Papers by Everton Tizo Pedroso
Prey capture is a determinant aspect in arachnid
sociality, since cooperative hunting allows the ... more Prey capture is a determinant aspect in arachnid
sociality, since cooperative hunting allows the individuals
access to very large prey. Although this behavior has been
extensively studied in some spiders, the knowledge about
some minor groups such as pseudoscorpions is still scarce.
The aim of this study was to analyze diet composition, prey
selectivity and prey size in Colombian populations of the
social pseudoscorpion Paratemnoides nidificator. We collected
prey captured by 112 colonies of P. nidificator as well
as their potential prey. We found that hymenopterans
(Formicidae) were the most consumed prey, while other
items found in the diet included dipterans, embiopterans,
hemipterans, mantids, neuropterans and spiders. When
comparing prey composition, we found a low similarity
between actual and potential prey. Paratemnoides nidificator
showed a positive selectivity towards ant species
which lacked strong defensive mechanisms, while avoiding
potentially dangerous species which possess stingers or
behaved aggressively. When evaluating size, we found that
P. nidificator is able to prey on arthropods up to eight times
larger than itself. These results suggest that by hunting in
groups, P. nidificator is able to capture not only larger prey,
but also prey which could be potentially dangerous for
solitary individuals such as some ant species.
Social parasitism is an intriguing model of arms-race coevolution, in which the parasite exploits... more Social parasitism is an intriguing model of arms-race coevolution, in which the parasite exploits the host social system. The parasite evolves to breakdown the host's defenses. We analyzed the role of 2 pseudoscorpion species that live in mixed colonies in the Brazilian Cerrado (tropical savannah). Multispecies aggregation is a rare phenomenon among arachnids. Mixed pseudoscorpion colonies were studied in nature and in the laboratory during a period of 7 years and the hypothesis of a relationship based on social parasitism between species was evaluated, including the main strategies involved. Experiments and direct behavioral observations indicated that the pseudoscorpion Parachernes melanopygus is a social parasite of Paratemnoides nidificator, able to invade host colonies and exploit their resources by simulating host nymphs' behavior. Although the host species has a recognition system, the parasite evades colony defenses by using a chemical camouflage mechanism. We find support for the hypothesis of a new model of social parasitism among phylogenetically distant pseudoscorpion species. To survive in the host colony, the parasite applies a combination of strategies, previously observed in social brood parasite ants and birds. This phenomenon provides new knowledge of the Arachnida group and also for known models of social parasitism.
MATRIPHAGY IN THE NEOTROPICAL PSEUDOSCORPION PARATEMNOIDES NIDIFICATOR (BALZAN 1888) (ATEMNIDAE
Journal of Arachnology, 2005
Journal of Natural History, 2012
A new species of Mesabolivar is described from Brazilian forests: Mesabolivar delclaroi. The mati... more A new species of Mesabolivar is described from Brazilian forests: Mesabolivar delclaroi. The mating behaviour, postembryonic development, number of egg sacs and eggs, birth rate, number of instars, developmental time until adulthood, sex ratio and size of cephalothorax (per instar) were recorded. The sexual behaviour was described and categorized into four steps: courtship, pre-copulation, copulation and post-copulation. After hatching, individuals presented five instars until maturity. The mean number of eggs (42 ± 16.6) and live births (31.5 ± 3.4) of the first egg sac were significantly greater than that of a second one (23.8 ± 3.8, and 19.25 ± 3.9, respectively). The developmental time from birth to adulthood (130.8 ± 9.6 days) did not differ significantly between egg sacs produced (128.61 ± 11.1). The size of the cephalothorax did not differ among adults or between sexes. The sex ratio revealed a shift in favour of females (4: 3).
Acta Ethologica, 2009
Despite the great biodiversity in the Arachnida, some taxa are still now poorly known, mainly in ... more Despite the great biodiversity in the Arachnida, some taxa are still now poorly known, mainly in terms of biology, ecology, and behavior. Pseudoscorpions are small arachnids (2–8 mm) that live in cryptic environments, being in general solitary predators of other invertebrates. The most studied Pseudoscorpion species are those from temperate areas, which revealed that Pseudoscorpiones present some level of sociality based on maternal care. Most developed sociality is seen in tropical species. Here, we reviewed this issue, presented examples of social behavior, and suggested the steps involved in the evolution of permanent sociality in the Neotropical Atemnidae genus, Paratemnoides. We discussed that the extended parental care, division of labor, cooperative breeding and feeding, and the tolerance among members dividing the same share could be considered enough to characterize a true social life, same in invertebrates.
Pseudoscorpions employ phoresy for dispersal, in which one animal attaches to another for transpo... more Pseudoscorpions employ phoresy for dispersal, in which one animal attaches to another for transportation. This study documents the occurrence and phoresy by Americhernes aff. incertus (Pseudoscorpiones: Chernetidae) on the fly Fannia canicularis (Diptera: Fanniidae) in a fragment of semi-deciduous seasonal Atlantic Forest, in the state of Pernambuco, northeast Brazil. The pseudoscorpions were found attached to the ventral surface of six individual flies. To our knowledge, no previous studies have shown the presence of Americhernes aff. incertus in the northeast Atlantic Forest and its use of flies as a dispersal method.
Gonioterma sp. é uma espécie monófaga de lepidóptero que constrói seus abrigos foliares
(AFs) em ... more Gonioterma sp. é uma espécie monófaga de lepidóptero que constrói seus abrigos foliares
(AFs) em Roupala montana, uma espécie arbórea comum na vegetação dos cerrados do Brasil central. No Parque Estadual de Caldas Novas (PESCAN), estado de Goiás, foi realizado um estudo que procurou investigar: 1) preferência do lepidóptero em construir seu AF de acordo com o tamanho da planta; 2) a composição, riqueza e as guildas dos artrópodes associados aos AFs; e, 3) possível associação entre o tamanho das plantas com a abundância dos artrópodes presentes nesses AFs. Os principais resultados revelaram que as mariposas fêmeas de Gonioterma sp. podem depositar seus ovos em R. montana com diferentes classes de tamanhos, porém com preferência por plantas de maior porte. Os
AFs apresentaram uma elevada riqueza e abundância de artrópodes de diferentes guildas, onde os mais representativos foram os predadores. Foi verificado associação positiva entre o tamanho de R. montana e a ocorrência de determinadas guildas de artrópodes. O papel exercido por Gonioterma sp. como engenheiro de ecossistema ficou destacado pela importância dos abrigos foliares produzidos por este animal como refúgios para a fauna de artrópodes locais.
A new species of Mesabolivar is described from Brazilian forests: Mesabolivar delclaroi. The mati... more A new species of Mesabolivar is described from Brazilian forests: Mesabolivar delclaroi. The mating behaviour, postembryonic development, number of egg sacs and eggs, birth rate, number of instars, developmental time until adulthood, sex ratio and size of cephalothorax (per instar) were recorded. The sexual behaviour was described and categorized into four steps: courtship, pre-copulation, copulation and post-copulation. After hatching, individuals presented five instars until maturity. The mean number of eggs (42 ± 16.6) and live births (31.5 ± 3.4) of the first egg sac were significantly greater than that of a second one (23.8 ± 3.8, and 19.25 ± 3.9, respectively). The developmental time from birth to adulthood (130.8 ± 9.6 days) did not differ significantly between egg sacs produced (128.61 ± 11.1). The size of the cephalothorax did not differ among adults or between sexes. The sex ratio revealed a shift in favour of females (4: 3).
Despite their abundance and diversity, Neotropical spiders have been the subject of relatively fe... more Despite their abundance and diversity, Neotropical spiders have been the subject 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.
Behavioural patterns of birds commonly vary
according to flock size and daily activity pattern. So... more 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.
Pseudoscorpions have the ability to attach themselves to a wide variety of more mobile arthropods... more Pseudoscorpions have the ability to attach themselves to a wide variety of more mobile arthropods. This
interaction has been termed phoresy. We report on a phoretic interaction of Semeiochernes armiger with a
giant tropical fly Pantophthalmus tabaninus in an Amazonian rain forest. Two males and two females of S.
armiger were found attached to the right posterior leg of the fly. In addition, more than two hundred mites
were found on the thorax of the host fly. Long term and detailed studies on the phoretic associations of
pseudoscorpions and hosts in the neotropical rain forest would contribute to a better understanding of these
interactions.
Social parasitism is an intriguing model of arms-race coevolution, in which the parasite exploits... more Social parasitism is an intriguing model of arms-race coevolution, in which the parasite exploits the host social system. The parasite
evolves to breakdown the host’s defenses. We analyzed the role of 2 pseudoscorpion species that live in mixed colonies in the Brazilian
Cerrado (tropical savannah). Multispecies aggregation is a rare phenomenon among arachnids. Mixed pseudoscorpion colonies were
studied in nature and in the laboratory during a period of 7 years and the hypothesis of a relationship based on social parasitism
between species was evaluated, including the main strategies involved. Experiments and direct behavioral observations indicated
that the pseudoscorpion Parachernes melanopygus is a social parasite of Paratemnoides nidificator, able to invade host colonies and
exploit their resources by simulating host nymphs’ behavior. Although the host species has a recognition system, the parasite evades
colony defenses by using a chemical camouflage mechanism. We find support for the hypothesis of a new model of social parasitism
among phylogenetically distant pseudoscorpion species. To survive in the host colony, the parasite applies a combination of strategies,
previously observed in social brood parasite ants and birds. This phenomenon provides new knowledge of the Arachnida group and
also for known models of social parasitism.
Division of labor is a strategy that maximizes the foraging and reproduc-
tive success of eusocia... more Division of labor is a strategy that maximizes the foraging and reproduc-
tive success of eusocial insects. Although some arachnids exhibit colony
structure and social organization similar to that of hymenopterans, tem-
poral 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.
Despite the great biodiversity in the Arachnida,
some taxa are still now poorly known, mainly in ... more Despite the great biodiversity in the Arachnida,
some taxa are still now poorly known, mainly in terms of
biology, ecology, and behavior. Pseudoscorpions are small
arachnids (2–8 mm) that live in cryptic environments, being
in general solitary predators of other invertebrates. The
most studied Pseudoscorpion species are those from
temperate areas, which revealed that Pseudoscorpiones
present some level of sociality based on maternal care.
Most developed sociality is seen in tropical species. Here,
we reviewed this issue, presented examples of social
behavior, and suggested the steps involved in the evolution
of permanent sociality in the Neotropical Atemnidae genus,
Paratemnoides. We discussed that the extended parental
care, division of labor, cooperative breeding and feeding,
and the tolerance among members dividing the same share
could be considered enough to characterize a true social
life, same in invertebrates.
Social behavior is rare among arachnids, and
“permanent-sociality” is a strategy documented only ... more Social behavior is rare among arachnids, and
“permanent-sociality” is a strategy documented only in a
few spider species. Here we describe the feeding and
dispersal behavior of Paratemnoides nidificator, a Neotropical
pseudoscorpion presenting “non-territorial permanent-sociality”.
Field and laboratory observations
(100 hours and 200 sessions over four years) and
manipulative experiments revealed that P. nidificator is
a generalist predator that lives in rough bark of trees, in
groups of 2 to 175 individuals (42.62 28.27; N=35
colonies; solitary individuals were never found), including
reproductive adults and nymphs. Individuals in groups
cooperatively capture prey four times larger than solitary
individuals. Adult hunters share food with siblings.
Reproduction in natural conditions occurs during the
hot/wet season, when food availability is high. Prey
diversity and abundance seem to be the main factor
limiting reproduction in this species. Phoresy (attachment
to a transporter animal) is the basic mode of dispersion in
P. nidificator. Grouped individuals use large animals as
vectors for dispersal, and once established they use the
vector as the first food item of the new colony. However,
they can also disperse by colony fission, newly docu-
mented herein for this taxon. The elaborate, cooperative
behavior in P. nidificator is unique among pseudoscorpions
and represents an excellent model for studies on the
evolution of sociality in invertebrates.
We studied the natural history and social behavior of Paratemnoides nidificator (Balzan
1888) in a... more We studied the natural history and social behavior of Paratemnoides nidificator (Balzan
1888) in a tropical savanna system. Females were responsible for all nymphal care. We observed, for the
first time in pseudoscorpions, the occurrence of matriphagy behavior by the offspring. During conditions
of food deprivation, the mother went out of the nest and passively awaited the protonymphs’ attack, not
reacting to the capture nor to the nymphs feeding on her body. We suggest that this extreme form of
parental care, matriphagy, can reduce cannibalism among protonymphs and facilitate the evolution of
social behavior in pseudoscorpions.
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Papers by Everton Tizo Pedroso
sociality, since cooperative hunting allows the individuals
access to very large prey. Although this behavior has been
extensively studied in some spiders, the knowledge about
some minor groups such as pseudoscorpions is still scarce.
The aim of this study was to analyze diet composition, prey
selectivity and prey size in Colombian populations of the
social pseudoscorpion Paratemnoides nidificator. We collected
prey captured by 112 colonies of P. nidificator as well
as their potential prey. We found that hymenopterans
(Formicidae) were the most consumed prey, while other
items found in the diet included dipterans, embiopterans,
hemipterans, mantids, neuropterans and spiders. When
comparing prey composition, we found a low similarity
between actual and potential prey. Paratemnoides nidificator
showed a positive selectivity towards ant species
which lacked strong defensive mechanisms, while avoiding
potentially dangerous species which possess stingers or
behaved aggressively. When evaluating size, we found that
P. nidificator is able to prey on arthropods up to eight times
larger than itself. These results suggest that by hunting in
groups, P. nidificator is able to capture not only larger prey,
but also prey which could be potentially dangerous for
solitary individuals such as some ant species.
(AFs) em Roupala montana, uma espécie arbórea comum na vegetação dos cerrados do Brasil central. No Parque Estadual de Caldas Novas (PESCAN), estado de Goiás, foi realizado um estudo que procurou investigar: 1) preferência do lepidóptero em construir seu AF de acordo com o tamanho da planta; 2) a composição, riqueza e as guildas dos artrópodes associados aos AFs; e, 3) possível associação entre o tamanho das plantas com a abundância dos artrópodes presentes nesses AFs. Os principais resultados revelaram que as mariposas fêmeas de Gonioterma sp. podem depositar seus ovos em R. montana com diferentes classes de tamanhos, porém com preferência por plantas de maior porte. Os
AFs apresentaram uma elevada riqueza e abundância de artrópodes de diferentes guildas, onde os mais representativos foram os predadores. Foi verificado associação positiva entre o tamanho de R. montana e a ocorrência de determinadas guildas de artrópodes. O papel exercido por Gonioterma sp. como engenheiro de ecossistema ficou destacado pela importância dos abrigos foliares produzidos por este animal como refúgios para a fauna de artrópodes locais.
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.
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.
interaction has been termed phoresy. We report on a phoretic interaction of Semeiochernes armiger with a
giant tropical fly Pantophthalmus tabaninus in an Amazonian rain forest. Two males and two females of S.
armiger were found attached to the right posterior leg of the fly. In addition, more than two hundred mites
were found on the thorax of the host fly. Long term and detailed studies on the phoretic associations of
pseudoscorpions and hosts in the neotropical rain forest would contribute to a better understanding of these
interactions.
evolves to breakdown the host’s defenses. We analyzed the role of 2 pseudoscorpion species that live in mixed colonies in the Brazilian
Cerrado (tropical savannah). Multispecies aggregation is a rare phenomenon among arachnids. Mixed pseudoscorpion colonies were
studied in nature and in the laboratory during a period of 7 years and the hypothesis of a relationship based on social parasitism
between species was evaluated, including the main strategies involved. Experiments and direct behavioral observations indicated
that the pseudoscorpion Parachernes melanopygus is a social parasite of Paratemnoides nidificator, able to invade host colonies and
exploit their resources by simulating host nymphs’ behavior. Although the host species has a recognition system, the parasite evades
colony defenses by using a chemical camouflage mechanism. We find support for the hypothesis of a new model of social parasitism
among phylogenetically distant pseudoscorpion species. To survive in the host colony, the parasite applies a combination of strategies,
previously observed in social brood parasite ants and birds. This phenomenon provides new knowledge of the Arachnida group and
also for known models of social parasitism.
tive success of eusocial insects. Although some arachnids exhibit colony
structure and social organization similar to that of hymenopterans, tem-
poral 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.
some taxa are still now poorly known, mainly in terms of
biology, ecology, and behavior. Pseudoscorpions are small
arachnids (2–8 mm) that live in cryptic environments, being
in general solitary predators of other invertebrates. The
most studied Pseudoscorpion species are those from
temperate areas, which revealed that Pseudoscorpiones
present some level of sociality based on maternal care.
Most developed sociality is seen in tropical species. Here,
we reviewed this issue, presented examples of social
behavior, and suggested the steps involved in the evolution
of permanent sociality in the Neotropical Atemnidae genus,
Paratemnoides. We discussed that the extended parental
care, division of labor, cooperative breeding and feeding,
and the tolerance among members dividing the same share
could be considered enough to characterize a true social
life, same in invertebrates.
“permanent-sociality” is a strategy documented only in a
few spider species. Here we describe the feeding and
dispersal behavior of Paratemnoides nidificator, a Neotropical
pseudoscorpion presenting “non-territorial permanent-sociality”.
Field and laboratory observations
(100 hours and 200 sessions over four years) and
manipulative experiments revealed that P. nidificator is
a generalist predator that lives in rough bark of trees, in
groups of 2 to 175 individuals (42.62 28.27; N=35
colonies; solitary individuals were never found), including
reproductive adults and nymphs. Individuals in groups
cooperatively capture prey four times larger than solitary
individuals. Adult hunters share food with siblings.
Reproduction in natural conditions occurs during the
hot/wet season, when food availability is high. Prey
diversity and abundance seem to be the main factor
limiting reproduction in this species. Phoresy (attachment
to a transporter animal) is the basic mode of dispersion in
P. nidificator. Grouped individuals use large animals as
vectors for dispersal, and once established they use the
vector as the first food item of the new colony. However,
they can also disperse by colony fission, newly docu-
mented herein for this taxon. The elaborate, cooperative
behavior in P. nidificator is unique among pseudoscorpions
and represents an excellent model for studies on the
evolution of sociality in invertebrates.
1888) in a tropical savanna system. Females were responsible for all nymphal care. We observed, for the
first time in pseudoscorpions, the occurrence of matriphagy behavior by the offspring. During conditions
of food deprivation, the mother went out of the nest and passively awaited the protonymphs’ attack, not
reacting to the capture nor to the nymphs feeding on her body. We suggest that this extreme form of
parental care, matriphagy, can reduce cannibalism among protonymphs and facilitate the evolution of
social behavior in pseudoscorpions.
sociality, since cooperative hunting allows the individuals
access to very large prey. Although this behavior has been
extensively studied in some spiders, the knowledge about
some minor groups such as pseudoscorpions is still scarce.
The aim of this study was to analyze diet composition, prey
selectivity and prey size in Colombian populations of the
social pseudoscorpion Paratemnoides nidificator. We collected
prey captured by 112 colonies of P. nidificator as well
as their potential prey. We found that hymenopterans
(Formicidae) were the most consumed prey, while other
items found in the diet included dipterans, embiopterans,
hemipterans, mantids, neuropterans and spiders. When
comparing prey composition, we found a low similarity
between actual and potential prey. Paratemnoides nidificator
showed a positive selectivity towards ant species
which lacked strong defensive mechanisms, while avoiding
potentially dangerous species which possess stingers or
behaved aggressively. When evaluating size, we found that
P. nidificator is able to prey on arthropods up to eight times
larger than itself. These results suggest that by hunting in
groups, P. nidificator is able to capture not only larger prey,
but also prey which could be potentially dangerous for
solitary individuals such as some ant species.
(AFs) em Roupala montana, uma espécie arbórea comum na vegetação dos cerrados do Brasil central. No Parque Estadual de Caldas Novas (PESCAN), estado de Goiás, foi realizado um estudo que procurou investigar: 1) preferência do lepidóptero em construir seu AF de acordo com o tamanho da planta; 2) a composição, riqueza e as guildas dos artrópodes associados aos AFs; e, 3) possível associação entre o tamanho das plantas com a abundância dos artrópodes presentes nesses AFs. Os principais resultados revelaram que as mariposas fêmeas de Gonioterma sp. podem depositar seus ovos em R. montana com diferentes classes de tamanhos, porém com preferência por plantas de maior porte. Os
AFs apresentaram uma elevada riqueza e abundância de artrópodes de diferentes guildas, onde os mais representativos foram os predadores. Foi verificado associação positiva entre o tamanho de R. montana e a ocorrência de determinadas guildas de artrópodes. O papel exercido por Gonioterma sp. como engenheiro de ecossistema ficou destacado pela importância dos abrigos foliares produzidos por este animal como refúgios para a fauna de artrópodes locais.
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.
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.
interaction has been termed phoresy. We report on a phoretic interaction of Semeiochernes armiger with a
giant tropical fly Pantophthalmus tabaninus in an Amazonian rain forest. Two males and two females of S.
armiger were found attached to the right posterior leg of the fly. In addition, more than two hundred mites
were found on the thorax of the host fly. Long term and detailed studies on the phoretic associations of
pseudoscorpions and hosts in the neotropical rain forest would contribute to a better understanding of these
interactions.
evolves to breakdown the host’s defenses. We analyzed the role of 2 pseudoscorpion species that live in mixed colonies in the Brazilian
Cerrado (tropical savannah). Multispecies aggregation is a rare phenomenon among arachnids. Mixed pseudoscorpion colonies were
studied in nature and in the laboratory during a period of 7 years and the hypothesis of a relationship based on social parasitism
between species was evaluated, including the main strategies involved. Experiments and direct behavioral observations indicated
that the pseudoscorpion Parachernes melanopygus is a social parasite of Paratemnoides nidificator, able to invade host colonies and
exploit their resources by simulating host nymphs’ behavior. Although the host species has a recognition system, the parasite evades
colony defenses by using a chemical camouflage mechanism. We find support for the hypothesis of a new model of social parasitism
among phylogenetically distant pseudoscorpion species. To survive in the host colony, the parasite applies a combination of strategies,
previously observed in social brood parasite ants and birds. This phenomenon provides new knowledge of the Arachnida group and
also for known models of social parasitism.
tive success of eusocial insects. Although some arachnids exhibit colony
structure and social organization similar to that of hymenopterans, tem-
poral 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.
some taxa are still now poorly known, mainly in terms of
biology, ecology, and behavior. Pseudoscorpions are small
arachnids (2–8 mm) that live in cryptic environments, being
in general solitary predators of other invertebrates. The
most studied Pseudoscorpion species are those from
temperate areas, which revealed that Pseudoscorpiones
present some level of sociality based on maternal care.
Most developed sociality is seen in tropical species. Here,
we reviewed this issue, presented examples of social
behavior, and suggested the steps involved in the evolution
of permanent sociality in the Neotropical Atemnidae genus,
Paratemnoides. We discussed that the extended parental
care, division of labor, cooperative breeding and feeding,
and the tolerance among members dividing the same share
could be considered enough to characterize a true social
life, same in invertebrates.
“permanent-sociality” is a strategy documented only in a
few spider species. Here we describe the feeding and
dispersal behavior of Paratemnoides nidificator, a Neotropical
pseudoscorpion presenting “non-territorial permanent-sociality”.
Field and laboratory observations
(100 hours and 200 sessions over four years) and
manipulative experiments revealed that P. nidificator is
a generalist predator that lives in rough bark of trees, in
groups of 2 to 175 individuals (42.62 28.27; N=35
colonies; solitary individuals were never found), including
reproductive adults and nymphs. Individuals in groups
cooperatively capture prey four times larger than solitary
individuals. Adult hunters share food with siblings.
Reproduction in natural conditions occurs during the
hot/wet season, when food availability is high. Prey
diversity and abundance seem to be the main factor
limiting reproduction in this species. Phoresy (attachment
to a transporter animal) is the basic mode of dispersion in
P. nidificator. Grouped individuals use large animals as
vectors for dispersal, and once established they use the
vector as the first food item of the new colony. However,
they can also disperse by colony fission, newly docu-
mented herein for this taxon. The elaborate, cooperative
behavior in P. nidificator is unique among pseudoscorpions
and represents an excellent model for studies on the
evolution of sociality in invertebrates.
1888) in a tropical savanna system. Females were responsible for all nymphal care. We observed, for the
first time in pseudoscorpions, the occurrence of matriphagy behavior by the offspring. During conditions
of food deprivation, the mother went out of the nest and passively awaited the protonymphs’ attack, not
reacting to the capture nor to the nymphs feeding on her body. We suggest that this extreme form of
parental care, matriphagy, can reduce cannibalism among protonymphs and facilitate the evolution of
social behavior in pseudoscorpions.