Trap Capture Research Articles

Capacitance Spectroscopy of Light Induced Trap States in Organic Solar Cells

The light-induced localized trap state density of states in organic bulk heterojunction solar cells is reported, based on capacitance–frequency and photocurrent spectroscopy measurements. Several different cell materials show qualitatively the same behavior. A deep trap is induced by prolonged white light illumination with state density of 1016–1017 cm–3 and is observed by both experimental techniques. The trap depth is 0.5–0.7 eV. The light soaking has no measurable effect on the localized band tail density of states. The observation of the effect in many materials is consistent with the model that traps are created by light-induced dissociation of C–H bonds. The data suggests that disorder enhances the trap creation. The data also allow an estimate of the trap capture cross section, which is discussed in terms of local transport anisotropy.

The Active Space of Mexican Rice Borer Pheromone Traps.

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive pest of sugarcane, Saccharum spp., rice, Oryza sativa L., and other graminaceous crops in the United States. Traps baited with the synthetic female sex pheromone of E. loftini are used for monitoring and management of this invasive pest. However, the active space, or radius of attraction, of these traps is not known. Two field experiments examined the effect of intertrap distance on trap captures with hexagonal arrays of traps deployed in rice stubble habitat in Texas (2011) and Louisiana (2013). Trap capture increased with increasing intertrap distance. Trap interference occurred at intertrap distances ≤50m in the 2011 experiment. Results from the experiment conducted in 2013 indicate that trap interference occurs at intertrap distances of 50m, but not at distances ≥100m. These results suggest that under field conditions, E. loftini pheromone traps attract males from distances of 50-100m. The active space of pheromone traps also was examined under controlled wind conditions by direct observation of male response to detection of the female sex pheromone. Eoreuma loftini males responded to the pheromone blend by becoming active, fanning their wings, and rapidly walking in circles. The mean distance from the pheromone source at which males responded was 47.6m. This work provides the first documentation of active space for traps baited with female sex pheromone for a crambid species, and these data will improve pheromone trap deployment strategies for E. loftini monitoring and management.

Significantly improved breakdown performances of propylene carbonate‐based nano‐fluids

It is found that propylene carbonate (PC)-based nano-fluids (NFs) exhibit substantially larger breakdown voltages and higher breakdown stabilities than that of pure PC when they contain various nano-particles with different conductivity and permittivity. However, both the fast electron scavenging model and the potential well model fail to explain these experimental phenomena rationally. It is proposed that the interaction region between nano-particles and PC will create myriad trap sites and capture electric charge carriers effectively. Therefore, the trapped and accumulated homo-charges can weaken the electric field intensity, increase the charge injection barrier height and reduce further charge injection in the vicinity of electrodes. This is the main physical mechanism for the enhanced dielectric performances of PC-based NFs.

Time evolution of secondary electron emission and trapped charge accumulation in polyimide film under various primary electron irradiation currents

Time-resolved evolution of secondary electron emission and trapped charge accumulation in polyimide film is investigated during two interval electrons bombardment, derived from the measurement of displacement current and secondary current via a hemispherical detector with the shielded grid. Under various irradiation current, secondary electron yield (SEY σ) at a certain injected energy decreases exponentially from initial amplitude σ0 to self-consistent steady value σ∞ close to 0.93. The time constant τ of charging process is characterized as a function of incident current Ip, and the results indicate that the formula Ip×τ is fitted by a hyperbolical law. The influence of Ip on the amount of trapped charge is studied and no significant change in its saturation value is observed. The evolution of SEY σ and trapped charge is dependent on incident dose Qp but not the incident rate Ip. Furthermore, the trap density and capture cross section are discussed.

Diurnal Activities of the Brown Stink Bug (Hemiptera: Pentatomidae) in and near Tasseling Corn Fields

Abstract The demand for effective management of the brown stink bug, Euschistus servus (Say), in corn and other crops has been increasing in recent years. To identify when and where the stink bugs are most likely to occur for targeted insecticide application, diurnal activities of stink bugs in and near the fields of tasseling corn plants were monitored using pheromone traps. Trap capture of the brown stink bugs in the corn field showed that the number of females was greater at corn field edges than in the interior, but there was no difference in male capture between the edge and interior. Stink bug dispersal within corn fields was further monitored using a mark–release–recapture technique, but the technique was not effective because only one of 158 marked individuals was recovered in the pheromone trap. To further understand the movement pattern among host plants, brown stink bugs were monitored continuously for 6 d near the tasseling corn fields using the pheromone traps. The number of females caught i...

Effects of the spatial repellent metofluthrin on landing rates of outdoor biting anophelines in Cambodia, Southeast Asia.

The emergence of artemisinin-resistant malaria in Southeast Asia is a major problem. The fact that many people become infected with malaria when they are outside has prompted the development of 'spatial' rather than topical repellents. The respective effects of one or four slow-release emanators of metofluthrin, a pyrethroid, were tested in Pailin, Pursat and Koh Kong, Cambodia. Numbers of mosquitoes counted in outdoor landing catches when one or four emanators were suspended close to the collector were compared with control collections. In Pailin, the effects of emanators on catches in Furvela tent traps and Centers for Disease Control (CDC) light traps suspended underneath houses were also investigated. Rate ratios were used to determine differences. A total of 29 255 mosquitoes were collected over 2934 h of landing collections, 87 nights of tent trapping and 81 nights of light trap capture. In Pailin, landing rates were reduced by 48% by a single emanator and by 67% by four emanators (P < 0.001). Similar reductions were observed in the number of mosquitoes collected in tent traps and the number of anophelines only collected in light traps. Results were similar in Pursat, but, for unknown reasons, those in Koh Kong showed no difference between control and metofluthrin collections (P > 0.05). These findings suggest that although the product can produce a significant effect, it requires further improvement.

To Catch a Fly: Landing and Capture of Ceratitis capitata in a Jackson Trap with and without an Insecticide.

Attractant-based traps are a cornerstone of detection, delimitation and eradication programs for pests such as tephritid fruit flies. The ideal trap and lure combination has high attraction (it brings insects to the trap from a distance) and high capture efficiency (it has a high probability of capturing the insect once it arrives at the trap). We examined the effect of an insecticide (DDVP) in combination with a pheromone lure (trimedlure) on capture of Ceratitis capitata using 1) digital images of surfaces of a Jackson trap analyzed via computer vision, and 2) counts of the number of flies caught in the trap and in the area under the trap. Our results indicate no significant difference in trap capture without or with insecticide (means ± SD = 324 ±135 and 356 ±108, respectively). However, significantly more dead flies were found around the trap with insecticide (92 ±53 with insecticide compared with 35 ±22 without), suggesting a possible decrease in trap efficiency due to mortality before insects enter the trap. Indeed, the average number of flies detected on all surfaces of the traps with insecticide was lower than that for lure-only (4.15±0.39 vs 8.30±1.18), and both were higher than control (no lure: 0.76 ±0.08). We found that the majority of fly sightings, 71% of the total, occurred on the inside panels of the lure-only traps, suggesting that increased efficiency of the Jackson trap may be obtained by adding a contact insecticide to those surfaces.

Effective monitoring of the population dynamics of Nezara viridula and Nezara antennata (Heteroptera: Pentatomidae) using a light trap in Japan

The southern green stink bug, Nezara viridula (L.), and its congeneric species, Nezara antennata Scott, are major agricultural pests in Japan. Here, I investigated seasonal trends in light trap capture rates, as well as female ovarian development of these two species from 2009 to 2014 in Kumamoto, Japan. Each year, both species first appeared in the traps in May, and large numbers were caught between July and August. Both mature and immature females were caught. For both species, ovarian development followed a similar seasonal pattern in 2009 and 2010, but the patterns differed between the species. The development of reproductive organs was similar to that in previous reports from wild populations, demonstrating the usefulness of light-trapped females in clarifying their life-history traits (e.g., the number of generations per year, the timing of oviposition, and timing of occurrence for each generation). The trap capture data of N. viridula until the end of July and its preceding winter temperatures were positively related. Thus, winter temperature is a useful predictor of the relative abundance of N. viridula in wild populations.

Temperature dependence of GaN MOS capacitor characteristics

AbstractGaN MOS capacitors on both as‐grown and dry/wet‐etched GaN surfaces are characterized by C‐V and G‐ω measurements at elevated temperatures. The nature of GaN/SiO2 interface traps are determined in detail by extracting interface trap density, surface potential fluctuation, trap time constant and capture cross‐section. When temperature increases, trap time constant decreases so that more traps become active and contribute to observed higher interface trap density, especially for traps at deeper energy levels. The deeper trap levels activated at higher temperatures also induce corresponding temperature‐dependent surface potential fluctuation variations. (© 2015 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Combining pheromone and kairomones for effective trapping of the pine sawyer beetle Monochamus galloprovincialis

AbstractMonochamus galloprovincialis (Olivier) (Coleoptera: Cerambycidae) is a secondary wood borer that acquired primordial importance since it was identified as the European vector of Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD). An effective trapping method is needed as a tool for managing this insect vector and allowing early detection of nematode transportation. Among effective attractants identified in recent years are the specific M. galloprovincialis aggregation pheromone, host pine kairomones such as α‐pinene and bark beetle kairomones like ipsenol and methyl‐butenol. The main objective of this study was to optimize the combination of these volatiles to improve lure attractiveness and specificity. Based on ten complementary field experiments, we found a pheromone dose‐response of trap catches. The best combination of attractants was the aggregation pheromone plus two bark beetle kairomones, ipsenol and methyl‐butenol. Addition of pine terpenes, such as α‐pinene, did not significantly improve M. galloprovincialis trap capture, but did increase catch of non target species, including natural enemies. The use of pine terpenes would be advisable only if priorizing to maximize removal of vectors. While this research has lead to the development a new, highly attractive commercial lure for mature pine sawyers, none of the tested blends were successful in attracting immature pine sawyer adults. Further investigation is needed to develop attractants for these beetles.

Sticky traps saturate with navel orangeworm in a nonlinear fashion

Trapping is an essential tool used to decide the need for and/or timing of an insecticide application. The assumption is that the information is accurate, but accuracy is dependent on trap reliability and efficacy. One factor that affects reliability is trap saturation, defined as the measurable decrease in trap capture due to reduced trapping effectiveness caused by the accumulation of insects already in a trap. In this study, we used unmated female navel orangeworm (NOW, Amyelois transitella (Walker)) as sex pheromone baits in wing traps that varied by color and glue/trapping surface in order to evaluate saturation thresholds and quantify trap effectiveness. Effectiveness decreased in each type of sticky trap as the number of insects caught increased, because of the accumulation of scales and insect bodies on the glue surface. The continued accumulation of insects further reduced trap capture, and this decrease in capture could be described by a regression using a power transformation. The resulting saturation equations that we calculated will help pest control advisers and growers interpret their trap data by better estimating the relationship between the number of males trapped versus those that visited the trap.

Ocelot (Leopardus pardalis) density in Eastern Ecuador based on capture–recapture analyses of camera trap data

The ocelot (Leopardus pardalis) is one of the most widespread neotropical felids but data on its distribution and population status in several countries are scarce. Here, we present estimates of density for lowland forest of eastern Ecuador. We used camera trap data and capture–recapture analyses to estimate ocelot density within a local area (~650 ha) within Yasuní Biosphere Reserve, recognized as a globally important area for biodiversity conservation. We estimated densities for dry and wet seasons (~2200 trap days total) using CAPTURE and both half and full values of the mean maximum distance moved (MMDM), as recommended for estimating densities. Estimated densities for the dry season were higher than during the wet season (dry: 41–74 ind/100 km2; wet: 32–52 ind/100 km2). Ocelots were captured more frequently at night than during the day and some individuals were captured more consistently in areas close to the Tiputini River. Density estimates for ocelots in the Yasuní region are somewhat higher than in other neotropical areas, but similar to other sites in the Amazon region. Based on the number of ocelots recorded in this relatively small study area, it is clear that the region is an important area for conservation. Further studies that take into account more complex estimates such as survival rates and migration as well as differences in growth and availability of resources could provide more evidence for the importance of this region.

A study on bloodsucking Tabanidae and Stomoxys calcitrans (Diptera) attacking horses and cows in Northern Scania, Sweden

&lt;p class="jbls"&gt;&lt;span lang="EN-US"&gt;In Sweden, during summer, grazing horses and cows are frequently exposed to bloodsucking flies. This study has been performed in the geographical areas of Gundrastorp (pasture) and Kämlehöjalt (wood pasture), in northern Scania, Sweden where the occurrences of biting flies may represent a scourge for domesticated animals. The distribution of biting flies, Tabanidae and &lt;em&gt;Stomoxys calcitrans&lt;/em&gt; (L) (known as stable flies) was studied by insect trapping using two Nzi traps, one for each habitat. No attractants have been used in order to improve trap capture rate. This research pointed out that tabanid and stable flies did not show any preference between the two landscape types or between hosts where they get their blood meal. Capture rates increased on days with high temperature. There were also differences in number between all types of weather for both tabanid and stable flies. In terms of species activity in all types of weather, 13 species of Tabanidae displayed some differences between them in each habitat. In the genus Tabanus, &lt;em&gt;Tabanus bromius&lt;/em&gt; and &lt;em&gt;Tabanus maculicornis&lt;/em&gt; showed similar patterns with regards to daily activity in different types of weather, being followed by &lt;em&gt;Haematopota pluvialis &lt;/em&gt;and&lt;em&gt; Hybomitra bimaculata&lt;/em&gt;. Moreover, with regards to the number of male and female tabanids collected in Nzi traps, a higher difference for each area was found. As a parallel survey, the landing behavior of each genus of collected tabanids on blue and black colors before going into Nzi traps showed the same variation during the experiments. Nzi traps set near the horses and cows have shown high efficiency in capturing biting flies, allowing animals to graze somewhat undisturbed.&lt;/span&gt;&lt;/p&gt;

Relating trap capture to abundance: a hierarchical state-space model applied to black sea bass (Centropristis striata)

Relating trap capture to abundance: a hierarchical state-space model applied to black sea bass (<i>Centropristis striata</i>)

Random telegraph signals originating from unrelaxed neutral oxygen vacancy centres in SiO 2

Unrelaxed neutral oxygen deficiency centres (ODCs) (V0 ODC II) in SiO2 have been identified as the cause of random telegraph signals (RTSs) in highly scaled n-type metal–oxide–semiconductor field-effect transistors. Variable temperature RTS measurements were performed to extract trap capture cross-sections, capture activation energy, relaxation energy associated with the gate oxide defects, and the trap energy in the SiO2 bandgap to determine the trap species and type. The results indicate that the electron is captured by a neutral ODC that is transformed into a negatively charged vacancy (V−). This is the first time V0 ODC II centre is confirmed to be the source of electron switching through RTS measurements defining four different trap characteristics.

Changes in Abundance of Larvae and Adults ofPopillia japonica(Coleoptera: Scarabaeidae: Rutelinae) and Other White Grub Species in Northwest Arkansas and Their Relation to Regional Temperatures

Summary The Japanese beetle is a relatively new pest in Arkansas that damages turfgrass, horticultural plants, and fruit crops. From 2005 to 2012, P. japonica mean weekly trap capture declined 98%. Previous studies showed there were few microbial and parasitoid natural enemies of P. japonica in the region, so fluctuations in P. japonica populations are likely due to abiotic factors, such as extremes of summer drought and heat along this invasive species' southwestern border.

Forest tent caterpillar, Malacosoma disstria (Lepidoptera: Lasiocampidae), mate-finding behavior is greatest at intermediate population densities: implications for interpretation of moth capture in pheromone-baited traps

The forest tent caterpillar, Malacosoma disstria Hubner (Lepidoptera: Lasiocampidae) is a native forest defoliator with a broad geographic range in North America. Forest tent caterpillars experience cyclical population changes and at high densities, repeated defoliation can cause reduced tree growth and tree mortality. Pheromone-based monitoring of forest tent caterpillar moths can provide information on spatial and temporal patterns of incipient outbreaks. Pheromone-baited trap capture of male moths correlates to the number of eggs and pupae in a population but this relationship breaks down at high population densities, when moth trap capture declines. The objective of the current study is to understand the mechanisms that reduce trap capture at high population densities. We tested two different hypotheses: 1) at high population densities, male moth orientation to pheromone sources is reduced due to competition for pheromone plumes; and 2) moths from high density populations will be in poor condition and less likely to conduct mate-finding behaviors than moths from low density populations. A field study showed non-linear effects of density on male moth capture in female-baited traps. The number of males captured increased up to an intermediate density level and declined at the highest densities. Field cage studies showed that female moth density affected male moth orientation to female-baited traps, as more males were recaptured at low than high female densities. There was no effect of male density on the proportion of males that oriented to female-baited traps. Moth condition was manipulated by varying larval food quantity. Although feeding regimes affected the moth condition (size), there was no evidence of an effect of condition on mate finding or close range mating behavior. In the field, it is likely that competition for pheromone plumes at high female densities during population outbreaks reduces the efficacy of pheromone-baited monitoring traps.

Roving and stationary release of adult sterile Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera; Tephritidae)

Sterile Insect Technique (SIT) is an environmentally-benign, species-specific method of pest control. The Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) is a polyphagous pest that may be managed via SIT. Sterile releases of B. tryoni were carried out in two separate field trials to compare the effectiveness of non-chilled adult (stationary release) and chilled adult (roving release) releases under field conditions in eastern Australia. The first study compared the recapture rates of sexually mature sterile male B. tryoni in cue-lure baited Lynfield traps when released as chilled adults and non-chilled adults, each on two release dates in an urban town. In a subsequent field study, trap capture rates of wild and sterile flies were monitored in three isolated towns in New South Wales that received either sterile non-chilled adult releases (Uranquinty), sterile chilled adult releases (Lockhart) or no sterile releases, i.e. control (Cootamundra). Wild fly larval counts (from whole picked fruit) were also obtained in both Uranquinty and Lockhart. In trial 1, for both release 1 and 2 respectively, a greater proportion of non-chilled flies (52.6% and 62.0%) than chilled flies (47.4% and 38.0%) were recaptured per trap. However, over the duration of the trial, recapture of chilled adult flies and non-chilled adult flies was 4.35 ± 0.54% and 3.27 ± 0.54% of all flies released, respectively. Overall, in both releases, adult flies designated for chilled adult release had lower recorded adult eclosion (except for release 2 when more chilled adults emerged) and flight compared with non-chilled adults. In trial 2, Lockhart (chilled adult release) wild fly numbers showed a significant decline four weeks after sterile release, despite both Uranquinty and Cootamundra displaying increases in wild fly numbers at this time. Chilled adults were significantly less likely to take flight than unchilled flies, but of those that dispersed, a greater proportion of the chilled flies were recaptured. Over the entire fruit collection period, there was a significant decline in the number of live larvae and the live larvae per fruit in Uranquinty and for seven consecutive weeks in Lockhart, which was also reflected in the total number of larvae and the total rate per fruit. The results are encouraging, particularly the use of chilled adult sterile release for the control of wild B. tryoni populations, and would provide a valuable tool for wild fly management.

An Evaluation of the Efficiency of Minnow Traps for Estimating the Abundance of Minnows in Desert Spring Systems

AbstractDesert springs are sensitive aquatic ecosystems that pose unique challenges to natural resource managers and researchers. Among the most important of these is the need to accurately quantify population parameters for resident fish, particularly when the species are of special conservation concern. We evaluated the efficiency of baited minnow traps for estimating the abundance of two at‐risk species, Foskett Speckled Dace Rhinichthys osculus ssp. and Borax Lake Chub Gila boraxobius, in desert spring systems in southeastern Oregon. We evaluated alternative sample designs using simulation and found that capture–recapture designs with four capture occasions would maximize the accuracy of estimates and minimize fish handling. We implemented the design and estimated capture and recapture probabilities using the Huggins closed‐capture estimator. Trap capture probabilities averaged 23% and 26% for Foskett Speckled Dace and Borax Lake Chub, respectively, but differed substantially among sample locations, through time, and nonlinearly with fish body size. Recapture probabilities for Foskett Speckled Dace were, on average, 1.6 times greater than (first) capture probabilities, suggesting “trap‐happy” behavior. Comparison of population estimates from the Huggins model with the commonly used Lincoln–Petersen estimator indicated that the latter underestimated Foskett Speckled Dace and Borax Lake Chub population size by 48% and by 20%, respectively. These biases were due to variability in capture and recapture probabilities. Simulation of fish monitoring that included the range of capture and recapture probabilities observed indicated that variability in capture and recapture probabilities in time negatively affected the ability to detect annual decreases by up to 20% in fish population size. Failure to account for variability in capture and recapture probabilities can lead to poor quality data and study inferences. Therefore, we recommend that fishery researchers and managers employ sample designs and estimators that can account for this variability.Received September 29, 2014; accepted January 29, 2015

Aphid Sex Pheromone Compounds Interfere with Attraction of Common Green Lacewings to Floral Bait.

Common green lacewings (Chrysoperla carnea complex) form a group of generalist predators important for biological control. Several reports show attraction of these insects to plant volatiles, and a highly attractive ternary compound floral bait has been developed. With aphids being a preferred prey of larvae, one might expect these lacewings to be attracted to aphid semiochemicals, for instance, to aphid sex pheromones, as found for several other green lacewing species. However, in a previous study, we found that traps containing aphid sex pheromone compounds (1R,4aS,7S,7aR)-nepetalactol (NEPOH), (4aS,7S,7aR)-nepetalactone (NEPONE), and a ternary floral bait attracted fewer individuals than those containing the ternary floral bait alone. In the present study, possible causes for this effect of NEPOH and NEPONE on trap capture were studied. We established that C. carnea complex catches in traps with a ternary floral lure were not influenced by the presence of Chrysopa formosa individuals in traps (attracted by NEPOH and NEPONE) or by synthetic skatole (a characteristic component of Chrysopa defense secretion). A direct negative effect of NEPOH and NEPONE on attraction of C. carneacomplex was found, suggesting active avoidance of these aphid sex pheromone components. This finding is surprising as the larvae of these lacewings prey preferentially on aphids. Possible mechanisms underlying this phenomenon are discussed.