Temperature and precipitation mismatches increase infection risk in amphibians.

The thermal mismatch hypothesis (TMH), the notion that cool- and warm-adapted hosts have higher infection risk during unusually warm and cool spells, respectively, was recently proposed to explain how temperature shifts driven by climate change influence host susceptibility to infections at a global scale. Despite substantial support for the TMH in the chytrid fungus (Batrachochytrium dendrobatidis, also commonly referred to as Bd) that is devastating amphibians worldwide, it remains unknown whether precipitation mismatches, in addition to temperature ones, affect infection risk. Here, we introduce the thermal-hydric mismatch hypothesis (THMH), which proposes that infection risk is shaped by mismatches resulting from the combined effects of temperature and precipitation.

Field experiments on the effects of fire on parasite transmission to amphibian hosts.

The emergence of infectious diseases is often associated with changes to host-pathogen ecology, and wildfires are known to profoundly modify the ecology of terrestrial and freshwater ecosystems. Nevertheless, few studies have employed manipulative experiments to quantify the effects of fire on infections across parasite species. In a mark-recapture study, prescribed burns did not significantly affect the densities of Cuban tree frog (CTF; Osteopilus septentrionalis) definitive hosts.

Host-consumed resources increase pathogen load of endoparasites more than integument-infecting parasites.

Pathogens use host resources for replication. Consequently, pathogen traits, such as where they infect a host, might allow pathogens to capitalize on host-consumed nutrients before the host. For instance, parasites with short generation times in the host gut or blood might benefit more from host-consumed resources than the host, whereas parasites in or on the host integument (e.

Human Schistosoma exposure risk in rice fields and an exploration of fish species for snail and schistosomiasis biocontrol.

Schistosomiasis is a devastating parasitic disease in which the infectious stage to humans is released by intermediate host snails. The Senegal River Basin (SRB) is a high-risk area for both urogenital and fecal human schistosomiasis and has extensive rice cultivation. However, occupational risk of schistosomiasis to people working in irrigated rice fields is not well established.

Use of snail traps for surveillance of schistosome-shedding snails in rice fields and fragile ecosystems.

Human schistosomiasis is a waterborne trematode disease that often affects communities already dealing with poverty and limited access to health care. Sampling to look for the snail intermediate host of schistosomiasis is often done in resource-poor settings with a sweep net, but this can be damaging to aquatic plants, such as rice. To address this issue, we tested a baited snail trap to use in fragile ecosystems and rice fields where sweep netting might not be advisable.

Impacts of Weather Anomalies and Climate on Plant Disease.

Predicting the effects of climate change on plant disease is critical for protecting ecosystems and food production. Here, we show how disease pressure responds to short-term weather, historical climate and weather anomalies by compiling a global database (4339 plant-disease populations) of disease prevalence in both agricultural and wild plant systems. We hypothesised that weather and climate would play a larger role in disease in wild versus agricultural plant populations, which the results supported.

Range maps and waterbody occupancy data for 1158 freshwater macroinvertebrate genera in the contiguous USA.

Range maps are used to estimate the geographic extent of taxa, providing valuable information for biodiversity and conservation research and management. Freshwater macroinvertebrates are not well-represented in the range map literature relative to freshwater vertebrates. To address this knowledge gap, we provide range maps for 1158 freshwater macroinvertebrate genera based on two decades of publicly available occurrence data from the USEPA National Aquatic Resource Surveys, which included 11,628 sites and 6,906,990 organisms across the contiguous USA.

Field and Laboratory Evidence That Chlorpyrifos Exposure Reduced the Population Density of a Freshwater Snail by Increasing Juvenile Mortality.

Pesticides have been frequently detected in global freshwater ecosystems, but attempts to document changes in population dynamics of organisms upon exposure to pesticides, establish a causal relationship between exposure and population effects, and identify the key toxic events within individuals under natural field conditions remain rare. Here, we used a field survey, a reciprocal cross-transplant experiment, and a laboratory toxicity experiment to build a compelling case that exposure to the insecticide chlorpyrifos was responsible for differences in snail () densities in eastern (ELL) and western basins of Liangzi Lake in China. Our field survey and reciprocal cross-transplant experiment revealed significant differences in snail densities, juvenile percentage, survival, and relative telomere length (RTL) in the two basins.

A meta-analysis on global change drivers and the risk of infectious disease.

Anthropogenic change is contributing to the rise in emerging infectious diseases, which are significantly correlated with socioeconomic, environmental and ecological factors. Studies have shown that infectious disease risk is modified by changes to biodiversity, climate change, chemical pollution, landscape transformations and species introductions. However, it remains unclear which global change drivers most increase disease and under what contexts.

Are novel or locally adapted pathogens more devastating and why? Resolving opposing hypotheses.

There is a rich literature highlighting that pathogens are generally better adapted to infect local than novel hosts, and a separate seemingly contradictory literature indicating that novel pathogens pose the greatest threat to biodiversity and public health. Here, using Batrachochytrium dendrobatidis, the fungus associated with worldwide amphibian declines, we test the hypothesis that there is enough variance in "novel" (quantified by geographic and phylogenetic distance) host-pathogen outcomes to pose substantial risk of pathogen introductions despite local adaptation being common. Our continental-scale common garden experiment and global-scale meta-analysis demonstrate that local amphibian-fungal interactions result in higher pathogen prevalence, pathogen growth, and host mortality, but novel interactions led to variable consequences with especially virulent host-pathogen combinations still occurring.

Integrating climate model projections into environmental risk assessment: A probabilistic modeling approach.

The Society of Environmental Toxicology and Chemistry (SETAC) convened a Pellston workshop in 2022 to examine how information on climate change could be better incorporated into the ecological risk assessment (ERA) process for chemicals as well as other environmental stressors. A major impetus for this workshop is that climate change can affect components of ecological risks in multiple direct and indirect ways, including the use patterns and environmental exposure pathways of chemical stressors such as pesticides, the toxicity of chemicals in receiving environments, and the vulnerability of species of concern related to habitat quality and use. This article explores a modeling approach for integrating climate model projections into the assessment of near- and long-term ecological risks, developed in collaboration with climate scientists.

Evaluating the effects of climate change and chemical, physical, and biological stressors on nearshore coral reefs: A case study in the Great Barrier Reef, Australia.

An understanding of the combined effects of climate change (CC) and other anthropogenic stressors, such as chemical exposures, is essential for improving ecological risk assessments of vulnerable ecosystems. In the Great Barrier Reef, coral reefs are under increasingly severe duress from increasing ocean temperatures, acidification, and cyclone intensities associated with CC. In addition to these stressors, inshore reef systems, such as the Mackay-Whitsunday coastal zone, are being impacted by other anthropogenic stressors, including chemical, nutrient, and sediment exposures related to more intense rainfall events that increase the catchment runoff of contaminated waters.

Meta-analysis reveals less sensitivity of non-native animals than natives to extreme weather worldwide.

Extreme weather events (EWEs; for example, heatwaves, cold spells, storms, floods and droughts) and non-native species invasions are two major threats to global biodiversity and are increasing in both frequency and consequences. Here we synthesize 443 studies and apply multilevel mixed-effects metaregression analyses to compare the responses of 187 non-native and 1,852 native animal species across terrestrial, freshwater and marine ecosystems to different types of EWE. Our results show that marine animals, regardless of whether they are non-native or native, are overall insensitive to EWEs, except for negative effects of heatwaves on native mollusks, corals and anemone.

Pseudacris regilla metamorphs acquire resistance to Batrachochytrium dendrobatidis after exposure to the killed fungus.

The pathogenic fungus Batrachochytrium dendrobatidis (Bd) is associated with drastic global amphibian declines. Prophylactic exposure to killed zoospores and the soluble chemicals they produce (Bd metabolites) can induce acquired resistance to Bd in adult Cuban treefrogs Osteopilus septentrionalis. Here, we exposed metamorphic frogs of a second species, the Pacific chorus frog Pseudacris regilla, to one of 2 prophylactic treatments prior to live Bd exposures: killed Bd zoospores with metabolites, killed zoospores alone, or a water control.

Ontogeny of immunity and potential implications for co-infection.

Immunity changes through ontogeny and can mediate facilitative and inhibitory interactions among co-infecting parasite species. In amphibians, most immune memory is not carried through metamorphosis, leading to variation in the complexity of immune responses across life stages. To test if the ontogeny of host immunity might drive interactions among co-infecting parasites, we simultaneously exposed Cuban treefrogs () to a fungus (, Bd) and a nematode () at tadpole, metamorphic and post-metamorphic life stages.

Density declines, richness increases, and composition shifts in stream macroinvertebrates.

Documenting trends of stream macroinvertebrate biodiversity is challenging because biomonitoring often has limited spatial, temporal, and taxonomic scopes. We analyzed biodiversity and composition of assemblages of >500 genera, spanning 27 years, and 6131 stream sites across forested, grassland, urban, and agricultural land uses throughout the United States. In this dataset, macroinvertebrate density declined by 11% and richness increased by 12.

Pyrethroid insecticides pose greater risk than organophosphate insecticides to biocontrol agents for human schistosomiasis.

Use of agrochemicals, including insecticides, is vital to food production and predicted to increase 2-5 fold by 2050. Previous studies have shown a positive association between agriculture and the human infectious disease schistosomiasis, which is problematic as this parasitic disease infects approximately 250 million people worldwide. Certain insecticides might runoff fields and be highly toxic to invertebrates, such as prawns in the genus Macrobrachium, that are biocontrol agents for snails that transmit the parasites causing schistosomiasis.

Experimental evidence that host species composition alters host-pathogen dynamics in a ranavirus-amphibian assemblage.

Losses in biodiversity can alter disease risk through changes in host species composition. Host species vary in pathogen susceptibility and competence, yet how changes in diversity alter host-pathogen dynamics remains unclear in many systems, particularly with respect to generalist pathogens. Amphibians are experiencing worldwide population declines linked to generalist pathogens, such as ranavirus, and thus represent an ideal group to investigate how host species composition affects disease risk.

Bluetongue Research at a Crossroads: Modern Genomics Tools Can Pave the Way to New Insights.

Bluetongue virus (BTV) is an arthropod-borne, segmented double-stranded RNA virus that can cause severe disease in both wild and domestic ruminants. BTV evolves via several key mechanisms, including the accumulation of mutations over time and the reassortment of genome segments.Additionally, BTV must maintain fitness in two disparate hosts, the insect vector and the ruminant.

Transmission potential of human schistosomes can be driven by resource competition among snail intermediate hosts.

Predicting and disrupting transmission of human parasites from wildlife hosts or vectors remains challenging because ecological interactions can influence their epidemiological traits. Human schistosomes, parasitic flatworms that cycle between freshwater snails and humans, typify this challenge. Human exposure risk, given water contact, is driven by the production of free-living cercariae by snail populations.