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Although exotic plants comprise a substantial portion of floristic biodiversity, their contributions to community and ecosystem processes are not well understood. We manipulated plant species richness in old-field communities to compare the impacts of native vs. exotic species on plant biomass, seed production, and arthropod community structure. Plants within diverse communities, regardless of whether they were native or exotic, had higher biomass and seed production than in monocultures and displayed positive complementarity. Increasing native or exotic plant richness also enhanced the richness of arthropods on plants, but exotics attracted fewer arthropod species for a given arthropod abundance than did natives. Additionally, when exotic and native plants grew together, exotics suppressed seed production of native species. Thus, exotic plants appear to contribute positively to some biodiversity functions, but may impact native communities over longer time frames by reducing native seed production and recruiting fewer arthropod species.

Energycane and biomass sorghum are two of the most promising cellulosic energy crops in the southeastern US. Research on these two energy crops has focused mainly on biomass production, and there is a lack of knowledge on their ability to promote biodiversity and ecosystem services. This paper presents results from a comprehensive study on ground-active arthropod diversity in seven sites across five states in the southeastern US (Florida, Georgia, Louisiana, Mississippi, and Texas). Pitfall traps were deployed four times during each crop season for energycane, biomass sorghum, and a local reference conventional crop from 2020 to 2022. Arthropod abundance (individuals/(trap × day)) values were 4.9 ± 0.46, 3.7 ± 0.18, and 2.6 ± 0.16 (mean ± stderr) for conventional crops, biomass sorghum, and energycane, respectively, with a significant difference found only between conventional crops and energycane. Individuals were identified to arthropod orders, and Hill’s diversity indices were calculated based on the number of individuals in each arthropod order instead of the number of individuals in each arthropod species. Order-based arthropod richness values were 5.3, 5.2, and 4.8 for biomass sorghum, conventional crops, and energycane, with significant difference found only between biomass sorghum and energycane. There was no significant difference in the order-based Shannon diversity and Simpson diversity between the three crop types. The effective number of arthropod orders for the two energy crops decreased from 5.0 to 3.4 to 2.9 with increasing order of diversity from arthropod richness to Shannon diversity to Simpson diversity. The explained variability by environmental factors also decreased with increasing Hill’s order of diversity. The results from this study indicate no significant advantage in order-based arthropod diversity in growing biomass sorghum and energycane. This research fills a critical knowledge gap in understanding the impacts of cellulosic energy crop production on biodiversity and ecosystem services.

1. The simplification of agricultural landscapes through the increase in cropped area has caused the loss of habitats for many species that fulfil important ecosystem services such as pest control and production. Evidence for detrimental effects on ecosystem services is scarce, particularly in tropical regions. 2. We studied the effect of the percentage of cropped land in the landscape and altitude in tropical agro-ecosystems in relation to crop pest regulation and yield. In the Colombian Andes, we established potato Solanum tuberosum plots along gradients of altitude and increasing proportion of cropped area to assess the effects on herbivores, their natural enemies, potato production and overall biodiversity. 3. Increasing altitude and percentage cropped land reduced the richness and abundance of herbivores and their natural enemies, except for the specialist Guatemalan potato moth Tecia solanivora, which showed the opposite response. 4. Potato yield was negatively affected by the presence of the Guatemalan potato moth, which increased in density as the percentage of cropped land and altitude increased. Other herbivores and natural enemies did not affect yield. 5. Synthesis and applications. Tropical landscapes at lower altitude or with smaller areas of cropped land suffered less from the presence of the potato moth, which had a negative effect on yield. Our results suggest that conservation of natural habitats like the endangered Andean ecosystems would benefit farmers through ecosystem services such as reduced pest damage, higher yield and increased functional biodiversity.

Rice production is often associated with high pesticide input. To improve farmers’ practice, sustainable management approaches are urgently needed, such as ecological engineering (EE), which aims at enhancing beneficial arthropods while reducing pesticides. Here, we implemented and tested EE in Cambodian rice fields by comparing: (i) fields not treated with pesticides (control); (ii) fields not treated with pesticides but with non-rice crops planted in the surrounding (EE); and (iii) conventionally farmed fields using pesticides (CR). Using benefit-cost analysis, we compared the economic value of each treatment. The non-rice crops preferred by men and women farmers as well as farmers’ willingness to implement EE were assessed using surveys. We sampled arthropod abundance and richness in rice fields and bunds during two seasons. During the dry season, we compared EE and CR among three Cambodian provinces. During the wet season, we specifically assessed the differences in EE, control and CR in arthropod abundance and rice yield in one province. While withholding from using pesticides did not result in a decrease in yield in EE and control treatments, parasitoid abundance was higher in both treatments during the wet season. The benefit–cost ratio was highest for EE and control treatments. Pesticides were likely the main driver causing low arthropod abundance, without any benefit towards increased rice yield. The proper implementation of EE coupled with farmers’ knowledge of ecologically based pest management is a promising solution towards sustainable rice production.

We argue that the genetic diversity of a dominant plant is important to the associated dependent community because dependent species such as herbivores are restricted to a subset of genotypes in the host-plant population. For plants that function as habitat, we predicted that greater genetic diversity in the plant population would be associated with greater diversity in the dependent arthropod community. Using naturally hybridizing cottonwoods (Populus spp.) in western North America as a model system, we tested the general hypothesis that arthropod alpha (within cross-type richness) and beta (among cross-type composition) diversities are correlated with cottonwood cross types from local to regional scales. In common garden experiments and field surveys, leaf-modifying arthropod richness was significantly greater on either the F1(1.54 times) or backcross (1.46 times) hybrid cross types than on the pure broadleaf cross type (P. deltoides Marshall or P. fremontii Watson). Composition was significantly different among three cross types of cottonwoods at all scales. Within a river system, cottonwood hybrid zones had 1.49 times greater richness than the broadleaf zone, and community composition was significantly different between each parental zone and the hybrid zone, demonstrating a hierarchical concentration of diversity. Overall, the habitats with the highest cottonwood cross-type diversity also had the highest arthropod diversity. These data show that the genetics of habitat is an important conservation concept and should be a component of conservation theory.

The interdependence of living organisms and related ecology concepts are often difficult for students to grasp if they only study them from textbooks. To really understand how habitat fragmentation affects biodiversity, it is best to allow students to study it in the field. In the activities described here, I used inquiry as a basis for experiential learning. Focusing on two natural areas of unequal size, students investigated the areas to assess arthropod species richness and examine whether it was correlated with the size of the area. By establishing 10 daily observation periods and identifying arthropods in each session, students observed firsthand the relationship of species richness to biodiversity and that the size of the natural area was not significant. This translated to a greater understanding of biodiversity and its role in the relationships of living organisms in a local ecosystem. Students also gained valuable insight into how scientific studies are conducted.

This chapter contains sections titled: Defining and assessing habitats in the landscape Habitat manipulations for conservation Practical conservation

Parasites are often hidden in their hosts and exhibit patchy spatial distributions. This makes them relatively difficult to detect and sample. Consequently we have poor knowledge of parasite diversities, distributions, and extinction. We evaluate our general understanding of parasite diversity and highlight the enormous bias in research on parasites such as helminths and arthropods that infect vertebrate hosts. We then focus on Myxozoa as an exemplary case for demonstrating uncharted parasite diversity. Myxozoans are a poorly recognized but speciose clade of endoparasitic cnidarians with complex life cycles that have radiated to exploit freshwater, marine, and terrestrial hosts by adopting strategies convergent to those of parasitic protists. Myxozoans are estimated to represent some 20% of described cnidarian species—greatly outnumbering the combined species richness of scyphozoans, cubozoans, and staurozoans. We summarize limited understanding of myxozoan diversification and geographical distributions, and highlight gaps in knowledge and approaches for measuring myxozoan diversity. We close by reviewing methods and problems in estimating parasite extinction and concerns about extinction risks in view of the fundamental roles parasites play in ecosystem dynamics and in driving host evolutionary trajectories.

1. Increasing landscape heterogeneity of agroecosystems can enhance natural enemy populations and promote biological control. However, little is known about the multiscale effects of landscape heterogeneity on arthropod communities in rice agroecosystems, especially in combination with trophic interactions. 2. We examined for the first time how landscape heterogeneity, measured by four independent metrics of landscape composition and configuration at three spatial scales, affected species abundance and species richness of rice arthropods within four functional groups and the abundance of the most common species at 28 sites in the Philippines. We additionally examined the influence of trophic interactions among these functional groups. 3. We found that both the compositional and configurational landscape heterogeneity in combination with trophic interactions determined the structure of rice-arthropod communities. Herbivore abundance decreased with increasing landscape diversity. The abundance of parasitoids and species richness of both parasitoids and predators increased with the structural connectivity of rice bunds. Fragmentation of the rice landscape had a clear negative effect on most arthropod groups, except for highly mobile predatory arthropods. Abundance of common predators and detritivore species decreased with increasing complexity in the shape of rice patches. 4. Trophic interactions, measured as the abundance of prey, outweighed the importance of landscape heterogeneity for predators. In contrast, parasitoids responded positively to configurational landscape heterogeneity but were unaffected by prey abundance. 5. Synthesis and applications. Our research shows how landscape heterogeneity and trophic interactions have different effects on different functional groups. While predator abundance was solely driven by the availability of prey, all other functional groups in the rice-arthropod community were significantly affected by the composition and configuration of surrounding landscape features. Landscape management aiming to improve biodiversity and biological control in rice agroeco-systems should promote a diversity of land uses and habitat types within 100-300 m radii to reduce the presence of pests. Management practices should also focus on maintaining smaller rice patches and the structural connectivity of rice bunds to enhance populations of the natural enemies of rice pests. Future research should focus on the temporal and spatial manipulation of rice fields to maximize the effects of biological control.

Most eukaryotic organisms are arthropods. Yet, their diversity in rich terrestrial ecosystems is still unknown. Here we produce tangible estimates of the total species richness of arthropods in a tropical rainforest. Using a comprehensive range of structured protocols, we sampled the phylogenetic breadth of arthropod taxa from the soil to the forest canopy in the San Lorenzo forest, Panama. We collected 6144 arthropod species from 0.48 hectare and extrapolated total species richness to larger areas on the basis of competing models. The whole 6000-hectare forest reserve most likely sustains 25,000 arthropod species. Notably, just 1 hectare of rainforest yields >60% of the arthropod biodiversity held in the wider landscape. Models based on plant diversity fitted the accumulated species richness of both herbivore and nonherbivore taxa exceptionally well. This lends credence to global estimates of arthropod biodiversity developed from plant models.