Efficient Egress of Escaping Ants Stressed with Temperature

In the present work we investigate the egress times of a group of Argentine ants (Linepithema humile) stressed with different heating speeds. We found that the higher the temperature ramp is, the faster ants evacuate showing, in this sense, a group-efficient evacuation strategy. It is important to note that even when the life of ants was in danger, jamming and clogging was not observed near the exit, in accordance with other experiments reported in the literature using citronella as aversive stimuli. Because of this clear difference between ants and humans, we recommend the use of some other animal models for studying competitive egress dynamics as a more accurate approach to understanding competitive egress in human systems.     

The Fungus-culturing Behavior of Ants

A colony of attine ants begins with a recently fecundated femalecarrying hyphae from the parental garden in a pellet in an infrabuccalpocket. All future food of the colony will be derived from thisnucleus. She digs a cavity in the ground, ejects this pelletand manures it with her liquid excrement. As the hyphae proliferate,eggs are laid on them and the colony is launched. She continuallylicks both the hyphae and the brood. Thus, both salivary andanal excretions play a vital role in the beginning of a colonyand this pattern is repeated by the resulting workers. About60–65% of them in Atta are the minima and these are intimatelyinvolved in brood and fungus care. Their excretions are disproportionatelylarge. About 1/3 of the workers in Atta are 4–6 mm mediaand these cut and prepare the substrate. The 7–9 mm maximasizes and the soldiers (over 9 mm) are less directly involvedin culturing the fungus. The effectiveness of fungus culturing is shown by the rapidbuild-up of gardens. The ants maintain their garden despitesurrounding contamination after a fragment with ants is introducedto a plate of sterile nutrient agar.     

Host Location Behavior in a Parasitoid of Imported Fire Ants

Female parasitoids use a hierarchy of cues to locate suitable hosts. We conducted a series of field observations and experiments to examine host location behavior in Pseudacteon tricuspis Borgmeier, a phorid parasitoid of Solenopsis invicta Buren worker ants. The parasitoids were frequently attracted to host workers at disturbed colonies, but were almost never attracted to host workers foraging at baits. When conspecific nonnestmate workers were introduced to baits, resulting in aggressive interactions, parasitoids appeared at the majority of baits. Moreover, larger numbers of parasitoids appeared at baits to which greater numbers of nonnestmate workers had been added. Addition of nonnestmate workers to disturbed colonies resulted in increased numbers of parasitoids attracted. Pseudacteon tricuspis did not display a pattern of uniform distribution at disturbed colonies but often was very abundant at some colony locations while absent or rare at nearby colony locations. Solenopsis invicta workers release alarm pheromones in aggressive interactions with nonnestmates, and this substance is likely an important chemical cue that attracts P. tricuspis flies to host workers from a distance.     

逃出香巴拉

在前往香巴拉的路上,我万万没有想到,这竟是我逃离香巴拉的一次历程,然而,这逃离的过程中却有着一段段美好的回忆……     

Ants distinguish neighbors from strangers

Summary Ants are known to distinguish their own nests and nestmates from all others, using colony-specific odors. Here I show that harvester ants (Pogonomyrmex barbatus) can further distinguish between two kinds of non-nestmates of the same species: neighbors and strangers. Interactions between colonies were thought to depend on the numbers of alien ants that each colony encounters on its territory. The results described here show that such interactions also depend on information about colony identity. Encounters on foraging trails with ants from neighboring colonies, deter foraging more than encounters with ants from distant ones. The history of interactions between particular pairs of colonies may have important effects on intraspecific competition for food.     

The Role of Trichocyst Discharge and Backward Swimming in Escaping Behavior of Paramecium from Dileptus margaritifer1

Trichocyst discharge is an effective defense of Paramecium against Dileptus margaritifer. The possible defensive function of backward swimming, which often follows trichocyst discharge upon Paramecium-Dileptus encounters was studied. Mutants incapable of backward swimming (pawnA in P. tetraurelia, cnrA in P. caudatum) escaped from dilepti nearly as frequently as wild-type cells. Double mutants (pawnA-nd7, cnrA-tnd2) were eaten nearly as frequently as mutants incapable of trichocyst discharge. Thus, in the defense of Paramecium against D. margaritifer, the role of backward swimming is minor, if any, compared to trichocyst discharge. Among escaped cells, about a half of wild-type and essentially none of pawnA (cnrA) cells showed backward swimming. Paramecium behavior during the encounter can be mimicked by the local, not global, application of lysozyme which is a strong secretagogue of trichocyst.     

Plant Size-dependent Escaping Behavior of Gregarious Nymphs of the Desert Locust, Schistocerca gregaria

The present study involves the tracking of marching bands of more than 300,000 gregarious nymphs of the desert locust, Schistocerca gregaria, to examine shelter plant preference and how species and size of shelter plants and nymphal group sizes jointly influence the escaping behavior of 4th- and 5th-instar gregarious nymphs. Field observations are conducted during daytime and night-time in the Sahara Desert in Mauritania. Three dominant plant species have been identified at the survey site: Hyoscyamus muticus, Panicum turgidum, and Nucularia perrini. The smallest mean plant size among the three plant species is H. muticus. Gregarious nymphs perch on all the three plant species irrespective of time, and form various sizes of groups ranging from <10 to >10,000 nymphs. Groups of gregarious locusts perching on the plants show either escaping or sheltering behavior in response to an approaching observer. Percentages of nymphal groups showing escaping behavior for H. muticus, P. turgidum and N. perrini are 96.4, 47.6 and 19.5 %, respectively. Defensive behavior is not affected by nymphal group size but by species and size of shelter plants. Nymphal groups tend to show escaping behavior when their perching plants are relatively small. No groups escape from their perching plants during night. These results might indicate that gregarious nymphs do not have a strong shelter plant preference and change their defensive behavior depending on species and size of sheltering plants and light conditions.     

Directed Aerial Descent Behavior in African Canopy Ants (Hymenoptera: Formicidae)

Several species of neotropical ants direct their aerial descent toward tree trunks during a fall from the forest canopy. The primary goal of this study was to determine if afrotropical arboreal ants exhibit similar gliding behavior. Ants were collected from nine tree crowns in late secondary forest at a hydrocarbon extraction site near Gamba, Gabon. Of the 32 species tested, the behavior was observed in five Cataulacus spp. and three Camponotus spp., making this the first report of gliding in African ants. Aerial glide performance (horizontal distance traveled per unit vertical drop distance) decreased with increasing body size among species and among individuals of Cataulacus erinaceus. Characteristics of directed descent behavior in C. erinaceous were very similar to those of the neotropical ant Cephalotes atratus.     

Ants benefit from attending facultatively myrmecophilous Lycaenidae caterpillars: evidence from a survival study

Workers of three ant species (Lasius niger, Lasius flavus, Myrmica rubra) were caged in the laboratory together with caterpillars and pupae of five species of lycaenid butterflies. Mortality of ants was 3–5 times higher when the ants were confined with larvae lacking a dorsal nectar organ (Lycaena phlaeas, Lycaena tityrus) rather than with caterpillars which possess a nectar gland (Aricia agestis, Polyommatus bellargus, P. icarus). For all five species, ant survival was always lower at the pupal stage (where a nectar organ is always absent) than at the caterpillar stage and was largely equivalent for the butterfly species tested. The experimental data confirm earlier estimates that ants can derive nutritive benefits from tending facultatively myrmecophilous lycaenid caterpillars, even though these caterpillars produce nectarlike secretions at low rates.     

Fungus Exposed Solenopsis invicta Ants Benefit from Grooming

We investigated aspects of resistance to entomopathogenic fungi in the social insect Solenopsis invicta, the red imported fire ant (RIFA). RIFA reared individually were significantly more susceptible to the entomopathogenic fungi Metarhizium anisopliae var. anisopliae M09 than reared in groups. Fungus exposed ants performed more self-grooming behavior when isolated as individuals and received more allo-grooming when accompanied with four healthy nestmates. Using fluorescence microscopy, we counted the number of fluorescein isothiocyanate (FITC)-labeled conidia on the cuticle of fungus exposed ants reared individually or as groups. The number of conidia on the surface of grouped ants decreased more rapidly than on isolated individuals. Allo-grooming behavior appears to be important in removing the conidia on the surface of RIFA. Individuals help fungus exposed ants by performing intensive grooming behaviors, which either risk infecting themselves or get them immunized as social immunity. We show evidence that contacting with fungus exposed ants would decrease susceptibility of nestmates to the fungus. All these results indicate that RIFA benefit from grooming behavior to fight against the fungal pathogens. Future advances in biological control of RIFA with entomopathogenic fungi are also discussed.     

Ants,Cataglyphis cursor,Use Precisely Directed Rescue Behavior to Free Entrapped Relatives

Although helping behavior is ubiquitous throughout the animal kingdom, actual rescue activity is particularly rare. Nonetheless, here we report the first experimental evidence that ants, Cataglyphis cursor, use precisely directed rescue behavior to free entrapped victims; equally important, they carefully discriminate between individuals in distress, offering aid only to nestmates. Our experiments simulate a natural situation, which we often observed in the field when collecting Catagyphis ants, causing sand to collapse in the process. Using a novel experimental technique that binds victims experimentally, we observed the behavior of separate, randomly chosen groups of 5 C. cursor nestmates under one of six conditions. In five of these conditions, a test stimulus (the “victim”) was ensnared with nylon thread and held partially beneath the sand. The test stimulus was either (1) an individual from the same colony; (2) an individual from a different colony of C cursor; (3) an ant from a different ant species; (4) a common prey item; or, (5) a motionless (chilled) nestmate. In the final condition, the test stimulus (6) consisted of the empty snare apparatus. Our results demonstrate that ants are able to recognize what, exactly, holds their relative in place and direct their behavior to that object, the snare, in particular. They begin by excavating sand, which exposes the nylon snare, transporting sand away from it, and then biting at the snare itself. Snare biting, a behavior never before reported in the literature, demonstrates that rescue behavior is far more sophisticated, exact and complexly organized than the simple forms of helping behavior already known, namely limb pulling and sand digging. That is, limb pulling and sand digging could be released directly by a chemical call for help and thus result from a very simple mechanism. However, it''s difficult to see how this same releasing mechanism could guide rescuers to the precise location of the nylon thread, and enable them to target their bites to the thread itself.     

Escaping from prison: an economic reassessment of Rutland Water

Recently in the water industry interest has been growing in solutions to widening demand-supply gaps. These include demand-management elements. The paper examines the 1970 decision by Parliament to build Rutland Water and concludes that, despite over-predictions of water demands, the very few hard facts then available concerning water economy measures would probably not have prevented the reservoir being authorised, had they been taken into account. By 1981, however, dramatic reductions in expected population and per capita public water supply growth had occurred, with much more evidence available concerning the scope of demand-management. It is suggested a similar decision on economic grounds would probably have been a negative one.