Ecology and behaviour of the weaver ant Camponotus (Myrmobrachys) senex

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.     

Prey choice and raiding behaviour of the Ponerine ant Pachycondyla analis (Hymenoptera: Formicidae)

Termite raiding behaviour of the African poneromorph ant Pachycondyla analis was studied at Mpala, Kenya. In all, 330 raids were observed with the raiding activity showing peaks in the morning and evening. Time spent at the termite source was positively correlated with the numbers of termites taken. The sizes of foraging parties, number of termites taken, distance travelled and time spent at termite sources also showed a positive correlation. Pachycondyla analis preyed significantly more on Microtermes spp. than they did on Odontotermes spp. but no significant differences were found in terms of predator efficiency even though many ants were injured in raids on Odontotermes spp. compared with those on Microtermes spp. Our results indicate that P. analis seems to forage optimally, balancing the costs of energy with prey reward and prey choices were not only influenced by prey abundance, but also by the costs of foraging, as influenced by prey defences, size and foraging behaviour.     

Architecture,composition and placement of nests of the Cipo Canastero Asthenes luizae (Aves: Furnariidae), a bird endemic to Brazilian mountaintops

Cipo Canastero (Asthenes luizae) is a bird endemic to Brazilian mountaintops, inhabiting rock outcrop habitats of the campos rupestres in the southern Espinhaço Range. Available data about Cipo Canastero’s breeding biology are scarce, incomplete or inconsistent. All nests found to date were built in the plant Vellozia nivea. Based on 84 nests found from 2009 to 2017 in four sites at Serra do Cipó, we described in detail their nesting habits focusing on three groups of characters: nest architecture, composition, and placement. Also, we described nest building. Our major new findings on the nesting habits of A. luizae were: three nest layers distinguishable, inner lining covering the entire nest interior, tunnels and tubes are absent, and the nest sites are not restricted to V. nivea. We recorded a wide range of nest sites, from ground, grasses and rupicolous bromeliads to shrubs and trees, including at least 30 supporting-plant species. Nest supports varied among study sites. Nest building lasted 22 days (one nest) and was done by both members of the pair. Our data can be useful for species conservation and contribute to the knowledge of the natural history of the genus Asthenes.     

Breeding biology of the threatened Campo Miner Geositta poeciloptera (Aves: Scleruridae), a Neotropical grassland specialist

The Campo Miner is a threatened grassland passerine endemic to the South American Cerrado, whose life history is almost unknown. In this paper, we studied during three breeding seasons (2014 to 2016) the breeding biology of a colour banded population of the species found in the Upper Rio Grande Grasslands, south-eastern Brazil. We found 98 nests, 81 of which became active and were monitored. The Campo Miner breeds in frequently burnt-and-grazed natural grasslands, successfully nesting in highly disturbed sites, such as dirt banks along roads and even in mine pits. The species is socially monogamous and both parents build the nest, which is a cavity/with-tunnel/simple/platform type. The nest chamber is lined with a platform made of grass fragments, charcoal, hairs, and mammal faeces. The most common clutch size is three eggs (n = 66), with some nests containing one (n = 1), two (n = 12) or four eggs (n = 2). The egg is white and pyriform and the incubation, performed by both parents, lasts 17.5 days. Mean nestling period is 15.5 days, with both parents feeding the young. Breeding season lasted for about 125 days (August to December) and multiple breeding attempts in a single season were common, with a maximum of three attempts recorded. All species of Scleruridae built their nests inside cavities dug in the soil with an access tunnel to it, where they lay a small clutch (usually 2–3 white eggs), but no other species in the family has been studied in detail to date. Further studies are required to understand why a species apparently tolerant to anthropogenic impacts such as G. poeciloptera can be so rare, patchily distributed and threatened throughout its range.     

The reproductive ecology of Leptodactylus fuscus (Anura,Leptodactylidae): new data from natural temporary ponds in the Brazilian Cerrado and a review throughout its distribution

Recent studies indicate that populations historically called Leptodactylus fuscus (Schneider, 1799) comprise at least three well‐differentiated lineages. Herein, we describe the reproductive ecology of a southeastern clade population of L. fuscus, and review the characters of the reproductive ecology for several populations of the northern and southeastern clades. Most reproductive activity occurred in December and January, which coincided with the highest rainfall period. Males had an aggregated spatial distribution in the central area of the ponds. Three courtship interactions were observed. A female was observed closing the entrance to a burrow with moist sand after oviposition. This behaviour is described for the first time in L. fuscus. The review of the reproductive biology of the northern and southeastern clades indicates a relatively high plasticity in L. fuscus. Furthermore, the results corroborate the suggestion, based on molecular data, that the northern and southeastern clades of L. fuscus represent distinct evolutionary units.     

The effects of forest fragmentation on the population ecology and natural history of a funnel-web spider

Habitat fragmentation strongly affects the abundance, distribution, body size and population genetics of invertebrates. Urban growth in Brazil has led to severe fragmentation, especially in the Atlantic Forest and savannas. The effects of this fragmentation on the common funnel-web spider Aglaoctenus lagotis were examined in two forest fragments within the interior savanna: a smaller fragment within an urban environment and a larger fragment within a rural environment. The reproductive period occurred in October, coinciding with the beginning of the rainy season, when the species was aggregated in the two forest fragments. The smaller fragment contained a larger population, and the spiders had a larger average prosoma size and web area. The presence of a larger population in a smaller area within the urban centre may reflect a limited dispersal ability, reduced predator abundance or low interspecific competition. The larger prosoma length and web area in the smaller habitat fragment suggest greater resource availability and a higher probability of capturing prey in the urban environment. In both areas, a larger number of capture threads was positively correlated with the presence of inquiline spiders in the webs. The genetic data indicate close similarity between and within the two areas, indicating that the species has low genetic variability or that the areas studied, consistent with their proximity, have separated only recently. Most savannas and forests in midwestern Brazil have recently undergone severe fragmentation, and further studies of this nature are needed.     

Assembly of Myrmelachista Roger (Formicidae: Formicinae) in twigs fallen on the leaf litter of Brazilian Atlantic Forest

The nests of Myrmelachista are found in tree trunk cavities and branches. The biology of these arboreal ants is still relatively unknown. We investigated the nesting behaviour of this genus in fallen dry twigs in the Atlantic rainforest of southeastern Brazil. Physical characteristics of the nests, colony demographics, presence of breeders and ant worker sizes were recorded. Samples were collected weekly for 12 months, along open, sunny and undisturbed trails within forest remnants. In all, 202 nests were collected and six species were recorded. Myrmelachista ruszkii had the highest population of immatures and the greatest number of nests found. Myrmelachista nodigera had the smallest workers, was the least populous and the colony was housed in the finest branches. These results expand the current knowledge about the diversity and biology of Myrmelachista in the Brazilian Atlantic forest, and describe polydomic nests and competitive behaviour of M. ruszkii.     

Effects of different ant species on the attendance of neighbouring hemipteran colonies and the outcomes for the host plant

Ants commonly participate simultaneously in mutualisms with honeydew-producing hemipterans and extrafloral nectar-bearing host plants. These interactions are based on the exchange of resources (honeydew and extrafloral nectar) for ant protection against natural enemies. The benefits may vary according to the species of ant interacting, and the outcomes for the host plant and hemipteran will depend on the results of the ant-plant-hemipteran relationship as a whole. We studied a plant-mealybug association with Camponotus crassus Mayr (Formicinae) and Ectatomma tuberculatum Olivier (Ectatomminae) in a Brazilian tropical savanna. We aimed to elucidate whether the frequency of visitation by different species of ants can be affected by neighbouring colonies of mealybugs, and whether these ant species influence the number of hemipterans in a different way. Furthermore, we intended to find out whether the interaction between ant and hemipteran has any effect on the proportion of fruit production or on the abundance of trophobiont and non-trophobiont herbivores, also influenced by the ant species. Our results show that neighbouring aggregations of mealybugs influenced the frequency of ant visitation and the ants affected the number of nymphs over time, with both positive results only for C. crassus. We also detected an indirect negative effect on proportion of fruit production and an increase in abundance of trophobiont and non-trophobiont herbivores in the presence of C. crassus-mealybug interaction. Thus, we provide further evidence that colonies of hemipterans interacting with ants can be beneficial for these herbivorous insects, but they are quite harmful to the host plant. Nevertheless, the outcomes can be highly conditional in relation to ant species.     

Foraging behaviour of three sphaerodactylin geckos on Trinidad and Tobago (Sauria: Gekkonomorpha: Sphaerodactylini: Gonatodes)

Taxonomic families of insectivorous lizards are usually characterized by one of two distinct foraging modes, namely ambush ‘sit-and-wait’ or active ‘widely foraging’. In the Gekkonomorpha the situation has been unclear and in dispute, and among these, that in the Sphaerodactylini is almost unreported. We, therefore, examined the foraging mode of three sphaerodactylin species on Trinidad and Tobago, in May—June 2000 (totalling 72 individuals, observations averaging 23.6 min/individual). In terms of species averages, Gonatodes vittatus, G. humeralis and G. ocellatus all moved for only 1.6–3.55% of observation time (PTM, percent time moving), and switched from sitting to locomoting only 0.18–0.36 times per minute (MPM, moves per minute). The genus thus is a strict sit-and-wait forager. In G. vittatus, the foraging mode was unaffected by sex or habitat structure. In all three species, foraging mode was unaffected by the time of day or air temperature. In G. humeralis, foraging activity (PTM or MPM) correlated with light intensity in the forest within a population (at least MPM) and among populations (at least PTM). Among the three species, too, foraging activity (PTM and MPM) ranked with light intensity during sampling. In all three species, the geckos perched for 68–76% of the time (at any height) with the head pointing down, apparently so as to see better. In conclusion, the three species are strict sit-and-wait' visual hunters that are dependent on light.     

Phyllostomid bats flying in daylight: a case from the Neotropics

Bats (Chiroptera), one of the most diverse groups in terms of taxonomy, morphology and ecology, are known for their nocturnal behaviour of flight and feeding. Although there is no consensus on the evolution of nocturnality in bats, many authors mention risk of predation, overheating, competition and mobbing by non-competitor species as arguments to justify nocturnal instead of daytime flight in bats. Herein we describe the first records of three genera of phyllostomid bats flying, foraging and drinking water during daytime in the Brazilian Amazon. All taxa were recorded drinking water, and some Phyllostomus sp. individuals were recorded foraging on termites, alongside birds. Risk of dehydration and overheating in roosts, as well as low competition in daytime, may explain the emergence of phyllostomid bats before sunset.     

Foraging ecology of the giant Amazonian ant Dinoponera gigantea (Hymenoptera,Formicidae, Ponerinae): activity schedule,diet and spatial foraging patterns

This study provides a detailed account of the natural history and foraging biology of the ponerine ant Dinoponera gigantea in a rainforest in north Brazil. The species nests on the ground and the colonies contain 70–96 workers. Ant activity is negatively correlated with temperature, and is more intense at dawn and dusk. Foragers leave the nest independently and search for food individually on the leaf litter, within ca 10 m around the nest. Workers are opportunistic feeders that collect seeds and fruits, and hunt for live prey as well as scavenge for dead animal matter. The dry weight of food items ranges from <10 mg (spiders, insect parts) to >400 mg (seeds, fruits). There is no nestmate recruitment during the search for or retrieval of food, irrespective of food type and size. Foragers have a high directional fidelity, and ants from neighbouring colonies may engage in ritualized territorial contests at the border of their foraging areas. The foraging ecology of D. gigantea is compared with other ponerine species living in tropical forests, as well as with other ant groups showing similar behavioural patterns.     

Natural history and ecology of foraging of the Camponotus crassus Mayr, 1862 (Hymenoptera: Formicidae)

ABSTRACT

Ants are abundant in terrestrial ecosystems, especially in the Brazilian Cerrado, where they can play several roles at different levels of the food chain, including protection of plants against herbivores. Although there are many studies that evaluate the ant–plant interaction in the Cerrado, little is known about the natural history of most species of ants. Camponotus crassus Mayr, 1862, for example, is considered one of the main agents of plant biotic defence in Cerrado. But there are no studies specifically focused on this species, which hinders the understanding of how arthropod–plant interactions are structured in Cerrado. Here, we describe the natural history and ecology of the foraging of the C. crassus. We conducted the study from January 2013 to December 2014 in 10 quadrants of 40 m² to measure: the abundance, density and distribution of nests, location of the nests, the internal structure of the nests, the daily foraging of workers out of the nest, the food items they collect and the existence of territoriality and dominance of the workers on the soil and vegetation. We found 18 nests, 13 in the soil and 5 in hollow trunks on the ground with variable internal structures. The distribution of nests is aggregate, with density of 0.045 nests/m² and average distance of 3.73 m between nests. The foraging activity occurs on the daytime during the rainy and dry season. Extrafloral nectar and honeydew were the resources most collected, comprising 83.33% of the resources in the rainy period and 30% in the dry period. Camponotus crassus is a dominant species, especially on vegetation, although it also forages on the soil. This is the first study to evaluate in detail the natural history and foraging ecology of C. crassus, a diurnal, aggressive and territorial ant that mainly forage climbing onto the plants.     

Foraging patterns and artificial fragrance choices of male orchid bees in the Brazilian Atlantic Rainforest

ABSTRACT

With the aim of increasing our knowledge concerning fragrance choices by male euglossine bees (Apidae, Euglossini), we investigated: (i) possible foraging patterns and choices of artificial fragrances explored by the most frequent species attracted to scent baits during the same season across consecutive years, sampled invariably in a same study area; (ii) the foraging patterns of populations of orchid bees surveyed in two similar forest habitats (Atlantic rainforest remnants) located 24 km apart, on Superagui Island (SI) and on a private reserve (RNSM), in southern Brazil. Although in both areas males attracted to scent baits were collected with insect nets and odour traps during the warm-wet season, the number of samplings were different in both study sites, totalling 15 samplings on RNSM and five on RNSM. In both areas four euglossine species were the most abundant: Euglossa annectans, E. stellfeldi, E. iopoecila and E. roderici. Overall, we can draw three main conclusions. Firstly, there were conspicuous patterns in regard to the set of fragrances visited by the four most abundant euglossine species over the three consecutive years of surveys on SI, with some shifts in fragrance choices found only for E. annectans and E. stellfeldi. Second, the most attractive fragrances used distinctively by each species were very similar in both study areas, indicating a local intraspecific similarity in the use of some main fragrances. Third, E. annectans showed a clear tendency to occupy a broader niche, which probably resulted in the highest percentages of niche overlap.     

Social facilitation and food partitioning in the queenless ant Dinoponera quadriceps (Hymenoptera: Formicidae)

Social facilitation occurs when an animal is more likely to behave in a certain way in response to other animals engaged in the same behaviour. For example, an individual returning to the nest with food stimulates other ants to leave and to forage. In the present study we demonstrate the existence of new facets in the colony organization of Dinoponera quadriceps: a positive feedback between the incoming food and the activation of new foragers, and the occurrence of incipient task partitioning during the food sharing. Lower-ranked workers located inside the nest process protein resources and higher-ranked workers handle smaller pieces and distribute them to the larvae. In conclusion, D. quadriceps has a decentralized pattern of task allocation with a double regulatory mechanism, which can be considered a sophisticated aspect of division of labour in ponerine ants.     

Ecology and field biology of two dominant Camponotus ants (Hymenoptera: Formicidae) in the Brazilian savannah

Camponotus renggeri and C. rufipes are very abundant in Brazilian cerrado savannah, where they feed extensively on liquid rewards and commonly associate with plants bearing extrafloral nectaries and honeydew-producing insects. Here, we provide a qualitative and quantitative field account on the natural history and ecology of these two ant species. The study was carried out in a cerrado reserve in south-eastern Brazil across a rainy/hot season (summer) and a dry/cold season (winter). The ants were found in two vegetation physiognomies: all nests of C. rufipes were located in the cerrado sensu stricto (scrub of shrubs and trees, 3–8 m tall), whereas C. renggeri occurred mostly in the cerradão (forest with more or less merging canopy, 10–12 m tall). Both species nested in fallen or erect dead trunks, as well as underground. In addition, C. rufipes built nests using dead plant material arranged or not around shrub bases. Colonies of C. rufipes were generally more populous than those of C. renggeri, and both species had colonies with more than one dealated queen. Both species were active mainly at night and foraged for resources near their nests, mainly extrafloral nectar and hemipteran honeydew (aphids and mealybugs). The average size of the home ranges of C. renggeri in cerrado sensu stricto and cerradão varied from ≈ 2.8 to 4.0 m² and apparently were not affected by season. In C. rufipes, however, foraging grounds in cerrado sensu stricto showed a twofold increase from dry/cold (≈ 4.5 m²) to rainy/hot season (≈ 9.8 m²). Our study highlights the importance of natural history data to understand the foraging ecology and role of these ants in cerrado savannah.     

Habitat selection and nest construction behaviour in some Afrotropical species of Ammophila (Hymenoptera: Sphecidae)

Nest construction behaviour and nest site selection are described for seven species of Afrotropical Ammophila.

Four species were atypical in their nest siting. Ammophila beniniensis selected shaded sites in well vegetated habitats, A. vulcania selected small clumps of vegetation in otherwise open habitats. A. insignis nested in vertical banks, old animal burrows and caves. A. braunsi is unique amongst Ammophila in its use of abandoned burrows of other wasps in non-friable clay soils. A. ferrugineipes, A. dolichodera and A. dolichocephala nested mostly in open habitats.

Methods of soil waste disposal, sealing of nests and their final coverage, differed interspecifically, in some cases intraspecifically, but often apparently in response to the habitat.

Temperature conditions, affected by habitat, influenced the depth to which nests were dug by some species. A. insignis switched sites in response to seasonal changes in temperature regimes in vertical banks.

The existence in particular species of both primitive and advanced aspects of nesting behaviour questions their use in assessing the evolutionary status of these species.     

Breeding behaviour of the Omei tree frog Rhacophorus omeimontis (Anura: Rachophoridae) in a subtropical montane region

Breeding behaviour of the Omei tree frog, Rhacophorus omeimontis, was studied during the egg-laying period (mid-April to late June) in south-west China. The operational sex ratio of the breeding population was male-biased at 3.0?±?0.8 (mean?±?SD) on a nightly basis in Pond A and 4.3?±?1.1 in Pond B. Pairs with a male clasping a female occurred in ponds first; the amplectant pairs moved to a neighbouring plant and then released foam in leaves 14–370 cm above the pond's water surface. Immediately, other males came to join the pair, forming an amplexing group of 2 to 7 males (for all 45 breeding units observed). Among the males no direct physical competition for possession of the females was observed. Females produced foam which surrounded the subsequently-laid eggs. The whole process of oviposition lasted 45–65 minutes. After ovipositing, males left the female, the female folded and lined neighbouring leaves with more foam produced to surround the eggs further. This process took 15–45 minutes. The numbers of eggs in a clutch ranged from 457 to 837 and eggs were between 2.9 and 3.4 mm in diameter; those two measures were negatively correlated with each other. Eggs hatched after 12–17 days; the larval period lasted 63–78 days. Fertilization success was positively related to the number of males participating in matings.     

Biogeographic analysis of the ant genus Gnamptogenys Roger in South-East Asia-Australasia (Hymenoptera: Formicidae: Ponerinae)

The distribution range of ants of the genus Gnamptogenys is analysed, with special reference to the Old World species, and two closely related genera: Rhytidoponera and Ectatomma. The study is based upon a cladistic biogeographic analysis, recognizing the following areas of endemism: Central America, South America, Philippine Islands, New Guinea, Australia, Solomons/Fiji and South-East Asia. These results are followed by a consensus of different information sources (phylogenetic, natural history, past and present distribution, palaeogeographical and palaeoclimatological) for explaining the present and past distribution of Gnamptogenys and related genera. The area cladogram shows repeated instances of sister relations between Old World and New World taxa at different depths within the tree. Subtree analysis further suggests a common sister relation between Gondwanan landmasses. The distribution of the Gnamptogenys is interpreted as a product of vicariance, starting with the separation of Gondwana, and subsequent dispersal into South-East Asia and Melanesia via rafting on the Australian craton. The desiccation of Australia during the Oligocene was detrimental to the presence of Gnamptogenys but favoured expansion of Rhytidoponera. The study illustrates that a cladistic biogeographic scenario may be supported by a consensus of data from various sources, and also suggests a pre-Tertiary diversification of ant fauna.     

Carton nest building and trophobiont manipulation in the south-east Asian ant Dolichoderus sulcaticeps (Mayr 1870) (Hymenoptera: Formicidae)

Dolichoderus sulcaticeps, a rare canopy living dolichoderine ant, was studied in the rainforest of Malaysia. It forms large polycalyc colonies comprising partial nests on trees and climbers. The three dimensional multichambered partial nests are situated on the leaf underside. Fibrous nest material is gathered from the surface of the nesting plants and soaked with water from the plant surface. Building activity, therefore, is strictly dependent on the presence of rainfall or dew. Within the cell with plant leaf surface contact, as well as on free feeding sites, non specific coccid and membracid throphobionts, are tended. Free feeding sites are permanently protected. Mealybugs are transported between existing and new free feeding sites, as well as to and from nest pavilions, especially during their construction or destruction. Prey hunting has not been observed in D. sulcaticeps. The workers, however, recruit to offered dead prey, and scavenged. During the day they were permanently on the surface of plants around their nests and feeding sites.