Natal rearing experience of animals may affect their behaviors, such as habitat selection and oviposition decision. As part of the overall fitness of insect parasitoids, successful host discrimination (distinguishing parasitized hosts from unparasitized hosts) is of paramount importance. In this study we examined whether and how parasitoids' natal rearing experience would affect their host discrimination ability according to host availability. We established separate colonies of Aphidius gifuensis Ashmead by continual rearing on two hosts, Sitobion avenae F. and Myzus persicae (Suzler), and quantified self superparasitism and self superparasitism versus parasitism ratio for the four combinations of parasitoid colonies and host species (S. aveane and M. persicae) at four host densities (30, 50, 100 or 150 per plant). Results showed that self superparasitism of M. persicae by A. gifuensis reared on S. avenae was significantly higher than by those reared on M. persicae, no matter whether the host densities were 30, 50, 100 or 150. Aphidius gifuensis reared on M. persicae significantly superparasitized more S. avenae than those reared on S. aveane only when host density was 30. Self superparasitism versus parasitism ratio of A. gifuensis from both colonies was always lower on natal hosts than on new hosts, and the difference was more pronounced as the host density decreased. These results suggested that natal rearing effects is important on host discrimination and oviposition decision of the parasitoid A. gifuensis. These effects promoted the parasitoid's host adaptation and made them confer greater fitness.

Honeybees (Apis mellifera L.) have been widely distributed around the world to serve as pollinators for agriculture. They can encounter metal pollutants through various routes of exposure, including foraging on contaminated plant resources. Chronic and acute toxicity tests were conducted on larvae using artificial diets and on foragers using solutions of 50% sucrose, which contained cadmium (Cd), copper (Cu) and lead (Pb). We found that mortality increased in both larvae and foragers in a dose-dependent manner. Control larvae had higher relative growth indices (RGI) from day 6 to day 10 compared to all metal treatments, demonstrating substantial negative effects of metals on development. Copper was the least toxic to larvae with an LC50 of 6.97 mg L(-1). For foragers, Pb had the highest LC50, which was 345 mg L(-1). Foragers and larvae accumulated substantial quantities of all metals, and subsequent sucrose consumption decreased after dosing. Overall, honeybee larvae and foragers suffered detrimental effects when they were exposed to ecologically-relevant concentrations of Cd, Cu and Pb.

Burning mouth syndrome (BMS) is a chronic pain disorder characterized by severe burning sensation in normal looking oral mucosa. Diagnosis of BMS remains to be a challenge to oral healthcare professionals because the method for definite diagnosis is still uncertain. In this study, a quantitative saliva proteomic analysis was performed in order to identify target proteins in BMS patients' saliva that may be used as biomarkers for simple, non-invasive detection of the disease. By using isobaric tags for relative and absolute quantitation labeling and liquid chromatography-tandem mass spectrometry to quantify 1130 saliva proteins between BMS patients and healthy control subjects, we found that 50 proteins were significantly changed in the BMS patients when compared to the healthy control subjects ( p ≤ 0.05, 39 up-regulated and 11 down-regulated). Four candidates, alpha-enolase, interleukin-18 (IL-18), kallikrein-13 (KLK13), and cathepsin G, were selected for further validation. Based on enzyme-linked immunosorbent assay measurements, three potential biomarkers, alpha-enolase, IL-18, and KLK13, were successfully validated. The fold changes for alpha-enolase, IL-18, and KLK13 were determined as 3.6, 2.9, and 2.2 (burning mouth syndrome vs. control), and corresponding receiver operating characteristic values were determined as 0.78, 0.83, and 0.68, respectively. Our findings indicate that testing of the identified protein biomarkers in saliva might be a valuable clinical tool for BMS detection. Further validation studies of the identified biomarkers or additional candidate biomarkers are needed to achieve a multi-marker prediction model for improved detection of BMS with high sensitivity and specificity.

The practice of burning agricultural waste is ubiquitous around the world, yet the external human capital costs from those fires have been underexplored. Using data from the National College Entrance Examination (NCEE) and agricultural fires detected by high-resolution satellites in China during 2005 to 2011, this paper investigates the impacts of fires on cognitive performance. To address the endogeneity of agricultural fires, we differentiate upwind fires from downwind fires. We find that a one-standard-deviation increase in the difference between upwind and downwind fires during the exam decreases the total exam score by 1.42 percent of a standard deviation (or 0.6 point), and further decreases the probability of getting into first-tier universities by 0.51 percent of a standard deviation.

Acetylene (C₂H₂) can be generated in contaminated groundwater sites as a consequence of chemical degradation of trichloroethene (TCE) by in situ minerals, and C₂H₂ is known to inhibit bacterial dechlorination. In this study, we show that while high C₂H₂ (1.3 mM) concentrations reversibly inhibit reductive dechlorination of TCE by Dehalococcoides mccartyi isolates as well as enrichment cultures containing D. mccartyi sp., low C₂H₂ (0.4 mM) concentrations do not inhibit growth or metabolism of D. mccartyi. Cocultures of Pelobacter SFB93, a C₂H₂-fermenting bacterium, with D. mccartyi strain 195 or with D. mccartyi strain BAV1 were actively sustained by providing acetylene as the electron donor and carbon source while TCE or cis-DCE served as the electron acceptor. Inhibition by acetylene of reductive dechlorination and methanogenesis in the enrichment culture ANAS was observed, and the inhibition was removed by adding Pelobacter SFB93 into the consortium. Transcriptomic analysis of D. mccartyi strain 195 showed genes encoding for reductive dehalogenases (e.g., tceA) were not affected during the C₂H₂-inhibition, while genes encoding for ATP synthase, biosynthesis, and Hym hydrogenase were down-regulated during C₂H₂ inhibition, consistent with the physiological observation of lower cell yields and reduced dechlorination rates in strain 195. These results will help facilitate the optimization of TCE-bioremediation at contaminated sites containing both TCE and C₂H₂.

Background

Aedes albopictus is a globally invasive mosquito and a major vector of arboviruses, including dengue, Zika and Chikungunya. Olfactory-related behaviors, particularly host-seeking, offer opportunities to disrupt the disease-transmission process. A better understanding of odorant receptors (ORs) may assist in explaining host selection and location, and contribute to novel strategy of vector control.

Methods

Based on previous prediction of 158 putative odorant receptors by Ae. albopictus genome analysis, 29 AalORs were selected for tissue-specific expression profiles in the present study. AalOrco (AalOR7), AalOR10 and AalOR88, highly expressed in female olfactory tissues, were chosen for further structure predictions as well as functional validation including calcium imaging assay in human embryonic kidney (HEK293) cells and RNA interference assay in Ae. albopictus. We also conducted electrophysiological and behavioral assays in mosquitoes after RNA interference of the three genes to determine their roles in host-seeking.

Results

The results support previous conclusions that individual conventional (ORXs) and Orco can form heteromeric complexes to recognize odorants and respond to components of human volatiles in HEK293 cells. The reduction of AalOrco transcript levels led to a significant decrease in host-seeking and confusion in host preference. In contrast, AalOR10 and AalOR88 knockdown mosquitoes showed no significant behavioral differences compared with controls. The functions of conventional ORs at least AalOR10 and AalOR88 are abolished with inhibited expression of the Orco gene orthologs, along with the concomitant relevant olfactory behavior.

Conclusions

Combining structural and functional data, we conclude that the product of the Orco gene in this mosquito is crucial for transmitting olfactory signaling and conventional ORs contribute directly to odorant recognition. Our results provide insight into the linkage between odorant receptors and host-seeking in this important vector species.

Interactions between bacterial microbiota and mosquitoes play an important role in mosquitoes' capacity to transmit pathogens. However, microbiota assemblages within mosquitoes and the impact of microbiota in environments on mosquito development and survival remain unclear. This study examined microbiota assemblages and the effects of aquatic environment microbiota on the larval development of the Aedes albopictus mosquito, an important dengue virus vector. Life table studies have found that reducing bacterial load in natural aquatic habitats through water filtering and treatment with antibiotics significantly reduced the larva-to-adult emergence rate. This finding was consistent in two types of larval habitats examined-discarded tires and flowerpots, suggesting that bacteria play a crucial role in larval development. Pyrosequencing of the bacterial 16S rRNA gene was used to determine the diversity of bacterial communities in larval habitats and the resulting numbers of mosquitoes under both laboratory and field conditions. The microbiota profiling identified common shared bacteria among samples from different years; further studies are needed to determine whether these bacteria represent a core microbiota. The highest microbiota diversity was found in aquatic habitats, followed by mosquito larvae, and the lowest in adult mosquitoes. Mosquito larvae ingested their bacterial microbiota and nutrients from aquatic habitats of high microbiota diversity. Taken together, the results support the observation that Ae. albopictus larvae are able to utilize diverse bacteria from aquatic habitats and that live bacteria from aquatic habitats play an important role in larval mosquito development and survival. These findings provide new insights into bacteria's role in mosquito larval ecology.

Honey bees (Apis mellifera L.) are important ecological and agricultural resources. They are among the most widely available pollinators and provide products as well as services. Unfortunately, honey bee populations are susceptible to several environmental threats, including heavy metal exposure. Honey bees can be exposed to heavy metals when foraging on contaminated honey and pollen resources, and in some cases by airborne exposure. We studied the joint acute and chronic effects of cadmium (Cd) and copper (Cu) on A. mellifera. A 1:1 solution of the two heavy metals increased larval developmental duration and the mortality of both larvae and foragers in a dose-dependent way, decreased forager feeding, increased body metal burdens, and disrupted the sucrose response behavior of foragers. In combination, Cd and Cu demonstrated a weakly synergistic effect on foragers, but for larvae an initially antagonistic effect at low doses changed to strongly synergistic response at higher concentrations. The sucrose response threshold of foragers decreased significantly when they were dosed with increasing concentrations of the metal mixtures. Overall, the fitness of honey bee larvae and foragers is detrimentally affected when these metals co-occur.

Background

The Asian tiger mosquito, Aedes albopictus, an increasingly relevant arboviral vector, has spread worldwide. However, currently available tools are limited in terms of effective monitoring of vector populations and accurate determination of the extent of viral transmission, especially before and during outbreaks. Therefore, it is essential to develop novel monitoring and surveillance tools, particularly those that target adult mosquitoes and enhance the trapping efficiency for Ae. albopictus.

Methods

A variety of human body odorants associated with different types of mosquito olfactory receptors were selected, and their attractiveness to Ae. albopictus was tested by a four-arm olfactometer. The optimal compatibility and proportion of the odorants, Mix-5, was observed via orthogonal design analyses. The attractiveness of Mix-5 to Ae. albopictus in the laboratory was assessed using Mosq-ovitraps and Electric Mosquito Killers. In the field, the effectiveness of generic BG-Lure, Mix-5 and a control treatment was compared with a baited Biogents Sentinel trap (BGS-trap) using a Latin square design.

Results

In the olfactometer experiments, the attractiveness of the selected candidate compounds at varying dilutions was poor when the individual compounds were used alone. The optimal combination, Mix-5, was generated based on orthogonal design analyses. In the laboratory, the average numbers of female Ae. albopictus mosquitoes attracted by the synthetic odorant blend Mix-5 were 27.00 and 27.50, compared with 12.00 and 14.83 for the control, when using Mosq-ovitraps and Electric Mosquito Killers, respectively. In the field, the average number of Ae. albopictus female mosquitoes trapped by Mix-5 was 9.67 females/trap, whereas the average numbers for BG-Lure and the control were 7.78 and 4.47, respectively. The lure also played an important role in attracting Culex quinquefasciatus mosquitoes, and the average numbers of Cx. quinquefasciatus female mosquitoes attracted by Mix-5, BG-Lure and the control were 18.78, 25.11 and 12.22, respectively.

Conclusions

A human odor-based bait blend was developed and exhibited enhanced effectiveness at attracting Ae. albopictus This blend can be used to monitor and trap dengue vector mosquitoes in Chinese cities.

Background

The surveillance of vector mosquitoes is essential for prevention and control of mosquito-borne diseases. In this study, we developed an internet-based vector mosquito monitor, MS-300, and evaluated its efficiency for the capture of the important vector mosquitoes, Aedes albopictus and Culex quinquefasciatus, in laboratory and field trials.

Methodology/principal findings

The linear sizes of adult Ae. albopictus and Cx. quinquefasciatus were measured and an infrared window was designed based on these data. A device to specifically attract these two species and automatically transmit the number of captured mosquitoes to the internet was developed. The efficiency of the device in capturing the two species was tested in laboratory, semi-field and open field trials. The efficiency results for MS-300 for catching and identifying Ae. albopictus in laboratory mosquito-net cages were 98.5% and 99.3%, and 95.8% and 98.6%, respectively, for Cx. quinquefasciatus. In a wire-gauze screened house in semi-field trials, the efficiencies of MS-300 baited with a lure in catching Ae. albopictus and Cx. quinquefasciatus were 54.2% and 51.3%, respectively, which were significantly higher than 4% and 4.2% without the lure. The real-time monitoring data revealed two daily activity peaks for Ae. albopictus (8:00-10:00 and 17:00-19:00), and one peak for Cx. quinquefasciatus (20:00-24:00). During a 98-day surveillance trial in the field, totals of 1,118 Ae. albopictus and 2,302 Cx. quinquefasciatus were captured by MS-300. There is a close correlation between the number of captured mosquitoes and the temperature in the field, and a positive correlation in the species composition of the captured samples among the mosquitoes using MS-300, BioGents Sentinel traps and human landing catches.

Conclusions/significance

The data support the conclusion that MS-300 can specifically and efficiently capture Ae. albopictus and Cx. quinquefasciatus, and monitor their density automatically in real-time. Therefore, MS-300 has potential for use as a surveillance tool for prevention and control of vector mosquitoes.