DDT and metabolites residues in the southern bent-wing bat (Miniopterus schreibersii bassanii) of south-eastern Australia

Occurrence of persistent organic pollutants and chlorpyrifos in Tadarida brasiliensis tissues from an agricultural production area in Argentina

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) are lipophilic and persistent compounds, with chronic toxicity that cause negative effects on the environment and organisms. The chlorpyrifos is an organophosphate insecticide and represent the main insecticide currently used in many countries. The concentrations of OCPs, PCBs, and chlorpyrifos were evaluated in liver, muscle, and gonad of females and males of Tadarida brasiliensis in an agricultural production area in Argentina. Pollutants were quantified by gas chromatography with electron capture detection. The general total concentration pattern among tissues was gonad > muscle > liver, with a higher ratio of pesticides (OCPs + chlorpyrifos) over PCBs in muscle and liver, while gonads showed higher concentrations of PCBs. The predominance of DDTs and endosulfans evidences the bioavailability of these compounds despite their use has ceased. Chlorpyrifos was the main pesticide detected in almost all samples of both sexes, probably due to its current intensive use. More researches about ecology and activity patterns is paramount in order to understand more accurately the accumulation and possible negative effects of these pollutants.

Novel passive detection approach reveals low breeding season survival and apparent lactation cost in a critically endangered cave bat

Capture-mark-recapture/resight (CMR) methods are used for survival-rate studies, yet are often limited by small sample sizes. Advances in passive integrated transponder (PIT) technology have enabled passive detection or ‘resight’ of marked individuals using large antennas with greater read-ranges than previously possible. We used passively-detected resight data and CMR models to study survival rates of the southern bent-winged bat Miniopterus orianae bassanii, a critically endangered, cave-dwelling bat. Over three years, we used PIT-tagging to monitor 2966 individuals at the species’ largest breeding aggregation, using daily detection data (> 1.6 million detections) to estimate seasonal survival probabilities, structured by age, sex and reproductive status, and parameterise population projection matrices. This has hitherto been impossible using traditional CMR methods due to disturbance risk and low recapture rates. Bats exhibited lowest apparent seasonal survival over summer and autumn, particularly for reproductive females in summer (when lactating) and juveniles in autumn (after weaning), and high survival in winter. Lowest survival rates coincided with severe drought in summer–autumn 2016, suggesting that dry conditions affect population viability. Under all likely demographic assumptions, population projection matrices suggested the population is in deterministic decline, requiring urgent action to reduce extinction risk. Passively-collected resight data can now be used in combination with CMR models to provide extensive, robust information for targeted wildlife population management.

Exposure to pesticides in bats

Bats provide a variety of ecological services that are essential to the integrity of ecosystems. Indiscriminate use of pesticides has been a threat to biodiversity, and the exposure of bats to these xenobiotics is a threat to their populations. This study presents a review of articles regarding the exposure of bats to pesticides published in the period from January 1951 to July 2020, addressing the temporal and geographical distribution of research, the studied species, and the most studied classes of pesticides. The research was concentrated in the 1970s and 1980s, mostly in the Northern Hemisphere, mainly in the USA. Of the total species in the world, only 5% of them have been studied, evaluating predominantly insectivorous species of the Family Vespertilionidae. Insecticides, mainly organochlorines, were the most studied pesticides. Most research was observational, with little information available on the effects of pesticides on natural bat populations. Despite the advances in analytical techniques for detecting contaminants, the number of studies is still insufficient compared to the number of active ingredients used. The effects of pesticides on other guilds and tropical species remain poorly studied. Future research should investigate the effects of pesticides, especially in sublethal doses causing chronic exposure. It is crucial to assess the impact of these substances on other food guilds and investigate how natural populations respond to the exposure to mixtures of pesticides found in the environment.

Polychromophilus melanipherus and haemoplasma infections not associated with clinical signs in southern bent-winged bats (Miniopterus orianae bassanii) and eastern bent-winged bats (Miniopterus orianae oceanensis)

While bats are often viewed as carriers of infectious disease agents, little research has been conducted on the effects these pathogens may have on the bat populations themselves. The southern bent-winged bat (Miniopterus orianae bassanii) is a critically endangered subspecies endemic to south-eastern Australia. Population numbers of this bat have declined over the past 50 years, but the reasons for this are unclear. As part of a larger study to determine if disease could be a contributing factor to this decline, southern bent-winged bats from several locations in Victoria and South Australia were captured and examined for the presence of the blood parasite, Polychromophilus melanipherus, and haemoplasmas (Mycoplasma sp.). Results were compared with those obtained from populations of the more common, partially sympatric, eastern bent-winged bat (Miniopterus orianae oceanensis) from three different locations in Victoria. Both organisms were found in both subspecies (prevalence of P. melanipherus 60% by PCR for southern bent-winged bats compared with 46% for eastern bent-winged bats; prevalence of haemoplasmas 10% for southern bent-winged bats compared with 8% for eastern bent-winged bats), with no association between the probability of infection, body weight, abnormal blood parameters or any other indicators of ill health. However, Victorian southern bent-winged bats had heavier burdens of P. melanipherus than both the South Australian southern bent-winged bats and eastern bent-winged bats. Further investigations are required to determine if these differences are impacting population health.

Dietary Exposure to Tebuconazole Affects Testicular and Epididymal Histomorphometry in Frugivorous Bats

This study evaluated the effects of a commercially recommended concentration (1 mL/L) of a fungicide tebuconazole (TBZ) on testicular and epididymal histomorphometry of Artibeus lituratus, following 7 and 30-day oral exposure. TBZ30 bats showed a reduction in the percentage of tubules and seminiferous epithelium, as well as a decrease in tubule and epithelium somatic indexes, and tubular diameter. Inversely, these animals showed increased percentage of intertubular compartment, Leydig cells and blood vessels. The volume of Leydig cells and their number per gram of testis also increased in TBZ30 bats. Alterations in epididymal morphometry were observed in all regions of the organ, with increase of ductal diameter in both exposure times. These results indicate that exposure to low concentration of TBZ resulted in testicular and epididymal morphometric changes in fruit bats, mainly at 30-day exposure, suggesting that functional alterations might be occurring in these organs and impacting reproductive capacity.

Effect of landscape tree cover, sex and season on the bioaccumulation of persistent organochlorine pesticides in fruit bats of riparian corridors in eastern Mexico

Riparian forests are recognized as important ecosystems for biodiversity conservation in transformed landscapes. Many animal species that use this type of vegetation facilitate its recovery through pollination and seed dispersal. In landscapes dominated by agrosystems and cattle ranching, persistent organochlorine pesticides (OCPs) in the riparian system may have an effect on the physiology and fitness of animals. In this study, we measured bioaccumulation of OCPs in the most abundant frugivorous bat, Sturnira hondurensis, from the upper part of La Antigua basin, Veracruz, Mexico and, from these data, estimated accumulation by the frugivorous bat community of riparian forests in contrasting, transformed (TL) and forested (FL) landscapes. Concentration of ΣDDT, Σdrines, Σclordano, ΣHCH, Σheptachlor and Σendosulfan was measured by gas-chromatography in 23 female and 33 male adult Sturnira captured during the dry and rainy seasons. Using censored data statistics, we found that the sex of the individual was significant for ΣHCH, and that interactions of landscape type (TL vs. FL) and season (dry vs. wet), and sex and season were significant for Σendosulfan and Σdrines, respectively. Mean ΣDDT (6.86 μg/g) and ΣHCH (28.22 μg/g) concentrations were lower than those reported for frugivorous bats in India but concentrations of Σdrines (13.86 μg/g) were higher than those reported in insectivorous bats. In our study sites, frugivorous bats are bioaccumulating higher amounts of OCPs in TL than in FL. We discuss the potential of this species as a bio-indicator of OCPs contamination in river basins.

Organic contaminants in bats: trends and new issues

Exposure to contaminants, often pesticides, has been implicated as a major factor contributing to decreases in bat populations. Bats provide essential ecosystem services and a sustained, thriving population is vital for ecosystem health. Understanding issues threatening their survival is crucial for their protection and conservation. This paper provides the first review for 12years on organic pollutants in bats and aims to investigate trends and any new issues impacting bat resilience. Organochlorine (OC) pesticides have been reported most often, especially in the older literature, with the dichlorodiphenyltrichloroethane (DDT) metabolite, dichlorodiphenyldichloroethylene (DDE), present at highest concentrations in tissues analyzed. The OC pesticide concentrations reported in bat tissues have declined significantly since the late 1970s, presumably as a result of restrictions in use. For example, DDE study mean concentrations over time periods 1970-1980, 1981-1999 and 2000-2013 ranged from 2.6-62, 0.05-2.31, 0.08-0.19ppm wet weight, respectively. Exposure, however, still occurs from remaining residues, many years after the compounds have been actively used. In recent years (2000-2013), a range of other organic chemicals have been reported in bat tissues including brominated flame retardants (polybrominated diphenyl ether at a mean concentration of 2.9ppm lipid weight) and perfluorinated compounds (perfluorooctanyl sulfonate at a mean concentration 0.09ppm wet weight). The persistent organic compounds concentrate in tissues with higher fat content notably back-depot fat. Numerous factors influence exposure, residues detected and concentrations in different individuals, species and tissues which must be understood to provide meaningful assessment of the impacts of exposure. Exposure can lead to not only acute and lethal impacts, but also physiological sub-lethal and chronic effects, often linked to the annual cycle of fat deposition and withdrawal. Current challenges for bat conservation include collation of a more extensive and standardized database of bat exposure, especially to current use pesticides and emerging contaminants, and better prediction and definition of toxicity end points notably for the sub-lethal effects. Understanding sub-lethal effects will be of greater importance for sustaining populations in the longer-term.

Short-term effects of a spinosyn's family insecticide on energy metabolism and liver morphology in frugivorous bats Artibeus lituratus (Olfers, 1818)

A new class of insecticide derived from fermentation of Sacharopolyspora spinosa - spinosad, has been indicated as being of low toxicity and a natural alternative to classical pesticides. In order to elucidate several aspects related to the morphophysiological changes induced by spinosad in Artibeus lituratus, the effects of a seven-day administration on plasma glucose, glycogen, protein and lipid concentrations were evaluated, and possible changes in liver cells were examined by histological analysis. Animals were fed with spinosyn-contaminated fruit through immersion in a solution. Data reporting on metabolism revealed a decrease in hind limb muscle lipid concentration in the treated group. Morphological analysis indicated a significant increase in liver cell diameter in treated animals compared to the control group. This study indicates that spinosyn, used at its recommended dose, does not affect general energy metabolism in A. lituratus but may affect some ultrastructural characteristics of liver cells.

Organochlorine and trace metal residues in adult southern bent-wing bat (Miniopterus schreibersii bassanii) in southeastern Australia

In recent times, the apparent population decline of the southern bent-wing bat (Miniopterus schreibersii bassanii) at Bat Cave, Naracoorte has been ascribed to pesticide use in the region, following the finding of organochlorine and orgaonophosphate insecticide residues in bat guano. Adult southern bent-wing bats were collected from Bat Cave and Starlight Cave in 2003. Organochlorine contaminants were detected in all carcass samples: p,p'-DDE was by far the most dominant contaminant with concentrations ranging from 11,000 to 59,000ngg(-1), followed by p,p'-DDT (110-1600ngg(-1)), p,p'-DDD (35-620ngg(-1)), summation operatorPCBs (33-490ngg(-1)), summation operatorchlordane and related compounds (7.9-270ngg(-1)), HCB (1.6-120ngg(-1)), HP epox. (3.1-230ngg(-1)), TCPMOH (3.8-38ngg(-1)), summation operatorHCHs (1.4-9.6ngg(-1)), and TCPMe (0.1-4.2ngg(-1)) (all values on lipid-weight basis). No significant difference in DDE, DDD, DDT, summation operatorDDT, summation operatorPCB, trans-chlordane, heptachlor epoxide, trans-nonachlor, alpha-HCH, beta-HCH, gamma-HCH, TCPMOH or TCPMe concentrations were observed either between sexes within sites, or between sites (p>0.05). However, there were significant differences in HCB and oxychlordane concentrations between sexes and between sites (p<0.05), between site differences in cis-nonachlor concentrations in male bats (p<0.05), and cis-chlordane concentrations between sexes at Starlight Cave, and between males of each site (p<0.05). There were also significant differences in the liver concentrations of some metals between sexes within sites (Ag, Cd, Co, Cu, Pb, Se, Zn), and between sites (Ag, Cd, Co, Cu, Hg, Pb, Se, V, Zn). Clustering or grouping of sites was observed when the OC data was expressed on a lipid-weight basis. These inter-site differences in OC concentrations reflect local exposure over a period of time, and do not unambiguously support any suggestion that we are witnessing incipient speciation. However, for conservation purposes, it may be prudent to assume that there are two sub-populations of M. s. bassani feeding in different locations in this region of southern Australia, rather than the single homogeneous population suggested by genetic studies.