Abstract: Current evidence suggests that in Hetaerina damselflies males exhibit lek mating system. In this study, in order to answer if the same occurs in Hetaerina rosea Selys, we manipulated vegetation substrates used as territories and quantified the number of visiting females, males defending territories and fight intensity. We also examined whether body size and wing pigmentation are selectable traits in male-male competition, and if age affects male territorial behavior. Our results showed that males with larger pigmented areas won more contests, independently of body size. Old males changed from territoriality to sneaking strategy. Contrary to other Hetaerina species, males of H. rosea do not display lek behavior, but defend resources according to the resource defense polygyny strategy
Abstract: Thrips are cosmopolitan and abundant insects with great diversity in the Neotropics, but taxonomic and crop pest aspects comprise almost all of our knowledge of these insects. Here we describe a unique case of an ectoparasite species, Aulacothrips dictyotus Hood (Heterothripidae), which infests and also uses as dispersal vector (phoresy behaviour) the hemipteran Enchenopa brasiliensis (Membracidae). Thrips fix themselves on the ventral region of their hosts, at the junction of thorax and abdomen. Phoresy takes place when the attached thrips are transported to other plants and/or host aggregations. Phoresy is a useful long range dispersal mechanism for this weakly flying thrip species. Out of the 6000 species of thrips described, most are phytophagous and fungivorous, and only A. dictyotus performs ectoparasitism and phoretic behaviour.
Abstract: We sampled the ant fauna associated with the extrafloral nectary-bearing plant Lualea multiflora in cerrado. Thirty trees were tagged and inspected three times per month during a period of 10 months. In each inspection the ant species and number of individuals were registered. The most frequent and abundant species were Camponotus crassus and Cephalotes pusillus, and after 18-19 samples new species were not found. Our study revealed the importance of considering the frequency of the ant species and not only their abundance for a correct interpretation of their importance in ant-plant interactions and showed that an extensive sampling methodology is needed to know the species involved in these interactions.
Abstract: of relatively few studies of behavioural ecology. The sexual behaviour and maternal
care of the spider Aglaoctenus lagotis (Lycosidae) is described here. We performed
experimental manipulations to test the hypothesis that males are attracted by
female cues in the web. Two predictions were tested: (a) webs used by a virgin female
will attract more males than webs used by an inseminated female; (b) the main cue
in the web is chemical, so webs recently used by virgin females will attract more
males than those that are not recently used. Additionally, we tested the hypothesis
that maternal care increases offspring survivorship. Results showed that males are
attracted by recently used webs (z = 0.0015; p = 0.037; z-test) and webs of virgin
females (z = 0.041; p = 0.036, z-test). Male sexual behaviour presented three different
categories: court, pre-mate and mate. After the mating, the females built a
cocoon that was transported adhered to the spinnerets and held by the last pair of
legs. After the hatching of the eggs, the young migrated to the dorsal region of the
mother’s body for 5 days. During maternal care the mother eliminates a yellowish
drop from its oral cavity, which is collected by the young. During the development
of the young until adulthood, the offspring that have their mother present in the
first stages of life have greater survival compared with those without maternal care.
Our results make it possible to perform comparative analyses between a South
American Lycosidae species and other species distributed worldwide.
Abstract: Current evidence suggests that ant–plant relationships
may influence species composition, abundance,
and interactions at the community scale. The main resource
that plants offer to ants is extrafloral nectar (EFN) and the
major part of published studies shown benefits from ants to
plants possessing EFNs. However, the complementary
question of whether and how ants benefit from EFNs is
rarely addressed. Here, we present the results of a longterm
study to demonstrate whether EFN has a positive
effect on ant colony fitness. We quantified colony growth
rate, survival and the final weight of individuals as measures
of benefit derived from EFN. Our results provide
clear evidence that EFN can have a significant positive
impact on the survivorship, growth and reproduction of the
Myrmicinae Cephalotes pusillus. In fact, a diet rich in EFN
(providing at least 30 cal per day) resulted in five times
more individuals per colony, greater body weights, and
more eggs. These results have shed new light on the relationships
between ants and EFN-bearing plants such as in
tropical and temperate systems. The ant C. pusillus is the
first case in which we have firm evidence that EFN
improves colony growth and development, corroborating
more than 100 years of experimental evidence of benefits
to plants in these widespread relationships
Abstract: Division of labor is a strategy that maximizes the foraging and reproductive
success of eusocial insects. Although some arachnids exhibit colony
structure and social organization similar to that of hymenopterans, temporal
polyethism has only been demonstrated in few species. The social
organization of cooperative pseudoscorpions Paratemnoides nidificator is
similar to that of social spiders, but it involves a clear division of labor.
Work allocation was experimentally investigated in colonies composed
of only one developmental stage (young or adults) or by one sex (males
or females), through laboratory manipulation. During 44 h of observation,
more than 14 000 behavioral repetitions were quantified, distributed
in 95 different types of behavioral acts, and grouped in 10
behavioral categories. The results showed that reproductive colonies of
P. nidificator are maintained by gender- and age-based activities. Males
and non-reproductive females performed the external cleaning of the
colony and prey capture. Reproductive females take care of the juveniles
and build reproductive silk chambers. Nymphs build most of the molt
chambers and perform internal cleaning. In the absence of nymphs,
male colonies survived 1–2 mo, while female colonies survived 3–4 mo.
In nymph colonies, work is readjusted so that all maintenance tasks are
executed. This is the first study clearly demonstrating division of tasks in
arachnids. It suggests that specialization is an adaptative and evolutionarily
old trait in this species. Unlike cooperative spiders, P. nidificator possesses
physiological (e.g. reproduction, ecdysis, lifespan) and behavioral
(e.g. behavioral synchrony or self-organization) characteristics that allow
task specialization.
Abstract: The question if ant behaviour and biological
limitations should be considered before generalisations
about the ant’s defensive capabilities in ant–plant relationships
was explored through a new experimental manipulation.
In the Brazilian tropical savanna, we tested the
protective action of Cephalotes pusillus Klug on the
extrafloral nectar-bearing plant Ouratea spectabilis Engl.
(Ochnaceae). Three treatments were performed: control
(free ant access), Cephalotes-treatment (access permitted
only to C. pusillus), and ant free treatment (no ants). No
difference was found in the levels of leaf herbivory among
experimental stems. Visitation by different ant species to
control stems translated into significantly greater fruit and
seed production by this stem category than by ant-free and
Cephalotes-treated stems. Thus, results showed that an
investigation of system’s natural history, ant’s morphological
traits, defensive capabilities and behaviour are needed
before a protective role is inferred to each associated ant
species.
Abstract: Behavioural patterns of birds commonly vary
according to flock size and daily activity pattern. Southern
lapwing behaviours and their relation with flock size were
studied, as well as the relationship between the frequency
of behaviours and the period of the day. Results showed
that the proportion of time spent in foraging and vigilance
was higher during the morning, when small groups were
more common, and decreased from midday on, when group
size increased. Maintenance and inactivity (sleeping)
behaviours presented the opposite pattern. Correlation
between flock size and period of the day, and their similar
effects on bird behaviour may be evidence that groups of
different sizes could have different functions throughout
the day. Our results show that southern lapwings seem to
form smaller flocks for feeding in the beginning of the day
and larger flocks later for different activities (e.g., maintenance
and sleeping). In this sense, it is possible that group
size variation throughout the day is related to different
demands for specific behaviours (functions) of groups,
according to the daily activity patterns of the birds.
Abstract: The causal mechanisms shaping and structuring ecological communities are among the
most important themes in ecology. The study of insect-plant interactions in trophic nets is pointed out
as basic to improve our knowledge on this issue. The cerrado tropical savanna, although extremely
diverse, distributed in more than 20% of the Brazilian territory and fi lled up with rich examples of
multitrophic interactions, is underexplored in terms of biodiversity interaction. Here, this ecosystem
is suggested as valuable to the study of insect-plant interactions whose understanding can throw a
new light at the ecological communities’ theory. Three distinct systems: extrafl oral nectary plants or
trophobiont herbivores and the associated ant fauna; fl oral herbivores-predators-pollinators; and plantsforest
engineers and associated fauna, will serve as examples to illustrate promising new pathways in
cerrado. The aim of this brief text is to instigate young researchers, mainly entomologists, to initiate
more elaborated fi eld work, including experimental manipulations in multitrophic systems, to explore
in an interactive way the structure that maintain preserved viable communities in the Neotropical
savanna.
Abstract: Weaver ants use silk produced by their larvae to build their nests. This behaviour is one of the more notable instances of social cooperation in animals; however, there are few studies of Brazilian species. This study investigated the ecology, natural history and behaviour of the weaver ant Camponotus (Myrmobrachys) senex in Brazil and showed that the weaver larvae have a fundamental function in nest building. The nests were always arboreal (one nest/plant), with a round form, beige in colour, and with leaves and shoots adhered to the silk nest. The average size was 34.24 cm and the average weight was 163.87 g; nests contained up to 50,000 individuals and several queens. Fusion and fission of colony parts were observed for C. senex. Worker ants were frequently observed feeding on honeydew, fruits and insects; and defended their territory. We suggest that C. senex larvae could be considered an effective caste, valuable in nest construction.
Abstract: ySudies of species survey are important to know the available natural resources and to get useful information about the ecological characteristics of a specific area. There are not studies, on this issue, related to social wasps, in the Triangulo Mineiro region. The present study describes the diversity of species found in fragments of the cerrado region in Uberlandia, MG, and their temporal distribution. The field study was conducted from October 2003 to September 2004, and 43 samplings were carried out'using active searching (24) and point sampling (19) methodologies. Twenty-nine species were found in 10 genera, Polybia and Polistes corresponding to 51.5% of the total listing. Mischocyttarus cerberus styx Richards represented 26.5% of the total individuals recorded by active searching and Agelaia pallipes (Olivier) corresponded to 57.6% by point sampling. Two species had their first record for the state of Minas Gerais: Polybia striata (Fabricius) and M cerberus styx. The studied fragments presented a high level of diversity (H' = 0.66 to 1.16), a large number of rare species and a few common species. To collect the more common species the point sampling method was satisfactory while active searching was better to collect the rarer species. The active searching methodology was more efficient than point sampling, however some species could only be collected by point sampling. These factors showed that in order to carry out a wasp survey, a combination of different collection methodologies seems to be more appropriate.
Abstract: We compared the effects of ant presence at extrafloral nectaries of Lafoensia pacari St. Hil. on herbivore damage and silicon accumulation. Plants that were accessible
to ants experienced lower herbivory levels over the first 3 mo of the experiment. After 3 mo, most leaves were fully expanded with inactive extrafloral nectaries; by
6 mo there was no effect of ant access on herbivore damage. Along with experiencing higher herbivory, plants in the ant-exclusion treatment had significantly higher
silicon levels in their leaves, suggesting that silicon serves as an induced defense in this ant–plant–herbivore interaction.
Abstract: The aim of this study was to determine if the mistletoe Struthanthus aff. polyanthus shows host specificity, and if host abundance and twig architecture influence this specificity in Cerrado (senso strictu). An area of 1.3 ha of natural savanna was sampled for the occurrence of the mistletoe. The twigs of the hosts were classified as vertical or horizontal, and the bark as smooth or rough. We sampled a total of 666 trees in the study site and 118 individuals (17.7%) hosted S. aff. polyanthus. The abundance of mistletoe was significantly affected by the bark type, but not by the twigs inclination. In the cerrado, S. aff. polyanthus seems to be a generalist, with a tendency to be more common on some hosts (Kielmeyera coriacea, Pouteria ramiflora and Styraxjerrugineus), prefering that with rough bark type. (c) 2005 Elsevier GmbH. All rights reserved.
Abstract: Interactions between ants and hemipterans (Auchenorryncha e Sternorryncha) are
important to understand the impact of multitrophic relationships on arthropod diversity on vegetation.
The present field study experimentally investigates the outcomes of a multispecies interaction involving
four components: ants, hemipteran trophobionts (Enchenopa brasiliensis Strümpel, chewing
herbivores, and host plant (Solanum lycocarpum St. Hill). The occurrence of temporal variation in
the outcomes of the relationships was also investigated. Results showed that ants were benefited by
a rich food source predictable in time and space, while membracids survived better under ant
attendance. Ant tending also had a positive impact on treehopper fecundity. Presence of ant-hemipteran
associations was demonstrated to benefit the host plant through a significant reduction in herbivory
caused by chewing insects
Abstract: In this study, we provide an ethograrn for the harvestman Ilhaia cuspidata and describe the daily activity pattern of captive individuals. We also provide a comparison between the behavioral repertory of this species with that of the syntopic Discocyrtus oliverioi. Five females and four males of l. cuspidata were maintained in the same terrarium from November 1999-November 2000 for qualitative and quantitative observations. Twenty behavioral acts were recorded, classified in seven categories and the relative frequency of each was determined: exploration (69.8%), resting (16.7%), feeding (6.3%), grooming (4.4%), social interactions (2.6%), reproduction (0.1%) and others (0.3%). There was a marked difference in the frequency of the behavioral categories between sexes: females fed more frequently than males and males were involved in social interactions more frequently than females. During most of the daylight hours, individuals remained inside shelters and became active from 19:00-09:00 h. Although l. cuspidata and D. oliverioi showed almost the same behavioral acts, there were quantitative differences in their repertories: the relative frequency of behavioral categories "resting" and "social interactions" were higher for L cuspidata whereas "reproduction" and "grooming" were higher for D. oliverioi. The main qualitative difference between these two species was related to the forms of parental care: females of D. oliverioi guard their eggs and first instar juveniles, whereas females of I. cuspidata scatter their eggs in time and space and do not actively protect their offspring. Since both species share the same habitats (sometimes in multi-species aggregations), the behavioral differences between them may be explained by particular morphological and physiological characteristics of the species, as well as by phylogenetic constraints.
Abstract: Biodiversity as a focus for conservation efforts has received increased attention since the second half of the last century. Until recently a more landscape-level view of biodiversity has prevailed. This essay proposes to discuss natural diversity in ways that embrace the extreme richness inherent in plant animal interactions, including not only trophic relationships, but also aspects of life history, biology, and behavior of related species. The ant-plant-herbivore systems in Cerrado vegetation are pointed out as good model for gaining a better understanding of "interaction biodiversity".
Abstract: Ecological studies of host - parasite interactions in the tropics are generally restricted to descriptive taxonomic aspects. The present study had as its objective identification of the metazoan ectoparasites of piranhas Pygocentrus nattereri, Serrasalmus spilopleura and S. marginatus in lentic and lotic environments in the Pantanal region, Brazil. We collected the samples in the Miranda River basin and in three ponds. We caught fishes using hook and line. We found that branchiuran crustaceans infested about 30% of the piranhas. We found four branchiuran species: Dolops carvalhoi, Argulus elongatus, Argulus aff. juparanaensis and Dipterolpetis hirundo, which represent new findings in host - parasite relationships in the Neotropics. When comparing lotic and lentic environments, we observed higher infestation rates in rivers than in ponds for all the hosts. P. nattereri had the highest prevalence and the intensity rates in both the environments. The body parts of hosts with the highest frequencies of parasitism were the ventral area in P. nattereri, the gullet area in S. spilopleura and ventral areas and external gills in S. marginatus. In relation to the prevalence of the parasites we observed significant differences between the hydrological seasons and the piranha species, nevertheless hosts were more parasitized in the dry season. The species with highest rates of infestation, P. nattereri and S. spilopleura, live in schools, which indicates that the high parasite load may be a direct consequence of the proximity between individuals. We believe that the higher rates of infestation in the dry season result from the increase in host density in drying ponds imitating the conditions found in fish farming. Seasonal changes in water level and temperature can also influence the rates of parasitism.
Abstract: We studied the association between the honeydew-
producing membracid Guayaquila xiphias and its
tending ants in the cerrado savanna of Brazil, during
1992 and 1993. Results showed that ants attack potential
enemies of G. xiphias, and that increased ant density
near the treehoppers affects the spatial distribution of
parasitoid wasps on the host plant, keeping them away
from brood-guarding G. xiphias females. Controlled antexclusion
experiments revealed that ant presence (seven
species) reduces the abundance of G. xiphias’ natural enemies
(salticid spiders, syrphid flies, and parasitoid
wasps) on the host plant. The data further showed that
ant-tending not only increased homopteran survival, but
also conferred a direct reproductive benefit to G. xiphias
females, which may abandon the first brood to ants and
lay an additional clutch next to the original brood. Two
years of experimental manipulations, however, showed
that the degree of protection conferred by tending ants
varies yearly, and that at initially high abundance of natural
enemies the ant species differ in their effects on
treehopper survival. Ant effects on treehopper fecundity
also varied with time, and with shifts in the abundance of
natural enemies. This is the first study to simultaneously
demonstrate conditionality in ant-derived benefits related
to both protection and fecundity in an ant-tended Membracidae,
and the first to show the combined action of
these effects in the same system.
Abstract: We investigate the ant fauna associated with the Neotropical treehopper, Guayaquila xiphias, on shrubs of Didymopanax vinosum in the cerrado (savanna) of SE Brazil. Treehoppers infested plane at the border of the cerrado almost euclusively and preferably fed near the apical meristem. During the reproductive phase of the host plant, however, the vast majority of the treehoppers aggregated on the inflorescences. We found 21 ant species harvesting honeydew at G. xiphias aggregations, the most frequent being Camponotus rufipes, Ectatomma edentatum, C. crassus, and C. renggeri. Such a taxonomic diversity of ants tending G. xiphias aggregations in the cerrado is far greater than that reported for any other ant-homopteran system. Daily turnover of ant species at a given treehopper aggregation was observed on 29 percent (64 out of 222) of the G. xiphias aggregations recorded on D. vinosum shrubs. Species replacements probably reflect distinct humidity and temperature ranges tolerated by the species, and may ultimately reduce interspecific competition at homopteran aggregations. Since predation and parasitism on G. xiphias can be severe, and tending: ants protect the homopterans against predators and parasitoids, the round-the-clock activity by ants at G. xiphias aggregations is regarded as crucial for the survival of these treehoppers in the cerrado.
Abstract: Heterothrips peixotoa Del-Claro, Marullo and Mound is described as new. It has remarkably pale forewings, and lives in the flowers of a malpighiaceous shrub in Brazilian cerrado. The sepals of each flower are S-shaped and enclose a central cavity within which the thrips live and breed. Although some large ants are unable to penetrate this cavity, other ants are small enough to enter the space between the petals and sepals, and this leads to a reduction in thrips numbers. Several other members of this genus of thrips are known from the flowers of other species of Malpighiaceae.
Abstract: A new species of the leaf-feeding genus Liothrips is described from Brazilian cerrado. It differs from similar members of the genus with a relatively short head in having antennal segments III-VI extensively yellow, but the legs dark and the forewings pale. The systematic position of the species is discussed, because it is unusually variable in the chaetotaxy; there are either one or two pairs of long postocular setae, and the males have either two or three pairs of long setae on tergite IX. This species is apparently monophagous on Didymopanax vinosum, on which it sometimes severely damages the apical leaves and meristem. Populations reach their maximum after the period of flower and leaf bud production
Abstract: The honeydew-producing treehopper, Guayaquila xiphias, is frequently tended by ants on shrubs of Didymopanax vinosum in the Brazilian savannah. Field experiments showed that the flicking of accumulated honeydew by untended treehoppers provides cues to ground-dwelling ants. Upon finding scattered honeydew droplets on the ground, the ants climb onto the host plant and start tending activity. Honeydew-soaked filter papers placed beneath unoccupied host plants induced significantly more ants to climb onto the plant than water-soaked papers. Because predation and parasitism on G. xiphias can be severe at early stages, and tending ants protect the homopterans against predators and parasitoids, the capacity to attract ants early in life can be crucial for treehopper survival. (C) 1996 The Association for the Study of Animal Behaviour.
Abstract: In the present study we tested whether ants (Camponotus spp.) would stop tending honeydew-producing membracids (Guayaquila xiphias) when an alternative sugar source was available on the host plant (Didymopanax vinosum). Results show that the discovery of an alternate sugar source (simulated extrafloral nectaries) did not provoke desertion by ants. Instead, tending of Guayaquila aggregations continued nearly the same as ant visitation to the honey solution increased steadily within the same period. An increase in the honeydew flow rate by Guayaquila aggregations probably explains why ant tending levels remained unchanged in the presence of an alternate sugar source. The current experimental study and available field evidence from cerrado vegetation do not support the prediction that ants would neglect honeydew-producing homopterans in the presence of extrafloral nectaries.
