Comment on “Comparison of ozone measurement methods in biomass burning smoke: an evaluation under field and laboratory conditions” (Long et al. 2021)

Long et al (2021) conducted a detailed study of possible interferents in measurements of surface O3 by UV spectroscopy, which measures the UV transmission in ambient and O3 scrubbed air. While we appreciate the careful work done in this analysis, there were several omissions and, in one case, the type of scrubber used was mis-identified as manganese dioxide (MnO2), when in fact it was manganese chloride (MnCl2). This misidentification led to the erroneous conclusion that all UV-based O3 instruments employing solid-phase catalytic scrubbers exhibit significant positive artifacts, whereas previous research found this not to be the case when employing MnO2 scrubber types. While the Long study, and our results, confirm the substantial bias in instruments employing an MnCl2 scrubber, a replication of the earlier work with an MnO2 scrubber type and no humidity correction is needed.

Mussels repair shell damage despite limitations imposed by ocean acidification

Bivalves frequently withstand shell boring attempts by predatory gastropods that result in shell damage that must be quickly repaired to ensure survival. While the processes that underlie larval shell development have been extensively studied within the context of ocean acidification (OA), it remains unclear whether shell repair is impaired by elevated pCO2. To better understand the stereotypical shell repair process, we monitored mussels (Mytilus edulis) with sublethal shell damage within both field and laboratory conditions to characterize the deposition rate, mineral composition, and structural integrity of repaired shell. These results were then compared with a laboratory experiment wherein mussels (Mytilus trossulus) repaired shell damage in one of seven pCO2 treatments (400–2500 µatm). Shell repair proceeded through four distinct stages; shell damage was first covered with an organic film, then mineralized over the course of weeks, acquiring the appearance of nacre after 8 weeks. OA did not impact the ability of mussels to close drill holes, nor the strength or density of the repaired shell after 10-weeks, as measured through mechanical testing and µCT analysis. However, as mussels progressed through each repair stage, significant interactions between pCO2, the length of exposure to treatment conditions, and the strength, inorganic content, and physiological condition of mussels within OA treatments were observed. These results suggest that, while OA may not prevent mussels from repairing shell damage, sustained exposure to elevated pCO2 may induce physiological stress responses that impose energetic constraints on the shell repair process.

The UV RESISTANCE LOCUS 8-Mediated UV-B Response Is Required Alongside CRYPTOCHROME1 For Plant Survival Under Sunlight In The Field

As sessile organisms, plants are subjected to fluctuating sunlight including potentially detrimental ultraviolet-B radiation (UV-B). In Arabidopsis thaliana, experiments under controlled conditions have shown that UV RESISTANCE LOCUS 8 (UVR8) controls photomorphogenic responses for acclimation and tolerance to UV-B; however, its long-term impacts on plant performance remain poorly understood in naturally fluctuating environments. Here we quantified the survival and reproduction of different Arabidopsis mutant genotypes in diverse field and laboratory conditions. We found that uvr8 mutants produced more fruits than wild type in growth chambers with artificial low UV-B conditions but not in natural field conditions. Importantly, independent double mutants of UVR8 and the blue-light photoreceptor gene CRYPTOCHROME 1 (CRY1) in two genetic backgrounds showed a drastic reduction in fitness in the field. UV-B attenuation experiments in field conditions and supplemental UV-B in growth chambers demonstrated that UV-B caused the conditional cry1 uvr8 lethality phenotype. RNA sequencing in different conditions revealed a large number of genes with statistical interaction of UVR8 and CRY1 mutations in the presence of UV-B in the field. Among them, Gene Ontology analysis identified enrichment of categories related to UV-B response, oxidative stress, photoprotection and DNA damage repair. Our study demonstrates the functional importance of the UVR8-mediated response across life stages in natura, which is partially redundant with CRY1, and provides an integral picture of gene expression associated with plant environmental responses under diverse environmental conditions.

Elucidation of Triadic Relationship Among Light Environment, Host Plant Quality, and Feeding Behavior of Zizeeria maha (Kollar) (Lepidoptera: Lycaenidae) IN Oxalis corniculata L. (Oxalidales: Oxalidaceae)

In the dynamics of light-plant-insect interaction, the light affects plant metabolisms which may directly influence the production of defensive secondary metabolites and may consequently alter the feeding behavior of herbivores. The present study aimed to investigate the triadic interactions by using Oxalis corniculata L. (Oxalidales: Oxalidaceae) and its specialist herbivore, Zizeeria maha (Kollar) (Lepidoptera: Lycaenidae), in relation to the light intensity of plant habitats and physicochemical properties of the plants which would affect the larval feeding behavior of Z. maha. Firstly, leaves of O. corniculate in the field with seven different light conditions were collected. A part of which was subjected to chemical analyses, and the rest was fed to Z. maha larvae to evaluate growth and feeding activity; larval period, death rate, weight, amount of consumption, and amount of frass were measured to calculate the relative growth rate, approximate digestion rate, and relative consumption rate. Secondly, light/shade mock environment test tests were conducted with laboratory-grown O. corniculata. The results under both field and laboratory conditions showed positive effects of light intensity on the production of the defensive compound, oxalic acid, in the plants. Furthermore, the larval feeding activity was higher when fed with leaves in higher light intensities. These results relate to our previous study that demonstrated oxalic acid stimulates the feeding of Z. maha larvae. Thus, the triadic interaction among light, O. corniculata, and Z. maha larvae could be explained by the light-driven up-regulated production of oxalic acid positively influenced the larval feeding.

Toxicity of entomopathogenic fungi against Spodoptera frugiperda larvae under laboratory conditions

Maize Fall Armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) is considered an economically important pest and becoming the main threat to food security. This polyphagous pest is widely distributed in various countries of the world especially tropical and subtropical regions. The toxicity of two entomopathogenic fungi such as Metarhizium anisopliae and Beauveria bassiana were evaluated against 2nd instar larvae of FAW under controlled conditions. The results showed that among tested entomopathogenic fungi, B. bassiana was found more toxic than M. anisopliae. B. bassiana caused 79% larval mortality while M. anisopliae 59%. M. anisopliae and B. bassiana were showed LT50 of 84.01 h and 80.99 h, respectively. M. anisopliae and B. bassiana were showed LC50 of 1.3×107 and 1.8×107 spores ml−1, respectively. The current study concluded that Entomopathogenic fungi can give effective control against early instar and further studies are needed to check the efficacy against older instars under field and laboratory conditions.

Environmental Toxicology of Perna Canaliculus

<p>New Zealand does not have a major problem with marine pollution but there is still a need to develop methods to monitor the environment and protect ecosystems. Although some previous studies in New Zealand have measured the concentrations of chemicals in tissues from marine organisms, few to date have developed biomarkers of contaminant exposure. In the current study attempts were made to develop biomarkers for heavy metal contamination in the endemic New Zealand greenshell mussel Perna canaliculus. Metallothionein (MT) gene nucleotide sequences were isolated from P. canaliculus by cloning PCR products from genomic DNA. Nine MT exon 2 amino acid sequences were deduced, some of which were characterised by unusual features, including the presence of atypical tyrosine and histidine residues and lower than usual numbers of metal binding cysteine residues. MT sequences isolated in the current study were compared with those from other mollusc species worldwide. A 2-D gel DIGE proteomic approach was used to detect proteins involved in response to low salinity or heavy metal contamination. In the salinity study, control mussels were killed at the start of the experiment and others were exposed to ambient (32 ppt) and reduced (14 ppt) salinity for 3 days. Approximately 115 proteins showed significant (t-test p < 0.01) differences in abundance between the three experimental groups. Two isoforms of tropomyosin and one isoform of actin were identified and these proteins have been implicated in previous studies in response to reduced salinity. The low number of proteins identified in this study and the heavy metal experiment highlights the difficulty in working with invertebrate species that are presently underrepresented in the DNA and protein sequence databases. In the heavy metal experiment P. canaliculus were exposed to either 34.3 micrograms 1^1 Hg or 0.486 mg 1^1 Cd in the laboratory for 3 days. Control mussels were held in identical conditions without added metal. Over 100 proteins were detected which showed significant (p < 0.01) differences in abundance between control and metal treated groups but these proteins could not be identified using MALDI-TOF mass fingerprinting or tandem mass spectrometry. Tissue and time specific differences in metal uptake were observed. Proteins which responded to heavy metals under laboratory conditions were compared to field samples from the Bay of Islands. Approximately 30 proteins were detected which appeared to be associated with the presence of heavy metals under both field and laboratory conditions. These results suggest that it may be possible to develop biomarkers for heavy metal contamination in P. canaliculus. Based on the average concentrations of metals detected in the Bay of Islands, the amount of metal consumed through a typical diet containing shellfish would be below the provisional tolerable weekly intake (PTWI). However, because Maori, Pacific Islanders and Asians consume a greater quantity of seafood than the general New Zealand public a risk assessment for these groups was calculated. A survey of the frequency, amount and species consumed by these groups is suggested to enable an adequate risk assessment to be made.</p>

Environmental Toxicology of Perna Canaliculus

<p>New Zealand does not have a major problem with marine pollution but there is still a need to develop methods to monitor the environment and protect ecosystems. Although some previous studies in New Zealand have measured the concentrations of chemicals in tissues from marine organisms, few to date have developed biomarkers of contaminant exposure. In the current study attempts were made to develop biomarkers for heavy metal contamination in the endemic New Zealand greenshell mussel Perna canaliculus. Metallothionein (MT) gene nucleotide sequences were isolated from P. canaliculus by cloning PCR products from genomic DNA. Nine MT exon 2 amino acid sequences were deduced, some of which were characterised by unusual features, including the presence of atypical tyrosine and histidine residues and lower than usual numbers of metal binding cysteine residues. MT sequences isolated in the current study were compared with those from other mollusc species worldwide. A 2-D gel DIGE proteomic approach was used to detect proteins involved in response to low salinity or heavy metal contamination. In the salinity study, control mussels were killed at the start of the experiment and others were exposed to ambient (32 ppt) and reduced (14 ppt) salinity for 3 days. Approximately 115 proteins showed significant (t-test p < 0.01) differences in abundance between the three experimental groups. Two isoforms of tropomyosin and one isoform of actin were identified and these proteins have been implicated in previous studies in response to reduced salinity. The low number of proteins identified in this study and the heavy metal experiment highlights the difficulty in working with invertebrate species that are presently underrepresented in the DNA and protein sequence databases. In the heavy metal experiment P. canaliculus were exposed to either 34.3 micrograms 1^1 Hg or 0.486 mg 1^1 Cd in the laboratory for 3 days. Control mussels were held in identical conditions without added metal. Over 100 proteins were detected which showed significant (p < 0.01) differences in abundance between control and metal treated groups but these proteins could not be identified using MALDI-TOF mass fingerprinting or tandem mass spectrometry. Tissue and time specific differences in metal uptake were observed. Proteins which responded to heavy metals under laboratory conditions were compared to field samples from the Bay of Islands. Approximately 30 proteins were detected which appeared to be associated with the presence of heavy metals under both field and laboratory conditions. These results suggest that it may be possible to develop biomarkers for heavy metal contamination in P. canaliculus. Based on the average concentrations of metals detected in the Bay of Islands, the amount of metal consumed through a typical diet containing shellfish would be below the provisional tolerable weekly intake (PTWI). However, because Maori, Pacific Islanders and Asians consume a greater quantity of seafood than the general New Zealand public a risk assessment for these groups was calculated. A survey of the frequency, amount and species consumed by these groups is suggested to enable an adequate risk assessment to be made.</p>

Chemical Composition and Insecticidal Potential of Six Essential Oils from Morocco against Dactylopius opuntiae (Cockerell) under Field and Laboratory Conditions

The carmine cochineal Dactylopius opuntiae (Cockerell) is the major insect pest of the prickly-pear cactus Opuntia ficus-indica (L.) in Morocco. The present study investigated the insecticidal activities of six essential oils (EOs) against nymphs and adult females of D. opuntiae applied singly or in combination with a detergent under laboratory and field conditions. Under laboratory conditions, M. pulegium and O. vulgare L. essential oils showed a high level of insecticidal activity at 5%, with 98% and 92% females’ mortality, respectively, 5 days after treatments. The M. pulegium and O. vulgaris oils at 5% applied in combination with black soap at (60 g/L) induced the highest toxic activity on adult females, 100% and 96% at 5 days after treatments, respectively. Under field conditions, M. pulegium and O. vulgare oils at 5% in combination with black soap (60 g/L) showed the highest adult female mortalities with 96.33 and 92.56%, respectively, 7 days after the first application. The double application of M. pulegium oil at 5% significantly increased the mortality of adult females up to 91%, 5 days after the second spray. GC-MS analysis revealed that the most abundant constituent of M. pulegium and O. vulgare oils was pulegone (84.69%) and durenol (76.53%), respectively. These findings showed that the use of M. pulegium and O. vulgare in combination with black soap or in double sprays could be incorporated in the management package for the control of the wild cochineal D. opuntiae, as a safe and natural alternative to chemical insecticides.

Measuring Leaf Water Potential

This article summarizes the basic concepts of leaf water potential measurements and two available methods for measuring leaf water potential under field and laboratory conditions. Written by Christian Bartell, Haimanote K. Bayabil, Bruce Schaffer, Fitsum Tilahun, and Fikadu Getachew, and published by the UF/IFAS Department of Agricultural and Biological Engineering, October 2021.

Powdery mildew resistance of barley accessions from Dagestan

Powdery mildew caused by the parasitic fungus Blumeria graminis (DC.) Golovin ex Speer f. sp. hordei Marchal is one of the most common diseases of barley. Growing resistant varieties can significantly minimize harmful effects of the pathogen. The specificity in the interaction between the fungus and its host plant requires a continuous search for new donors of the resistance trait. The powdery mildew resistance of 264 barley accessions from Dagestan and genetic control of the trait in resistant forms were studied under field and laboratory conditions. Forty-seven barley lines carrying previously identified powdery mildew resistance genes were also examined. During three years, the experimental material was evaluated under severe infection pressure at the Dagestan Experiment Station of VIR (North Caucasus, Derbent). Juvenile resistance against the Northwest (St. Petersburg, Pushkin) pathogen population was evaluated in a climatic chamber. The genetic control of B. graminis resistance in the selected accessions was studied with the application of hybridological and molecular analyses. The level of genetic diversity of Dagestan barley for effective resistance to powdery mildew is very low. Only two accessions, VIR-23787 and VIR-28212, are resistant against B. graminis at both seedling and adult plant stages. The high-level resistance of breeding line VIR-28212 originating from barley landrace VIR-17554 (Ep-80 Abyssinien) from Ethiopia is controlled by the recessive gene mlo11. Accession VIR-17554 is heterogeneous for the studied trait, with the powdery mildew resistant genotypes belonging to two varieties, dupliatrum (an awnless phenotype) and nigrinudum (an awned phenotype). In accession VIR-23787, a recessive resistance gene distinct from the mlo11 allele was identified. This accession is supposed to be protected by a new, effective pathogen resistance gene.