likelihood of survival. [ABSTRACT FROM AUTHOR]

Social learning can be a shortcut for acquiring locally adaptive information. Animals that live in social groups have better access to social information, but gregarious and nonsocial species are also frequently exposed to social cues. Thus, social learning might simply reflect an animal's general ability to learn rather than an adaptation to social living. Here, we investigated social learning and the effect of frequency of social exposure in nonsocial, juvenile Port Jackson sharks, Heterodontus portusjacksoni. We compared (1) Individual Learners, (2) Sham-Observers, paired with a naïve shark, and (3) Observers, paired with a trained demonstrator, in a novel foraging task. We found that more Observers learnt the foraging route compared to Individual Learners or Sham-Observers, and that Individual Learners took more days to learn. Training frequency did not affect learning rate, suggesting acquisition occurred mostly between training bouts. When demonstrators were absent, 30% of observers maintained their performance above the learning criterion, indicating they retained the acquired information. These results indicate that social living is not a prerequisite for social learning in elasmobranchs and suggest social learning is ubiquitous in vertebrates. • Nonsocial, juvenile Port Jackson sharks learnt faster with trained demonstrators. • Acquisition occurred between training bouts. • Social living is not a prerequisite for social learning in elasmobranchs. [ABSTRACT FROM AUTHOR]

1. Aggregative feeding of larvae is widespread in the Lepidoptera, and many hypotheses have been proposed to explain the adaptive significance of this trait. Group feeding occurs disproportionately more in species with aposematic, chemically defended larvae compared with species with cryptic, non‐chemically defended larvae, consistent with the hypothesis that group feeding provides an enhanced aposematic signal to natural enemies. Most species characterised as having chemically defended larvae are cryptic during the first instar, when they are most highly aggregated and most vulnerable to predation. 2. The benefits of group feeding in terms of decreased predation were explored for first‐instar larvae of the pipevine swallowtail, Battus philenor, a species that sequesters aristolochic acids from its Aristolochia host plant and exhibits aposematism in later instars and as adults. We found that groups of larvae with experimentally enhanced aristolochic acid content had significantly lower survivorship due to predation both in the field and in laboratory experiments compared with groups of larvae without enhanced chemical defence. 3. A laboratory experiment found that aristolochic acid does not deter the generalist predator Hippodamia convergens. 4. No evidence was found that was consistent with the hypothesis that group feeding and increased sequestered chemical defence interact to decrease rates of larval mortality in non‐aposematic, first‐instar larvae. Future research on chemical defence, aposematism, and aggregative feeding should continue to appreciate that particular chemical defences and feeding behaviours are not universally effective against all natural enemies. [ABSTRACT FROM AUTHOR]

The problem being investigated is the spontaneous rise of the herd instinct in an artificial population, where the population members have no explicit stimuli for such instinct implanted in their original behavior patterns. The simulations are focused on the creation of the herd instinct in the population that originally does not reveal the gregarious behavior. In this agent-based model, the members of the population (agents) move over a limited region, look for renewable food, reproduce, escape a threat and die. The evolution of the herd instinct is simulated. No explicit instinct is imposed on the agents. It is pointed out that both the search for food and fear are factors that cause the rise of the herd instinct. The evolution of the amount of the instinct is slow and needs long model time intervals, running over several hundred generations of the agents. The herd instinct is inherited from parent agents during the reproduction, with certain random deviation. This makes the total amount of the instinct evolve and reach an optimal level. [ABSTRACT FROM AUTHOR]

Abstract Optimal breeding conditions for locust swarms often include heavy rainfall and flooding, exposing individuals to the risk of immersion and anoxia. We investigated anoxia tolerance in solitarious and gregarious adults of the Australian Plague Locust, Chortoicetes terminifera , by measuring the time to enter an anoxic coma after submersion in water, the time for recovery of ventilation and the ability to stand on return to air. We found a longer time to succumb in immature adults that we attribute to a larger tracheal volume. Time to succumb was also longer after autotomizing the hindlegs to reduce the energetic cost of muscular activity. Time to recover was longer in gregarious males and this developed during maturation, suggesting an increase in the cost of neural processing associated with social interactions under crowded conditions. Short-term changes in rearing conditions had effects that we interpret as stress responses, potentially mediated by octopamine. Highlights • We investigated tolerance to water immersion in solitarious and gregarious adults of the Australian Plague Locust. • The time taken to enter an anoxic coma correlated positively with tracheal volume and negatively with muscular activity. • The time taken to recover from an anoxic coma was longer in gregarious males; which became apparent during adult maturation. [ABSTRACT FROM AUTHOR]

The tachinid fly, Sturmia convergens (Wiedemann, 1824) is one of the most important parasitoids, causing heavy mortality in Danaus chrysippus (Linnaeus, 1758). The present work documents for the first time, the gregarious behavior of S. convergens in the host larvae. The parasitoid can very well complete its development within the larval stage of the host. A single host larva is capable of provisioning the full development of up to 8 larvae of S. convergens. The study also reports them as true larval and larval-pupal parasitoids of D. chrysippus on Calotropis gigantea (Linnaeus) Dryand, 1811. [ABSTRACT FROM AUTHOR]

Leptocoris augur is a phytosuccivorous pest of kusum plant, S.oleosa. By its desapping habit, it causes seeds inviable. It occurs throughout the year on and under the host tree. Though, its population fluctuates seasonally, the bug form aposematic aggregations on the ripe fallen fruits of kusum during May to July. In rest months of the year, aggregation of nymphs and adults occurs on the blackish seeds. During gregariousness younger nymphs are surrounded by adults and older nymphs (4th and 5th nymphs). Gregariousness occurs for feeding and protection from enemies as well as for maintaining temperature in the group during winter. Large aggregations are also observed on the bark of the tree trunk. Adult bugs are red with membrane of wings black. The nymphs are bright red. In aggregation red and black colour show warning mimicry for protection from natural enemies. In an aggregation 5 to 126 bugs and nymphs are observed. Pheromones and other chemicals secreted by bugs and perceived by 4th clavate segments of antennae help in making clusters. [ABSTRACT FROM AUTHOR]

The objective of the model is to simulate the migrations of social groups over certain geographical regions, influenced by the gregarious effect and individual behavior patterns. The people move in search of better work opportunities and welfare. The model components are regions and individuals belonging to certain social groups. A region is characterized by more than 30 parameters, such as geographical data, actual population statistics, education facilities, and work opportunities. For the social groups, the parameters include the demographic and educational statistics. The simulated individuals attempt to optimize their welfare by moving over the model map. Spontaneous migration, without apparent goal, is also considered. The region parameters change owing to the number and the parameters of incoming individuals, which provides a dynamic and nonlinear feedback. The qualitative results reveal that the model never reaches a steady state and that the social groups remain in periodical movement. The simulations are agent-based. No differential equations (like in the System Dynamics approach) or any extant theory or mathematical model is used. [ABSTRACT FROM AUTHOR]

Sex pheromones have rarely been studied in parasitoids, and it remains largely unknown how male and female parasitoids locate each other. We investigated possible attraction (and repellency) between the sexes of two braconid wasps belonging to the same genus, the gregarious parasitoid, Cotesia glomerata (L.), and the solitary parasitoid, Cotesia marginiventris (Cresson). Males of both species were strongly attracted to conspecific virgin females. Interestingly, in C. glomerata, the males were repelled by mated females, as well as by males of their own species. This repellency of mated females was only evident hours after mating, implying a change in pheromone composition. Males of C. marginiventris were also no longer attracted, but not repelled, by mated females. Females of both species showed no attraction to the odors of conspecific individuals, male or female, and C. glomerata females even appeared to be repelled by mated males. Moreover, the pheromones were found to be highly specific, as males were not attracted by females of the other species. Males of Cotesia glomerata even avoided the pheromones of female Cotesia marginiventris, indicating the recognition of non-conspecific pheromones. We discuss these unique responses in the context of optimal mate finding strategies in parasitoids.

Recurrent locust population outbreaks have a tremendous impact on ecosystems and economies around the globe. These population outbreaks are associated with a shift from the usual solitary locust phase to a gregarious one. Most molecular research on locusts is focused on uncovering the basis underlying the change to gregariousness. With the increasing availability of 'omics' data, the research on this subject is entering a functional testing era. In order to successfully test functionality of a gene or molecule, quantitative measurements of the level of gregariousness are needed. Currently no valid molecular marker is available, thus the assessment of the degree of locust gregariousness is based on mathematical modeling. However, the absence of one single model means heterogeneity and implies that researchers have to spend time and effort building one for their specific experiments. Here, we offer a script to simplify extraction of the data from locust behavioral video tracks. We also suggest two mathematical equations for assessing the levels of gregariousness of one of the most notorious pest locusts - Schistocerca gregaria ( Forskål) ( Orthoptera: Acrididae). One model uses morphometric variables and is valid for the comparison of nymphs, whereas the other has no morphometric variables and is for testing the adults and the same specimens of non-molted nymphs. The sensitivity of these models was optimized and the effects of sex, developmental stage, and locust size were considered. The models were tested with independent samples and were found to work both for solitary and gregarious locusts. They were also found to be quantitative and could be used to distinguish populations of different densities and states. We therefore offer accessible, reliable, time, and effort-saving tools for researchers to use. The use of these models by multiple laboratories would standardize and homogenize methodologies to the benefit of reliable results and interpretations. [ABSTRACT FROM AUTHOR]

Larvae of Dendrocerus carpenteri Curtis ( Hymenoptera: Megaspilidae) develop as solitary ectoparasitoids on the prepupae and pupae of primary aphid parasitoids inside the aphid mummy. First instars are aggressive and kill potential competitors; however, facultative gregarious development of two, and occasionally three, larvae may occur under superparasitism. To test the hypothesis that gregarious larvae share host resources equally, adult dry mass is compared between three brood types: 'double' mummies containing (i) two males; (ii) two females; or (iii) one male plus one female, respectively. Resource rivalry varies with the sex of the competing larvae. Surviving adults differ significantly in size if both wasps are of the same sex, male or female. A minimum amount of resources is required for a larva to be viable; this threshold does not differ between sexes and is independent of the sex of a competing larva. The outcome of competition between a male larva and a female larva varies with the amount of the available resources, with neither sex being inherently dominant over the other. Females are eight times more likely to be larger than a male competitor if the amount of host resources is ≥0.116 mg, whereas males can win over a female competitor in terms of adult size if the available resources are <0.116 mg. It is suggested that rivalry between larvae for limiting host resources constrains the transition from solitary to gregarious development and should be considered in studies of parasitoid life-history evolution. [ABSTRACT FROM AUTHOR]

Eubrontes giganteus is a common ichnospecies of large dinosaur track in the Early Jurassic rocks of the Hartford and Deerfield basins in Connecticut and Massachusetts, USA. It has been proposed that the trackmaker was gregarious based on parallel trackways at a site in Massachusetts known as Dinosaur Footprint Reservation (DFR). The gregariousness hypothesis is not without its problems, however, since parallelism can be caused by barriers that direct animal travel. We tested the gregariousness hypothesis by examining the orientations of trackways at five sites representing permanent and ephemeral lacustrine environments. Parallelism is only prominent in permanent lacustrine rocks at DFR, where trackways show a bimodal orientation distribution that approximates the paleoshoreline. By contrast, parallel trackways are uncommon in ephemeral lacustrine facies, even at sites with large numbers of trackways, and those that do occur exhibit differences in morphology, suggesting that they were made at different times. Overall, the evidence presented herein suggests that parallelism seen in Hartford Basin Eubrontes giganteus is better explained as a response to the lake acting as a physical barrier rather than to gregariousness. Consequently, these parallel trackways should not be used as evidence to support the hypothesis that the trackmaker was a basal sauropodomorph unless other evidence can substantiate the gregariousness hypothesis. [ABSTRACT FROM AUTHOR]

Gregarious flowering of bamboo species impacts ecosystem properties and conservation, but documentation of these periodic events is difficult. Here, we compare the characteristics of flowering sites and un-flowered patches of an arrow bamboo (Fargesia qinlingensis) in the Qinling Mountains, China, over a five-year period (2003-2007) after a mast flowering event (2003). We examined flowering culm and seedling characteristics in relation to questions regarding the evolution of delayed flowering. Density of live culms decreased over the five years in both flowering sites and un-flowered patches. New shoots regenerated only in un-flowered patches. Chemical constituent allocation varied among culm parts (stems, branches, and leaves). Crude protein and extract ether in branches and leaves were less in flowering culms than in un-flowered culms. Seedling density was lower than expected based on floret counts, suggesting predation of seeds. Seedling density was significantly greater in flowering sites than in un-flowered patches and decreased over time. Seedlings performed better in flowering sites than in un-flowered patches based on their height, leaf number per seedling, and average leaf length, while fertilization on flowering sites had no significant effect on seedling growth, suggesting a saturation of resources. This study suggested that the characteristics of bamboos and bamboo stands were dramatically altered during this flowering event, enhancing seedling establishment and growth, and supporting mostly the habitat modification hypothesis of delayed reproduction.

Gregarious larvae that use chemical communication to feed and move together are widespread among folivorous insects, although social behaviour has been studied almost exclusively in a few temperate zone genera. The Menapis (or variable) tigerwing butterfly Mechanitis menapis mantineus Hewitson (Lepidoptera, Nymphalidae, Danainae, Ithomiini) is a neotropical species whose larvae feed gregariously on Solanaceae host plants. In laboratory experiments conducted in the Ecuador cloud forest, M. menapis caterpillars are attracted to silk produced by conspecifics and show no evidence of pheromone production. Indeed, caterpillars consistently choose arenas with silk over bare arenas but do not show a preference for arenas marked with abdominal cuticular surface residues. Mechanitis menapis caterpillars on silk-coated plants are both more mobile and more cohesive than those on control plants. Nonetheless, caterpillars move independently over unmarked surfaces and groups do not make rapid collective choices between two food sources. Collective behaviour in M. menapis thus appears to be based on aggregation on collectively produced silk to facilitate feeding, as well as using this silk to maintain cohesion. Silk production is common in caterpillars, although M. menapis appears to be unique among species studied so far in using silk to maintain group cohesion. [ABSTRACT FROM AUTHOR]

Temperament is a key criterion in the selection of horses for both leisure and competitive riding to ensure optimal performance and safety. The Tennessee Walking Horse ( TWH) is described as a calm, docile breed and is often used as a trail, show and pleasure horse. However, among horse owners and caretakers, there are anecdotes supporting familial and disciplinal typical behaviors and personalities. To investigate the contribution of genetics to temperament, we collected a behavior questionnaire, brief training history and identifying information for 276 TWH, as well as blood or hair samples for DNA. Factor analysis was conducted on the 20-item questionnaire for the set of 216 horses that met inclusion thresholds. Factor analysis identified four temperament factors in TWH: 'anxious', 'tractable', 'agonistic' and 'gregarious'. These four factors account for 64% of the total trait variance. DNA from 113 TWHs were selected and genotyped using the Equine SNP70 bead chip for three separate genome-wide association studies ( GWAs) using the factor 1-anxious, factor 2-tractable and factor 3-agonistic scores as the phenotype. Quantitative association analysis identified significant candidate loci for each factor that warrant further investigation. [ABSTRACT FROM AUTHOR]

Eubrontes giganteus is a common ichnospecies of large dinosaur track in the Early Jurassic rocks of the Hartford and Deerfield basins in Connecticut and Massachusetts, USA. It has been proposed that the trackmaker was gregarious based on parallel trackways at a site in Massachusetts known as Dinosaur Footprint Reservation (DFR). The gregariousness hypothesis is not without its problems, however, since parallelism can be caused by barriers that direct animal travel. We tested the gregariousness hypothesis by examining the orientations of trackways at five sites representing permanent and ephemeral lacustrine environments. Parallelism is only prominent in permanent lacustrine rocks at DFR, where trackways show a bimodal orientation distribution that approximates the paleoshoreline. By contrast, parallel trackways are uncommon in ephemeral lacustrine facies, even at sites with large numbers of trackways, and those that do occur exhibit differences in morphology, suggesting that they were made at different times. Overall, the evidence presented herein suggests that parallelism seen in Hartford Basin Eubrontes giganteus is better explained as a response to the lake acting as a physical barrier rather than to gregariousness. Consequently, these parallel trackways should not be used as evidence to support the hypothesis that the trackmaker was a basal sauropodomorph unless other evidence can substantiate the gregariousness hypothesis.

The migratory locust, Locusta migratoria, shows remarkable phenotypic plasticity at behavioral, physiological, and morphological levels in response to fluctuation in population density. Our previous studies demonstrated that dopamine (DA) and the genes in the dopamine metabolic pathway mediate phase change in Locusta. However, the functions of different dopamine receptors in modulating locust phase change have not been fully explored. In the present study, DA concentration in the brain increased during crowding and decreased during isolation. The expression level of dopamine receptor 1 (Dop1) increased from 1 to 4 h of crowding, but remained unchanged during isolation. Injection of Dop1 agonist SKF38393 into the brains of solitary locusts promoted gregarization, induced conspecific attraction-response and increased locomotion. RNAi knockdown of Dop1 and injection of antagonist SCH23390 in gregarious locusts induced solitary behavior, promoted the shift to repulsion-response and reduced locomotion. By contrast, the expression level of dopamine receptor 2 (Dop2) gradually increased during isolation, but remained stable during crowding. During the isolation of gregarious locusts, injection of Dop2 antagonist S(-)-sulpiride or RNAi knockdown of Dop2 inhibited solitarization, maintained conspecific attraction-response and increased locomotion; by comparison, the isolated controls displayed conspecific repulsion-response and weaker motility. Activation of Dop2 in solitary locusts through injection of agonist, R(-)-TNPA, did not affect their behavioral state. Thus, DA-Dop1 signaling in the brain of Locusta induced the gregariousness, whereas DA-Dop2 signaling mediated the solitariness. Our study demonstrated that Dop1 and Dop2 modulated locust phase change in two different directions. Further investigation of Locusta Dop1 and Dop2 functions in modulating phase change will improve our understanding of the molecular mechanism underlying phenotypic plasticity in locusts. [ABSTRACT FROM AUTHOR]

Despite its distribution throughout the tropics and subtropics, the pygmy killer whale (Feresa attenuata) is one of the most poorly known species of odontocetes (Cetacea: Delphinidae). We used the opportunity of a mass stranding of six animals in New Caledonia (early February 2006) to gather information about their biology. Four animals, including three males and one female, were found dead, and morphometrics, including dental counts, were collected. Two live mature males of 236 and 246 cm total length (TL), respectively, were closely monitored and sampled via blood analysis. As it was not likely to survive, the second animal was euthanized and necropsied. Following the euthanasia of the larger animal, the smaller one, which was probably staying out of social solidarity, returned on its own to the open sea. The necropsy revealed the presence of cardiopulmonary collapse and enlarged and congested testes. Blood parameters confirmed a deteriorating health status for both animals, enhanced by starvation. Some of the relative morphometric measurements of all six stranded pygmy killer whales seemed to be larger for these animals living in the southwest Pacific as compared to the literature for this species. We hypothesize that this group of pygmy killer whales was probably pushed through the Coral Sea toward the New Caledonian lagoon by Hurricane Jim, which occurred in the area from 26 January until 2 February. These observations reveal January as a potential part of the mating season in this area for this rare, elusive, and unknown species. It also supports the notion that early sacrifice of distressed, terminal animals could be a way to improve the survival rate of other less traumatized individuals during cetacean mass strandings. [ABSTRACT FROM AUTHOR]

Gregarious feeding by insect herbivores is a widely observed, yet poorly understood, behavioral adaptation. Previous research has tested the importance of group feeding for predator deterrence, noting the ubiquity of aposematism among group-feeding insects, but few studies have examined the role of feeding facilitation for aggregates of insect herbivores. We tested the hypothesis that group feeding has facilitative effects on performance of the saddleback caterpillar, Acharia stimulea Clemens, a generalist herbivore of deciduous trees. In an understory forest setting, we reared caterpillars alone or in groups on two different host plants, white oak (Quercus alba L.) and American beech (Fagus grandifolia Ehrlich), and recorded multiple measures of insect performance during regular field censuses. As predicted, A. stimulea caterpillars feeding in groups on white oak had increased relative growth rates compared with caterpillars feeding alone, and the magnitude of this facilitative effect varied among censuses, conferring benefits both early and late in development. By contrast, no facilitative effects of group feeding were detected on beech, suggesting that the benefits of facilitative feeding may be host specific. On both hosts, caterpillar development time was slightly faster for group-feeding cohorts compared with their solitary counterparts. Because early instar caterpillars are particularly vulnerable to predation and parasitism, even modest increases in growth rates and reductions in development time may decrease exposure time to enemies during these vulnerable stages. On both hosts, group feeding also reduced the trade-off between individual development time and cocoon mass, suggesting that feeding efficiency is improved in group feeders relative to solitary caterpillars. [ABSTRACT FROM AUTHOR]

Phoretic insects utilize other animals to disperse to new environments. We recently discovered how egg parasitoids use an exciting phoretic strategy to reach egg-laying sites of their butterfly hosts. In the laboratory, female Trichogramma wasps detect and mount mated female cabbage white butterflies that emit an anti-aphrodisiac pheromone. Hardly any information exists about the natural occurrence of phoresy in wasps of this genus. Therefore, we monitored the presence of phoretic Trichogramma wasps on lepidopteran hosts in the field. Only female wasps were found at low prevalence on six lepidopteran species. Wasps were mostly found on female hosts and mainly on abundant solitary host species. This is the first report of phoretic Trichogramma wasps on butterflies in nature. We suggest that phoresy is only one of several strategies used by these polyphagous egg parasitoids. The evolution of phoresy is discussed in relation to the nutritional ecology of egg parasitoids. [ABSTRACT FROM AUTHOR]

The tree species Gilbertiodendron newberyi Burgt (Leguminosae: Caesalpinioideae) is described and illustrated. The new species is related to G. ogoouense (Pellegr.) J. Léonard s.s. Trees of G. newberyi can grow to 51 m high and 197 cm trunk diam. The new species is ectomycorrhizal, grows gregariously, and presents ballistic seed dispersal. G. newberyi is endemic to Korup National Park in Cameroon, and is assessed as Endangered D under the criteria of IUCN. [ABSTRACT FROM AUTHOR]

Raccoons (Procyon lotor), like most carnivores, are nocturnal and secretive and consequently difficult to observe. We used proximity-detecting collars to determine effects of sex, age, and season on contact rate and duration; document patterns of seasonal contact rates by dyad type and determine whether patterns were random; identify dyads that exhibited contact rates significantly greater than expected and document the persistence of these positive associations across seasons; and document frequency of den sharing as an additional measure of positive associations at an urban study site with a high-density raccoon population. Contact rate and duration were affected by dyad type, season, and their interaction. Male--male (MM) dyads exhibited higher contact values than male--female (MF) or female--female (FF) dyads, and contact parameters were greater during winter and spring than summer and autumn. Contact parameters for MM and FF dyads were not affected by age of dyad members, whereas those of MF dyads were affected by age and its interaction with season. MF dyads with older individuals exhibited greater contact parameters, and this effect was greatest during winter. For all dyad types and seasons, except FF dyads during winter, observed distributions of contact rates differed from expected. Males formed groups, with most positively associated dyads persisting across seasons, and females were associated almost exclusively with members of only 1 male group. Some positively associated MF dyads occurred during autumn and continued through spring. Positively associated FF dyads occurred at a lower rate and were ephemeral, seldom lasting more than 1 season. FF and MF dyads exhibited a greater proportion of low-frequency contacts with conspecifics than expected during all seasons, except winter, which may function to maintain amicable relationships between neighbors or reinforce dominance hierarchies and create a framework for more complex social behaviors. Raccoons appear to live in a fission--fusion society, with many short-term acquaintances and a few long-term associations. [ABSTRACT FROM AUTHOR]

We studied the nesting behavior of the pig-nosed turtle, Carettochelys insculpta, in northern Australia. We used remote camera systems and focal observations to test the hypothesis that the nesting behavior in C. insculpta is similar to that of its closest relatives, the softshell turtles (Trionychidae). Carettochelys nested at night, in contrast to diurnal nesting in the majority of softshell turtles. Observations of groups of turtles in the water prior to nesting indicated gregarious or social behavior. On average, gravid turtles emerged around 6 times onto 1-2 beaches spanning 2 nights. Turtles nested at around 2100 ± 3 h, when sand temperatures at nest depth were near their maxima. Minimum air and water temperatures during nesting were 17.5°C and 24.6°C, respectively. Nesting turtles spent an average of 27 min on a beach, similar to softshell turtles but shorter than reported for most other turtle species. Relatively short nesting duration in these species may be caused by the ease in excavating a chamber in sand and the close proximity of nesting areas to water. Overall, the nesting sequence reflected the conservative nesting behavior in turtles, was similar to that of softshells, but differed in subtle ways. Empty nest chambers, commonly referred to in the literature as ''test holes'', were sometimes the result of abandonment resulting from incidental contact between turtles searching for a nest site. [ABSTRACT FROM AUTHOR]

Group foraging can be beneficial for ungulates by decreasing the time required for vigilance, but it can also prove costly because of competition. To determine responses to gregarious behaviour, we studied foraging activity and vigilance of impala ( Aepyceros melampus) near Kruger National Park, South Africa. We measured time spent foraging, vigilant, moving, grooming, engaging in social interactions and determined herd size and group distribution (i.e. density). We calculated accepted food abundance (AFA), food ingestion rate, steps per minute and percent vigilance for female, bachelor male and herd male impala. There was no relationship between herd size and vigilance, but vigilance decreased with increasing density ( t1,311 = 4.91, P <0.0001). Additionally, AFA decreased ( t1,61 = 5.96, P <0.0001) and steps per minute increased ( t1,311 = 14.38, P < 0.0001) as more individuals fed in close proximity to each other. Impala could be altering their behaviour to accommodate a perceived change in resources because of intraspecific competition and these adjustments might be related more to the distribution of herd members than to herd size. Further studies should examine the behaviour of gregarious animals in relation to the distribution of herd members in addition to group size. [ABSTRACT FROM AUTHOR]

The tree species Berlinia korupensis Mackinder & Burgt is described as new. The species is endemic to the southern part of Korup National Park in Cameroon. Seventeen trees have been found so far, the largest being 42 m high and having a trunk diam. of 88 cm. The new species is assessed as Critically Endangered (CR D) under the criteria of IUCN. Two distribution maps are included; one map indicating the single locality in Cameroon near the Nigerian border where the new species was found and another map of the permanent plot where 14 of the 17 trees were recorded. A line drawing is also included, along with colour photographs of the flowers and the trunk. [ABSTRACT FROM AUTHOR]

Barnacle cypris larvae respond to many cues when selecting a settlement site. The settlement of over a million larvae on tiles of different textures, orientations and densities of incumbent settlers was measured on the rocky intertidal at Great Cumbrae, Scotland. Half of the tiles were replaced every tide whereas the others simultaneously accumulated settlers. Factor effects varied on each tide, and converged in the accumulating deployment. Increasing incumbent density led to net loss of settlement, which was less probable on the textures on which fastest settlment occurred ('very fine'), and more probable on those on which settlement was slowest ('smooth'). More settlement occurred on down-facing orientations during daylight and vice versa. Cue ranks were non-linear, so a path analysis model quantified the relative influence of each factor. Gregariousness was the most influential cue measured, although unmeasured factors had greater effects, highlighting the complexity of settlement influences in this species. [ABSTRACT FROM AUTHOR]

Many marine invertebrate larvae respond behaviourally to environmental settlement cues, yet behaviours are often only inferred from settlement patterns or are limited to laboratory studies. The behaviour of wild cypris larvae of Semibalanus balanoides L. was filmed on settlement tiles in the field. Tiles were of five different textures with a nested treatment of crude conspecific adult extract (AE). The effects of texture and AE on eleven defined behaviours were analysed. Texture affected the gross and net exploratory distances, velocity, acceleration and time spent exploring. AE attracted more cyprids during the first minute of immersion and increased the time spent on surfaces. Relatively few arrivals that either travel far and fast, or exit the surface rapidly, may indicate a lower chance of settlement. An increase in time spent on a surface may increase the probability of being in contact with the surface when the sign stimulus to settle occurs. [ABSTRACT FROM AUTHOR]

Group living can incur both benefits and costs, mediated by different mechanisms. In many gregarious caterpillars, collective use of a network of silk trails is thought to improve foraging. Grouping, i.e., close contact with conspecifics, has been postulated to have both positive (thermoregulation and predator defense) and negative (competition and pathogen transmission) effects. The present experiment distinguishes between silk produced by group members and grouping per se in their effects on growth and development of both early and late larval stadia of the forest tent caterpillar [ Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae)] in a laboratory context. For both developmental stadia tested, pre-established silk trails decreased latency to food finding and hence increased food consumption and growth rate. For younger larvae, pre-established silk also decreased investment in silk production. Grouping young caterpillars accelerated development at the expense of growth, possibly as a mechanism to avoid intraspecific competition in later larval stadia. In older caterpillars, grouping decreased meal duration, suggesting that competition can indeed occur towards the end of larval development, even in the presence of surplus food. This led to a decrease in growth without any effect on instar duration. The benefits of exogenous silk thus decreased during larval development, whereas the costs associated with crowding increased. Ontogenetic shifts in grouping are common in many taxa: the present study is among the first to provide empirical evidence for an adaptive explanation of observed ontogenetic changes in aggregative behavior. [ABSTRACT FROM AUTHOR]

Desert locusts (Schistocerca gregaria) can undergo a profound transformation between solitarious and gregarious forms, which involves widespread changes in behaviour, physiology and morphology. This phase change is triggered by the presence or absence of other locusts and occurs over a timescale ranging from hours, for some behaviours to change, to generations, for full morphological transformation. The neuro-hormonal mechanisms that drive and accompany phase change in either direction remain unknown. We have used high-performance liquid chromatography (HPLC) to compare amounts of 13 different potential neurotransmitters and/or neuromodulators in the central nervous systems of final instar locust nymphs undergoing phase transition and between long-term solitarious and gregarious adults. Long-term gregarious and solitarious locust nymphs differed in 11 of the 13 substances analysed: eight increased in both the brain and thoracic nerve cord (including glutamate, GABA, dopamine and serotonin), whereas three decreased (acetyicholine, tyramine and citrnlline). Adult locusts of both extreme phases were similarly different. Isolating larval gregarious locusts led to rapid changes in seven chemicals equal to or even exceeding the differences seen between long-term solitarious and gregarious animals. Crowding larval solitarious locusts led to rapid changes in six chemicals towards gregarious values within the first 4 h (by which time gregarious behaviours are already being expressed), before returning to nearer long-term solitarious values 24 h later. Serotonin in the thoracic ganglia, however, did not follow this trend, but showed a ninefold increase after a 4 h period of crowding. After crowding solitarious nymphs for a whole larval stadium, the amounts of all chemicals, except octopamine, were similar to those of long-term gregarious locusts. Our data show that changes in levels of neuroactive substances are widespread in the central nervous system and reflect the time course of behaviourai and physiological phase change. [ABSTRACT FROM AUTHOR]

Locusts have fascinated researchers for several decades, because they have the remarkable ability to undergo phase transition from the harmless solitary to the swarm-forming gregarious phase. However, the physiological and endocrine mechanisms, underlying phase polymorphism, are only partially unravelled. Nevertheless, besides the ‘classical’ hormones, pacifastin-related peptides have been suggested to play a role in phase transition. Here, we present the first quantitative and comparative analysis of locust transcripts, in particular pacifastin-related precursor (SGPP-1–3) mRNAs, between isolated-reared (solitary) and crowd-reared (gregarious) desert locusts, revealing a phase-dependent transcriptional regulation of the corresponding genes. While the SGPP-1 and SGPP-3 transcripts were most abundant in fat body from crowd-reared males, corresponding to significantly higher levels than in isolated-reared males, the SGPP-2 transcript was detected most abundantly in brain from crowd-reared male locusts. Furthermore, SGPP-2 transcript levels in brain, testes, fat body, and accessory glands from crowd-reared males significantly exceeded the levels in solitary locusts. [Copyright &y& Elsevier]

Sluggish movement is common in chemically defended insects. We have recently shown that sluggish movement can be beneficial to prey when it fails to release the attack response of an ambush (=motion-oriented) predator. Here, we test the hypothesis that sluggish movement and chemical defense (i.e., repugnant odor) together are more defensive than either alone. We manipulated the movement and odor of lubber grasshoppers to produce four prey types: (1) sluggish-moving and high odor, (2) sluggish-moving and low odor, (3) fast-moving and high odor, and (4) fast-moving and low odor. We then offered these prey to frogs. In two independent experiments, frogs attacked prey type 1 (i.e., sluggish-moving and high-odor prey) significantly later than they attacked the other prey types. Hence, the defenses of sluggish movement and repugnant odor can act together to produce a prey that is better defended than prey with either defense alone. This may help explain why these two traits commonly cooccur in insects. [ABSTRACT FROM AUTHOR]

Models explaining the appearance of gregariousness in insect parasitoids assume the presence of a tolerance gene that enables nonsiblicidal behaviour in gregarious larvae. Under this assumption, nontolerant individuals should attack and kill tolerant individuals when sharing a host, making this behaviour susceptible to invasion by nontolerant individuals. We propose an alternative hypothesis where gregarious larvae retain their aggressiveness but are less mobile. We tested this hypothesis with two sympatric and congeneric species of Mymaridae, Anaphes victus and Anaphes listronoti, respectively, solitary and gregarious egg parasitoids of a Curculionidae, Listronotus oregonensis. Results obtained in competition experiments and from direct observation of movement in mymariform larvae of both species support the reduced mobility hypothesis. By being immobile while retaining their fighting capacity, A. listronoti mymariform larvae appear to optimize host utilization through gregarious development, but can still defend themselves against sympatric aggressive species. [ABSTRACT FROM AUTHOR]

Recent studies indicate that many of the nocturnal prosimian primates are gregarious rather than solitary. This paper shows that the spectral tarsier is gregarious during its nightly activity period as well as in its sleeping tree. Using mist nets and radiotelemetry, focal follows were conducted on six groups at Tangkoko Nature Reserve in Sulawesi, Indonesia. During 442 focal follows, 1072 encounters between a focal adult group member and another adult were observed. The number of encounters ranged from as few as 0 to as many as 18 encounters per night. Intra-group encounters lasted from less than 1 min to as long as 3 hr 12 min. Nearly one-half of all social behavior occurred between adult females and males. There were also substantial rates of social interaction between the two adult females in one group, and between sub-adults of the opposite sex in neighboring groups. Am. J. Primatol. 51:89–101, 2000. © 2000 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]