Large Ants Research Articles

Insect pollination of mango in northern Australia

Large native insect species were shown to pollinate mango (Mangifera indica L.) in northern Australia. The pollinators, in decreasing order of efficiency, were wasps, bees, large ants and large flies. It was found that the most efficient pollinators were those that carried large numbers of pollen grains on their thoraces and used a short proboscis or short mouth parts to feed on nectar. Large Diptera and the native bee, Trigona sp., frequently moved from tree to tree and thus were probably the most effective cross pollinators. Of randomly selected hermaphrodite mango flowers, 36% were pollinated.

Quantification and modification of worker size variation in the fire antSolenopsis invicta

Solenopsis invicta workers display a slight polymorphism over a size range of head widths from 0.45 mm to 1.50 mm. Those measuring through 0.80 mm were designated small, through 1.00 mm, medium, and through 1.50 mm, large. Mature field colonies have small, medium, and large worker ratios of 45%, 42%, and 16% respectively. Queens founding colonies in the lab produced initial broods of minim workers, the smallest and only individuals a queen rears by herself. As colony populations grew, size classes of larger ants accumulated until after 7 months, ants with head widths ranging in size from 0.50–1.50 mm were produced. Size class distributions were skewed such that small, medium, and large ants made up 88%, 11% and 1% of the population, respectively. Newly mated queens were adopted into small (500 ants), medium (2000 ants), and large (15,000 ants) experimental colonies of field ants of three ranges of worker size variation (9 treatments). No effect of worker size variation on pupal production or pupal size was detected. The mean numbers and mean head width of pupae in their initial broods were: (1) greater than those of newly founded colonies (minims were lacking); and, (2) correlated to experimental colony size. Both pupal numbers and mean pupal size increased throughout the 4-month experiment even though worker number was kept constant.

Moss Capsules as Food of the Harvester Ant, Messor

Harvester ants, Messor spp., were observed feeding on moss capsules in a winter when no other food sources were available. The ants climbed up the seta, gnawed off the capsules and carried them to their nests. In the semiarid region where this phenomenon was observed, suitable climatic conditions for spore maturation are rare, and feeding of ants on moss sporophytes even more strongly reduces reproduction by spores. An ecological study carried out during the years 1977-80 included observations on the harvester ant (Messor spp.) as a seed collector. The locality for research was in the Northern Negev of Israel (20 km NW of Beer-Sheva), in a plain covered by loess, elevation 100 m a.s.l. with average annual rainfall of 250 mm. It is a semiarid annual grassland densely covered by mosses during the early winter. The mosses revive and their spores germinate following the first rain (which may occur between October and January), and they dry out with the desiccation of the upper soil layer. Periods between rains are usually too long to enable mosses to complete their life cycle and produce sporophytes before drying out. Winter of 1979-80 was exceptional in its prolonged and densely spaced rains. Conditions resulting from this were highly favourable for mosses, and sporophytes were formed abundantly. By the end of January and the beginning of February, mosses on the loess plain were bearing mature sporophytes, while phanerogams were still at their vegetative growing stage. The dense tufts of sporophytes that appeared simultaneously made them suitable for predators at a time when no seeds were available. The widespread mosses on the loess plain are Aloina aloides var. ambigua (Bruch & Schimp.) Craig, Crossidium crassinerve De Not., to a lesser extent Bryum bicolor Dicks., and some others. The majority of sporophytes of Aloina mature about two weeks before those of Crossidium (mid-January, instead of the beginning of February). Capsules of both species are borne on a straight seta (the setae of Aloina are longer and have larger capsules than those of Crossidium); in Bryum the seta is inclined. HARVESTING Observed for Aloina aloides, January 15, 1980. Harvesting ants (Messor ebeninus and a few colonies of M. semirufus) climb up the seta, check the capsules with their mandibles (possibly to judge size), turn their body downward and gnaw through the seta at the base of the capsule (Fig. 1, then both fall to the ground. The capsules are then carried to the nests. Observed for Crossidium crassinerve, February 1, 1980. In the meantime, all Aloina sporophytes had been harvested. The ants were found to be active in nearby patches of Crossidium. They climbed up the seta (shorter in this species) but did not turn around before cutting the capsules. Some large ants harvested the capsules while remaining on the ground. In Bryum bicolor, which is sparsely distributed, the inclined capsules were cut off by the ant in the two ways mentioned above, depending on the size of the ant and the sporophytes (Fig. 2). TRANSPORT Observed February 1, 1980. Ants transporting Crossidium sporophytes were seen to form a line, which in one case reached 15 m in length. The average pace of transport of capsules into the nest 007-2745/80/524-525$0.45/0 This content downloaded from 157.55.39.105 on Fri, 07 Oct 2016 04:53:56 UTC All use subject to http://about.jstor.org/terms 1980] LORIA & HERRNSTADT: MOSS CAPSULES 525 ~` 'C ~L ?__ -' ? ~`?t. r; i'~ ~R ?

Anomalous apetaly: localized character displacement in Ranunculus eschscholtzii

Apetaly is usually a rare variation in populations of the widespread hexaploid alpine Ranunculus eschscholtzii Schlecht. In certain high rainfall sections of the western Cascade Mountains of Washington, where populations of the hexaploid have been found in mixed association with those of a diploid relative, R. suksdorfii (elsewhere ecologically well separated though sympatric), the apetalous condition almost completely replaces the normal form. Any petal-bearing flowers of the hexaploid attract the flying pollen vectors (mainly syrphids) which also visit the overwhelmingly more numerous diploid species. Any resulting hybrids between the two species are sterile. Apetalous flowers are avoided by the syrphid pollinators. These flowers, nevertheless, regularly produce full sets of viable fruits. This may be attributed to the regular foraging visits of large terrestrial ants. The apetalous condition of R. eschscholtzii appears to have replaced the normal form in the high rainfall areas because only it can continue to reproduce and maintain the species in the presence of R. suksdorfii and the syrphid pollinators. This regional intensification of reproductive barriers between species already genetically isolated by their difference in ploidy, and between which hybrids have zero fitness, is interpreted as a case of character displacement involving both competition for a resource (pollinators) and hybrid sterility.

The multiple recruitment systems of the african weaver ant Oecophylla longinoda (Latreille) (Hymenoptera: Formicidae)

1. African weaver ants (Oecophylla longinoda) utilize no less than five recruitment systems to draw nestmates from the leaf nests to the remainder of the nest tree and to the foraging areas beyond: (a) recruitment to new food sources, mediated by odor trails produced from the rectal gland, a newly discovered exocrine organ, together with tactile stimuli presented during mouth-opening, antennation, and head-waggling; (b) recruitment to new terrain, entailing odor trails released from the rectal gland and tactile stimulation through antennation: (c) emigration to new sites; (d) short-range recruitment to territorial intruders, during which the terminal abdominal sternite is maximally exposed and dragged for short distances over the ground to release an attractant from the sternal gland, a second newly discovered structure; and (e) long-range recruitment to intruders, mediated by odor trails from the rectal gland and by antennation and intense body jerking. These systems exist in addition to the elaborate pheromone-mediated alarm communication previously described by Bradshaw et al. (1975). In aggregate, the alarm and recruitment systems of O. longinoda constitute the most complex of such repertories thus far discovered in ants. 2. Weaver ants recognize new terrain by means of both visual and olfactory cues, with the latter being the more effective. When major workers cannot cross gaps to the terrain by walking, they attempt to make the traverse by building bridges with their bodies. Individuals are attracted to the bridge site visually, but when the bridge is complete, they recruit nestmates to the new terrain with rectal-gland odor trails. 3. Workers mark newly acquired home range with randomly placed drops of fluid extruded from the rectal vesicle. They distinguish their own domain from that of alien conspecific colonies in part by means of the odor of the anal spots. When a section of terrain is found unmarked, the rate of anal-drop deposition is accelerated, even when adjacent areas are already heavily marked. 4. The anal substance is a true territorial pheromone: workers respond to alien spots initially with hostility and aversion, then by recruiting nestmates to the vicinity. In laboratory experiments, workers entering an arena simultaneously with workers from alien colonies always gained the initial advantage in the ensuing conflict if they had previously been allowed to mark the arena. When the arena was placed in a spatial position familiar to one colony but possessed a floor previously marked by the second colony, the second colony still won. To our knowledge these results represent the first demonstration of a true territorial pheromone in the social insects. 5. During foraging the Oecophylla workers move independently of one another and are distributed at random (Poisson distributed) or with slight temporary clumping of no more than two or three workers. Short-range recruitment of intruders causes the ants to shift to a more distinctly clumped pattern, involving as many as ten or more workers, at the same time that long-range recruitment brings more defenders into the vicinity. Together the two forms of response result in a more efficient capture of intruders that are too large to be immobilized by only one or two workers. 6. The complex recruitment and territorial behavior displayed by O. longinoda is considered to be part of the adaptation of these relatively large ants to a strongly arboreal existence. The similarity of four of the recruitment systems to each other (1 a, b, c, and e above) is interpreted as an example of signal economy in the evolution of social insect communication systems. The parallel evolution has been enhanced by the lack of any strong functional distinction between territorial defense and predation (see Discussion). 6. Signal ritualization appears to have occurred in at least two contexts: the modification of body thrusting during territorial battles into the jerking signal used in long-range recruitment of nestmates to enemies; and the adoption of anal excrement in the chemical marking of territories.

Direct ingestion of plant sap from cut leaves by the leaf-cutting ants Atta cephalotes (L.) and acromyrmex octospinosus (reich) (Formicidae, Attini)

AbstractIngestion of radiolabelled plant juices from cut surfaces of leaves during foraging and during substrate preparation for the fungus garden was demonstrated for laboratory colonies of the leaf-cutting ants Atta cephalotes (L.) and Acromyrmex octospinosus (Reich). Using P32 isotope, up to one-third of the radioactivity in the leaves was taken in directly by the colony as a whole, but this was much less when C14 was used. Additional plant material was taken in by the ants via the fungus garden. Large numbers of ants spend time in investigating cut surfaces of leaves and also in cutting and crimping leaves. Ingestion of plant material during these processes could play an important nutritional role in the colony and this may explain why many ants return from foraging apparently unladen. Large ants obtained most of their plant juice intake during foraging and the medium and small ants took much of theirs during substrate preparation. Inhibitory chemicals did not affect cutting but they reduced drinking and also reduced the intake of P32 from leaves during substrate preparation. The ants also ingested different amounts of P32 from leaves of different acceptability. It is suggested that leaf-cutting ants use fungus culture as a means of ‘sidestepping’ plant inhibitors. Nutrients are ingested directly from leaves when these are palatable, and the less palatable components are made available to the ants via the fungus.

A Portable Battery-Operated Aspirator (Ant Collector)1

To satisfy the increasing demands for live ants in our research program, it became necessary to design and develop portable collection equipment which was more efficient and versatile than previously described devices. These equipment needs are summarized as follows: portable, with weight not to exceed 15 lb; easily usable for collecting large ants; battery-operated and requiring minimum of battery changes during 1 day; batteries rechargeable overnight; and easily repaired, with interchangeable parts.

Versuche zur Frage der Futterverteilung und Wasseraufnahme beiFormica polyctena (Först.)

The distribution of food in outside workers ofFormica polyctena is determined by begging time and not by the sequence in which the ants are fed. Larger ants are given no preference in feeding. In thirsty condition ants take in, besides normal water, also the soil capillary water. It will be faster conducted to the middle gut than honey solution.

SIXTEEN YEARS' EXPERIENCE WITH FORMIC ACID AS A THERAPEUTIC AGENT.

My attention was first drawn to the medicinal qualities of formic acid by a semi-secret preparation styled by its manufacturer, Hensel, Ferrum formicarum oxidatum oxydulatum. This was in 1888. The same or a similar preparation is now sold by a homeopathic drug house under the name of tonicum. HISTORICAL REVIEW. There is no doubt in my mind that Hensel's formic acid compound is a latter-day transformation of Hoffmann's Vinegar of Magnanimity, in which a preparation of ants played the leading role. In the seventeenth century this famous vinegar had found entrance in all European courts and was employed by men and women as a general tonic, stomachic and diuretic, and probably also as an aphrodisiac. For formic acid seems to possess certain qualities stimulating sexual appetite (in South America a species of large ants are consumed), and the proprietary tonics demanding a good sale, as a general rule, are

CABINET PEST DETERRENT

One of the most worrying things an entomologist has to put up with is that after carefully making a collection his most valued specimens are nearly eaten away, either with mites or the Dermestes beetle.For the benefit of my brother enthusiasts, let me give briefly my personal experience. Last June captures at light were very good and numerous. Many rare insects were taken and set out. The settingboards were placed on a shelf. By the morning the contents of three boards were literally eaten away by large black ants, house flies, and the little black and orange beetle. If my thoughts had been candidly expressed I am afraid my reputation would have been irretrievably lost, so I hunted around for a remedy and was soon successful in finding one.