We measured individual decisions regarding the adjustments of time, distance and direction of foraging in Dinoponera quadriceps. We observed two colonies in an area of secondary Atlantic Forest, FLONA-ICMBio, in Northeastern Brazil. The workers were individually marked. We recorded the displacement of workers, their returns to the nest with and without food, the time spent searching for food, maximum and total distance, inter-trip latency and direction of trips. The time spent searching for food, maximum distance and transport velocity did not vary with food size. The previous trip success reduced the latency between foraging trips and increased the percentage of success on the next trip. However, this previous success did not demonstrate a significant variation relative to the time spent searching on the next trip or direction of search. The workers maintained an individual directional fidelity during foraging. The adjustments of these foraging variables under individual control contributed to the efficiency at the colony level. D. quadriceps is compatible with the central place theory and risk sensitivity model of behavior.

This study characterizes the foraging activity of the queenless ant Dinoponera quadriceps (Kempf) (Hymenoptera: Formicidae) in its natural environment by testing the hypotheses that foraging activity presents both daily and seasonal rhythmic variations, and that these rhythms are related to environmental variables. Four colonies of D. quadriceps were observed in an area of secondary Atlantic forest in northeastern Brazil. Data collection was performed over 72 h every three months during an annual cycle. Both daily and seasonal foraging activity rhythms of D. quadriceps colonies were related to environmental factors, but colony differences also explained part of foraging variations. Foraging activity of D. quadriceps colonies was predominantly diurnal independently of season. In the early dry season, the colonies had two activity peaks, one in the morning and another in the afternoon, with a decrease in foraging at midday; however, during the rest of the year, foraging activity was distributed more evenly throughout the daylight hours. The daily rhythm of foraging activity was likely determined by an endogenous circadian rhythm year-round, but in the dry season, temperature and relative humidity also influenced daily foraging activity, with a negative effect of temperature and a positive effect of relative humidity. On a seasonal scale, foraging activity peaked in the early dry season and suddenly declined at the end of this season, increasing again at the late rainy season. The seasonal rhythm of foraging was negatively related to relative humidity and positively related to prey availability.

Epilepsy affects at least 50 million people worldwide, and the available treatment is associated with various side effects. Approximately 20-30% of the patients develop seizures that persist despite careful monitored treatment with antiepileptic drugs. Thus, there is a clear need for the development of new antiepileptic drugs, and the venoms can be an excellent source of probes. In this context, while there are studies on venoms from snakes, scorpions, and spiders, little is known regarding venom from ants. The aim of this study was to investigate the potential pro- and anticonvulsant effects of the venom from the ant Dinoponera quadriceps (Kempf) in Swiss mice. After the injection of the crude venom (DqTx-5, 50, and 500 mg/mL) in the lateral ventricle of mice, we observed a reduction of exploration and grooming behaviors, as well as an increase in immobility duration. In addition, the crude venom induced procursive behavior and tonic-clonic seizures at the highest concentration. Conversely, the preadministration of the denatured venom (AbDq) at the concentration of 2 mg/mL protected the animals against tonic-clonic seizures (66.7%) and death (100%) induced by administration of bicuculline. Taken together, the findings demonstrate that D. quadriceps venom might be potential source of new pro- and anticonvulsants molecules.

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In social insects, task allocation can be more complex than workers merely falling into discrete task groups. Any activity performed by the colony cannot be fully understood in isolation from other activities because they may be interrelated. Investigating activities other than foraging is crucial to understanding the global functioning and organization of ant colonies. This study attempts to characterize the nest maintenance activity of the ponerine queenless ant, Dinoponera quadriceps, in its natural environment to determine the effects of environmental variables on the variations in both seasonal and daily rhythms and to discuss its differences and possible relationships to foraging. Four colonies of D. quadriceps were observed in an area of Atlantic Forest in northeastern Brazil. Data collection was performed over a period of 72 h every three months during an entire annual cycle. Nest maintenance activity in D. quadriceps colonies was observed during both the light and dark phases of the day. There was no significant difference between the day phases in the number of workers involved in this task. On the other hand, D. quadriceps colonies exhibited seasonal variation in nest maintenance activity, peaking in the early rainy season. The seasonal rhythm of nest maintenance was positively correlated with relative humidity and negatively correlated with prey availability and rainfall. Our results indicate the existence of an annual variation in the nest maintenance activity of D. quadriceps associated with environmental variables. However, it occurs equally both at night and day, countering the hypothesis that there is a daily rhythm.