Morfología y hábitos en Anastrepha distincta Greene 1934 (DIPTERA: TEPHRITIDAE) Asociada a dos especies de Inga MILL en Cerro Azul -Altos de Pacora, Panamá.

El objetivo de este trabajo fue caracterizar las formas biológicas y los hábitos de A. distincta y relacionar la densidad poblacional con la precipitación y la disponibilidad del recurso en Cerro Azul-Altos de Pacora durante el 2003. En el área de estudio se seleccionaron dos especies de Inga en fructificación de las cuales se colectaron los frutos para realizar los ensayos y obtener muestras de las diferentes formas biológicas de A. distincta. Adicionalmente se trabajó con los registros de capturas de adultos de Anastrepha del 1991-94 al 2003 realizado por el Programa de Monitoreo de moscas de la fruta, lo que nos permitió evaluar la dinámica poblacional de adultos de A. distinta. Las larvas de tercer estadio de A. distincta de Cerro Azul-Altos de Pacora no pudieron ser identificadas empleando la clave de Steck el al (1990) y los 61 caracteres evaluados para la descripción de los adultos variaron escasamente entre los especímenes examinados. En el área de estudio se lograron identificar nueve especies de Inga, siendo I. edulis Mart e.I. oerstediana Benth. Las especies evaluadas durante el 2003. I. edulis presentó el mayor porcentaje e intensidad de infestación e I. oerstediana constituye un nuevo reporte como hospedera de A. distincta. El 60% del total de larvas colectadas se ubicaron en el ápice del fruto. Las poblaciones de adultos de A. distincta en 11 años de capturas en Cerro Azul- Altos de Pacora se caracterizaron por variar grandemente de año en año y por presentar una marcada estacionalidad, con las mayores capturas en junio La precipitación es el factor que puede explicar la dinámica poblacional de A. distincta ya que el inicio de la época lluviosa es el inductor de la emergencia de los adultos y porque este factor puede estar determinando la fenología de las plantas hospederas

High sensitivity of invertebrate detritivores from tropical streams to different pesticides

Freshwater organisms are often sensitive to pesticides, but their sensitivity varies across different taxa and with pesticide type and action mode, as shown by multiple acute toxicity tests. Such variability hampers predictions about how freshwater ecosystems may be altered by pesticide toxicity, which is especially critical for understudied areas of the world such as the tropics. Furthermore, there is little information about the sensitivity of some organisms that are key components of stream food webs; this is the case of litter-feeding detritivorous invertebrates, which contribute to the fundamental process of litter decomposition. Here, we examined the sensitivity of three common detritivores [Anchytarsus sp. (Coleoptera: Ptilodactylidae), Hyalella sp. (Amphipoda: Hyalellidae) and Lepidostoma sp. (Trichoptera: Lepidostomatidae)] to three pesticides commonly used (the insecticides bifenthrin and chlorpyrifos and the fungicide chlorothalonil) using acute (48 or 96 h) toxicity tests. Our study demonstrates that common-use pesticides provoke the mortality of half their populations at concentrations of 0.04?2.7 ?g L-1. We found that all species were sensitive to the three pesticides, with the highest sensitivity found for chlorpyrifos. Additionally, we used the approach of species sensitivity distributions (SSD) to compare our study species with Daphnia magna and other temperate and tropical invertebrates. We found that the study species were among the most sensitive species to chlorpyrifos and chlorothalonil. Our results suggest that tropical detritivores merit special attention in ecological risk assessment of pesticides and highlight the need for accurate ecotoxicological information from ecologically relevant species in the tropics

Extreme climate events can slow down litter breakdown in streams

Extreme temperatures have increased in intensity, duration and frequency in the last century, with potential consequences on key ecological processes such as organic matter breakdown. Many stream ecosystems are fueled by the breakdown of terrestrial leaf litter, which is exposed to atmospheric conditions for certain periods of time before entering the stream. Thus, extreme warming or freezing events may affect the litter physicochemical structure, which could translate into altered breakdown within the stream. The above prediction was tested by exposing litter of common riparian tree species in southern Chile to freezing (-20 oC; dry or wet litter) or heating (40 oC) and comparing breakdown with control litter exposed to room temperature (20 oC), separating the effects of different breakdown agents (i.e., leaching, microorganisms and detritivores). The greatest effects were found in wet litter subjected to freezing; this treatment significantly increased leaching in the short term (48 h) and slowed down breakdown in the long term (30 days), mostly due to the inhibition of microbial breakdown. Heating also retarded microbial breakdown, but the effect was smaller. Our results suggest that short-term extreme temperatures-particularly cold ones-have the potential to slow down litter breakdown in streams, which will most likely impact global biogeochemical cycles where streams play a key role

Microplastic concentration, distribution and dynamics along one of the largest Mediterranean-climate rivers: A whole watershed approach

Microplastics (MPs) have been recognized as one of the most ubiquitous environmental pollutants globally. They have been found in all ecosystems studied to date, threatening biological diversity, ecosystem functioning and human health. The present study aimed to elucidate the environmental and anthropogenic drivers of MP dynamics in the whole catchment of the Biotin) river, one of the largest rivers in South America. MP concentration and characteristics were analysed in 18 sites subjected to different sources of pollution and other human-related impacts. The sampling sites were classified in relation to altitudinal zones (highland, midland and lowland) and ecosystem types (fluvial and reservoir), and different water and territorial environmental variables were further collated and considered for analysis. Seven types of micmplastic polymers were identified in the samples analysed, with a catchment mean (+/- SE) MP concentration of 22 +/- 0.4 particles m(-3) 5 and MP presence being significantly higher in lowlands (26 +/- 2 particle m(-3)) and in reservoirs (42 +/- 14 particle m(-3)). The most abundant type of MP was fragments (84%), with a mean concentration of 37 +/- 6 particles m(-3). Overall, MP concentrations were low compared to those found in other studies, with a strong influence of human population size

Global distribution of a key trophic guild contrasts with common latitudinal diversity patterns

Most hypotheses explaining the general gradient of higher diversity toward the equator are implicit or explicit about greater species packing in the tropics. However, global patterns of diversity within guilds, including trophic guilds (i.e., groups of organisms that use similar food resources), are poorly known. We explored global diversity patterns of a key trophic guild in stream ecosystems, the detritivore shredders. This was motivated by the fundamental ecological role of shredders as decomposers of leaf litter and by some records pointing to low shredder diversity and abundance in the tropics, which contrasts with diversity patterns of most major taxa for which broad-scale latitudinal patterns haven been examined. Given this evidence, we hypothesized that shredders are more abundant and diverse in temperate than in tropical streams, and that this pattern is related to the higher temperatures and lower availability of high-quality leaf litter in the tropics. Our comprehensive global survey (129 stream sites from 14 regions on six continents) corroborated the expected latitudinal pattern and showed that shredder distribution (abundance, diversity and assemblage composition) was explained by a combination of factors, including water temperature (some taxa were restricted to cool waters) and biogeography (some taxa were more diverse in particular biogeographic realms). In contrast to our hypothesis, shredder diversity was unrelated to leaf toughness, but it was inversely related to litter diversity. Our findings markedly contrast with global trends of diversity for most taxa, and with the general rule of higher consumer diversity at higher levels of resource diversity. Moreover, they highlight the emerging role of temperature in understanding global patterns of diversity, which is of great relevance in the face of projected global warming

IBISCA: une étude à grande échelle de la biodiversité des arthropodes dans une forêt du Panama

info:eu-repo/semantics/nonPublishe

A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration

The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO₂production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback

IBISCA-Panama, a large-scale study of arthropod beta-diversity and vertical stratification in a lowland rainforest: rationale, description of study sites and field methodology

info:eu-repo/semantics/publishe

IBISCA-Panama, a large-scale study of arthropod beta-diversity and vertical stratification in a lowland rainforest : rationale, study sites and field protocols.

IBISCA-Panama (?Investigating the BIodiversity of Soil and Canopy Arthropods?, Panama module) represents a large-scale research initiative to quantify the spatial distribution of arthropod biodiversity in a Neotropical forest, using a combination of (1) international collaboration, (2) a set of common research questions, and (3) an integrated experimental design. Here, we present the rationale of the programme, describe the study sites, and outline field protocols. In the San Lorenzo Protected Area of Panama, twelve 20 x 20 m sites, all less than 2 km apart, were surveyed for plants and arthropods, from the ground to the upper canopy. Access to the canopy and its fauna was facilitated by fogging, single-rope techniques and a variety of devices such as a canopy crane, the ?SolVin-Bretzel? canopy raft, the canopy bubble and Ikos. IBISCA-Panama represented the first attempt to combine these complementary techniques of canopy access in a large-scale investigation. Such techniques provided spatial replication during initial field work performed in September-October 2003. Temporal replication across seasons consisted of subsequent field work of varying intensity during dry, early wet and late wet periods in 2004. Arthropods were surveyed using 14 different protocols targeting the soil, litter, understorey, mid-canopy and upper canopy habitats. These protocols included: WINKLER sifting; BERLESE-TULLGREN; hand-collecting of galls and social insects; fogging; beating; woodrearing; baits; and various types of traps such as pitfall, small and large flight-interception, sticky, light, and Malaise traps. Currently, analyses of arthropod distribution in this forest concentrate on a set of 63 focal taxa representing different phylogenies and lifehistories. IBISCA-Panama may be considered as a model for largescale research programmes targeting invertebrate biodiversity. Its collaborative modus operandi can be applied to answer a variety of pressing ecological questions related to forest biodiversity, as evidenced by the recent development of further IBISCA programmes in other parts of the world