No abstract

In tropical forests, one of the most commonly encountered relationships between parasites and insects is that between the fungus Ophiocordyceps (Ophiocordycipitaceae, Hypocreales, Ascomycota) and ants, especially within the tribe Camponotini. Here, we describe three newly discovered host-specific species, Ophiocordyceps camponoti-atricipis, O. camponotibispinosi and O. camponoti-indiani, on Camponotus ants from the central Amazonian region of Brazil, which can readily be separated using morphological traits, in particular the shape and behavior of the ascospores. DNA sequence data support inclusion of these species within the Ophiocordyceps unilateralis complex.

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Dinoponera Roger 1861 has been revised several times. However, species limits remain questionable due to limited collection and undescribed males. We re-evaluate the species boundaries based on workers and known males. We describe the new species Dinoponera hispida from Tucuruí, Pará, Brazil and Dinoponera snellingi from Campo Grande, Mato Grosso do Sul, Brazil and describe the male of Dinoponera longipes Emery 1901. Additionally, we report numerous range extensions with updated distribution maps and provide keys in English, Spanish and Portuguese for workers and known males of Dinoponera. ResumenEl género Dinoponera Roger 1861 ha sido revisado varias veces. Sin embargo, la distribución geográfica de las especies de este género todavía es cuestionable debido a colecciones limitadas, y a que en general los machos continúan sin descripción. Reevaluamos los límites geográficos de las especies utilizando caracteres merísticos y morfométricos basados en obreras y machos conocidos. Describimos las nuevas especies Dinoponera hispida de Tucuruí, Pará, Brasil, y Dinoponera snellingi de Campo Grande, Mato Grosso do Sul, Brasil, y describimos el macho de Dinoponera longipes Emery 1901. Además, reportamos numerosas extensiones nuevas de las distribuciones geográficas con sus respectivos mapas actualizados, y proporcionamos claves de identificación en inglés, español, y portugués para las obreras y los machos conocidos del género Dinoponera. ReseARCH ARtiClePaul A. Lenhart et al. / Journal of Hymenoptera Research 31: 119-164 (2013) 120 Resumo O género Dinoponera Roger1861, é tem revisados varios vezes. No entanto, a clarificação das especies ainda segue questionável devido a um coleção limitado, e a que em geral os representantes do sexo masculino continuam sem descrição. Reavaliamos os limitas de espécies utilizado caráteres merísticos e morfométricos, baseado em operários e machos conhecidos. Descrevemos novas espécies Dinoponera hispida de Tucuruí, Para, Brasil e Dinoponera snellingi de Campo Grande, Mato Grosso do Sul, Brasil, e descrevemos o macho de Dinoponera longipes Emery 1901. Además, reportamos distribuições geográficas com seus respetivos mapas atualizados, e proporcionamos chaves de identificação em inglês, espanhol, e português para operários e machos conhecidos do género Dinoponera.

We tested the hypotheses that rates of decomposition in a desert should be higher following single large rain events of 25 mm than evenly spaced 6 mm events and that supplemental rainfall should result in higher populations of soil biota. There were no significant differences in mass losses of creosotebush, Larrea tridentata, leaf litter on plots receiving water supplementation and no added water. On some sampling dates, there were higher mass losses in the 6 mm·week treatment. Weekly rainfall produced higher coefficients of variation in mass losses than the other rainfall regimes. A single event pulse compared with weekly pulses of rainfall during the normal "dry" period resulted in no differences in mass losses. Microarthropods and nematodes exhibited numerical responses to supplemental rainfall but the litter microflora did not. These studies provide direct experimental evidence that the conventional wisdom linking decomposition to rainfall in deserts is wrong. The studies also suggest that the effects of litter fauna on surface litter decomposition are minimal; therefore, future studies should focus on activites of the microflora.

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Spiders have been shown to be important predators on ant populations, although ant mortality may be low. Western widow spider (Latrodectus hesperus) predation on Pogonomyrmex rugosus ant nests is slight, less than 0.2% of the nest population per day. Yet, the ants respond by halting foraging temporarily and may even close the nest entrace with pebbles. If spiders are removed from such nests, the ants become active within 24 h and within five days foraging activity reaches higher levels than at any previous time of the year.Ants have at least four responses to spiders predation: 1) Moving the nest entrace; 2) posting of "guards"; 3) attacking the spiders; 4) halting foraging. Pogonomyrmex rugosus practices the fourth response, although it results in losses of food intake into the nest. This is apparently the only option available. If the ants continue to forage, the spider density may increase, resulting in heavy mortality of the ants.

This investigation compares the energy budgets of three species of Pogonomyrmex harvester ants along an altitudinal transect in southern California. All three demonstrate similar seasonal patterns, with high foraging activity and high respiratory costs in mid-summer and little or no activity during winter. Respiration, predominantely metabolism of the workers, was estimated to account for 84-92% of the energy assimilated by the nests. The remaining 8-16% of the energy was invested in the production of new individuals. However, total production was not correlated with food input. It is suggested that worker care of the brood may be the most important determinant of brood production, and thus food may not be a direct limiting resource in harvester ants.A higher percentage of production is invested in workers than in reproductives in all three species. The species usually partition similar proportions of energy between the production of males and females, but since females are larger, more males are produced. Although the species are in different habitats and have very different numbers of workers per nest, the numbers of sexuals produced per nest are similar. The sex-ratio appears to be ecologically determined. Nests that were provided with additional food invested more energy in the production of males. Control nests, nests which had food removed and older nests invested more in the production of females or invested equally in the production of the two sexes.