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Entomological radars need to address the problem of insect density estimation. Here, a Ku-band experimental entomological radar with two-dimensional scanning mode is used to collect insect echo data. The nearest neighbour method is used to associate the traces of the same insect. Then, the insects are classified according to their radar cross-sections (RCSs) and heights. Then, the corresponding radar-effective sampling volumes are calculated. So, we can get the density of insects with different RCSs at any height layer. Finally, the densities of insects with different RCSs at the same height layer are accumulated to obtain the total insect density at each height layer. [ABSTRACT FROM AUTHOR]

Spittlebugs are the vectors of the bacterium Xylella fastidiosa Wells in Europe, the causal agent of olive dieback epidemic in Apulia, Italy. Selection and distribution of different spittlebug species on host-plants were investigated during field surveys in 2016−2018 in four olive orchards of Apulia and Liguria Regions of Italy. The nymphal population in the herbaceous cover was estimated using quadrat samplings. Adults were collected by sweeping net on three different vegetational components: herbaceous cover, olive canopy, and wild woody plants. Three species of spittlebugs were collected: Philaenus spumarius L., Neophilaenus campestris (Fallén), and Aphrophora alni (L.) (Hemiptera: Aphrophoridae). Philaenus spumarius was the predominant species both in Apulia and Liguria olive groves. Nymphal stages are highly polyphagous, selecting preferentially Asteraceae Fabaceae plant families, in particular some genera, e.g., Picris, Crepis, Sonchus, Bellis, Cichorium, and Medicago. Host-plant preference of nymphs varies according to the Region and through time and nymphal instar. In the monitored sites, adults peak on olive trees earlier in Apulia (i.e., during inflorescence emergence) than in Liguria (i.e., during flowering and beginning of fruit development). Principal alternative woody hosts are Quercus spp. and Pistacia spp. Knowledge concerning plant selection and ecological traits of spittlebugs in different Mediterranean olive production areas is needed to design effective and precise control strategies against X. fastidiosa vectors in olive groves, such as ground cover modifications to reduce populations of spittlebug vectors.

Positive thigmotactic behavior is associated with the ability to hide from predators and is important to explain aggregation and collective patterns in various animals. For example, this behavior has been observed in woodlice, domiciliary cockroaches, ants, and fish. Lately, research on different species is focused on the importance of animal personality for ecological and evolutionary processes, individual fitness and group cohesion. In fact, it is generally expected to find some degree of interindividual consistent differences for a behavior, unless specific circumstances, like predator attacks, hide the presence of personalities. In this research, we analyzed the individual thigmotactic preference of domiciliary cockroaches (Periplaneta americana (Linnaeus, 1758) (Blattodea: Blattidae)) and how it affected the fleeing behavior of isolated individuals inside a shelter after receiving a light stimulus. We notably highlight how isolated individuals show different consistent preferences regarding their position in the shelter, which is due to the individual thigmotaxis level, before the fleeing behavior. During the fleeing itself, cockroaches nearer to the wall, and therefore with more positive thigmotaxis, showed slower reaction lantencies to the stimulus. We propose that thigmotaxis homogenizes the interindividual differences among individuals and is important to explain the individual and collective fleeing behavior. [ABSTRACT FROM AUTHOR]

Larval populations of Clunio sp.1 are reported for the first time from marine fouling samples obtained in Hurghada during November 2015. This is a new record for the Egyptian Red Sea fauna. A full structural description of the larva is provided and its local distribution is discussed. [ABSTRACT FROM AUTHOR]

Most species that are negatively impacted when their densities are low aggregate to minimize this effect. Aggregation has the potential to change how Allee effects are expressed at the population level. We studied the interplay between aggregation and Allee effects in the mountain pine beetle ( Dendroctonus ponderosae Hopkins), an irruptive bark beetle that aggregates to overcome tree defenses. By cooperating to surpass a critical number of attacks per tree, the mountain pine beetle is able to breach host defenses, oviposit, and reproduce. Mountain pine beetles and Hymenopteran parasitoids share some biological features, the most notable of which is obligatory host death as a consequence of parasitoid attack and development. We developed spatiotemporal models of mountain pine beetle dynamics that were based on the Nicholson-Bailey framework but which featured beetle aggregation and a tree-level attack threshold. By fitting our models to data from a local mountain pine beetle outbreak, we demonstrate that due to aggregation, attack thresholds at the tree level can be overcome by a surprisingly low ratio of beetles per susceptible tree at the stand level. This results confirms the importance of considering aggregation in models of organisms that are subject to strong Allee effects. [ABSTRACT FROM AUTHOR]

Although changes to interspecific relationships can significantly alter the composition of insect assemblages, they are often ignored when assessing impacts of environmental change. Long-term ground beetle data were used in this study to analyse ecological networks from three habitats at two sites in Scotland. A Bayesian Network inference algorithm was used to reveal interspecific relationships. The significance and strength of relationships between species (nodes) were estimated along with other network properties. Links were identified as positive relationships if co-occurrences of beetles correlated positively, and as negatives relationships if there was a negative correlation between the occurrences of the species. Most of the species had few links and only 10% of the nodes were connected with several links. Calathus fuscipes , a common carabid in the samples, was the most connected, with nine links to other species. More interspecific relationships were found to be positive than negative, with 48 and 23 links, respectively. The modular structure of the network was assessed and eight separate sub-networks were found. Habitat preferences of the species were clearly represented in the structure of the sets of those five sub-networks containing more than one species and were in line with the findings of the indicator species analysis. In our study, we showed that generated Bayesian networks can model interspecific relationships between carabid species. Due to the relative ease of the collection of field data and the high information content of the results, this method could be incorporated into everyday ecological analysis. [ABSTRACT FROM AUTHOR]

Sphenophorus incurrens Gyllenhal (Coleoptera: Curculionidae) is an insect that feeds mainly on plants of the family Poaceae in the Neotropics. In Mexico, this weevil is an emergent pest of sugarcane. In this study, first the behavioral responses of both sexes to conspecifics were evaluated in a Y-tube olfactometer. Second, the volatiles of S. incurrens were sampled by the dynamic headspace technique and analyzed by gas chromatography coupled with electroantennographic detection (GC-EAD). Third, the antennal-active compound was identified by gas chromatography coupled with mass spectrometry. Finally, the biological activity of the identified compound was evaluated in laboratory and field tests. Our results showed that males emitted a pheromone that attracts both sexes. The GC-EAD analysis of the male volatiles showed that one peak elicited antennal responses from male and female weevils. The compound was identified as 2-methyl-4-octanol. Laboratory and field tests showed that the identified compound is attractive to both sexes of this weevil species, confirming its pheromonal activity. [ABSTRACT FROM AUTHOR]

We present a biologically plausible dynamics model to simulate swarms of flying insects. Our formulation, which is based on biological conclusions and experimental observations, is designed to simulate large insect swarms of varying densities. We use a force-based model that captures different interactions between the insects and the environment and computes collision-free trajectories for each individual insect. Furthermore, we model the noise as a constructive force at the collective level and present a technique to generate noise-induced insect movements in a large swarm that are similar to those observed in real-world trajectories. We use a data-driven formulation that is based on pre-recorded insect trajectories. We also present a novel evaluation metric and a statistical validation approach that takes into account various characteristics of insect motions. In practice, the combination of Curl noise function with our dynamics model is used to generate realistic swarm simulations and emergent behaviors. We highlight its performance for simulating large flying swarms of midges, fruit fly, locusts and moths and demonstrate many collective behaviors, including aggregation, migration, phase transition, and escape responses. [ABSTRACT FROM AUTHOR]

Vespula germanica is a social wasp that has become established outside its native range in many regions of the world, becoming a major pest in the invaded areas. In the present work we analyze social communication processes used by V. germanica when exploiting un-depleted food sources. For this purpose, we investigated the arrival pattern of wasps at a protein bait and evaluated whether a forager recruited conspecifics in three different situations: foragers were able to return to the nest (full communication), foragers were removed on arrival (communication impeded), or only one forager was allowed to return to the nest (local enhancement restricted). Results demonstrated the existence of recruitment in V. germanica, given that very different patterns of wasp arrivals and a higher frequency of wasp visits to the resource were observed when communication flow between experienced and naive foragers was allowed. Our findings showed that recruitment takes place at a distance from the food source, in addition to local enhancement. When both local enhancement and distant recruitment were occurring simultaneously, the pattern of wasp arrival was exponential. When recruitment occurred only distant from the feeder, the arrival pattern was linear, but the number of wasps arriving was twice as many as when neither communication nor local enhancement was allowed. Moreover, when return to the nest was impeded, wasp arrival at the bait was regular and constant, indicating that naive wasps forage individually and are not spatially aggregated. In conclusion, this is the first study to demonstrate recruitment in V. germanica at a distance from the food source by modelling wasps’ arrival to a protein-based resource. In addition, the existence of correlations when communication was allowed and reflected in tandem arrivals indicates that we were not in the presence of random processes. [ABSTRACT FROM AUTHOR]

In social insects, secretions of the exocrine gland may modulate their behavior. Although many glands have their functions elucidated, this is absent for the intramandibular glands in ants. To study the function of intramandibular gland secretions in the antNeoponera villosa, its compounds were subjected to behavioral analyses. These analyses revealed a significant increase in the walking time of ants exposed to the nestmate mandible extract. The results suggest that intramandibular gland compounds ofN. villosamay play the role of alarm or scent trial pheromones. [ABSTRACT FROM AUTHOR]

Plum curculio, Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae), is a key pest of stone and pome fruits in North America. The behavioral response of adults of different physiological states (sex, age, diet, and mating status) to three commercially available synthetic lures, benzaldehyde (BZ) and plum essence (PE), the male-produced aggregation pheromone, grandisoic acid (GA), or their combinations, was studied in the laboratory. Four choice olfactometer bioassays demonstrated significant attraction of both sexes to PE lure. Both BZ and GA lures were not attractive to plum curculio when tested as commercially formulated. PE had higher release rate (1.51 mg/hr) than BZ (0.36 mg/hr) and GA (ca. 0.04 mg/hr), suggesting that the higher attractiveness of PE may be due to its relatively higher release rates. Tests with combined lures showed a neutral effect of combining GA with PE and an inhibitory effect of combining BZ with PE. The physiological conditions of the weevils had no significant effect on their response to the lures. Olfactometer tests with pure 1,2,4-trichlorobenzene (TCB) confirmed that this compound was inhibitory to plum curculio. These results are discussed in relation to the contrasting field reports which implicated BZ + GA as an effective attractant for plum curculio. [ABSTRACT FROM AUTHOR]

The article describes the importance of the aggregate way of life of leaf beetles' larvae G. viminalis (Linnaeus, 1758) in the laboratory conditions. The obtained data prove that the aggregate way of life of G. viminalis larvae has a significant impact on the intensity of their feeding, growth and development. It is concluded that such coexistence of larvae allows them to build a defense strategy, ensuring survival in groups at early stages of development. [ABSTRACT FROM AUTHOR]

Pathogens are predicted to pose a particular threat to eusocial insects because infections can spread rapidly in colonies with high densities of closely related individuals. In ants, there are two major castes: workers and reproductives. Sterile workers receive no direct benefit from investing in immunity, but can gain indirect fitness benefits if their immunity aids the survival of their fertile siblings. Virgin reproductives (alates), on the other hand, may be able to increase their investment in reproduction, rather than in immunity, because of the protection they receive from workers. Thus, we expect colonies to have highly immune workers, but relatively more susceptible alates. We examined the survival of workers, gynes, and males of nine ant species collected in Peru and Canada when exposed to the entomopathogenic fungus Beauveria bassiana. For the seven species in which treatment with B. bassiana increased ant mortality relative to controls, we found workers were significantly less susceptible compared with both alate sexes. Female and male alates did not differ significantly in their immunocompetence. Our results suggest that, as with other nonreproductive tasks in ant colonies like foraging and nest maintenance, workers have primary responsibility for colony immunity, allowing alates to specialize on reproduction. We highlight the importance of colony-level selection on individual immunity in ants and other eusocial organisms. [ABSTRACT FROM AUTHOR]

In many species of insects, larvae are distributed in an aggregated fashion. As they may differ in size and size matters to predation risk, small larvae may be less likely to fall prey to predators when near large and therefore better-defended larvae. We hypothesize that the small larvae may profit even more when these large larvae are siblings. We tested this hypothesis on kinship-dependent survival in groups of larvae of the Western flower thrips ( Frankliniella occidentalis) exposed to a predatory mite ( Iphiseius degenerans). Our experiments showed that small larvae in sibling groups survive significantly better than in non-sibling groups, but only when such groups consisted of a mixture of small and large larvae. To test whether the survival effect we found is due to familiarity of thrips larvae growing up together (i.e. on one leaf), we also measured survival in sibling groups of larvae grown up on different leaves and in non-sibling groups of larvae grown up on the same leaf. These experiments showed an increased survival of small thrips larvae only in groups of sibling larvae from the same leaf. Non-sibling larvae did not show an increased survival when they come from the same leaf. Our results indicated that the increased survival in sibling groups was only partly due to the familiarity effect we tested. Growing up together did not return the same survival effect for non-siblings as it did for siblings. We conclude that growing up together is a necessary but not sufficient condition for discrimination in thrips larvae. [ABSTRACT FROM AUTHOR]

During the mating season, honeybee males, the drones, gather in congregation areas 10-40 m above ground. When a receptive female, a queen, enters the congregation, drones are attracted to her by queen-produced pheromones and visual cues and attempt to mate with the queen in mid-air. It is still unclear how drones and queens find the congregations. Visual cues on the horizon are most probably used for long-range orientation. For shorter-range orientation, however, attraction by a drone-produced aggregation pheromone has been proposed, yet so far its existence has not been confirmed conclusively. The low accessibility of congregation areas high up in the air is a major hurdle and precise control of experimental conditions often remains unsatisfactory in field studies. Here, we used a locomotion compensator-based walking simulator to investigate drones' innate odor preferences under controlled laboratory conditions. We tested behavioral responses of drones to 9-oxo-2-decenoic acid (9-ODA), the major queen-produced sexual attractant, and to queen mandibular pheromone (QMP), an artificial blend of 9-ODA and several other queen-derived components. While 9-ODA strongly dominates the odor bouquet of virgin queens, QMP rather resembles the bouquet of mated queens. In our assay, drones were attracted by 9-ODA, but not by QMP. We also investigated the potential attractiveness of male-derived odors by testing drones' orientation responses to the odor bouquet of groups of 10 living drones or workers. Our results demonstrate that honeybee drones are attracted by groups of other drones (but not by workers), which may indicate a role of drone-emitted cues for the formation of congregations. [ABSTRACT FROM AUTHOR]

Due to the problem of identification, Chironomidae larvae, although very abundant, are often avoided or not properly used in bioassessment programs. The aim of this work was to test how different aggregation processes-taxonomic resolution and the random aggregation approach (best practicable aggregation of species-BestAgg) affect the analysis of chironomid communities regarding any information loss. The self-organizing map method, together with classification strength analysis and Spearman's rank correlation, revealed that the genus-level and BestAgg-abundance matrix most accurately approximated the species-level community pattern. The subfamily-level dataset was ineffective at presenting the chironomid community structure, with a substantially lower concordance with the species-level dataset. The biologic environmental gradients analyses presented the same set of important environmental variables for the species-level, genus-level, and BestAgg-abundance matrix. The indicator values analysis showed that indicator genera provide information very close to that gained from species indicators. According to our results, the numeric relationship between species and higher taxa influences taxonomic scaling, limiting Chironomidae family aggregation, with acceptable information loss only up to genus level. In addition, the BestAgg approach, with the maximum level of aggregation, properly assesses the community structure and consequently describes environmental conditions. [ABSTRACT FROM AUTHOR]

Background In social groups, dominant individuals may socially inhibit reproduction of subordinates using aggressive interactions or, in the case of highly eusocial insects, pheromonal communication. It has been hypothesized these two modes of reproductive inhibition utilize conserved pathways. Here, we use a comparative framework to investigate the chemical and genomic underpinnings of reproductive dominance in the primitively eusocial wasp Polistes metricus. Our goals were to first characterize transcriptomic and chemical correlates of reproductive dominance and second, to test whether dominance-associated mechanisms in paper wasps overlapped with aggression or pheromone-related gene expression patterns in other species. To explore whether conserved molecular pathways relate to dominance, we compared wasp transcriptomic data to previous studies of gene expression associated with pheromonal communication and queen-worker differences in honey bees, and aggressive behavior in bees, Drosophila, and mice. Results By examining dominant and subordinate females from queen and worker castes in early and late season colonies, we found that cuticular hydrocarbon profiles and genome-wide patterns of brain gene expression were primarily associated with season/social environment rather than dominance status. In contrast, gene expression patterns in the ovaries were associated primarily with caste and ovary activation. Comparative analyses suggest genes identified as differentially expressed in wasp brains are not related to queen pheromonal communication or caste in bees, but were significantly more likely to be associated with aggression in other insects (bees, flies), and even a mammal (mice). Conclusions This study provides the first comprehensive chemical and molecular analysis of reproductive dominance in paper wasps. We found little evidence for a chemical basis for reproductive dominance in P. metricus, and our transcriptomic analyses suggest that different pathways regulate dominance in paper wasps and pheromone response in bees. Furthermore, there was a substantial impact of season/social environment on gene expression patterns, indicating the important role of external cues in shaping the molecular processes regulating behavior. Interestingly, genes associated with dominance in wasps were also associated with aggressive behavior in bees, solitary insects and mammals. Thus, genes involved in social regulation of reproduction in Polistes may have conserved functions associated with aggression in insects and other taxa. [ABSTRACT FROM AUTHOR]

Research on the evolution of cooperative groups tends to explore the costs and benefits of cooperation, with less focus on the proximate behavioral changes necessary for the transition from solitary to cooperative living. However, understanding what proximate changes must occur, as well as those pre-conditions already in place, is critical to understanding the origins and evolution of sociality. The California harvester ant Pogonomyrmex californicus demonstrates population-level variation in colony founding over a close geographic range. In adjacent populations, queens either found nests as single individuals (haplometrosis) or form cooperative groups of nonrelatives (pleometrosis). We compared aggregation, aggression, and tolerance of queens from one pleometrotic and two haplometrotic populations during nest initiation, to determine which behaviors show an evolutionary shift and which are present at the transition to pleometrosis. Surprisingly, within-nest aggregative behavior was equally present among all populations. In nesting boxes with multiple available brood-rearing sites, both queen types readily formed and clustered around a single common brood pile, suggesting that innate attraction to brood (offspring) facilitates the transition to social aggregation. In contrast, queens from the three populations differed in their probabilities of attraction on the ground to nest sites occupied by other queens and in levels of aggression. Our results suggest that some key behavioral mechanisms facilitating cooperation in P. californicus are in place prior to the evolution of pleometrosis and that the switch from aggression to tolerance is critical for the evolution of stable cooperative associations. [ABSTRACT FROM AUTHOR]

Terrestrial isopods are known to be sensitive to humidity, brightness or temperature. Until now, aggregation was assumed to depend on these sensitivities as a result of individual preferences. In this paper, we show that the social component is also important in the isopod aggregation phenomenon. In experimental arenas with two identical shelters up to nearly 90% of woodlice aggregated under shelters. This aggregation was quick as in 10 minutes most of the animals aggregated, irrespective of their density. Nonetheless, 10-15% of the animals walked around the arena, rarely forming very small and short-lasting aggregates outside shelters. Woodlice aggregated preferably under one of the shelters in 77% of experiments. Indeed, almost 80% of the animals out of 40, 60 or 80 animals in the arena aggregated under one shelter. In arenas with 100 individuals the aggregations were proportionally smaller (70%). Our results revealed that 70 animals was a maximum number of woodlice in an aggregate. We concluded that the location of aggregates is strongly governed by individual preferences but the dynamics of aggregation and collective choice are controlled by social interaction between congeners. The tested densities of the animals in the arena did not impact the aggregation patterns. [ABSTRACT FROM AUTHOR]

The article offers information on a study related to hilltopping in insects belonging to the subfamilies Myopinae and Dalmanniinae, which is behavior of males aggregating on a peak and mating with the females flying there. It further informs that several studies were previously conducted for studying hilltoping in species including Conopidae. It mentions that hilltoping is a strategy which is adopted for mate finding in insects which includes rare species or widely dispersed species.

Ladybird beetles (Coleoptera: Coccinellidae) are predators of aphid and psyllid species and are often released or encouraged into timber plantations as natural enemies of economic pests. Some temperate coccinellid species overwinter in mass aggregations; however, little is known about coccinellid aggregations in Australia. Aggregations of Harmonia conformis were observed only on stone walls of a camp shelter near Shelley, Victoria in July 2014. Publication of more observational records and dedicated surveys will determine if old stone walls and buildings in managed landscapes have the potential to provide overwintering habitat for natural enemies and other beneficial insects. [ABSTRACT FROM AUTHOR]

We suggest that male aggregation in Euphydryas may be a side effect of their mate-finding behavior. Euphydryas males investigate any flying object that resembles a female and, as a result, spend much of their time chasing each other. Under some circumstances, this male-male chasing behavior can lead to the "incidental" formation of male aggregations. We tested our "incidental aggregation" hypothesis with a population of E. anicia that occurs on a flat plain, thereby eliminating topographical factors that may bias male movement. In three of four years the distribution of males was significantly aggregated. Observations of male movements indicate that when their flight is uninterrupted by encounters with other butterflies, males tend to follow highly directional straight paths. However, when they encounter other males, females, or even non-conspecifics, the directionality of their movement breaks down; that is, the direction of the flight after a chase is not correlated with the direction of the flight before the chase. Using a computer simulation, we show that the tendency of males to chase each other results in a clumped distribution of males. A behavior that is presumably adaptive-namely, to investigate all possible mates-therefore has an incidental effect on the pattern of male movement, resulting in the formation of male aggregations. [ABSTRACT FROM AUTHOR]

Many insect species form aggregations in either the larval or adult stage. The evolution of gregariousness in insects may seem disadvantageous because aggregations are easily discovered by a predator and because insects are small and slow in relation to many potential predators that then have the capacity to consume an entire group. For animals in general, a benefit of group living may be a decreased risk of predator attack on any particular individual. For insects, this effect, called dilution, can be a consequence of distastefulness, which limits the number of prey that a predator can take. A model is developed in which we vary the risk of detection in relation to group size and the degree of prey distastefulness and aposematic coloration, both of which affect the number of prey a predator samples during avoidance learning. According to the model, members of small groups may have a higher rate of death from predation than solitary individuals, but above a certain minimum group size, group members do better than solitary individuals. As group size increases above the minimum value, group members suffer fewer and fewer deaths from predation. However, other factors, unrelated to predation, constrain group size. For gregariousness to be advantageous, such constraints must be weak enough to allow groups larger than the minimum size. Our model predicts that (1) gregarious insect species should be distasteful, and the evolution of distastefulness should precede that of gregariousness; (2) the distribution of group sizes among species should show a bimodal form; and (3) the largest aggregations should be found in forms that have fewer constraints unrelated to predation on group size. The agreement between these predictions and data is discussed. [ABSTRACT FROM AUTHOR]

Densities of two allochronic, geographically overlapping populations of periodical cicadas were censused in the eggnest stage in order to test the hypothesis that larger populations can be supported when the root-feeding nymphs are of different ages. In a frequently burned chest-high stand of scrub oak (Quercus ilicifolia) on Long Island, Magicicada septendecim emerged in 1974 (Brood XIV), then again in 1978 (Brood I) from under the same individual plants over an area of about 1.2 x 3.5 km. Adjacent to this, in the same vegetation, periodical cicadas emerged in 1974 but not in 1978. A nested scheme of sampling revealed significantly higher total eggnest densities when Broods I and XIV occupied the same ground than when Brood XIV existed by itself. The major component of variation in density was among quadrats within plots. That is, cicadas exhibited patchiness on a small scale (metres) which was not reflected in patchiness on a larger scale (tens of metres). Microspatial distributions were thus patchy in both Brood I and XIV, yet dense patches of one brood were usually not correlated with dense patches of the other. Apparently the vegetation appears about as uniform to the cicadas as it does to the human observer, the primary cause of the patchy oviposition pattern being either mutual attraction among oviposition females or lack of dispersal from the chorusing and mating centers. The degree of patchiness is inversely density-dependent, in that the most patchy distributions were invariably those with lowest density. However, several plots with low density were not very patchy. This pattern makes biological sense, remembering that mutual attraction cannot operate unless the animals perceive one another, and at low densities they may sometimes do so and sometimes not. Further analysis, plotting mean crowding against mean density (following Iwao 1968) suggests that mutual attraction among females is weakened at high densities. As modes of data analysis, both kinds of plots-mean crowding vs. mean density and patchiness vs. mean density-bring out patterns that would not otherwise be apparent. In this connection, we offer an empirical definition for the concept, density-independent aggregation." [ABSTRACT FROM AUTHOR]

Spittlebugs are the vectors of the bacterium Xylella fastidiosa Wells in Europe, the causal agent of olive dieback epidemic in Apulia, Italy. Selection and distribution of different spittlebug species on host-plants were investigated during field surveys in 2016–2018 in four olive orchards of Apulia and Liguria Regions of Italy. The nymphal population in the herbaceous cover was estimated using quadrat samplings. Adults were collected by sweeping net on three different vegetational components: herbaceous cover, olive canopy, and wild woody plants. Three species of spittlebugs were collected: Philaenus spumarius L., Neophilaenus campestris (Fallén), and Aphrophora alni (L.) (Hemiptera: Aphrophoridae). Philaenus spumarius was the predominant species both in Apulia and Liguria olive groves. Nymphal stages are highly polyphagous, selecting preferentially Asteraceae Fabaceae plant families, in particular some genera, e.g., Picris, Crepis, Sonchus, Bellis, Cichorium, and Medicago. Host-plant preference of nymphs varies according to the Region and through time and nymphal instar. In the monitored sites, adults peak on olive trees earlier in Apulia (i.e., during inflorescence emergence) than in Liguria (i.e., during flowering and beginning of fruit development). Principal alternative woody hosts are Quercus spp. and Pistacia spp. Knowledge concerning plant selection and ecological traits of spittlebugs in different Mediterranean olive production areas is needed to design effective and precise control strategies against X. fastidiosa vectors in olive groves, such as ground cover modifications to reduce populations of spittlebug vectors. [ABSTRACT FROM AUTHOR]

The challenges of maintaining cohesion while making collective decisions in social or aggregating insects can result in the emergence of a leader or leaders. Larval aggregations of the steel-blue sawfly Perga affinis forage nocturnally, and some larvae lead the aggregation on foraging trips more often than expected by chance. We investigated the relationship between these leader and follower roles by comparing the weight and growth of individual larvae with different roles. Our observations reveal no significant difference between the growth of leaders and followers, suggesting that the role of leadership may not provide direct foraging benefits. However, by experimentally manipulating the social structure of larval aggregations, we found that individuals within aggregations that comprise a mixture of leaders and followers enjoy higher growth rates than those in aggregations comprising a single behavioural type. These data demonstrate, for the first time, individual benefits to maintaining a balance of leader and follower roles within larval aggregations, and highlight the importance of considering the perspectives of both leaders and followers when investigating the evolutionary significance of this behavioural variation within animal groups. [ABSTRACT FROM AUTHOR]