Terrestrial Isopods Porcellio scaber and Oniscus asellus (Crustacea: Isopoda) Increase Bacterial Abundance and Modify Microbial Community Structure in Leaf Litter Microcosms: a Short-Term Decomposition Study.

Invasive terrestrial isopods are likely to have altered leaf litter decomposition processes in North American forests, but the mechanisms underlying these alterations and the degree to which they differ among isopod species are poorly characterized. Using mixed-deciduous leaf litter microcosms, we quantified the effects of two common, invasive isopods (Oniscus asellus and Porcellio scaber) on short-term leaf litter decomposition and microbial community structure and function. Microcosms containing ground litter and a microbial inoculant were exposed to one of the two isopod species or no isopods for 21 days. Mass loss was then quantified as the change in litter dry mass after leaching, and microbial respiration was quantified as the mass of CO2 absorbed by soda lime. Litter leachates were plated on agar to quantify culturable bacterial and fungal abundance, and denaturing gradient gel electrophoresis of amplified leachate microbial DNA was used to characterize shifts in microbial community structure. Isopod presence increased litter mass loss by a modest ~ 6%, but did not affect litter microbial respiration. Bacterial abundance increased significantly in the presence of isopods, while fungal abundance was either unchanged or reduced. Overall litter microbial species richness was reduced by isopods, with O. asellus specifically reducing fungal abundance and diversity. Isopods modified the microbial community structure by suppressing four bacterial and one fungal species, while promoting growth of four other bacterial species (two unique to each isopod species) and two fungal species (one which was unique to O. asellus).

Toward Sustainable Environmental Quality: Priority Research Questions for North America.

Anticipating, identifying, and prioritizing strategic needs represent essential activities by research organizations. Decided benefits emerge when these pursuits engage globally important environment and health goals, including the United Nations Sustainable Development Goals. To this end, horizon scanning efforts can facilitate identification of specific research needs to address grand challenges. We report and discuss 40 priority research questions following engagement of scientists and engineers in North America. These timely questions identify the importance of stimulating innovation and developing new methods, tools, and concepts in environmental chemistry and toxicology to improve assessment and management of chemical contaminants and other diverse environmental stressors. Grand challenges to achieving sustainable management of the environment are becoming increasingly complex and structured by global megatrends, which collectively challenge existing sustainable environmental quality efforts. Transdisciplinary, systems-based approaches will be required to define and avoid adverse biological effects across temporal and spatial gradients. Similarly, coordinated research activities among organizations within and among countries are necessary to address the priority research needs reported here. Acquiring answers to these 40 research questions will not be trivial, but doing so promises to advance sustainable environmental quality in the 21st century. Environ Toxicol Chem 2019;38:1606-1624. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Flexing the PECs: Predicting environmental concentrations of veterinary drugs in Canadian agricultural soils.

Veterinary drugs administered to food animals primarily enter ecosystems through the application of livestock waste to agricultural land. Although veterinary drugs are essential for protecting animal health, their entry into the environment may pose a risk for nontarget organisms. A means to predict environmental concentrations of new veterinary drug ingredients in soil is required to assess their environmental fate, distribution, and potential effects. The Canadian predicted environmental concentrations in soil (PECsoil) for new veterinary drug ingredients for use in intensively reared animals is based on the approach currently used by the European Medicines Agency for VICH Phase I environmental assessments. The calculation for the European Medicines Agency PECsoil can be adapted to account for regional animal husbandry and land use practices. Canadian agricultural practices for intensively reared cattle, pigs, and poultry differ substantially from those in the European Union. The development of PECsoil default values and livestock categories representative of typical Canadian animal production methods and nutrient management practices culminates several years of research and an extensive survey and analysis of the scientific literature, Canadian agricultural statistics, national and provincial management recommendations, veterinary product databases, and producers. A PECsoil can be used to rapidly identify new veterinary drugs intended for intensive livestock production that should undergo targeted ecotoxicity and fate testing. The Canadian PECsoil model is readily available, transparent, and requires minimal inputs to generate a screening level environmental assessment for veterinary drugs that can be refined if additional data are available. PECsoil values for a hypothetical veterinary drug dosage regimen are presented and discussed in an international context. Integr Environ Assess Manag 2017;13:331-341. © 2016 Her Majesty the Queen in Right of Canada. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC. Reproduced with the permission of the Minister of Health.

Sublethal effects of Cry 1F Bt corn and clothianidin on black cutworm (Lepidoptera: Noctuidae) larval development.

Black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is an occasional pest of maize (corn), Zea mays L., that may cause severe stand losses and injury to corn seedlings. The efficacy of the neonicotinoid seed treatment clothianidin at two commercially available rates and their interaction with a transgenic corn hybrid (Bt corn), trait expressing the Bacillus thuringiensis variety aizawai insecticidal toxin Cry 1Fa2, against black cutworm larvae was investigated. Clothianidin at a rate of 25 mg kernel(-1) on Bt corn increased larval mortality and reduced larval weight gains additively. In contrast, weights of larvae fed non-Bt corn seedlings treated with clothianidin at a rate of 25 mg kernel(-1) increased significantly, suggesting either compensatory overconsumption, hormesis, or hormoligosis. Both Bt corn alone and clothianidin at a rate of 125 mg kernel(-1) applied to non-Bt corn seedlings caused increased mortality and reduced larval weight gains. In two field trials, plots planted with Bt corn hybrids consistently had the highest plant populations and yields, regardless of whether they were treated with clothianidin at the lower commercial rate of 25 mg kernel(-1) The use of Bt corn alone or in combination with the low rate of clothianidin (25 mg kernel(-1)) seems suitable as a means of suppressing black cutworm in no-tillage cornfields, although rescue treatments may still be necessary under severe infestations. Clothianidin alone at the low rate of 25 mg kernel(-1) is not recommended for black cutworm control until further studies of its effects on larval physiology and field performance have been completed.

Phenology and field biology of black cutworm (Lepidoptera: Noctuidae) in Ontario no-till corn.

Black cutworm, Agrotis ipsilon (Hufnagel), is an occasional corn, Zea mays L., pest that is attracted to no-till fields. Understanding the phenology of black cutworm in Ontario no-till corn, particularly the time of arrival of adults in relation to the onset of crop damage and the stages of larvae that coincide with vulnerable corn seedling leaf stages, is important for their effective control. Pheromone and blacklight trap captures of moths first occurred in early April, whereas significant influxes did not occur until mid- to late April. Males and females were often captured simultaneously, in contrast to findings in Iowa and Illinois where males were captured in pheromone traps on average 3 wk ahead of females or males in blacklight traps. This may be a reflection of a more mature source population for the influxes into Ontario because first captures also were later than in the United States. Females arrived mated and corn seedling cutting occurred within 137 degree-days (DD) (base 10.4 degrees C) of first capture in Ontario corn. Cutworms were present in cornfields before planting, and the mean age of larvae increased along with corn leaf stage, suggesting that no new recruitment took place after planting. The apparent synchrony between corn and cutworm phenology in the northern areas of corn production seems more related to the availability and quality of food for young larvae relative to the development of the crop then the time of arrival of moths.