Tropical Pyramids: Dung Beetle Richness, Abundance, and Biomass

Volume is a proxy for biomass in hard bodied arthropods (P \u3c 0.0001). I constructed biomass-volume equations for Neotropical (P \u3c 0.0001), temperate (P \u3c 0.0001) and 12 Neotropical genera of scarabs, of which 11 were highly significant. The effect of short term (\u3c 1 year) alcohol storage on volume was negligable. I found scarab volume on geologically old soils in the Amazon was one-third that of the geologically young Amazon (P \u3c 0.0001). Species richness (P = 0.0002), Chao 1 (P = 0.0003), Fisher’s (P = 0.008) and Margalef indices (P = 0.0003) were greater on young soils. Menhinick (P = 0.54), Simpson (P = 0.54) and rarefied species richness (P = 0.24), which correct for sample size differences, indicated no difference in diversity. Young Amazonian soils likely support a higher volume and abundance of scarabs than old soils, but diversity across Amazonia may be similar. I compared beta-diversity of scarab communities across Amazonia. Species rank-abundance curves did not differ among sites whereas volume-abundance distributions and volume-rank abundance curves indicated a larger range of scarab sizes in Brazil than Ecuador. At local levels (\u3c62 km), communities were similar whereas at large distances (\u3e1750 km), they were different. Differences between Brazil and Ecuador may be explained by varied soil age and productivity. I examined the effects of tropical forest fragmentation on scarabs, comparing my results with three other studies from the same site. Among 1, 10, and 100-ha fragments and continuous forest, I found two important trends; beetle biomass and species richness increased with fragment area per sampling effort. Comparing all four studies, diversity increased with fragment size, and by my rarefaction analyses, two studies demonstrated beetle volume increased with fragment size. Average beetle size increased with fragment area, suggesting a shift in dung beetle guild structure and functionality. Tropical-temperate comparsions demonstrated a lower scarab species richness and larger average body size in temperate forests compared with tropical forests. Volume and abundance per trap-day did not segregate along these divisions. The observed latitudinal gradient may be explained by spatial heterogeneity hypotheses and the body size gradient resembles Bergmann’s rule

Dung beetle communities: A neotropical-north temperate comparison

Dung beetle communities have been compared across north temperate latitudes. Tropical dung beetle communities appear to be more diverse based on studies using different methodologies. Here, we present results from a standardized sampling protocol used to compare dung beetle communities across five neotropical forests in Brazil and Ecuador and two warm, north temperate forests in Mississippi and Louisiana. Species richness in the tropical forests was three to seven times higher than the temperate forests, as would be expected by studies of other taxa across tropical and temperate latitudes. Average body size in the temperate forests was larger than the tropical forests, as predicted by Bergmann's rule. Dung beetle abundance and volume per trap-day were generally higher in Ecuador than Brazil, and higher in Mississippi than Louisiana, but there were no tropical-temperate differences. Species rank-abundance curves were similar within countries and between countries. Rank-volume distributions indicated a smaller range of beetle body sizes in Ecuador versus Brazil or the USA. Community similarity was high within countries and low between countries. Community differences between Brazil and Ecuador sites may be explained by differences in productivity based on geological age of the soils

Forest disturbance and vector transmitted diseases in thelowland tropical rainforest of central Panama

objective To explore possible changes in the community attributes of haematophagous insects as afunction of forest disturbance. We compare the patterns of diversity and abundance, plus thebehavioural responses of three epidemiologically distinct vector assemblages across sites depictingvarious levels of forest cover.methods Over a 3-year period, we sampled mosquitoes, sandflies and biting-midges in forestedhabitats of central Panama. We placed CDC light traps in the forest canopy and in the understorey togather blood-seeking females.results We collected 168 405 adult haematophagous dipterans in total, including 26 genera and 86species. Pristine forest settings were always more taxonomically diverse than the disturbed forest sites,confirming that disturbance has a negative impact on species richness. Species of Phlebotominae andCulicoides were mainly classified as climax (i.e. forest specialist) or disturbance-generalist, which tendto decrease in abundance along with rising levels of disturbance. In contrast, a significant portion ofmosquito species, including primary and secondary disease vectors, was classified as colonists (i.e.disturbed-areas specialists), which tend to increase in numbers towards more disturbed forest habitats.At pristine forest, the most prevalent species of Phlebotominae and Culicoides partitioned the verticalniche by being active at the forest canopy or in the understorey; yet this pattern was less clear indisturbed habitats. Most mosquito species were not vertically stratified in their habitat preference.conclusion We posit that entomological risk and related pathogen exposure to humans is higher inpristine forest scenarios for Culicoides and Phlebotominae transmitted diseases, whereas forestdisturbance poses a higher entomological risk for mosquito-borne infections. This suggests that theDilution Effect Hypothesis (DEH) does not apply in tropical rainforests where highly abundant, yetunrecognised insect vectors and neglected zoonotic diseases occur. Comprehensive, community levelentomological surveillance is, therefore, the key for predicting potential disease spill over in scenariosof pristine forest intermixed with anthropogenic habitats. We suggest that changes in forest qualityshould also be considered when assessing arthropod-borne disease transmission risk.objective To explore possible changes in the community attributes of haematophagous insects as afunction of forest disturbance. We compare the patterns of diversity and abundance, plus thebehavioural responses of three epidemiologically distinct vector assemblages across sites depictingvarious levels of forest cover.methods Over a 3-year period, we sampled mosquitoes, sandflies and biting-midges in forestedhabitats of central Panama. We placed CDC light traps in the forest canopy and in the understorey togather blood-seeking females.results We collected 168 405 adult haematophagous dipterans in total, including 26 genera and 86species. Pristine forest settings were always more taxonomically diverse than the disturbed forest sites,confirming that disturbance has a negative impact on species richness. Species of Phlebotominae andCulicoides were mainly classified as climax (i.e. forest specialist) or disturbance-generalist, which tendto decrease in abundance along with rising levels of disturbance. In contrast, a significant portion ofmosquito species, including primary and secondary disease vectors, was classified as colonists (i.e.disturbed-areas specialists), which tend to increase in numbers towards more disturbed forest habitats.At pristine forest, the most prevalent species of Phlebotominae and Culicoides partitioned the verticalniche by being active at the forest canopy or in the understorey; yet this pattern was less clear indisturbed habitats. Most mosquito species were not vertically stratified in their habitat preference.conclusion We posit that entomological risk and related pathogen exposure to humans is higher inpristine forest scenarios for Culicoides and Phlebotominae transmitted diseases, whereas forestdisturbance poses a higher entomological risk for mosquito-borne infections. This suggests that theDilution Effect Hypothesis (DEH) does not apply in tropical rainforests where highly abundant, yetunrecognised insect vectors and neglected zoonotic diseases occur. Comprehensive, community levelentomological surveillance is, therefore, the key for predicting potential disease spill over in scenariosof pristine forest intermixed with anthropogenic habitats. We suggest that changes in forest qualityshould also be considered when assessing arthropod-borne disease transmission risk

A Dung beetle assemblage in an urban park in Louisiana

We examined the dynamics of a dung beetle community over the course of a year in a forested urban park in Baton Rouge, LA. Dung beetle volume per trap-day and abundance peaked during March and the months of August through November, with species richness highest during March. The subfamily Aphodiinae dominated the community during the cold months, and Scarabaeinae dominated it during the warm months. The relationship of these patterns to local temperature and precipitation is discussed

Volume as a predictor for biomass: Equations for neotropical Scarabaeidae

Volume is a proxy for biomass in hard-bodied arthropods. We constructed a highly significant overall equation relating biomass and volume for Neotropical dung beetles (Scarabaeidae). In addition, we constructed separate equations for 12 Neotropical genera of scarabs, of which 11 were highly significant. In general, linear functions explained the relationship between biomass and volume equally well as log-transformed data. In addition, we tested the effects of alcohol storage on volume over the course of a year and found no significant change in dung beetle volume. Because scarab volume is not affected by alcohol storage up to a period of 1 yr, the biomass-volume equation we have provided for fresh specimens may be valid to quantify biomass of specimens stored in alcohol. © 2006 Entomological Society of America

The old and young Amazon: Dung beetle biomass, abundance, and species diversity

The Amazon Basin can be divided into two geomorphological regions based on the age of its soils: young ( 300 mya). We tested the effects of soil age on dung beetle communities by comparing biomass, abundance, and species between reserves in Ecuador on young soils and reserves in Brazil on old soils. Beetle biomass in the old Amazon was one-third that in the young Amazon, and beetle abundance in the old Amazon was one-fourth that in the young Amazon. Species richness, rarefied to equal sample sizes, was not significantly different between old and young soils. These data suggest young soils of the Amazon support a significantly greater biomass and abundance of dung beetles than old soils, but that species richness across the Basin is similar. As dung beetles are bio-indicators of mammals, our data support previous studies indicating a greater biomass of mammals on young versus old Amazon soils. © 2007 The Author(s)

Dung Beetle Communities: a Neotropical-North Temperate Comparison

Dung beetle communities have been compared across north temperate latitudes. Tropical dung beetle communities appear to be more diverse based on studies using different methodologies. Here, we present results from a standardized sampling protocol used to compare dung beetle communities across five neotropical forests in Brazil and Ecuador and two warm, north temperate forests in Mississippi and Louisiana. Species richness in the tropical forests was three to seven times higher than the temperate forests, as would be expected by studies of other taxa across tropical and temperate latitudes. Average body size in the temperate forests was larger than the tropical forests, as predicted by Bergmann's rule. Dung beetle abundance and volume per trap-day were generally higher in Ecuador than Brazil, and higher in Mississippi than Louisiana, but there were no tropical-temperate differences. Species rank-abundance curves were similar within countries and between countries. Rank-volume distributions indicated a smaller range of beetle body sizes in Ecuador versus Brazil or the USA. Community similarity was high within countries and low between countries. Community differences between Brazil and Ecuador sites may be explained by differences in productivity based on geological age of the soils

Disturbance and mosquito diversity in the lowland tropical rainforest of central Panama

The Intermediate Disturbance Hypothesis (IDH) is well-known in ecology providing an explanation for the role of disturbance in the coexistence of climax and colonist species. Here, we used the IDH as a framework to describe the role of forest disturbance in shaping the mosquito community structure, and to identify the ecological processes that increase the emergence of vector-borne disease. Mosquitoes were collected in central Panama at immature stages along linear transects in colonising, mixed and climax forest habitats, representing diferent levels of disturbance. Species were identifed taxonomically and classifed into functional categories (i.e., colonist, climax, disturbance-generalist, and rare). Using the Huisman-Olf-Fresco multi-model selection approach, IDH testing was done. We did not detect a unimodal relationship between species diversity and forest disturbance expected under the IDH; instead diversity peaked in old-growth forests. Habitat complexity and constraints are two mechanisms proposed to explain this alternative postulate. Moreover, colonist mosquito species were more likely to be involved in or capable of pathogen transmission than climax species. Vector species occurrence decreased notably in undisturbed forest settings. Old-growth forest conservation in tropical rainforests is therefore a highly-recommended solution for preventing new outbreaks of arboviral and parasitic diseases in anthropic environments.The Intermediate Disturbance Hypothesis (IDH) is well-known in ecology providing an explanation for the role of disturbance in the coexistence of climax and colonist species. Here, we used the IDH as a framework to describe the role of forest disturbance in shaping the mosquito community structure, and to identify the ecological processes that increase the emergence of vector-borne disease. Mosquitoes were collected in central Panama at immature stages along linear transects in colonising, mixed and climax forest habitats, representing diferent levels of disturbance. Species were identifed taxonomically and classifed into functional categories (i.e., colonist, climax, disturbance-generalist, and rare). Using the Huisman-Olf-Fresco multi-model selection approach, IDH testing was done. We did not detect a unimodal relationship between species diversity and forest disturbance expected under the IDH; instead diversity peaked in old-growth forests. Habitat complexity and constraints are two mechanisms proposed to explain this alternative postulate. Moreover, colonist mosquito species were more likely to be involved in or capable of pathogen transmission than climax species. Vector species occurrence decreased notably in undisturbed forest settings. Old-growth forest conservation in tropical rainforests is therefore a highly-recommended solution for preventing new outbreaks of arboviral and parasitic diseases in anthropic environments