Adult Mosquito and Butterfly Exposure to Permethrin and Relative Risk Following ULV Sprays from a Truck-Mounted Sprayer.

Ground applications of adulticides via a specialized truck-mounted sprayer are one of the most common practices for control of flying adult mosquitoes. Aerosols released to drift through a targeted area persist in the air column to contact and kill flying mosquitoes, but may also drift into adjacent areas not targeted by the applications where it may affect nontarget insects such as imperiled butterflies. This study compared the risk of permethrin to adult mosquitoes and adult butterflies to assess the likelihood that the butterflies would be affected following such sprays. Permethrin toxicity values were determined for Aedes aegypti and Culex quinquefasciatus (LD50s of 81.1 and 166.3 ng/g dw, respectively) and then combined with published toxicity data in a species sensitivity distribution for comparison with published permethrin toxicity data for adult butterflies. The sensitivity distributions indicated adult butterflies and mosquitoes are similarly sensitive, meaning relative risk would be a function of exposure. Exposure of adult butterflies and adult mosquitoes to permethrin was measured following their exposure to ULV sprays in an open field. Average permethrin concentrations on adult mosquitoes (912-38,061 ng/g dw) were typically an order of magnitude greater than on adult butterflies (110-11,004 ng/g dw) following each spray, indicating lower risk for butterflies relative to mosquitoes. Despite lower estimated risk, 100% mortality of adult butterflies occurred following some of the sprays. Additional studies could help understand exposure and risk for butterflies in densely vegetated habitats typical near areas treated by ULV sprays.

Mortality and Cholinesterase Inhibition in Butterflies Following Aerial Naled Applications for Mosquito Control on the National Key Deer Refuge.

Natural resource managers are concerned about the impacts of aerial ultra-low volume spray (ULV) of insecticides for mosquito control (i.e., mosquito adulticides) and seek science-driven management recommendations that reduce risk but allow vector control for nearby human populations. Managers at the National Key Deer Refuge (Florida Keys, FL) are concerned for ULV effects upon conservation efforts for imperiled butterflies (Florida leafwing [Anaea troglodyta floridalis] and Bartram's hairstreak [Strymon acis bartrami] butterflies). No-spray zones were designated for protection of those butterflies, but their effectiveness for mitigation is unclear. To address this uncertainty, cholinesterase activity (ChE) and mortality were monitored for caged butterflies gulf fritillary [Agraulis vanilla] and great southern white [Ascia monuste]) deployed on the Refuge during three aerial ULV applications of the insecticide naled. Residue samplers also were deployed to estimate butterfly exposure. Spray efficacy against mosquitoes was assessed by deploying caged mosquitoes at the same locations as the butterflies. Average naled residue levels on filter paper samplers in the target area (1882-2898 µg/m2) was significantly greater than in the no-spray zone (9-1562 µg/m2). Differences between the no-spray zone and target area for butterfly mortality and ChE were inconsistent. Average mortality was significantly lower, and average ChE was significantly higher in the no-spray zone for larvae of one species but not for larvae of the other species. Mosquito mortality did not differ significantly between the two areas. Data from the present study reflect the inconsistent effectiveness of no-spray zones on the Refuge using standard methods employed at the time by the vector control agency in the Florida Keys and possibly by other vector control agencies in similar coastal environments. Furthermore, these findings helped to guide the design and to improve the conservation value of future no-spray zone delineations while allowing for treatment in areas where mosquito control is necessary for vector-borne disease reduction.

Low-Level Dietary Clothianidin Exposure Preferentially Causes Prepupal Mortality of Monarch Butterflies (Danaus plexippus).

Data from prior research indicate the prepupal stage of the monarch butterfly life cycle is more sensitive to clothianidin exposure than the larval stage. A set of experiments was conducted to determine if the dietary clothianidin exposures that cause prepupal mortality are environmentally relevant. Monarch larvae were raised from egg to pupae on clothianidin-contaminated swamp milkweed plants (Asclepias incarnata). Larval growth as well as larval and prepupal survival were monitored throughout the experiments, in which the exposures ranged from 1.4 to 2793.1 ng/g leaf. Exposures of 5.4 to 46.9 ng/g leaf resulted primarily in prepupal mortality, whereas higher exposures of 1042.4 to 2793.1 ng/g leaf resulted exclusively in larval mortality, indicating the prepupal stage is more sensitive to clothianidin exposure than the larval stage. A median lethal concentration and a 10% lethal concentration of 37 and 6 ng/g leaf, respectively, were estimated for prepupal mortality. Both effect concentrations are within the range of clothianidin concentrations reported in leaves collected from wild milkweed plants, indicating prepupal mortality is an environmentally relevant effect. Environ Toxicol Chem 2024;43:2039-2044. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Permethrin Contamination of Sawgrass Marshes and Potential Risk for the Imperiled Klot's Skipper Butterfly (Euphyes pilatka klotsi).

Nontarget effects from mosquito control operations are possible in habitats adjacent to areas targeted by ultra-low-volume (ULV) sprays of permethrin for adult mosquito control. We assessed the risks of permethrin exposure to butterflies, particularly the imperiled Klot's skipper, when exposed to ground-based ULV sprays. Samples of larval host plant leaves (sawgrass) were collected in June (in mosquito season) and January (outside mosquito season) of 2015 from sawgrass marsh habitats of the National Key Deer Wildlife Refuge (Big Pine Key, FL, USA) and analyzed for permethrin. Permethrin detection was higher in June (detected on 70% of samples) than in January (30%), and concentrations were significantly higher in June (geomean = 2.1 ng/g, median = 2.4) relative to January (0.4 ng/g, median = 0.2). Dietary risk for 4th to 5th-instar larvae was low based on the measured residues. The AGricultural DISPersal model (Ver. 8.26) was used to estimate permethrin residues on sawgrass following ULV sprays (deposited residues) to estimate immediate postspray risk. Estimated deposited residues (33-543 ng/g) were much higher than measured residues, which leads to a higher risk likelihood for butterfly larvae immediately after ULV sprays. The difference between estimated and measured residues, and between the two risk estimations, reflects uncertainty in risk estimates based on the measured residues. Research on modeling deposited pesticide residues following ground-based ULV spray is limited. More research on estimating deposited pesticide residues from truck-mounted ULV sprayers could help reduce uncertainty in the risk predictions for nontarget insects like butterflies. Environ Toxicol Chem 2024;43:267-278. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Custom microarray construction and analysis for determining potential biomarkers of subchronic androgen exposure in the Eastern Mosquitofish (Gambusia holbrooki).

BACKGROUND: The eastern mosquitofish (Gambusia holbrooki) has the potential to become a bioindicator organism of endocrine disrupting chemicals (EDCs) due to its androgen-driven secondary sexual characteristics. However, the lack of molecular information on G. holbrooki hinders its use as a bioindicator coupled with biomarker data. While traditional gene-by-gene approaches provide insight for biomarker development, a holistic analysis would provide more rapid and expansive determination of potential biomarkers. The objective of this study was to develop and utilize a mosquitofish microarray to determine potential biomarkers of subchronic androgen exposure. To achieve this objective, two specific aims were developed: 1) Sequence a G. holbrooki cDNA library, and 2) Use microarray analysis to determine genes that are differentially regulated by subchronic androgen exposure in hepatic tissues of 17ß-trenbolone (TB) exposed adult female G. holbrooki. RESULTS: A normalized library of multiple organs of male and female G. holbrooki was prepared and sequenced by the Illumina GA IIx and Roche 454 XLR70. Over 30,000 genes with e-value ≤ 10⁻4 were annotated and 14,758 of these genes were selected for inclusion on the microarray. Hepatic microarray analysis of adult female G. holbrooki exposed to the vehicle control or 1 µg/L of TB (a potent anabolic androgen) revealed 229 genes upregulated and 279 downregulated by TB (one-way ANOVA, p < 0.05, FDR α = 0.05, fold change > 1.5 and < -1.5). Fifteen gene ontology biological processes were enriched by TB exposure (Fisher's Exact Test, p < 0.05). The expression levels of 17ß-hydroxysteroid dehydrogenase 3 and zona pellucida glycoprotein 2 were validated by quantitative polymerase chain reaction (qPCR) (Student's t-test, p < 0.05). CONCLUSIONS: Coupling microarray data with phenotypic changes driven by androgen exposure in mosquitofish is key for developing this organism into a bioindicator for EDCs. Future studies using this array will enhance knowledge of the biology and toxicological response of this species. This work provides a foundation of molecular knowledge and tools that can be used to delve further into understanding the biology of G. holbrooki and how this organism can be used as a bioindicator organism for endocrine disrupting pollutants in the environment.

Petroleum hydrocarbons in semipermeable membrane devices deployed in the Northern Gulf of Mexico and Florida keys following the Deepwater Horizon incident.

The Deepwater Horizon (DWH) oil spill from April to July of 2010 contaminated Gulf of Mexico waters through release of an estimated 4.1 × 106 barrels of oil. Beginning in June of 2010, semipermeable membrane devices (SPMDs) were deployed near areas with sensitive marine habitats (Alabama Alps and Western Shelf) potentially exposed to that oil. Elevated TPAH50 concentrations, flux rates and similarity of histograms and diagnostic ratios for polycyclic aromatic hydrocarbons (PAH) from SPMDs to weathered floating oil collected during the DWH spill indicates the Alabama Alps habitats were affected. While not affected by oil from the DWH spill, the temporal pattern of PAH contamination of SPMDs deployed near the Western Shelf between July 2010 and March 2011 could indicate prevailing currents affected contaminant transport to the Western Shelf Area (East and West Flower Garden, Sonnier, and Stetson Banks) from non-DWH sources, including oil and gas exploration, shipping, and Mississippi River effluent.

Uptake and toxicity of clothianidin to monarch butterflies from milkweed consumption.

Recent concern for the adverse effects from neonicotinoid insecticides has centered on risk for insect pollinators in general and bees specifically. However, natural resource managers are also concerned about the risk of neonicotinoids to conservation efforts for the monarch butterfly (Danaus plexippus) and need additional data to help estimate risk for wild monarch butterflies exposed to those insecticides. In the present study, monarch butterfly larvae were exposed in the laboratory to clothianidin via contaminated milkweed plants from hatch until pupation, and the effects upon larval survival, larval growth, pupation success, and adult size were measured. Soils dosed with a granular insecticide product led to mean clothianidin concentrations of 10.8-2,193 ng/g in milkweed leaves and 5.8-58.0 ng/g in larvae. Treatment of soils also led to clothianidin concentrations of 2.6-5.1 ng/g in adult butterflies indicating potential for transfer of systemic insecticides from the soil through plants and larvae to adult butterflies. Estimated LC50s for total mortality (combined mortality of larvae and pupae) and EC50 for larval growth were variable but higher than the majority of concentrations reported in the literature for clothianidin contamination of leaves.

Copper desorption in flooded agricultural soils and toxicity to the Florida apple snail (Pomacea paludosa): implications in Everglades restoration.

Copper (Cu) desorption and toxicity to the Florida apple snail were investigated from soils obtained from agricultural sites acquired under the Comprehensive Everglades Restoration Plan. Copper concentrations in 11 flooded soils ranged from 5 to 234 mg/kg on day 0 and from 6.2 to 204 mg/kg on day 28 (steady-state). The steady-state Cu concentration in overlying water ranged from 9.1 to 308.2 microg/L. In a 28-d growth study, high mortality in snails occurred within 9 to 16 d in two of three soil treatments tested. Growth of apple snails over 28 d was affected by Cu in these two treatments. Tissue Cu concentrations by day 14 were 12-23-fold higher in snails exposed to the three soil treatments compared to controls. The endangered Florida snail kite and its main food source, the Florida apple snail, may be at risk from Cu exposure in these managed agricultural soil-water ecosystems.

Management of Arthropod Pathogen Vectors in North America: Minimizing Adverse Effects on Pollinators.

Tick and mosquito management is important to public health protection. At the same time, growing concerns about declines of pollinator species raise the question of whether vector control practices might affect pollinator populations. We report the results of a task force of the North American Pollinator Protection Campaign (NAPPC) that examined potential effects of vector management practices on pollinators, and how these programs could be adjusted to minimize negative effects on pollinating species. The main types of vector control practices that might affect pollinators are landscape manipulation, biocontrol, and pesticide applications. Some current practices already minimize effects of vector control on pollinators (e.g., short-lived pesticides and application-targeting technologies). Nontarget effects can be further diminished by taking pollinator protection into account in the planning stages of vector management programs. Effects of vector control on pollinator species often depend on specific local conditions (e.g., proximity of locations with abundant vectors to concentrations of floral resources), so planning is most effective when it includes collaborations of local vector management professionals with local experts on pollinators. Interventions can then be designed to avoid pollinators (e.g., targeting applications to avoid blooming times and pollinator nesting habitats), while still optimizing public health protection. Research on efficient targeting of interventions, and on effects on pollinators of emerging technologies, will help mitigate potential deleterious effects on pollinators in future management programs. In particular, models that can predict effects of integrated pest management on vector-borne pathogen transmission, along with effects on pollinator populations, would be useful for collaborative decision-making.

Baseline aquatic contamination and endocrine status in a resident fish of Biscayne National Park.

Surface water, sediment, and fish from Biscayne Bay, coastal wetlands adjacent to the Bay, and canals discharging into the Bay were sampled for determination of baseline contamination in Biscayne National Park. While the number of contaminants detected in canal waters was greater during the wet season than the dry season, no seasonal difference was evident for Biscayne Bay or coastal wetland waters. Estrogen equivalency (as 17ß-estradiol equivalents), as predicted by the Yeast Estrogen Screen, for extracts of passive water samplers deployed in canals and wetlands was elevated during the wet relative to the dry season. Generally, contamination in water, sediments, and fish was greater in the canals than in Biscayne Bay and the wetlands. Guideline levels for sediment contaminant were exceeded most frequently in canals relative to the coastal wetlands and the Bay. Further investigation is necessary to better understand the impact of contaminants in Biscayne National Park.

Synthetic ultraviolet light filtering chemical contamination of coastal waters of Virgin Islands national park, St. John, U.S. Virgin Islands.

Contamination of surface waters by synthetic ultraviolet light (UV) filtering chemicals is a concern for the Virgin Islands National Park (VINP). Discrete water samples were collected from VINP bays to determine UV filter chemical presence in the coastal waters. Spatial distribution and the potential for partitioning between subsurface waters and the sea surface microlayer (SML) were also examined. The UV filter chemicals 4-methylbenzylidene camphor, benzophenone-3, octinoxate, homosalate, and octocrylene were detected at concentrations up to 6073 ng/L (benzophenone-3). Concentrations for benzophenone-3 and homosalate declined exponentially (r(2)=0.86 to 0.98) with distance from the beach. Limited data indicate that some UV filter chemicals may partition to the SML relative to the subsurface waters. Contamination of VINP coastal waters by UV filter chemicals may be a significant issue, but an improved understanding of the temporal and spatial variability of their concentrations would be necessary to better understand the risk they present.

Contaminants assessment in the coral reefs of Virgin Islands National Park and Virgin Islands Coral Reef National Monument.

Coral, fish, plankton, and detritus samples were collected from coral reefs in Virgin Islands National Park (VIIS) and Virgin Islands Coral Reef National Monument (VICR) to assess existing contamination levels. Passive water sampling using polar organic chemical integrative samplers (POCIS) and semi-permeable membrane devices found a few emerging pollutants of concern (DEET and galaxolide) and polynuclear aromatic hydrocarbons. Very little persistent organic chemical contamination was detected in the tissue or detritus samples. Detected contaminants were at concentrations below those reported to be harmful to aquatic organisms. Extracts from the POCIS were subjected to the yeast estrogen screen (YES) to assess potential estrogenicity of the contaminant mixture. Results of the YES (estrogen equivalency of 0.17-0.31 ng/L 17-ß-estradiol) indicated a low estrogenicity likelihood for contaminants extracted from water. Findings point to low levels of polar and non-polar organic contaminants in the bays sampled within VICR and VIIS.

Risk assessment for adult butterflies exposed to the mosquito control pesticide naled.

A prospective risk assessment was conducted for adult butterflies potentially exposed to the mosquito control insecticide naled. Published acute mortality data, exposure data collected during field studies, and morphometric data (total surface area and fresh body weight) for adult butterflies were combined in a probabilistic estimate of the likelihood that adult butterfly exposure to naled following aerial applications would exceed levels associated with acute mortality. Adult butterfly exposure was estimated based on the product of (1) naled residues on samplers and (2) an exposure metric that normalized total surface area for adult butterflies to their fresh weight. The likelihood that the 10th percentile refined effect estimate for adult butterflies exposed to naled would be exceeded following aerial naled applications was 67 to 80%. The greatest risk would be for butterflies in the family Lycaenidae, and the lowest risk would be for those in the family Hesperidae, assuming equivalent sensitivity to naled. A range of potential guideline naled deposition levels is presented that, if not exceeded, would reduce the risk of adult butterfly mortality. The results for this risk assessment were compared with other risk estimates for butterflies, and the implications for adult butterflies in areas targeted by aerial naled applications are discussed.

The relationship between total cholinesterase activity and mortality in four butterfly species.

The relationship between total cholinesterase activity (TChE) and mortality in four butterfly species (great southern white [Ascia monuste], common buckeye [Junonia coenia], painted lady [Vanessa cardui], and julia butterflies [Dryas julia]) was investigated. Acute contact toxicity studies were conducted to evaluate the response (median lethal dose [LD50] and TChE) of the four species following exposure to the organophosphate insecticide naled. The LD50 for these butterflies ranged from 2.3 to 7.6 µg/g. The average level of TChE inhibition associated with significant mortality ranged from 26 to 67%, depending on the species. The lower bounds of normal TChE activity (2 standard deviations less than the average TChE for reference butterflies) ranged from 8.4 to 12.3 µM/min/g. As a percentage of the average reference TChE activity for the respective species, the lower bounds were similar to the inhibition levels associated with significant mortality, indicating there was little difference between the dose resulting in significant TChE inhibition and that resulting in mortality.

Sediment copper bioavailability to freshwater snails in south Florida: risk implications for the Everglade snail kite (Rostrhamus sociabilis plumbeus).

Many properties being acquired as part of the Comprehensive Everglades Restoration Plan (CERP) are heavily contaminated with copper. Estimated copper bioaccumulation in the Florida apple snail (Pomacea paludosa) has led to the prediction of risk to the Everglade snail kite (Rostrhamus sociabilis plumbeus) at some CERP projects. Field study results presented in this paper examine the relationship between copper levels in sediments, snails, and other biota. Copper concentrations in all biota (snails, aquatic vascular plants, and periphyton) were strongly correlated with those in sediments. No correlation with water copper concentrations was evident. Mean copper concentrations in snails ranged from 23.9 mg/kg at the reference site to 732 mg/kg at a high copper site. Calculated biota-sediment accumulation factors (BSAFs) ranged from 36.7 to 7.0 over the range of copper levels in sediments. BSAFs were highest at low copper levels in sediments and declined sharply as copper levels in sediment increased. Risk for the snail kite is discussed in light of the results of this study.

Chorioallantoic membranes indicate avian exposure and biomarker responses to environmental contaminants: a laboratory study with White Leghorn chickens (Gallus domesticus).

PCB and endosulfan concentrations in the chorioallantoic membrane (CAM) of white leghorn chickens (Gallus domesticus) were evaluated as indicators of hepatic cytochrome P450 isozyme activity in hens and chicks as well as toxicant concentrations in eggs and hens. Sixteen hens were randomly divided into four groups of four and dosed with a mixture of PCB105 (2,3,3',4,4'-pentachlorobiphenyl), PCB156(2,3,3',4,4',5-hexachlorobiphenyl), PCB189 (2,3,3',4,4',5,5'-heptachlorobiphenyl), and technical grade endosulfan (3:1 ratio of alpha and beta isomers) at three different dose groups. The first 10 fertile eggs laid by each hen were collected, the even-numbered eggs incubated until hatched, and the odd numbered eggs were analyzed for test chemicals. Strong (r2), significantly positive (p value) relationships were found between total PCB mass (ng) in CAMs and both total PCB concentrations (ng/g wet wt) in adults (r2 = 0.91, p = 0.0001) and eggs (r2 = 0.87, p = 0.0001). The relationship between total PCB mass in CAMs and hepatic cytochrome p450 isozyme activity in chicks (r2 = 0.49, p = 0.0001) and hens (r2 = 0.45, p = 0.014) was also significant but not as strong. This study shows that CAMs can be used to estimate avian exposure to PCBs and resultant biological response.