Scholarly Works, Entomology

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RNAi-Mediated Silencing of Laccase 2 in Culex pipiens Pupae via Dehydration and Soaking Results in Multiple Defects in Cuticular Development
Naumenko, Anastasia N.; Fritz, Megan L. (MDPI, 2024-03-14)
Mosquitoes transmit a range of pathogens, causing devastating effects on human health. Population genetic control strategies have been developed and successfully used for several mosquito species. The most important step in identifying potential targets for mosquito control is the understanding of gene function. RNA interference (RNAi) is a powerful tool for gene silencing which has been widely used to study gene function in insects via knockdown of expression. The success of RNAi in insects depends on the efficient delivery of dsRNA into the cells, with microinjections being the most commonly used to study mosquito gene function. However, microinjections in the pupal stage lead to significant mortality in Aedes and Culex species, and few studies have performed microinjections in Culicinae pupae. Advanced techniques, such as CRISPR/Cas9 knockout, require establishing individual mosquito lines for each gene studied, and maintaining such lines may be limited by the insect-rearing capacity of a laboratory. Moreover, at times gene knockout during early development (embryo stage) has a deleterious effect on mosquito development, precluding the analysis of gene function in the pupal and adult stages and its potential for mosquito control. There is a need for a simple procedure that can be used for the fast and reliable examination of adult gene function via RNAi knockdown. Here, we focus on the aquatic stages of the mosquito life cycle and suggest a quick and easy assay for screening the functional role of genes in Culex pipiens mosquitoes without using microinjections. By dehydration of early stage pupae and subsequent rehydration in highly concentrated dsRNA, we achieved a moderate knockdown of laccase 2, a gene that turns on in the pupal stage and is responsible for melanization and sclerotization of the adult cuticle.
SARS-CoV-2 Specific Nanobodies Neutralize Different Variants of Concern and Reduce Virus Load in the Brain of h-ACE2 Transgenic Mice
Pavan, María Florencia; Bok, Marina; Betanzos San Juan, Rafael; Malito, Juan Pablo; Marcoppido, Gisela Ariana; Franco, Diego Rafael; Militelo, Daniela Ayelen; Schammas, Juan Manuel; Bari, Sara Elizabeth; Stone, William; López, Krisangel; Porier, Danielle LaBrie; Muller, John Anthony; Auguste, Albert Jonathan; Yuan, Lijuan; Wigdorovitz, Andrés; Parreño, Viviana Gladys; Ibañez, Lorena Itat (MDPI, 2024-01-25)
Since the beginning of the COVID-19 pandemic, there has been a significant need to develop antivirals and vaccines to combat the disease. In this work, we developed llama-derived nanobodies (Nbs) directed against the receptor binding domain (RBD) and other domains of the Spike (S) protein of SARS-CoV-2. Most of the Nbs with neutralizing properties were directed to RBD and were able to block S-2P/ACE2 interaction. Three neutralizing Nbs recognized the N-terminal domain (NTD) of the S-2P protein. Intranasal administration of Nbs induced protection ranging from 40% to 80% after challenge with the WA1/2020 strain in k18-hACE2 transgenic mice. Interestingly, protection was associated with a significant reduction in virus replication in nasal turbinates and a reduction in virus load in the brain. Employing pseudovirus neutralization assays, we identified Nbs with neutralizing capacity against the Alpha, Beta, Delta, and Omicron variants, including a Nb capable of neutralizing all variants tested. Furthermore, cocktails of different Nbs performed better than individual Nbs at neutralizing two Omicron variants (B.1.529 and BA.2). Altogether, the data suggest the potential of SARS-CoV-2 specific Nbs for intranasal treatment of COVID-19 encephalitis.
Portable, low-cost samplers for distributed sampling of atmospheric gases
Hurley, James; Caceres, Alejandra; McGlynn, Deborah; Tovillo, Mary; Pinar, Suzanne; Schuerch, Roger; Onufrieva, Ksenia; Isaacman-VanWertz, Gabriel (2023-10-13)
Volatile organic compounds (VOCs) contribute to air pollution both directly, as hazardous gases, and through their reactions with common atmospheric oxidants to produce ozone, particulate matter, and other hazardous air pollutants. There are enormous ranges of structures and reaction rates among VOCs, and consequently a need to accurately characterize the spatial and temporal distribution of individual identified compounds. Current VOC measurements are often made with complex, expensive instrumentation that provides high chemical detail, but is limited in its portability and requires high expense (e.g., mobile labs) for spatially resolved measurements. Alternatively, periodic collection of samples on cartridges is inexpensive but demands significant operator interaction that can limit possibilities for time-resolved measurements or distributed measurements across a spatial area. Thus, there is a need for simple, portable devices that can sample with limited operator presence to enable temporally and/or spatially resolved measurements. In this work, we describe new portable and programmable VOC samplers that enable simultaneous collection of samples across a spatially distributed network, validate their reproducibility, and demonstrate their utility. Validation experiments confirmed high precision between samplers as well as the ability of miniature ozone scrubbers to preserve reactive analytes collected on commercially available adsorbent gas sampling cartridges, supporting simultaneous field deployment across multiple locations. In indoor environments, 24-hour integrated samples demonstrate observable day-to-day variability, as well as variability across very short spatial scales (meters). The utility of the samplers was further demonstrated by locating outdoor point sources of analytes through the development of a new mapping approach that employs a group of the portable samplers and back projection techniques to assess a sampling area with higher resolution than stationary sampling. As with all gas sampling, the limits of detection depend on sampling times and the properties of sorbent and analyte. Limit of detection of the analytical system used in this work is on the order of nanograms, corresponding to mixing ratios of 1-10 pptv after one hour of sampling at the programmable flow rate of 50-250 sccm enabled by the developed system. The portable VOC samplers described and validated here provide a simple, low-cost sampling solution for spatially and/or temporally variable measurements of any organic gases that are collectable on currently available sampling media.
3D X-ray analysis of the subterranean burrowing depth and pupal chamber size of Laricobius (Coleoptera: Derodontidae), a specialist predator of Adelges tsugae (Hemiptera: Adelgidae)
Hillen, Ashleigh P.; Foley, Jeremiah R.; Salcedo, Mary K.; Socha, John J.; Salom, Scott M. (Oxford University Press, 2023-05-01)
The non-native hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), has caused a significant decline of eastern hemlock, Tsuga canadensis L. (Pinales: Pinaceae), and Carolina hemlock, Tsuga caroliniana Engelmann (Pinales: Pinaceae), in eastern North America. Biological control of HWA has focused on the use of 2 Laricobius spp. (Coleoptera: Derodontidae), natural predators of HWA, which require arboreal and subterranean life phases to complete their development. In its subterranean phase, Laricobius spp. are subject to abiotic factors including soil compaction or soil-applied insecticides used to protect hemlock from HWA. This study used 3D X-ray microcomputed tomography (micro-CT) to identify the depth at which Laricobius spp. burrows during its subterranean lifecycle, characterize pupal chamber volume, and determine whether soil compaction had a significant effect on these variables. The mean burrowing depth in the soil of individuals was 27.0 mm ± 14.8 (SD) and 11.4 mm ± 11.8 (SD) at compaction levels of 0.36 and 0.54 g/ cm3, respectively. The mean pupal chamber volume was 11.15 mm3 ± 2.8 (SD) and 7.65 mm3 ± 3.5 (SD) in soil compacted at 0.36 and 0.54 g/cm3, respectively. These data show that soil compaction influences burrowing depth and pupal chamber size for Laricobius spp.This information will help us better identify the effect of soil-applied insecticide residues on estivating Laricobius spp. and soil-applied insecticide residues in the field. Additionally, these results demonstrate the utility of 3D micro-CT in assessing subterranean insect activity in future studies.
The chromosome-scale genome assembly for the West Nile vector Culex quinquefasciatus uncovers patterns of genome evolution in mosquitoes
Ryazansky, Sergei S.; Chen, Chujia; Potters, Mark; Naumenko, Anastasia N.; Lukyanchikova, Varvara; Masri, Reem A.; Brusentsov, Ilya I.; Karagodin, Dmitriy A.; Yurchenko, Andrey A.; dos Anjos, Vitor L.; Haba, Yuki; Rose, Noah H.; Hoffman, Jinna; Guo, Rong; Menna, Theresa; Kelley, Melissa; Ferrill, Emily; Schultz, Karen E.; Qi, Yumin; Sharma, Atashi; Deschamps, Stéphane; Llaca, Victor; Mao, Chunhong; Murphy, Terence D.; Baricheva, Elina M.; Emrich, Scott; Fritz, Megan L.; Benoit, Joshua B.; Sharakhov, Igor V.; McBride, Carolyn S.; Tu, Zhijian; Sharakhova, Maria V. (2024-01-25)
Background: Understanding genome organization and evolution is important for species involved in transmission of human diseases, such as mosquitoes. Anophelinae and Culicinae subfamilies of mosquitoes show striking differences in genome sizes, sex chromosome arrangements, behavior, and ability to transmit pathogens. However, the genomic basis of these differences is not fully understood. Methods: In this study, we used a combination of advanced genome technologies such as Oxford Nanopore Technology sequencing, Hi-C scaffolding, Bionano, and cytogenetic mapping to develop an improved chromosome-scale genome assembly for the West Nile vector Culex quinquefasciatus. Results: We then used this assembly to annotate odorant receptors, odorant binding proteins, and transposable elements. A genomic region containing male-specific sequences on chromosome 1 and a polymorphic inversion on chromosome 3 were identified in the Cx. quinquefasciatus genome. In addition, the genome of Cx. quinquefasciatus was compared with the genomes of other mosquitoes such as malaria vectors An. coluzzi and An. albimanus, and the vector of arboviruses Ae. aegypti. Our work confirms significant expansion of the two chemosensory gene families in Cx. quinquefasciatus, as well as a significant increase and relocation of the transposable elements in both Cx. quinquefasciatus and Ae. aegypti relative to the Anophelines. Phylogenetic analysis clarifies the divergence time between the mosquito species. Our study provides new insights into chromosomal evolution in mosquitoes and finds that the X chromosome of Anophelinae and the sex-determining chromosome 1 of Culicinae have a significantly higher rate of evolution than autosomes. Conclusion: The improved Cx. quinquefasciatus genome assembly uncovered new details of mosquito genome evolution and has the potential to speed up the development of novel vector control strategies.
Moving past the challenges and misconceptions in urban adaptation research
Winchell, Kristin M.; Aviles-Rodriguez, Kevin J.; Carlen, Elizabeth J.; Miles, Lindsay S.; Charmantier, Anne; De Leon, Luis F.; Gotanda, Kiyoko M.; Rivkin, L. Ruth; Szulkin, Marta; Verrelli, Brian C. (Wiley, 2022-11-21)
Although the field of urban evolutionary ecology has recently expanded, much progress has been made in identifying adaptations that arise as a result of selective pressures within these unique environments. However, as studies within urban environments have rapidly increased, researchers have recognized that there are challenges and opportunities in characterizing urban adaptation. Some of these challenges are a consequence of increased direct and indirect human influence, which compounds long-recognized issues with research on adaptive evolution more generally. In this perspective, we discuss several common research challenges to urban adaptation related to (1) methodological approaches, (2) trait–environment relationships and the natural history of organisms, (3) agents and targets of selection, and (4) habitat heterogeneity. Ignoring these challenges may lead to misconceptions and further impede our ability to draw conclusions regarding evolutionary and ecological processes in urban environments. Our goal is to first shed light on the conceptual challenges of conducting urban adaptation research to help avoid the propagation of these misconceptions. We further summarize potential strategies to move forward productively to construct a more comprehensive picture of urban adaptation, and discuss how urban environments also offer unique opportunities and applications for adaptation research.
The millipede family Striariidae Bollman, 1893. VIII. Three new genera and four new species of minute millipedes from Oregon and Washington, USA (Diplopoda, Chordeumatida, Striarioidea)
Shear, William A.; Marek, Paul E. (Magnolia Press, 2023-04-14)
We describe three new genera and four new species of small, litter-dwelling millipedes from the states of Oregon and Washington, USA: Miniaria ramifera, n. gen., n. sp., Miniaria richarti, n. gen., n. sp., Tigraria oregonensis, n. gen., n. sp., and Kingaria prattensis, n. gen., n. sp. Some of the unusual characters of these species are discussed, including a new type of sensory array on the third tarsus of males and a newly observed mandibular gland.
The identity of Neocnemodon calcarata (Loew) (Diptera: Syrphidae), a specialized flower fly predator of woolly apple aphid
Bergh, J. Christopher; Marek, Paul E.; Short, Brent D.; Skevington, Jeffrey H.; Thompson, F. Christian (2023-03-05)
The names and identities of the specialized flower fly predators of the Woolly Apple Aphid, Eriosoma lanigerum (Hausmann, 1802) are fixed. These predators, Neocnemodon calcarata (Loew, 1866) and Neocnemodon vitripennis (Meigen, 1822), are important biological control agents as they prey on both arboreal and root colonies of the aphid. A lectotype is designated for Pipiza calcarata Loew, 1866, and type notes of N. calcarata and N. vitripennis are provided.
Expression of anti-chikungunya single-domain antibodies in transgenic Aedes aegypti reduces vector competence for chikungunya virus and Mayaro virus
Webb, Emily M.; Compton, Austin; Rai, Pallavi; Chuong, Christina; Paulson, Sally L.; Tu, Zhijian; Weger-Lucarelli, James (Frontiers, 2023-06-12)
Chikungunya virus (CHIKV) and Mayaro virus (MAYV) are closely related alphaviruses that cause acute febrile illness accompanied by an incapacitating polyarthralgia that can persist for years following initial infection. In conjunction with sporadic outbreaks throughout the sub-tropical regions of the Americas, increased global travel to CHIKV- and MAYV-endemic areas has resulted in imported cases of MAYV, as well as imported cases and autochthonous transmission of CHIKV, within the United States and Europe. With increasing prevalence of CHIKV worldwide and MAYV throughout the Americas within the last decade, a heavy focus has been placed on control and prevention programs. To date, the most effective means of controlling the spread of these viruses is through mosquito control programs. However, current programs have limitations in their effectiveness; therefore, novel approaches are necessary to control the spread of these crippling pathogens and lessen their disease burden. We have previously identified and characterized an anti-CHIKV single-domain antibody (sdAb) that potently neutralizes several alphaviruses including Ross River virus and Mayaro virus. Given the close antigenic relationship between MAYV and CHIKV, we formulated a single defense strategy to combat both emerging arboviruses: we generated transgenic Aedes aegypti mosquitoes that express two camelid-derived anti-CHIKV sdAbs. Following an infectious bloodmeal, we observed significant reduction in CHIKV and MAYV replication and transmission potential in sdAb-expressing transgenic compared to wild-type mosquitoes; thus, this strategy provides a novel approach to controlling and preventing outbreaks of these pathogens that reduce quality of life throughout the tropical regions of the world.
Testing Novel Seed Treatments and Soil-Applied Insecticides Against Wireworm in Corn, 2023
Bekelja, Kyle; Malone, Sean (Oxford University Press, 2024-01)
A Novel Insecticide, Isocycloseram, Shows Promise as an Alternative to Chlorpyrifos Against a Direct Pest of Peanut
Bekelja, Kyle; Malone, Sean; Mascarenhas, Victor; Taylor, Sally V. (2024-01)
Larvae of the southern corn rootworm (SCR) Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae) are primary pests of peanut in the Virginia-Carolina region of the United States, and are relatively sporadic pests in southern states such as Georgia, Alabama, and Florida. Peanuts have strict quality standards which, when they are not met, crop value is diminished by more than 65%. Management of direct pests like SCR is therefore crucial to maintaining the economic viability of the crop. The soil-dwelling nature of SCR larvae complicates management due to difficulties associated with monitoring and predicting infestations. Non-chemical management options are limited in this system; preventative insecticide applications are the most reliable management strategy for at-risk fields. Chlorpyrifos was the standard product for larval SCR management in peanut until its registration was revoked in 2022, leaving no effective chemical management option for larvae. We tested a novel insecticide, isocycloseram, for its ability to reduce pod scarring, pod penetration, and non-SCR pod damage in field studies conducted in Suffolk, Virginia in 2020 – 2022. Overall injury was low in 2020 and 2022, and in 2022 there was not a significant effect of treatment. In 2021, two simulated chemigation applications of isocycloseram in July significantly reduced pod scarring and overall pod injury relative to chlorpyrifos and the untreated control. Our results suggest that isocycloseram may become an effective option for managing SCR in peanut, although more work is needed to understand the mechanisms by which it is effective as a soil-applied insecticide.
Exploring the immunogenicity of an insect-specific virus vectored Zika vaccine candidate
Tanelus, Manette; López, Krisangel; Smith, Shaan; Muller, John A.; Porier, Danielle L.; Auguste, Dawn I.; Stone, William B.; Paulson, Sally L.; Auguste, Albert J. (Springer, 2023-12-01)
Zika virus (ZIKV) is an important re-emerging flavivirus that presents a significant threat to human health worldwide. Despite its importance, no vaccines are approved for use in humans. Insect-specific flaviviruses (ISFVs) have recently garnered attention as an antigen presentation platform for vaccine development and diagnostic applications. Here, we further explore the safety, immunogenicity, and efficacy of a chimeric ISFV-Zika vaccine candidate, designated Aripo-Zika (ARPV/ZIKV). Our results show a near-linear relationship between increased dose and immunogenicity, with 1011 genome copies (i.e., 108 focus forming units) being the minimum dose required for protection from ZIKV-induced morbidity and mortality in mice. Including boosters did not significantly increase the short-term efficacy of ARPV/ZIKV-vaccinated mice. We also show that weanling mice derived from ARPV/ZIKV-vaccinated dams were completely protected from ZIKV-induced morbidity and mortality upon challenge, suggesting efficient transfer of maternally-derived protective antibodies. Finally, in vitro coinfection studies of ZIKV with Aripo virus (ARPV) and ARPV/ZIKV in African green monkey kidney cells (i.e., Vero-76) showed that ARPV and ARPV/ZIKV remain incapable of replication in vertebrate cells, despite the presence of active ZIKV replication. Altogether, our data continue to support ISFV-based vaccines, and specifically the ARPV backbone is a safe, immunogenic and effective vaccine strategy for flaviviruses.
Jasmonic and salicylic induced defensive response in wine grapes against Drosophila suzukii (Diptera: Drosophilidae)
Hussein, Barkat; War, Abdul Rasheed; Pfeiffer, Douglas G. (Cell Press, 2023-06)
To better understand the elicitor induced defense in wine grapes against Drosophila suzukii (Matsumura), two varieties, Pinot Noir and Chardonnay, were sprayed with jasmonic acid (JA) and salicylic acid (SA). Total phenols, total flavonoids, total tannins and total soluble sugars were quantified. Oviposition preference by D. suzukii in response to JA and SA applications were also studied. Behavioral response of D. suzukii to various sugars was recorded. The effect of flavonoids (gallic acid, catechin, quercetin at 100 and 500 ppm) on mortality of D. suzukii was also studied in CAFE assay. Our results showed that JA and SA application significantly affected phenol, flavonoid and tannin contents of grapes. Reduced injury was observed in treated plants; this reduction was more pronounced in Chardonnay than Pinot Noir. The number of eggs laid by D. suzukii females was lower in JA and SA-treated plants; this reduction was more pronounced under no-choice conditions than under choice conditions. In prandial behavior, sucrose solution (5%), glucose solution (5%), fructose solution (5%), sucrose (5%) + yeast (5%) solutions and yeast solutions (5%) showed higher attraction of D. suzukii females compared to control treatments. Among flavonoids, catechin (100 ppm) showed higher mortality of D. suzukii than rest of the treatments. The results of this study can be used for developing management strategies of D. suzukii in wine grapes and related crops.
Dendrochronology reveals different effects among host tree species from feeding by Lycorma delicatula (White)
Dechaine, Andrew C.; Pfeiffer, Douglas G.; Kuhar, Thomas P.; Salom, Scott M.; Leskey, Tracy C.; McIntyre, Kelly C.; Walsh, Brian; Speer, James H. (Frontiers, 2023-09-01)
The spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), was first detected in the United States in Berks County, Pennsylvania, in 2014. Native to China, this phloem-feeding planthopper threatens agricultural, ornamental, nursery, and timber industries in its invaded range through quarantine restrictions on shipments, as well as impacts on plants themselves. The long-term impacts of L. delicatula feeding on tree species have not been well studied in North America. Using standard dendrochronological methods on cores taken from trees with differing levels of L. delicatula infestation and systemic insecticidal control, we quantified the impact of L. delicatula feeding on the annual growth of four tree species in Pennsylvania: Ailanthus altissima, Juglans nigra, Liriodendron tulipifera, and Acer rubrum. The results suggest that L. delicatula feeding is associated with the diminished growth of A. altissima, but no change was observed in any other tree species tested. The results also suggest that systemic insecticides mitigate the impact of L. delicatula feeding on A. altissima growth.
Discovery of facultative parthenogenesis in a new world crocodile
Booth, Warren; Levine, Brenna A.; Corush, Joel B.; Davis, Mark A.; Dwyer, Quetzal; De Plecker, Roel; Schuett, Gordon W. (Royal Society, 2023-06-07)
Over the past two decades, there has been an astounding growth in the documentation of vertebrate facultative parthenogenesis (FP). This unusual reproductive mode has been documented in birds, non-avian reptiles - specifically lizards and snakes - and elasmobranch fishes. Part of this growth among vertebrate taxa is attributable to awareness of the phenomenon itself and advances in molecular genetics/genomics and bioinformatics, and as such our understanding has developed considerably. Nonetheless, questions remain as to its occurrence outside of these vertebrate lineages, most notably in Chelonia (turtles) and Crocodylia (crocodiles, alligators and gharials). The latter group is particularly interesting because unlike all previously documented cases of FP in vertebrates, crocodilians lack sex chromosomes and sex determination is controlled by temperature. Here, using whole-genome sequencing data, we provide, to our knowledge, the first evidence of FP in a crocodilian, the American crocodile, Crocodylus acutus. The data support terminal fusion automixis as the reproductive mechanism; a finding which suggests a common evolutionary origin of FP across reptiles, crocodilians and birds. With FP now documented in the two main branches of extant archosaurs, this discovery offers tantalizing insights into the possible reproductive capabilities of the extinct archosaurian relatives of crocodilians and birds, notably members of Pterosauria and Dinosauria.
The role of Culex territans mosquitoes in the transmission of Batrachochytrium dendrobatidis to amphibian hosts
Reinhold, Joanna M.; Halbert, Ella; Roark, Megan; Smith, Sierra N.; Stroh, Katherine M.; Siler, Cameron D.; McLeod, David S.; Lahondère, Chloé (2023-11-16)
Background Mosquitoes are the deadliest organisms in the world, killing an estimated 750,000 people per year due to the pathogens they can transmit. Mosquitoes also pose a major threat to other vertebrate animals. Culex territans is a mosquito species found in temperate zones worldwide that feeds almost exclusively on amphibians and can transmit parasites; however, little is known about its ability to transmit other pathogens, including fungi. Batrachochytrium dendrobatidis (Bd) is a topical pathogenic fungus that spreads through contact. With amphibian populations around the world experiencing mass die-offs and extinctions due to this pathogen, it is critical to study all potential modes of transmission. Because Cx. territans mosquitoes are in contact with their hosts for long periods of time while blood-feeding, we hypothesize that they can transmit and pick up Bd. Methods In this study, we first assessed Cx. territans ability to transfer the fungus from an infected surface to a clean one under laboratory conditions. We also conducted a surveillance study of Bd infections in frogs and mosquitoes in the field (Mountain Lake Biological station, VA, USA). In parallel, we determined Cx. territans host preference via blood meal analysis of field caught mosquitoes. Results We found that this mosquito species can carry the fungus to an uninfected surface, implying that they may have the ability to transmit Bd to their amphibian hosts. We also found that Cx. territans feed primarily on green frogs (Rana clamitans) and bullfrogs (Rana catesbeiana) and that the prevalence of Bd within the frog population at our field site varied between years. Conclusions This study provides critical insights into understanding the role of amphibian-biting mosquitoes in transmitting pathogens, which can be applied to disease ecology of susceptible amphibian populations worldwide.
La Crosse Virus Circulation in Virginia, Assessed via Serosurveillance in Wildlife Species
Faw, Lindsey R.; Riley, Jennifer; Eastwood, Gillian (MDPI, 2023-06-30)
Mosquito-borne La Crosse virus (LACV; family: Peribunyaviridae) is the leading cause of pediatric arboviral encephalitis in the United States, with clinical cases generally centered in the Midwest and Appalachian regions. Incidence of LACV cases in Appalachian states has increased, such that the region currently represents the majority of reported LACV cases in the USA. The amount of reported LACV cases from Virginia, however, is minimal compared to neighboring states such as North Carolina, West Virginia, and Tennessee, and non-Appalachian regions of Virginia are understudied. Here we examine the hypothesis that LACV is circulating widely in Virginia, despite a low clinical case report rate, and that the virus is circulating in areas not associated with LACV disease. In this study, we screened local mammalian wildlife in northwestern counties of Virginia using passive surveillance via patients submitted to wildlife rehabilitation centers. Blood sera (527 samples; 9 species, 8 genera) collected between October 2019 and December 2022 were screened for neutralizing antibodies against LACV, indicating prior exposure to the virus. We found an overall LACV seroprevalence of 1.90% among all wild mammals examined and reveal evidence of LACV exposure in several wild species not generally associated with LACV, including eastern cottontails and red foxes, along with established reservoirs, eastern gray squirrels, although there was no serological evidence in chipmunks. These data indicate the circulation of LACV in Virginia outside of Appalachian counties, however, at a lower rate than reported for endemic areas within the state and in other states.
Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance
Dively, Galen P.; Kuhar, Tom P.; Taylor, Sally V.; Doughty, Helene; Holmstrom, Kristian; Gilrein, Daniel O.; Nault, Brian A.; Ingerson-Mahar, Joseph; Huseth, Anders; Reisig, Dominic; Fleischer, Shelby; Owens, David; Tilmon, Kelley; Reay-Jones, Francis; Porter, Pat; Smith, Jocelyn; Saguez, Julien; Wells, Jason; Congdon, Caitlin; Byker, Holly; Jensen, Bryan; DiFonzo, Chris; Hutchison, William D.; Burkness, Eric; Wright, Robert; Crossley, Michael; Darby, Heather; Bilbo, Tom; Seiter, Nicholas; Krupke, Christian; Abel, Craig; Coates, Brad S.; McManus, Bradley; Fuller, Billy; Bradshaw, Jeffrey; Peterson, Julie A.; Buntin, David; Paula-Moraes, Silvana; Kesheimer, Katelyn; Crow, Whitney; Gore, Jeffrey; Huang, Fangneng; Ludwick, Dalton C.; Raudenbush, Amy; Jimenez, Sebastian; Carrière, Yves; Elkner, Timothy; Hamby, Kelly (MDPI, 2023-06-25)
Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020–2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa.
A new species of Illacme from southern California (Siphonophorida, Siphonorhinidae)
Marek, Paul E.; Hall, Charity L.; Lee, Cedric; Bailey, James; Berger, Matt C.; Kasson, Matt T.; Shear, William (Pensoft, 2023-06)
The millipede fauna inhabiting deep soil are poorly known. They are small and threadlike, slow moving, lacking pigmentation, and rarely encountered due to their obscure underground way of life. One family, the Siphonorhinidae, encompasses four genera and 12 species in a fragmentary distribution in California, southern Africa, Madagascar, the Malay Archipelago, and Indo-Burma. The family is represented in the Western Hemisphere by a single genus, Illacme Cook & Loomis, 1928 from California, with its closest known relative, Nematozonium filum Verhoeff, 1939, from southern Africa. A new species of this family is documented from soil microhabitats in the Los Angeles metropolitan area, Illacme socal Marek & Shear, sp. nov. Based on this discovery and the recent documentation of other endogean millipede species, we show that these grossly understudied subterranean fauna represent the next frontier of discovery. However, they are threatened by encroaching human settlement and habitat loss, and conservation of this species and other subterranean fauna is of high importance.
Effects of Hemlock Woolly Adelgid Control Using Imidacloprid on Leaf-Level Physiology of Eastern Hemlock
McDonald, Kelly M.; Seiler, John R.; Wang, Bingxue; Salom, Scott M.; Rhea, Rusty J. (MDPI, 2023-06-14)
Widespread mortality of eastern hemlock (Tsuga canadensis [L.] Carr.) has been occurring due to the introduction of hemlock woolly adelgid (Adelges tsugae Annand) (HWA), threatening millions of hectares of hemlock-dominated forests in the eastern United States. HWA feeds at the base of needles and removes stored carbohydrates, which can impact leaf-level physiology, contributing to the decline of the tree. However, these physiological mechanisms in HWA-infested hemlocks are still not clearly understood. We investigated hemlock leaf physiology year-round at three forested sites with various degrees of infestation. At each site, half the trees were treated with imidacloprid (Merit^® 2 F, Bayer, Kansas City, MO, USA) while the rest were left untreated. Imidacloprid is widely used to control HWA but can itself have phytotoxic effects. After one growing season, there was an increase in photosynthetic rates (7.5%, p = 0.0163) and stomatal conductance (7.1%, p = 0.0163) across sites in the trees treated with imidacloprid. After two years, the imidacloprid treatment also increased bud break from 22.5% to 88.7% at Fishburn (the most severely impacted site) and from 22.7% to 58.9% at Mountain Lake (the least impacted site), and slightly increased chlorophyll fluorescence for treated trees at Fishburn. Chemical treatment also slightly increased water use efficiency at Mountain Lake. These results suggest that HWA is causing tree mortality largely through a reduction in leaf area caused by decreasing bud break and also by a slight, but significant, reduction in leaf-level photosynthesis and stomatal conductance.

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