The Influence of Extrafloral Nectaries on Arboreal Ant Species Richness in Tree Communities

Studies investigating the role of resource availability in the species richness patterns can elucidate ecological processes and contribute to conservation strategies. In this study, we test two hypotheses: i) arboreal ant species richness increases with abundance of extrafloral nectaries-bearing trees; and ii) arboreal ant species richness increases with the diversity of extrafloral nectaries-bearing trees. We used data of ant sampling and tree inventories from 30 plots of Brazilian Cerrado. Arboreal ant species richness was positively influenced by the proportional abundance of extrafloral nectaries-bearing trees, total tree density and total tree diversity. There was no effect of species richness of extrafloral nectaries-bearing trees. Coefficient of determination of proportional abundance of extrafloral nectaries-bearing trees was larger when compared to coefficient obtained using tree density as explanatory variable. These results suggest that variation in arboreal ant species richness is better explained by extrafloral nectaries-bearing tree abundance than total tree density. Generalist foraging behavior of sampled ant species may explain their association with proportional abundance of extrafloral nectariesbearing trees and their non-significant relation with proportional richness of extrafloral nectaries-bearing tree species. Extrafloral nectaries-bearing trees abundance may be a specific estimate of the amount of food resource available in plots. Thus, this is a more specific way to quantify which resources may explain variation of the arboreal ant species richness in tree communities. We hope these results will be helpful to understanding the local variation in ant species richness and as criteria to biodiversity conservation

A Day in the Life of the Giant Ant Dinoponera lucida Emery, 1901 (Hymenoptera, Formicidae): Records of Activities and Intraspecific Interactions

Ants present a wide variety of nesting sites, feeding habits, and trophic interactions, but the biology of most species remains unknown. Dinoponera lucida is a poneromorph ant forest-specialist and solitary forager, endemic to the Brazil’s Atlantic Forest. Herein we describe foraging activities, guard and maintenance of the nests, orientation mode, and intraspecific interactions performed by D. lucida. We found three nests distant from each other at least 8.5 m, and the mean reached distance by a worker was 3.8 m. The workers showed colony fidelity and random forage in their territory. We observed two non-agonistic interactions between workers from the same nest, and two agonistic interactions between foraging workers from different nests. The low frequency of agonistic interactions suggests that workers from different nests are unlikely to forage in the same area. Our results expand the knowledge on ants’ natural history through data on foraging activities, guard and maintenance of the nests, orientation mode and intraspecific interactions

Litter Surface Temperature: A Driving Factor Affecting Foraging Activity in Dinoponera lucida (Hymenoptera: Formicidae)

Dinoponera lucida is a poneromorph ant endemic to the Atlantic Forest of Brazil. The species is classified as endangered in Brazil’s Red List due to its peculiar reproductive biology and high habitat fragmentation. Herein, we characterize D. lucida foraging activity and response to litter surface temperature in a lowland forest remnant in south-eastern Brazil. The mean flow of workers at nest openings was 3.8 ± 0.6 per hour, mean foraging trip was 14.2 ± 2.2 min, and mean foraging distance was 3.8 ± 0.4 m. The time spent per foraging trip and litter surface temperature were positively correlated. Flow of workers at nest openings was higher with mean temperature of litter surface between 21.0 and 27.0 °C. Our results show that D. lucida has a diurnal foraging activity related to habitat temperature. Our data contribute to the knowledge about the ecology of D. lucida and support the hypothesis of optimal food foraging regulated by habitat temperature. In addition, the better understanding of D. lucida activity patterns can assist on conservation planning of this endangered and endemic ant

How much leaf area do insects eat? A data set of insect herbivory sampled globally with a standardized protocol

Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant–herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species

Response of ant community to habitat fragmentation

A fragmentação de habitats tem sido apontada como uma das principais causas de alterações na riqueza, abundância e composição de espécies em ambientes tropicais. O objetivo da tese foi testar hipóteses relativas a alterações no número e composição de espécies de formigas devido a mecanismos biológicos gerados pela fragmentação florestal. Os principais testados foram: invasão por espécies da matriz, colonização e extinção, efeitos de borda e de forma. Os dados do primeiro e segundo artigo foram coletados, respectivamente em17 e 18 fragmentos na região de Viçosa com áreas variando de 3 a 300 ha e em dez pastagens ao redor destes. As coletas nos fragmentos foram realizadas durante três anos consecutivos, o que permitiu o estudo das taxas de extinção local e colonização, enquanto as coletas na matriz foram realizadas apenas em um dos três anos. Foram usadas armadilhas do tipo pitfall com diferentes iscas e as coletas foram feitas com três diferentes níveis de amostragem de acordo com a área dos fragmentos. Para a realização do terceiro artigo foram feitas coletas em dez fragmentos com áreas variando entre 3 e 100 ha aproximadamente, nos quais foram feitas dez amostras de 1m2 de serapilheira na borda e dez no centro. A serapilheira foi peneirada e colocada num extrator de Winkler para a extração das formigas. A área e o isolamento dos fragmentos foram determinados a partir de fotos aéreas. Quando foi usado esforço amostral proporcional observou-se aumento do número de espécies com aumento da área dos remanescentes. Além disso, fragmentos menores mostraram- se mais homogêneos em termos de composição de espécies do que os maiores e potencialmente mais sujeitos à invasão por espécies de matriz, uma vez que apresentaram, proporcionalmente, um maior número de espécies em comum com a matriz que os grandes. Embora o grau de isolamento não tenha influenciado na taxa de colonização, as taxas de extinção local foram maiores nos fragmentos menores, padrão que pode ser explicado pela menor densidade populacional apresentada pelas formigas nestes remanescentes. Ainda que as taxas de colonização não tenham variado, formigas generalistas colonizam mais freqüentemente os fragmentos pequenos, enquanto formigas especialistas de florestas colonizam mais os grandes. Também há diferenças em relação às taxas de extinção, sendo que formigas generalistas apresentam uma maior extinção dentro dos fragmentos que as especialistas, independentemente da área. Há mais espécies de formigas no centro do que na borda dos fragmentos e não se observou aumento do número de espécies à medida que se distancia da borda. Conclui-se, portanto, que a fragmentação causa alterações na composição de espécies de formigas e que estas alterações são mais pronunciadas em fragmentos pequenos, os quais sustentam populações menores e estão mais sujeitos à invasão e a efeitos de borda e de forma, uma vez que apresentam uma maior borda relativa.Habitat fragmentation has been pointed as a main cause of changes of species richness, abundance and composition in tropical environments. This thesis aimed to test hypotheses relative to alterations of ant species richness and composition generated by forest fragmentation. The mechanisms tested were: invasion by matrix species, colonization and extinction, and edge and shape effects. Data from the first and second paper presented were collected in 17 ad 18 remnants, respectively, in the region of Viçosa, varying from 3 to 300 ha and in ten pastures around the remnants. Sampling have been carried out during three consecutive years, allowing the study of the local extinction and colonization rates, whereas sampling in the matrix occurred in only one of these three years. Baited pitfall traps were used and the number of samples in the remnants was proportional to their areas. Sampling of the third paper of this thesis were carried out in ten remnants with areas ranging from 3 to 100 ha, in which ten 1m2 samples of litter were collected in the edge of the remnants, and other ten in the center of the remnants. Litter samples were sifted and put into a Winkler extractor, to remove the ants. Remnant areas and isolation were determined using aerial photographs. Proportional sampling showed an increase of species richness with increase of remnant area. Furthermore, smaller remnants were more homogeneous in species composition than larger remnants, and potentially more invasion-prone by matrix species, because they presented proportionally more species in common with the matrix than larger remnants. Even though the degree of isolation has not influenced the colonization rate, the local extinction rates were higher in the smaller remnants, pattern that may be explained by the smaller ant population density in these remnants. Although the colonization rates did not vary with remnant area, generalist ants colonized more frequently the smaller remnants, whereas specialist ants colonized more the larger remnants. There were also differences in relation to the extinction rates within remnants, and generalist ants presented higher extinction in the forests, independently of their areas. There were higher species richness in the center than remnants edge, and there were no relationship between species richness and the distance from the forest edge. Concluding, forest fragmentation caused alterations on ant species composition and these changes are more pronounced in smaller remnants, which sustain smaller populations and are more prone to invasion and to edge and shape effects, because they present a higher relative edge.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Oviposição de Diaphania hyalinata L. (Lepidoptera, Pyralidae) afetada pela face foliar e tricomas

The objective of this work was to study the effects of the leaf blades and present trichomes in squash leaves (Curcubita pepo) on the oviposition of . D. hyalinata. Two bioassays were conducted: one of free choice and another of confinement. The trichomes were counting in leaf blades of 10 leaves. In the bioassay of free choice the oviposition was larger in abaxial leaf blade than in the adaxial, which was only verified in leaves in natural position in the confinement bioassay. It was verified in the bioassay of free choice increase of the oviposition when the position of the leaf blades was inverted. The abaxial leaf blade presented larger total number of non-glandular trichomes and of glandular trichomes type P than the adaxial leaf blade. The adaxial leaf blade, on the other hand, presented larger number of glandular trichomes types C and the total of glandular trichomes that to the abaxial leaf blade.Este trabalho teve por objetivo estudar os efeitos das faces foliares e dos tricomas em folhas de abóbora (Curcubita pepo) sobre a oviposição de D. hyalinata. Foram realizados dois bioensaios: um de livre escolha e outro de confinamento. Foi realizada contagem de tricomas nas faces foliares de 10 folhas. No bioensaio de livre escolha a oviposição foi maior na face abaxial que na adaxial, fato este que só foi verificado em folhas em posição normal no bioensaio de confinamento. Verificou-se no bioensaio de livre escolha aumento da oviposição quando inverteu-se a posição das faces foliares. A face abaxial apresentou maior número total de tricomas tectores e de tricomas glandulares tipo P do que a face adaxial, já a face adaxial apresentou maior número de tricomas glandulares tipos C, O e total de tricomas glandulares do que à face abaxial