RESUMEN
Ants benefit myrmecophytic plants by two main activities defending them from herbivores and offering nutrients. Ants' territorial defence behaviour also benefits their myrmecophytic plants; in the case of trees, this behaviour includes eliminating structural parasites (epiphytes and lianas). These benefits could also occur with myrmecophytic epiphytes by decreasing the abundance of competing epiphytes. In two subunits of a tropical dry forest in the centre of Mexico, we (i) recorded the diversity of ants associated with the myrmecophyte Tillandsia caput-medusae, and experimentally tested: (ii) the effect of the ants associated with the myrmecophyte in the removal of its seeds and the seeds of other sympatric non-myrmecophyte species of Tillandsia; and (iii) if seed remotion by ants corresponds with epiphyte load in the preferred (Bursera copallifera) and limiting phorophyte species (B. fagaroides, Ipomoea pauciflora and Sapium macrocarpum). In five trees per species, we tied seed batches of T. caput-medusae, T. hubertiana, T. schiedeana and T. recurvata. One seed batch was close, and the other far away from a T. caput-medusae with active ants. Between forest subunits, ant richness was similar, but diversity and evenness differed. Ants diminish seed establishment of all the Tillandsia species; this effect is stronger in the forest subunit with a large ant diversity, maybe because of ant competition. Seed remotion by ants is independent of phorophyte species identity. Although ants can provide benefits to T. caput-medusae, they also could be lowering their abundance.
RESUMEN
New state and host records are provided for 28 species of Buprestidae collected in Morelos, Mexico in the following genera: Acmaeodera Eschscholtz 1829, Actenodes Dejean 1833, Agrilus Curtis 1825, Brachys Dejean 1833, Chrysobothris Eschscholtz 1829, Leiopleura Deyrolle 1864, Lius Deyrolle 1864, Pachyschelus Solier 1833, and Tetragonoschema Thomson 1857.
Asunto(s)
Escarabajos , Animales , MéxicoRESUMEN
A revision of the Central American species of the genus Brachiacantha was undertaken to update the knowledge of the Central American species of the genus. Material of several collections was reviewed, using original descriptions and keys, and comparing with the type material. Twenty-five species of the genus Brachiacantha were found in Central American material, including nine new species: B. nubes Nestor-Arriola, Toledo-Hernández and Solís, sp. nov., B. dentata Nestor-Arriola, Toledo-Hernández and Solís, sp. nov., B. isthmena Nestor-Arriola, Toledo-Hernández and Solís, sp. nov., B. aurantiapleura Nestor-Arriola, Solís and Toledo-Hernández, sp. nov., B. invertita Nestor-Arriola, Toledo-Hernández and Solís, sp. nov., B. papiliona Nestor-Arriola, Toledo-Hernández and Solís, sp. nov., B. tica Nestor-Arriola, Toledo-Hernández and Solís, sp. nov., B. hexaspina González, Vetrovec and Nestor-Arriola, sp. nov., and B. mimica Nestor-Arriola and Toledo-Hernández, sp. nov. Nomenclatural changes include Brachiacantha gorhami (Weise), comb. nov., B. guatemalensis (Gorham), comb. nov., and Brachiacantha duodecimguttata Leng, syn. nov. for B. lepida Mulsant. The male genitalia of the species B. fenestrata Gorhan, B. octostigma Mulsant, B. aperta Weise, and B. cachensis Gorhan are described and illustrated for the first time. New records include B. indubitabilis Crotch and B. bipartita Mulsant (Costa Rica and Guatemala), B. gorhami (Weise) (El Salvador), and B. cachensis Gorham (Panamá). A key to the species is included.
RESUMEN
Three new species of Diplotaxis Kirby are described and illustrated, D. balam sp. nov. from Guatemala, and D. chiapasensis sp. nov. and D. complanatis sp. nov. from Mexico. The new species have a flattened body and are included in the trapezifera species group. An updated key to the trapezifera species group is given.
RESUMEN
Despite its high ecological importance, the commensal interactions at community level are poorly studied. In tropical dry forests (TDF) there is a great diversity of species adapted to the high seasonality that characterizes them; however, little is known regarding how the spatial and temporal availability of resources generates changes in the pattern of commensal interactions. We experimentally studied changes in the diversity, composition, and pattern of interactions in spatio-temporal associations between the saproxylophagous beetles and their host trees in a TDF in Morelos, Mexico. A total of 65 host tree species were selected, from which 16 wood sections were obtained per species. These sections were exposed in the field to allow oviposition by the cerambycids under four different (spatio-temporal) treatments. We analyzed the network structure and generated indices at species level (i.e., specialization, species strength, and effective partners) and those related to physical characteristics of the wood (hardness and degradation rate) and the cerambycids (body size). In total, 1,323 individuals of 57 species of cerambycids emerged. Our results showed that, independently of the space and time, the network presented a nested and modular structure, with a high specialization degree and a high turnover of cerambycid species and their interactions. In general, we found that the cerambycids are mostly associated with softwood species with a lower decomposition rate of wood, as well as with the most abundant host species. The commensalistic interactions between the cerambycids and their host trees are highly specialized but are not spatio-temporally static. The high turnover in the interactions is caused by the emergence patterns of cerambycids, which seem to restrict their use to certain species. The knowledge of the spatio-temporal variation in Cerambycidae-host tree interactions allows us to predict how environmental and structural changes in the habitat can modify the species ensemble, and therefore its interactions.
Asunto(s)
Escarabajos/fisiología , Interacciones Huésped-Parásitos/fisiología , Árboles/parasitología , Animales , Biodiversidad , Escarabajos/patogenicidad , Ecosistema , Femenino , Bosques , Especificidad del Huésped , México , Oviposición , Análisis Espacio-Temporal , Simbiosis/fisiología , Clima Tropical , MaderaRESUMEN
Global climate change is expected to affect temperature and precipitation patterns worldwide, which in turn is likely to affect insect phenology, distribution and diversity. To improve our understanding of such processes, it is important to understand how insects may respond to changes in seasonality, and how these affect their activity, patterns of distribution and species richness. The tropical dry forest (TDF) is a highly seasonal ecosystem, for which two seasons are commonly described (rainy and dry) and there is a lack of information on the combined effect of both precipitation and temperature on the insect communities. In order to evaluate the seasonal patterns in the community of Cerambycidae in a TDF, historical climatic variables were obtained, and an annual sampling of the family was carried out, using three collection techniques. We found that the Cerambycidae family showed a more complex response to climate, than simply the rainy and dry season of the year. The relationship between diversity and composition of cerambycids with changes in temperature and precipitation showed four seasonal communities which were synchronized with phenological processes of the TDF. Climate change could reduce biodiversity, causing seasonal patterns to lose complexity, either because the climatic characteristics of a season disappear and/or because the duration of a season expands, these changes will modify the ecological processes of the TDF, since they would generate changes in the flora and fauna associated with the different seasons.
RESUMEN
New synonyms and new data are presented on Brachiacantha Dejean, 1837, species belonging to the dentipes group. Coccinella laevis Thunberg, 1781, nomen oblitum and Brachiacantha decora Casey, 1899, syn. nov. are recognized as synonyms of B. bistripustulata (Fabricius, 1801); B. dentipes americana Leng, 1911, syn. nov. is synonymized with B. dentipes (Fabricius, 1801); new Neotropical localities are included for B. barberi Gordon, 1985, B. quadrillum LeConte, 1858, B. subfasciata Mulsant, 1850, and B. tau LeConte, 1859. Brachiacantha erythrura Mulsant, 1850, is added to the dentipes group and redescribed, the male genitalia are illustrated and a map of the distribution of this species is provided. A key to all species of the group is included. New data about hosts and prey are added for B. bistripustulata and other species.
Asunto(s)
Escarabajos , Animales , MasculinoRESUMEN
Seed depredation is recognized as a determining factor in plant community structure and composition. Ants are primary consumers of seeds influencing abundance of epiphytes on trees. This study was conducted in two subunits of a tropical dry forest established on different soil substrates in San Andrés de la Cal, Tepoztlán, in Morelos, Mexico, and experimentally tested whether seed removal activity is higher in tree species with smaller epiphyte loads compared to those with greater epiphyte loads. Five trees were selected at random from six species of trees with high (preferred hosts) or low (limiting hosts) epiphyte loads. Seed removal differed among hosts and different soil substrates in the forest. On relating seed removal to the abundance of arboreal ants, the most consistent pattern was that lower seed removal was related to lower ant abundance, while high seed removal was associated with intermediate to high ant abundance. Epiphyte seed removal by ants influences epiphyte abundance and can contribute considerably to a failure to establish, since it diminishes the quantity of seeds available for germination and establishment.
RESUMEN
Five new species of the genus Brachiacantha Dejean (Coccinellidae) from Mexico and Central America are described and illustrated. The species B. angulata sp. nov., B. truncata sp. nov., B. brevicuspidata sp. nov. and B. robustihamata sp. nov. are consistent with the dentipes group. The species B. brevihamata sp. nov. is consistent with the fifth group of Leng (1911); the species shares some characteristics with South American species.
Asunto(s)
Escarabajos , Distribución Animal , Animales , América Central , MéxicoRESUMEN
Seed dispersal permits the colonization of favorable habitats and generation of new populations, facilitating escape from habitats that are in decline. There is little experimental evidence of the factors that limit epiphyte dispersion towards their hosts. In a tropical dry forest in central Mexico, we monitored the phenology of dispersion of epiphyte species of the genus Tillandsia; we tested experimentally whether precipitation could cause failures in seed dispersal and whether seed capture differs among vertical strata and between host species with high (Bursera copallifera) and low (Conzattia multiflora) epiphyte loads. With the exception of one species that presents late dispersion and low abundance, all of the species disperse prior to the onset of the rainy season. However, early rains immobilize the seeds, affecting up to 24% of the fruits in species with late dispersion. We observed that Tillandsia seeds reach both Bursera and Conzattia hosts, but found that adherence to the host is 4-5 times higher in Bursera. Furthermore, seeds liberated from Bursera travel shorter distances and up to half may remain within the same crown, while the highest seed capture takes place in the upper strata of the trees. We conclude that dispersion of Tillandsia seeds is limited by early rains and by the capture of seeds within the trees where populations concentrate. This pattern of capture also helps to explain the high concentrations of epiphytes in certain hosts, while trees with few epiphytes can be simultaneously considered deficient receivers and efficient exporters of seeds.
Asunto(s)
Lluvia , Tillandsia/fisiología , Árboles/fisiología , México , Semillas/fisiología , Clima TropicalRESUMEN
Two new species of the genus Phaea Newman are described from Mexico. Phaea chemsaki sp. nov. from Chiapas, and P. parallela sp. nov. from Morelos. The descriptions are supplemented with photographs.
Asunto(s)
Escarabajos/anatomía & histología , Escarabajos/clasificación , Animales , Femenino , Masculino , México , Especificidad de la EspecieRESUMEN
We record 116 genera and 366 species of Chrysomelidae from the state of Morelos, Mexico. This represents an increase of 9.3% in the species richness of these beetles for the state. Also, Morelos is currently the third most diverse state in leaf beetles within Mexico, with 16.78% of total species recorded for the country. The most diverse genera were Calligrapha, Disonycha, Blepharida, Leptinotarsa, Cryptocephalus, Systena, Alagoasa, Diabrotica and Pachybrachis, each with more than eight species. Most of these genera contain large, showy beetles. When the chrysomelid fauna is more fully understood, some of the genera of tiny beetles will likely prove to be more diverse.
Asunto(s)
Escarabajos/clasificación , Distribución Animal , Animales , Lista de Verificación , Ecosistema , MéxicoRESUMEN
Herbivory activates the synthesis of allelochemicals that can mediate plant-plant interactions. There is an inverse relationship between the activity of xylophages and the abundance of epiphytes on Ipomoea murucoides. Xylophagy may modify the branch chemical constitution, which also affects the liberation of allelochemicals with defense and allelopathic properties. We evaluated the bark chemical content and the effect of extracts from branches subjected to treatments of exclusion, mechanical damage and the presence/absence of epiphytes, on the seed germination of the epiphyte Tillandsia recurvata. Principal component analysis showed that branches without any treatment separate from branches subjected to treatments; damaged and excluded branches had similar chemical content but we found no evidence to relate intentional damage with allelopathy; however 1-hexadecanol, a defense volatile compound correlated positively with principal component (PC) 1. The chemical constitution of branches subject to exclusion plus damage or plus epiphytes was similar among them. PC2 indicated that palmitic acid (allelopathic compound) and squalene, a triterpene that attracts herbivore enemies, correlated positively with the inhibition of seed germination of T. recurvata. Inhibition of seed germination of T. recurvata was mainly correlated with the increment of palmitic acid and this compound reached higher concentrations in excluded branches treatments. Then, it is likely that the allelopathic response of I. murucoides would increase to the damage (shade, load) that may be caused by a high load of epiphytes than to damage caused by the xylophages.