Search

Primary forests are known to have positive effects on the biodiversity of surrounding secondary forests. However, it is unclear whether primary forest remnants affect the feeding habits of consumers that inhabit secondary forests. Here, we examined whether the feeding habits of ants (Formicidae: Hymenoptera) belonging to four taxonomic groups ( Camponotus gigas , Odontomachus rixosus , Pachycondyla spp., and Polyrhachis spp.) differed in Macaranga secondary forests with different proportions of surrounding primary forest remnants in Sarawak, Malaysia. In the secondary forests, our previous study showed that species diversity of ants significantly increased as the proportion of surrounding primary forest remnants increased. We explored feeding habits by measuring carbon and nitrogen isotope ratios (δ 13 C and δ 15 N). We also estimated the diet age of the ants, which represents the lag time between primary production and utilization by ants, by performing radiocarbon (Δ 14 C) measurements. δ 13 C of ants and litter decreased with the increase in primary forest remnants, likely indicating a more closed canopy cover around the sites. Meanwhile, baseline-corrected δ 15 N of ants, which considered the variation in plant δ 15 N among study sites, or diet ages of the ants did not show significant response to the proportion of the surrounding primary forest remnants. δ 13 C, δ 15 N, and diet ages showed consistent differences among the ant taxa across different proportions of primary forest remnants. These isotopic patterns suggest that, in contrast to the effect on species diversity, surrounding primary forest remnants did not markedly affect the feeding habits of the ants that persisted in the secondary forests.

Several fungal pathogens of ants have been reported as members of the family Ophiocordycipitaceae in the order Hypocreales. Surveys in the south of Thailand have shown specimens showing characteristics that are morphologically similar to Ophiocordyceps unilateralis, a very common ant pathogen, by producing a lateral pad on one side of the stroma and producing whole ascospores. Phylogenetic analyses of the partial elongation factor tef1-α and the internal transcribed spacer regions ITS1-5.8S-ITS2 rDNA have shown that this is a distinct species from O. unilateralis. The morphological characters of Ophiocordyceps halabalaensis differs from O. unilateralis in the possession of bigger perithecia and ascospores, and molecular analyses have shown that this ant-specific fungus is sufficiently different from O. unilateralis, deserving the naming of a new species. Aspects of morphology, host association/host-specificity, and taxonomic position are discussed.

Despite the recognition of the functional role of Hymenoptera (ants, bees and wasps) and Isoptera (termites) in tropical ecosystems, their detailed feeding habits are not well known. To examine the feeding habits of these groups, we measured nitrogen (N) and carbon (C) stable isotope ratios (δ15N and δ13C) of hymenopterans (12 families, ≥16 genera and ≥32 species) and isopterans (one family and 10 species) collected in a tropical rain forest, Sarawak, Malaysia. We compared the isotopic signatures of these insects to those previously reported for other consumers collected in the same forest. The δ15N and δ13C values of these insects overlapped with those of the other consumers, indicating that they have access to diverse C and N sources in the forest. The δ15N values of ants and termites indicated that their feeding habits range along a continuum from herbivory (i.e. dependent on honeydew and nectar) to predation and from wood-feeders to soil-feeders, respectively. In addition, the δ15N values of wasps varied greatly from −0.1‰ (Braconidae sp.) to 8.6‰ (Bembix sp.), suggesting that their feeding habits also range from omnivory to predation. The ant species Camponotus gigas had δ13C values similar to those of invertebrate detritivores and omnivores rather than to those of invertebrate herbivores, although the diet of this species consists mostly of honeydew. This discrepancy suggests that the ant uses carbohydrates as an energy source, the isotopic signatures of which are not well retained in the body tissues. Values of both δ15N and δ13C of the predatory army ant Leptogenys diminuta and the soil-feeding termite Dicuspiditermes nemorosus did not differ significantly, indicating that both trophic level and the humification of feeding substrates can increase the isotopic signatures of terrestrial consumers.

In a 5-ha area of primary lowland rain forest in Borneo, we observed four polydomous colonies of the night-active giant ant Camponotus gigas. The nonover- lapping, three-dimensional territories in the canopy had a ground size up to 0.8 ha. C. gigas showed a distinct territo- rial behavior: (1) specific "barrack" nests, especially con- taining many majors, were situated at the borders and were established during long-term territorial conflicts; (2) trunk trails were regularly patrolled by majors that attacked alien conspecifics and some other ant species violently; and (3) sentinels, often involved in long-enduring conflicts with neighboring ant colonies, defended the borders at bridge- heads. Interspecific conflicts with sympatric Camponotus species always led to violent, "bloody" fights of all castes. Intraspecific conflicts, however, were solved by ritual fights ("front leg boxing") of majors. C. gigas performed a de- escalation strategy to end short periods of true intraspecific "ant war" that we provoked experimentally. Artificially induced ritualized combats continued over weeks also in the absence of baits, indicating that borders may become established by long-term conflicts of attrition. We discuss the differences between ritual fights in desert and rain- forest ants and apply Lanchester's theory of battles to our findings.

In Kinabalu National Park, Borneo we observed four colonies of the Malaysian giant ant Camponotus gigas in a primary forest. These predominantly nocturnal ants have underground nests, but forage in huge three-dimensional territories in the rain forest canopies. The colony on which our study was mainly focused had 17 nests with about 7000 foragers and occupied a territory of 0.8 ha. To improve observation and manipulation possibilities, these nests were linked at ground level by 430 m of artificial bamboo trail. A group of specialist transport worker ants carried food from `source' nests at the periphery to the central `sink' nest of the queen. Transport of food between nests started immediately after the evening exodus of the foragers. Transporter ants formed a physical subcaste among the minors and behaved according to predictions of the central-place foraging theory. Their load size was about five times that of the average forager and grew proportionally with head width. Longer distances were run by ants with greater head width and larger gross weight. Transporter ants that ran more often took heavier loads. Experiments with extra-large baits revealed that C. gigas used long-range recruitment to bring foragers from different nests to "bonanzas" at far distant places. The foraging strategy of C. gigas is based on a polydomous colony structure in combination with efficient communication, ergonomic optimization, polyethism and an effective recruitment system.

The foraging behaviour of the giant ant Camponotus gigas, was studied in primary lowland rainforest in Brunei. Nests, found mainly in soil at the base of trees or in fallen timber, were present at a density of 14 per hectare. Foragers were active nearly 24 h per day but much higher levels of activity were recorded at night. By day major and minor workers foraged singly or in small groups on the ground, and by night they ascended in a steady stream into the canopy. It is suggested that the canopy is avoided during the day due to high temperatures and low humidity, and the ground is avoided at night due to increased predatation risks. Overall, < 10% of foragers returned laden suggesting that most feeding took place while foraging. The most common food item retrieved was fungus although arthropods and arthropod remains, vertebrate remains and small fruits and seeds were also gathered. Relatively more arthropods were retrieved at night. By watching individually marked ants, it was found that different individ...

Three large tropical rain forest ant species (Camponotus gigas, Diacamma intricatum and Odontoponera transversa) in primary lowland dipterocarp forest, Brunei Darussalam, were not found to be significantly negatively associated spatially or in occurrences at baits. Food overlap was found to be high, and time overlap quite low, but not in the species of high food overlap. No evidence of resource partitioning was found, although each species had food preferences. Positive associations are likely to be microhabitat mediated.

Esp. C. gigas Latr. [[worker]] [[queen]] et [[male]] recoltes a Sumatra par le Dr C. Klaesi (collection Autran). La [[worker]] a de 17 a 28 mill., la [[worker]] 30 mill, et le [[male]] 17 mill. ��� [[worker]] Tumpang Hiang et Amoberen a Borneo, recoltes par M. Grabow (Musee de Berlin). Johore, presqu'ile de Malacca (Musee de Calcutta)., Published as part of Forel, A., 1886, ��tudes myrm��cologiques en 1886., pp. 131-215 in Annales de la Societe Entomologique de Belgique 30 on page 42

29. C. gigas Ltr. Es ist mir nur der kleine [[worker]] aus Borneo (im Mus. Caes.) bekannt. Laenge: 20 - 22 mm. Schwarz, fast matt, Hinterleib roth, die Geissel, Hueften, Schenkel und das Stielchen braunroth, manchmal sind die Hueften, Schenkel und das Stielchen braeunlich gelb, Ende der Schenkel so wie die Schienen und Tarsen schwarz. Die abstehende Behaarung ist ziemlich reichlich, auf den Beinen aber spaerlich; die anliegende Pubescenz ist ziemlich spaerlich. Der Kopf ist laenglich oval, hinter den Augen verengt, aber keinen Hals bildend. Die Mandibeln sind sehr fein und sehr seicht lederartig gerunzelt und weitlaeufig grob punctirt. Der Clypeus ist glaenzend, fein lederartig gerunzelt, scharf gekielt, vorne in einen Lappen verlaengert, der Vorderrand desselben ist gerade, kaum ausgerandet und jedes Eck in ein Zaehnchen ausgezogen. Die uebrigen Kopftheile sind ebenfalls fein lederartig gerunzelt, eben so der Thorax, der ziemlich klein und compress ist. Das Stielchen traegt oben eine sehr dicke, kleine knotenfoermige Schuppe mit vorderer convexer und hinterer abschuessiger Flaeche. Der Hinterleib ist fein quergerunzelt. Die Schienen sind vierseitig, jede Seite bildet eine Rinne, das 1. Tarsenglied ist ebenfalls vierseitig. Die Sporne sind dornfoermig., Published as part of Mayr, G., 1862, Myrmecologische Studien., pp. 649-776 in Verhandlungen der Zoologisch-Botanischen Gesellschaft in Wien 12 on page 669