A Review of the Natural History and Laboratory Culture Methods for the Yellow Dung Fly, Scathophaga stercoraria

The yellow dung fly Scathophaga stercoraria (L.) (Diptera: Scathophagidae) is a widespread and locally abundant fly associated with the dung of large mammals, especially farm animals. This species has recently become a standard test organism for evaluating toxic effects of veterinary pharmaceuticals in livestock dung. In this context, a review of its natural history and a general description of the field and laboratory rearing methods of this species are provided here to benefit the scientific community as well as government regulators and applicants of eco-toxicological studies. For guidance, means and ranges are included for all relevant standard life history traits stemming from previously published data on Swiss populations

Effect of Tillage and Planting Date on Seasonal Abundance and Diversity of Predacious Ground Beetles in Cotton

A 2-year field study was conducted in the southern High Plains region of Texas to evaluate the effect of tillage system and cotton planting date window on seasonal abundance and activity patterns of predacious ground beetles. The experiment was deployed in a split-plot randomized block design with tillage as the main-plot factor and planting date as the subplot factor. There were two levels for each factor. The two tillage systems were conservation tillage (30% or more of the soil surface is covered with crop residue) and conventional tillage. The two cotton planting date window treatments were early May (normal planting) and early June (late planting). Five prevailing predacious ground beetles, Cicindela sexguttata F., Calosoma scrutator Drees, Pasimachus spp., Pterostichus spp., and Megacephala Carolina L. (Coleoptera: Carabidae), were monitored using pitfall traps at 2-week intervals from June 2002 to October 2003. The highest total number of ground beetles (6/trap) was observed on 9 July 2003. Cicindela sexguttata was the dominant ground dwelling predacious beetle among the five species. A significant difference between the two tillage systems was observed in the abundances of Pterostichus spp. and C. sexguttata. In 2002. significantly more Pterostichus spp. were recorded from conventional plots (0.27/trap) than were recorded from conservation tillage plots (0.05/trap). Significantly more C. sexguttata were recorded in 2003 from conservation plots (3.77/trap) than were recorded from conventional tillage plots (1.04/trap). There was a significant interaction between year and tillage treatments. However, there was no significant difference in the abundances of M. Carolina and Pasimachus spp. between the two tillage practices in either of the two years. M. Carolina numbers were significantly higher in late-planted cotton compared with those observed in normal-planted cotton. However, planting date window had no significant influence on the activity patterns of the other species. Ground beetle species abundance, diversity, and species richness were significantly higher in conservation tillage plots. This suggests that field conditions arising from the practice of conservation tillage may support higher predacious ground beetle activity than might be observed under field conditions arising from conventional tillage practices

First assessment of the comparative toxicity of ivermectin and moxidectin in adult dung beetles: Sub-lethal symptoms and pre-lethal consequences

Among macrocyclic lactones (ML), ivermectin (IVM) and moxidectin (MOX) potentially affect all Ecdysozoan species, with dung beetles being particularly sensitive. The comparative effects of IVM and MOX on adult dung beetles were assessed for the first time to determine both the physiological sub-lethal symptoms and pre-lethal consequences. Inhibition of antennal response and ataxia were tested as two intuitive and ecologically relevant parameters by obtaining the lowest observed effect concentration (LOEC) values and interpolating other relevant toxicity thresholds derived from concentration-response curves (IC50, as the concentration of each ML where the antennal response is inhibited by half; and pLC50, as the quantity of ingested ML where partial paralysis was observed by half of treated individuals) from concentration-response curves. Both sub-lethal and pre-lethal symptoms obtained in this study coincided in that IVM was six times more toxic than MOX for adult dung beetles. Values of LOEC, IC50 and pLC50 obtained for IVM and MOX evaluated in an environmental context indicate that MOX, despite needing more time for its elimination in the faeces, would be half as harmful to dung beetles as IVM. This approach will be valuable to clarify the real impact of MLs on dung beetle health and to avoid the subsequent environmental consequences

Biomagnifcation and body distribution of ivermectin in dung beetles

We thank the staf of Doñana Biological Reserve (DBR-ICTS), Doñana National Park, and Los Alcornocales Natural Park, especially D. Paz, F. Ibáñez, P. Bayón, M. Malla and D. Ruiz for logistic facilities for the field work and permissions (2019107300000904/IRM/MDCG/mes) to collect cattle dung and dung beetles. We are grateful to J. Castro and A. Rascón for technical assistance. We also thank A. V. Giménez-Gómez for her technical assistance in the laboratory work. We thank also F.-T Krell and the two anonymous reviewers for their constructive comments. Financial support was provided by the project CGL2015-68207-R of the Secretaría de Estado de Investigación–Ministerio de Economía y Competitividad.A terrestrial test system to investigate the biomagnifcation potential and tissue-specifc distribution of ivermectin, a widely used parasiticide, in the non-target dung beetle Thorectes lusitanicus (Jekel) was developed and validated. Biomagnifcation kinetics of ivermectin in T. lusitanicus was investigated by following uptake, elimination, and distribution of the compound in dung beetles feeding on contaminated faeces. Results showed that ivermectin was biomagnifed in adults of T. lusitanicus when exposed to non-lethal doses via food uptake. Ivermectin was quickly transferred from the gut to the haemolymph, generating a biomagnifcation factor (BMFk) three times higher in the haemolymph than in the gut after an uptake period of 12 days. The fat body appeared to exert a major role on the biomagnifcation of ivermectin in the insect body, showing a BMFk 1.6 times higher than in the haemolymph. The results of this study highlight that the biomagnifcation of ivermectin should be investigated from a global dung-based food web perspective and that the use of these antiparasitic substances should be monitored and controlled on a precautionary basis. Thus, we suggest that an additional efort be made in the development of standardised regulatory recommendations to guide biomagnifcation studies in terrestrial organisms, but also that it is necessary to adapt existing methods to assess the efects of such veterinary medical products

Dung removal increases under higher dung beetle functional diversity regardless of grazing intensification

Dung removal by macrofauna such as dung beetles is an important process for nutrient cycling in pasturelands. Intensification of farming practices generally reduces species and functional diversity of terrestrial invertebrates, which may negatively affect ecosystem services. Here, we investigate the effects of cattle-grazing intensification on dung removal by dung beetles in field experiments replicated in 38 pastures around the world. Within each study site, we measured dung removal in pastures managed with low- and high-intensity regimes to assess between-regime differences in dung beetle diversity and dung removal, whilst also considering climate and regional variations. The impacts of intensification were heterogeneous, either diminishing or increasing dung beetle species richness, functional diversity, and dung removal rates. The effects of beetle diversity on dung removal were more variable across sites than within sites. Dung removal increased with species richness across sites, while functional diversity consistently enhanced dung removal within sites, independently of cattle grazing intensity or climate. Our findings indicate that, despite intensified cattle stocking rates, ecosystem services related to decomposition and nutrient cycling can be maintained when a functionally diverse dung beetle community inhabits the human-modified landscape

Plant hybrid zones affect biodiversity: tools for a genetic-based understanding of community structure

Plant hybrid zones are dynamic centers of ecological and evolutionary processes for plants and their associated communities. Studies in the wild and in gardens with synthetic crosses showed that hybrid eucalypts supported the greatest species richness and abundances of insect and fungal taxa. In an updated review of 152 case studies of taxa associated with diverse hybridizing systems, there were 43 (28%) cases of hybrids being more susceptible than their parent species, 7 (5%) resistant, 35 (23%) additive, 35 (23%) dominant, and 32 (21%) showed no response to hybridization. Thus, most taxa respond to hybrids in ways that result in equal or greater abundance, and hybrids tend to accumulate the taxa of their parent species. These studies suggest that genetic-based plant traits affect the distribution of many species and that the variation in hybrids can be used as tools to examine the genetic components of community structure and biodiversity. Several patterns have emerged thus far. (1) Genetic variation between classes of hybrids (e.g., F1's vs. backcrosses) may equal or even exceed that found between species. (2) As a reflection of this genetic variation, herbivores are more likely to differentiate between hybrid classes than they are to differentiate between pure plant species. (3) The communities associated with different hybrid classes can differ from one another as well as from their parental species. (4) Generalist and specialist herbivores predictably vary in their responses to hybrids. (5) Plant hybrid zones may represent essential habitat for some arthropod species. (6) Even nesting birds respond to hybridizing plants. (7) Including multiple trophic levels and taxa from microbes to vertebrates, susceptible hybrid genotypes support greater biodiversity than resistant genotypes. (8) The effects of hybridization on common or keystone species can either positively or negatively affect biodiversity. The indirect impacts of hybridization on biodiversity may exceed the direct impacts and may result in 'apparent' herbivore resistance or susceptibility at the community level. (9) Although hybrids are often maligned, exotic or problem hybrids generally result from human disturbances, whereas native hybrids are part of natural ecosystems and should be conserved. Three predictions are made: (1) Intermediate genetic differences between the parental species will result in the greatest genetic variation in the hybrid zone, which in turn will have a positive effect on biodiversity. (2) Bidirectional introgression enhances species richness on hybrids, whereas F1 sterility and unidirectional introgression limit the accumulation of species on hybrids. (3) Although susceptible hybrids are likely to support the greatest biodiversity, the impacts of hybridization on keystone species will be crucial in determining the overall effect