Effects of Biogents Sentinel Trap Field Placement on Capture Rates of Adult Asian Tiger Mosquitoes,Aedes albopictus

The Biogents® Sentinel (BGS) trap is the standard tool to monitor adult Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae), the Asian tiger mosquito. BGS traps are commonly placed in residential properties during surveillance operations, but locations within properties may have significant differences in ambient light, temperature, and humidity (e.g. between a sunlit lawn and shady underbrush). We examined the effect of BGS trap placement on Ae. albopictus capture rates in three residential properties in Monmouth County, New Jersey, USA. In each property we visually selected locations as shade, partial shade, and sun. Traps in “partial shade” locations were under vegetation and were exposed to filtered sunlight during some parts of the day while “shaded” locations were never exposed to direct sunlight. Locations defined as “sun” were exposed to direct sunlight for large parts of the day. We placed a BGS trap in each of the three location types and used small data loggers to measure temperature, relative humidity, and light exposure at each trap during a 24-hour deployment. To address temporal variability, we made seven separate measurements from 31 August to 22 September 2010. We found that “partial shade” and “full shade” locations did not differ but that “full sun” locations had significantly higher light exposure, higher temperature, and lower humidity. Importantly, Ae. albopictus catches (males, females, or both) were consistently and significantly over 3 times higher in traps located in shaded locations. To further investigate the effects of local temperature and humidity on surveillance we examined Ae. albopictus collections from 37 BGS traps fitted with data loggers and deployed weekly from August through mid October, during the 2009 season, in three urban sites in Mercer County, NJ. We confirmed that local climate influences capture rates and that Ae. albopictus surveillance projects need to monitor trap placement carefully for maximum efficiency.     

Significance of enhancement for calculations based on the action spectrum for photosynthesis

Calculations of the errors involved in measuring “photo-synthetically active radiation” in different ways are based on the assumption that the photosynthetic rate of a leaf in “white” light is equal to the sum of the products of (a) the photo-synthetic rate per unit of incident energy flux (action spectrum) by (b) the spectral energy flux distribution of the white light, the products being summed over all wavelengths at which the action spectrum is greater than zero. The calculations are valid only if the effects of different wavelengths are independent and additive. Although interactions are well documented in photo-synthesis (“enhancement”), tests showed that the photosynthetic rates of leaves of six species, in four different types of white light, were within ±7% of the rates calculated in this way.     

The role of light-harvesting complex I in excitation energy transfer from LHCII to photosystem I in Arabidopsis

Photosynthesis powers nearly all life on Earth. Light absorbed by photosystems drives the conversion of water and carbon dioxide into sugars. In plants, photosystem I (PSI) and photosystem II (PSII) work in series to drive the electron transport from water to NADP⁺. As both photosystems largely work in series, a balanced excitation pressure is required for optimal photosynthetic performance. Both photosystems are composed of a core and light-harvesting complexes (LHCI) for PSI and LHCII for PSII. When the light conditions favor the excitation of one photosystem over the other, a mobile pool of trimeric LHCII moves between both photosystems thus tuning their antenna cross-section in a process called state transitions. When PSII is overexcited multiple LHCIIs can associate with PSI. A trimeric LHCII binds to PSI at the PsaH/L/O site to form a well-characterized PSI–LHCI–LHCII supercomplex. The binding site(s) of the “additional” LHCII is still unclear, although a mediating role for LHCI has been proposed. In this work, we measured the PSI antenna size and trapping kinetics of photosynthetic membranes from Arabidopsis (Arabidopsis thaliana) plants. Membranes from wild-type (WT) plants were compared to those of the ΔLhca mutant that completely lacks the LHCI antenna. The results showed that “additional” LHCII complexes can transfer energy directly to the PSI core in the absence of LHCI. However, the transfer is about two times faster and therefore more efficient, when LHCI is present. This suggests LHCI mediates excitation energy transfer from loosely bound LHCII to PSI in WT plants.

The light-harvesting antennae of photosystem I facilitate energy transfer from trimeric light-harvesting complex II to photosystem I in the stroma lamellae membrane.     

Picosecond Time-Resolved Fluorescence from Detergent-Free Photosystem I Particles

Picosecond time-resolved fluorescence measurements have been taken on a detergent-free P700-enriched complex at room temperature isolated from the blue-green alga Phormidium luridum with a chlorophyll a to reaction center ratio of 100. Emission at greater than 665 nm is characterized by two exponential-decay components. A fast component, which dominates the initial decay with an average lifetime of 16 ps and 87% amplitude, is attributed to excitations in the core antenna chlorophyll-proteins, which are rapidly trapped by the primary electron donor, P700. A second component, with an average lifetime of 106 ps and 13% amplitude, is attributed to the peripheral antenna proteins. For 532-nm, 30-ps pulse excitation the results are virtually independent of fluence in the range of 2 × 10¹² to 4 × 10¹⁶ photons/cm² and the oxidation state of P700. Addition of sodium dodecyl sulfate to 0.1% causes the second component's lifetime to increase by an average of a factor of 2.5. Only minor changes are observed in the first component's lifetime and the relative amplitudes of the two components. Two fractions isolated from the detergent-treated samples have also been examined. Our results indicate that excitation energy transfer within photosystem I is very efficient and that the excitation kinetics of the antennae may be limited by the trapping rate of P700 or strongly affected by the heterogeneity of the antennae.     

Relative Humidity and the Killing of Bacteria: The Survival of Damp Serratia marcescens in Air

The viability of washed moist cells of Serratia marcescens after storage has been measured in relation to variations in the prior treatment of the cells and in conditions of storage. The factors considered were: (i) water content during storage; (ii) method of arriving at water content (partial drying in vacuum or freeze-drying and addition of water); (iii) presence or absence of air during storage.

Increasingly rapid decay occurs as the water content at which the cells are stored is diminished from above 90% to 20 or 30% (“critical” water content). It occurs in presence or absence of air and it occurs whether the final water content is approached by removal of water from wet cells or by addition of water to freeze-dried cells.

The rate of decay during storage at 20 to 30% water is somewhat diminished by the presence of air (“protective” effect of air).

As the water content is further reduced to less than 10%, the stability of cells stored in a vacuum approaches that of wet cells. In presence of air the reverse is true: the stability decreases until at less than 1% water, the decay rate is about as great as at the “critical” water content (“toxic” effect of air).

Particularly rapid decay of S. marcescens at the “critical” water content has escaped attention in aerosol studies because accurate control of relative humidity (RH) in this region, RH 94 to 99%, is virtually impossible in such studies. On the other hand, values of decay rates referred to measured water contents are quite unreliable in the 20 to 80% RH zone because the corresponding variation of water content is too small to measure reliably. Thus data of the kind reported in this paper cannot be directly compared to the published results of studies of air-borne bacteria, although they are relevant to the practical question of air-borne infection in humid atmospheres.

     

Computer Simulation of Radial Immunodiffusion: II. Selection of an Algorithm for the Antibody-Antigen Reaction in Gels

An algorithm needed for computer simulation of immunodiffusion has been deduced from existing theories of the in vitro reaction between antibody and antigen. The “Goldberg most probable polymer distribution” theory provides a formula that gives the amount of free antibody, free antigen, and diffusible complexes from extreme antibody excess through extreme antigen excess for any valences of antibody and antigen. As is shown here, that formula can be used even for those reactions producing complexes, cyclical or otherwise, that may precipitate as well as for those reactions involving heterogeneity of binding avidities. It is necessary, however, to specify an extent of reaction parameter. Five limiting expressions for this parameter are proposed as options for the basic algorithm. These are identified as: (a) the “Heidelberger-Kendall complete reaction” option, (b) the “Singer-Campbell constant avidity” option, (c) the “Hudson extensive antibody heterogeneity” option, (d) a new “extensive antigen heterogeneity” option, and (e) the “Goldberg critical extent of reaction” option. Literature data showing need for the various options are presented.     

Uncovering a Microbial Enigma: Isolation and Characterization of the Streamer-Generating,Iron-Oxidizing,Acidophilic Bacterium “Ferrovum myxofaciens”

A betaproteobacterium, shown by molecular techniques to have widespread global distribution in extremely acidic (pH 2 to 4) ferruginous mine waters and also to be a major component of “acid streamer” growths in mine-impacted water bodies, has proven to be recalcitrant to enrichment and isolation. A modified “overlay” solid medium was devised and used to isolate this bacterium from a number of mine water samples. The physiological and phylogenetic characteristics of a pure culture of an isolate from an abandoned copper mine (“Ferrovum myxofaciens” strain P3G) have been elucidated. “F. myxofaciens” is an extremely acidophilic, psychrotolerant obligate autotroph that appears to use only ferrous iron as an electron donor and oxygen as an electron acceptor. It appears to use the Calvin-Benson-Bassham pathway to fix CO₂ and is diazotrophic. It also produces copious amounts of extracellular polymeric materials that cause cells to attach to each other (and to form small streamer-like growth in vitro) and to different solid surfaces. “F. myxofaciens” can catalyze the oxidative dissolution of pyrite and, like many other acidophiles, is tolerant of many (cationic) transition metals. “F. myxofaciens” and related clone sequences form a monophyletic group within the Betaproteobacteria distantly related to classified orders, with genera of the family Nitrosomonadaceae (lithoautotrophic, ammonium-oxidizing neutrophiles) as the closest relatives. On the basis of the phylogenetic and phenotypic differences of “F. myxofaciens” and other Betaproteobacteria, a new family, “Ferrovaceae,” and order, “Ferrovales,” within the class Betaproteobacteria are proposed. “F. myxofaciens” is the first extreme acidophile to be described in the class Betaproteobacteria.     

Measurement of the fluorescence lifetime of chlorophyll a in vivo

New measurements have been made of fluorescence lifetime (τ) of chlorophyll a in the algae Chlorella pyrenoidosa, Porphyridium cruentum, Anacystis nidulans, and in spinach chloroplast. τ-values of 0.6 and 0.7 nsec were obtained with green plants. Anacystis and Porphyridium gave a τ of 0.5 nsec. The previously described two stage decay of fluorescence in vivo in these organisms could not be confirmed. This observation could have been caused by a second wave of light emission from the exciting hydrogen lamp (not detected in earlier work). The lifetimes found in this study (calculated, as before, by the method of convolution integrals) were close to those found by other observers for “low” excitation intensities; the value first reported from this laboratory (1.0-1.7 nsec) may have corresponded to “high” excitation intensity.     

Composition and Function of Thylakoid Membranes from Grana-rich and Grana-deficient Chloroplast Mutants of Barley

Chlorophyll-deficient barley (Hordeum vulgare) mutants were studied that had chlorophyll a/b ratios either higher or lower than the wild type. Mutants with high ratios (>5.2) had a reduced proportion of their photosynthetic lamellae appressed into grana (“grana-deficient” mutants) compared with wild type (chlorophyll a/b = 3.2), while the majority of lamellae in the chloroplasts with low chlorophyll a/b ratios (2.0-2.4) were organized into grana (“grana-rich” mutants).     

Ethylene Production and Respiratory Behavior of the rin Tomato Mutant

Little or no change in ethylene or CO₂ production occurred in rin tomato mutant fruits monitored for up to 120 days after harvest. Of the abnormally ripening tomatoes investigated, including “Never ripe” (Nr Y a h, Nr c l₂ r), “Evergreen” (gf r) and “Green Flesh” (gf), only rin did not show a typical climacteric and ethylene rise.     

Genome-wide association scan shows genetic variants in the FTO gene are associated with obesity-related traits

The obesity epidemic is responsible for a substantial economic burden in developed countries and is a major risk factor for type 2 diabetes and cardiovascular disease. The disease is the result not only of several environmental risk factors, but also of genetic predisposition. To take advantage of recent advances in gene-mapping technology, we executed a genome-wide association scan to identify genetic variants associated with obesity-related quantitative traits in the genetically isolated population of Sardinia. Initial analysis suggested that several SNPs in the FTO and PFKP genes were associated with increased BMI, hip circumference, and weight. Within the FTO gene, rs9930506 showed the strongest association with BMI (p = 8.6 ×10⁻⁷), hip circumference (p = 3.4 × 10⁻⁸), and weight (p = 9.1 × 10⁻⁷). In Sardinia, homozygotes for the rare “G” allele of this SNP (minor allele frequency = 0.46) were 1.3 BMI units heavier than homozygotes for the common “A” allele. Within the PFKP gene, rs6602024 showed very strong association with BMI (p = 4.9 × 10⁻⁶). Homozygotes for the rare “A” allele of this SNP (minor allele frequency = 0.12) were 1.8 BMI units heavier than homozygotes for the common “G” allele. To replicate our findings, we genotyped these two SNPs in the GenNet study. In European Americans (N = 1,496) and in Hispanic Americans (N = 839), we replicated significant association between rs9930506 in the FTO gene and BMI (p-value for meta-analysis of European American and Hispanic American follow-up samples, p = 0.001), weight (p = 0.001), and hip circumference (p = 0.0005). We did not replicate association between rs6602024 and obesity-related traits in the GenNet sample, although we found that in European Americans, Hispanic Americans, and African Americans, homozygotes for the rare “A” allele were, on average, 1.0–3.0 BMI units heavier than homozygotes for the more common “G” allele. In summary, we have completed a whole genome–association scan for three obesity-related quantitative traits and report that common genetic variants in the FTO gene are associated with substantial changes in BMI, hip circumference, and body weight. These changes could have a significant impact on the risk of obesity-related morbidity in the general population.     

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Huanglongbing (HLB), presumably caused by the bacterium “Candidatus Liberibacter asiaticus,” is a devastating citrus disease associated with excessive preharvest fruit drop. Lasiodiplodia theobromae (diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, diplodia was found in “Ca. Liberibacter asiaticus”-positive juice from HLB-symptomatic fruit (S) but not in “Ca. Liberibacter asiaticus”-negative juice. Therefore, the incidence of diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of diplodia in the AZ-C of HLB-symptomatic (S; “Ca. Liberibacter asiaticus” threshold cycle [C_T] of <30) than in the AZ-C of in asymptomatic (AS; “Ca. Liberibacter asiaticus” C_T of ≥30) fruit. In agreement with the qPCR results, 2 weeks after exposure to ethylene, the incidences of SER in S fruit were 66.7% (Hamlin) and 58.7% (Valencia), whereas for AS fruit the decay rates were 6.7% (Hamlin) and 5.3% (Valencia). Diplodia colonization of S fruit AZ-C was observed by scanning electron microscopy and confirmed by PCR test and morphology of conidia in isolates from the AZ-C after surface sterilization. Diplodia C_T values were negatively correlated with ethylene production (R = −0.838 for Hamlin; R = −0.858 for Valencia) in S fruit, and positively correlated with fruit detachment force (R = 0.855 for Hamlin; R = 0.850 for Valencia), suggesting that diplodia colonization in AZ-C may exacerbate HLB-associated preharvest fruit drop.     

The Effectiveness of Three Regions in Mitochondrial Genome for Aphid DNA Barcoding: A Case in Lachininae

Background

The mitochondrial gene COI has been widely used by taxonomists as a standard DNA barcode sequence for the identification of many animal species. However, the COI region is of limited use for identifying certain species and is not efficiently amplified by PCR in all animal taxa. To evaluate the utility of COI as a DNA barcode and to identify other barcode genes, we chose the aphid subfamily Lachninae (Hemiptera: Aphididae) as the focus of our study. We compared the results obtained using COI with two other mitochondrial genes, COII and Cytb. In addition, we propose a new method to improve the efficiency of species identification using DNA barcoding.

Methodology/Principal Findings

Three mitochondrial genes (COI, COII and Cytb) were sequenced and were used in the identification of over 80 species of Lachninae. The COI and COII genes demonstrated a greater PCR amplification efficiency than Cytb. Species identification using COII sequences had a higher frequency of success (96.9% in “best match” and 90.8% in “best close match”) and yielded lower intra- and higher interspecific genetic divergence values than the other two markers. The use of “tag barcodes” is a new approach that involves attaching a species-specific tag to the standard DNA barcode. With this method, the “barcoding overlap” can be nearly eliminated. As a result, we were able to increase the identification success rate from 83.9% to 95.2% by using COI and the “best close match” technique.

Conclusions/Significance

A COII-based identification system should be more effective in identifying lachnine species than COI or Cytb. However, the Cytb gene is an effective marker for the study of aphid population genetics due to its high sequence diversity. Furthermore, the use of “tag barcodes” can improve the accuracy of DNA barcoding identification by reducing or removing the overlap between intra- and inter-specific genetic divergence values.     

The Influence of Two Naturally Occurring Factors, from the Leaves of Ricinus Communis, on the Fluorescence Induction of Higher Plant Chloroplasts and Intact Algae

Changes in fluorescence induction, brought about by incubation of chloroplasts (Zea mays) in an aqueous extract of Ricinus leaf, have been divided, on the basis of speed of manifestation, into two categories: “fast” changes and “slow” changes (i.e. those observed after 5 min and 1½ hr of incubation, respectively). The former, which include a large increase in the magnitude of the fast component of variable fluorescence and a retardation of decay from maximum to minimum levels of fluorescence, have been ascribed to inhibition of electron transport at a site beyond that of 3-(p-chlorophenyl)-1,1-dimethylurea (CMU)—i.e., towards system I; these changes result from the action of a fraction of the extract consisting of molecules of small size. The latter changes, which include a marked attenuation of the variable part of fluorescence induction, have been associated with system II and may arise from inhibition of electron flow between water and Q or from decrease in number of functional reaction centers; these changes result from the activity of a proteinaceous fraction of the extract, that simultaneously converts the low temperature steady-state emission spectrum of the chloroplasts into a one-banded one, with maximum at 698 nm.     

M tuberculosis in the Adjuvant Modulates Time of Appearance of CNS-Specific Effector T Cells in the Spleen through a Polymorphic Site of TLR2

DC deliver information regulating trafficking of effector T cells along T-cell priming. However, the role of pathogen-derived motives in the regulation of movement of T cells has not been studied. We hereinafter report that amount of M tuberculosis in the adjuvant modulates relocation of PLP139-151 specific T cells. In the presence of a low dose of M tuberculosis in the adjuvant, T cells (detected by CDR3 BV-BJ spectratyping, the so-called “immunoscope”) mostly reach the spleen by day 28 after immunization (“late relocation”) in the SJL strain, whereas T cells reach the spleen by d 14 with a high dose of M tuberculosis (“early relocation”). The C57Bl/6 background confers a dominant “early relocation” phenotype to F1 (SJL×C57Bl/6) mice, allowing early relocation of T cells in the presence of low dose M tuberculosis. A single non-synonymous polymorphism of TLR2 is responsible for “early/late” relocation phenotype. Egress of T lymphocytes is regulated by TLR2 expressed on T cells. Thus, pathogens engaging TLR2 on T cells regulate directly T-cell trafficking, and polymorphisms of TLR2 condition T-cell trafficking upon a limiting concentration of ligand.     

Energy trapping and detrapping by wild type and mutant reaction centers of purple non-sulfur bacteria

Time-correlated single photon counting was used to study energy trapping and detrapping kinetics at 295 K in Rhodobacter sphaeroides chromatophore membranes containing mutant reaction centers. The mutant reaction centers were expressed in a background strain of Rb. sphaeroides which contained only B880 antenna complexes and no B800-850 antenna complexes. The excited state decay times in the isolated reaction centers from these strains were previously shown to vary by roughly 15-fold, from 3.4 to 52 ps, due to differences in the charge separation rates in the different mutants (Allen and Williams (1995) J Bioenerg Biomembr 27: 275–283). In this study, measurements were also performed on wild type Rhodospirillum rubrum and Rb. sphaeroides B880 antenna-only mutant chromatophores for comparison. The emission kinetics in membranes containing mutant reaction centers was complex. The experimental data were analyzed in terms of a kinetic model that involved fast excitation migration between antenna complexes followed by reversible energy transfer to the reaction center and charge separation. Three emission time constants were identified by fitting the data to a sum of exponential decay components. They were assigned to trapping/quenching of antenna excitations by the reaction center, recombination of the P⁺H^– charge-separated state of the reaction center reforming an emitting state, and emission from uncoupled antenna pigment-protein complexes. The first varied from 60 to 160 ps, depending on the reaction center mutation; the second was 200–300 ps, and the third was about 700 ps. The observed weak linear dependence of the trapping time on the primary charge separation time, together with the known sub-picosecond exciton migration time within the antenna, supports the concept that it is energy transfer from the antenna to the reaction center, rather than charge separation, that limits the overall energy trapping time in wild type chromatophores. The component due to charge recombination reforming the excited state is minor in wild type membranes, but increases substantially in mutants due to the decreasing free energy gap between the states P^* and P⁺H^–.Abbreviations PSU photosynthetic unit - Bchl bacteriochlorophyll - Bphe bacteriopheophytin - P reaction center primary electron donor - RC reaction center - Rb. Rhodobacter - Rs. Rhodospirillum - EDTA (ethylenediamine)tetraacetic acid - Tris tris(hydroxymethyl)aminomethane Author for correspondence     

Impact of Land Use Intensity on the Species Diversity of Arbuscular Mycorrhizal Fungi in Agroecosystems of Central Europe

The impact of land use intensity on the diversity of arbuscular mycorrhizal fungi (AMF) was investigated at eight sites in the “three-country corner” of France, Germany, and Switzerland. Three sites were low-input, species-rich grasslands. Two sites represented low- to moderate-input farming with a 7-year crop rotation, and three sites represented high-input continuous maize monocropping. Representative soil samples were taken, and the AMF spores present were morphologically identified and counted. The same soil samples also served as inocula for “AMF trap cultures” with Plantago lanceolata, Trifolium pratense, and Lolium perenne. These trap cultures were established in pots in a greenhouse, and AMF root colonization and spore formation were monitored over 8 months. For the field samples, the numbers of AMF spores and species were highest in the grasslands, lower in the low- and moderate-input arable lands, and lowest in the lands with intensive continuous maize monocropping. Some AMF species occurred at all sites (“generalists”); most of them were prevalent in the intensively managed arable lands. Many other species, particularly those forming sporocarps, appeared to be specialists for grasslands. Only a few species were specialized on the arable lands with crop rotation, and only one species was restricted to the high-input maize sites. In the trap culture experiment, the rate of root colonization by AMF was highest with inocula from the permanent grasslands and lowest with those from the high-input monocropping sites. In contrast, AMF spore formation was slowest with the former inocula and fastest with the latter inocula. In conclusion, the increased land use intensity was correlated with a decrease in AMF species richness and with a preferential selection of species that colonized roots slowly but formed spores rapidly.     

A linkage analysis toolkit for studying allosteric networks in ion channels

A thermodynamic approach to studying allosterically regulated ion channels such as the large-conductance voltage- and Ca²⁺-dependent (BK) channel is presented, drawing from principles originally introduced to describe linkage phenomena in hemoglobin. In this paper, linkage between a principal channel component and secondary elements is derived from a four-state thermodynamic cycle. One set of parallel legs in the cycle describes the “work function,” or the free energy required to activate the principal component. The second are “lever operations” activating linked elements. The experimental embodiment of this linkage cycle is a plot of work function versus secondary force, whose asymptotes are a function of the parameters (displacements and interaction energies) of an allosteric network. Two essential work functions play a role in evaluating data from voltage-clamp experiments. The first is the conductance Hill energy W_H[g], which is a “local” work function for pore activation, and is defined as kT times the Hill transform of the conductance (G-V) curve. The second is the electrical capacitance energy W_C[q], representing “global” gating charge displacement, and is equal to the product of total gating charge per channel times the first moment (V_M) of normalized capacitance (slope of Q-V curve). Plots of W_H[g] and W_C[q] versus voltage and Ca²⁺ potential can be used to measure thermodynamic parameters in a model-independent fashion of the core gating constituents (pore, voltage-sensor, and Ca²⁺-binding domain) of BK channel. The method is easily generalized for use in studying other allosterically regulated ion channels. The feasibility of performing linkage analysis from patch-clamp data were explored by simulating gating and ionic currents of a 17-particle model BK channel in response to a slow voltage ramp, which yielded interaction energies deviating from their given values in the range of 1.3 to 7.2%.     

Use of road underpasses by mammals and a monitor lizard in eastern Australia and consideration of the prey‐trap hypothesis

Road networks continue to expand globally with predictable effects on ecological systems. Research into the effectiveness of road underpasses and overpasses for wildlife has been concentrated in North America and Europe. In Australia, most studies of underpasses have been of relatively short duration and without reference sites to give context to the measured rates of use. We studied 5–7 road underpasses at two locations in eastern Australia over 2–3 years, comparing camera trap detections of animals in underpasses with those at nearby forest sites. Three species of large macropod (wallabies and kangaroos) were frequently detected in the underpasses, with some underpasses traversed 1–4 times per week, and in many cases exceeded detections in the forest. The lace monitor (Varanus varius) was detected in all underpasses, often once per week during spring and summer, and infrequently in the forest. At each location, a different small macropod species, including one regionally threatened, showed a higher probability of detection in one underpass compared with several of the forest sites. The vulnerable koala (Phascolarctos cinereus) was detected infrequently in underpasses and in the adjoining forest. The short‐beaked echidna (Tachyglossus aculeatus) had a high probability of detection in a single underpass. The “prey‐trap hypothesis” postulates that predators will exhibit increased activity at underpasses as a consequence of prey being funneled. We found the red fox (Vulpes vulpes) had high activity in some underpasses. However, its activity coincided less than expected with the activity of the mammals most at risk to it. Our results provide no consistent support for the “prey‐trap hypothesis.” Instead, our study confirms the generic value of underpasses for a range of medium‐large mammals as well as one large reptile. Habitat adjoining underpasses exert a strong influence on their use and require greater consideration to maximize underpass use.