Workers select mates for queens: a possible mechanism of gene flow restriction between supercolonies of the invasive Argentine ant

Some invasive ants form large networks of mutually non-aggressive nests, i.e., supercolonies. The Argentine ant Linepithema humile forms much larger supercolonies in introduced ranges than in its native range. In both cases, it has been shown that little gene flow occurs between supercolonies of this species, though the mechanism of gene flow restriction is unknown. In this species, queens do not undertake nuptial flight, and males have to travel to foreign nests and cope with workers before gaining access to alien queens. In this study, we hypothesized that male Argentine ants receive interference from workers of alien supercolonies. To test this hypothesis, we conducted behavioral and chemical experiments using ants from two supercolonies in Japan. Workers attacked males from alien supercolonies but not those from their own supercolonies. The level of aggression against alien males was similar to that against alien workers. The frequency of severe aggression against alien males increased as the number of recipient workers increased. Cuticular hydrocarbon profiles, which serve as cues for nestmate recognition, of workers and males from the same supercolony were very similar. Workers are likely to distinguish alien males from males of their own supercolony using the profiles. It is predicted that males are subject to considerable aggression from workers when they intrude into the nests of alien supercolonies. This may be a mechanism underlying the restricted gene flow between supercolonies of Argentine ants. The Argentine ant may possess a distinctive reproductive system, where workers participate in selecting mates for their queens. We argue that the aggression of workers against alien males is a novel form of reproductive interference.     

Response surface method for modeling the removal of carbon dioxide from a simulated gas using water absorption enhanced with a liquid-film-forming device

This paper presents the results from using a physical absorption process to absorb gaseous CO_2mixed with N_2using water by producing tiny bubbles via a liquid-film-forming device(LFFD)that improves the solubility of CO_2in water.The influence of various parameters—pressure,initial CO_2concentration,gas-to-liquid ratios,and temperature—on the CO_2removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method(RSM)with a central composite design(CCD).Based on the analysis,a high efficiency of CO_2capture can be reached in conditions such as low pressure,high CO_2concentration at the inlet,low gas/liquid ratio,and low temperature.For instance,the highest removal efficiency in the RSM–CCD experimental matrix of nearly 80%occurred for run number 20,which was conducted at 0.30 MPa,CO_2concentration of 35%,gas/liquid ratio of 0.71,and temperature of 15°C.Furthermore,the coefficients of determination,R~2,were 0.996 for the removal rate and 0.982 for the absorption rate,implying that the predicted values computed by the constructed models correlate strongly and fit well with the experimental values.The results obtained provide essential information for implementing this method properly and effectively and contribute a promising approach to the problem of CO_2capture in air pollution treatment.     

Elementary budget of stag beetle larvae associated with selective utilization of nitrogen in decaying wood

Wood degradation by insects plays important roles for the forest matter cycling. Since wood is deficient in nitrogen compared to the insect body, wood-feeding insects need to assimilate the nitrogen selectively and discard an excess carbon. Such a stoichiometric imbalance between food and body will cause high metabolic cost; therefore, wood-feeding insects may somehow alleviate the stoichiometric imbalance. Here, we investigated the carbon and nitrogen budgets of the larvae of stag beetle, Dorcus rectus, which feed on decaying wood. Assimilation efficiency of ingested wood was 22%, and those values based on the carbon and nitrogen were 27 and 45%, respectively, suggesting the selective digestion of nitrogen in wood. Element-based gross growth efficiency was much higher for nitrogen (45%) than for carbon (3%). As a result, the larvae released 24% of the ingested carbon as volatile, whereas almost no gaseous exchange was observed for nitrogen. Moreover, solubility-based elementary analysis revealed that the larvae mainly utilized alkaline-soluble-water-insoluble fraction of wood, which is rich in nitrogen. Actually, the midgut of the larvae was highly alkaline (pH 10.3). Stag beetle larvae are known to exhibit coprophagy, and here we also confirmed that alkaline-soluble-water-insoluble nitrogen increased again from fresh feces to old feces in the field. Stable isotope analysis suggested the utilization of aerial nitrogen by larvae; however, its actual contribution is still disputable. Those results suggest that D. rectus larvae selectively utilize alkaline-soluble nitrogenous substrates by using their highly alkaline midgut, and perhaps associate with microbes that enhance the nitrogen recycling in feces.     

Studies on transitory laxative effects of sorbitol and maltitol: II: Differences in laxative effects among various foods containing the sweetening agents

We studied the laxative effect of sweetening agents, hydrogenated glucose syrup (HGS) containing 88–92% maltitol, and sorbitol contained in various foods. The subjects were 89 volunteers (64 males and 25 females). Foods used in the study were tablets, bevarages, chewing gum, jelly, adzuki-bean jelly, chocolate and candies which contained one of the two sweetening agents.The doses of the sweetening agents were 0.4 g/kg for sweets in tablet form and 20 g for the other foods. Approximately 10% of the subjects exhibited diarrhea after taking tablets as a control; approximately 20% did so after taking HGS except for adzuki-bean jelly; and approximately 30% did so after taking sorbitol. There was no significant difference between HGS and the control substance. The incidence of diarrhea tended to be higher with the two sweetening agents only when contained in adzuki-bean jelly. The length of time between the ingestion of test substances and the first onset of diarrheal stool varied widely from less than one hour to 23 hours among individuals. However, adzuki-bean jelly diarrhea was induced within 5 hours in all subjects. Soft stool accounted for 60 – 90% of the macroscopic findings of diarrheal stool. Chief complaints of abdominal symptoms were gurgling, flatus and lower abdominal pain.     

Suppression of arsenic leaching from excavated soil and the contribution of soluble and insoluble components in steel slag on arsenic immobilization

Environmental Science and Pollution Research - A huge amount of soil is excavated by tunnel and road construction projects in urban, coastal, and mountainous regions. These projects enable the...     

Comparative survey of levels of chlorinated cyclodiene pesticides in breast milk from some cities of China, Korea and Japan

Exposure of mothers to organochlorine pesticides (OCPs) was assessed by measuring the levels of 20 OCPs in 70 human breast milk samples pooled from 210 individuals from China, Korea and Japan. The OCPs were analyzed using gas chromatography/mass spectrometry (GC/MS) in electron capture negative ionization (ECNI) monitoring. The results showed that β-hexachlorocyclohexane and hexachlorobenzene were one order of magnitude higher in China than in the other nations, whereas chlordanes and polychlorinated biphenyl levels were highest in Japan. Heptachlor epoxide, dieldrin, endrin, toxaphenes and mirex were detected in most samples, and levels of these chemicals were significantly higher in Japan (0.8-4.5 ng g⁻¹ lipid), followed by Korea (0.2-4.7 ng g⁻¹ lipid), and lowest in China (less than 1.0 ng g⁻¹ lipid). α- and β-endosulfans were detected at a range of 0.9-1.5 ng g⁻¹ lipid levels in all samples analyzed, and their levels were higher in Korean than in Chinese samples.     

Predicting the particle size distribution of fine-grained and sandy soils using deep learning for classifying recovered soils separated from tsunami deposits

Journal of Material Cycles and Waste Management - Disaster wastes, particularly those generated in the tsunami, comprise soil and sediments, and recovered soil is yielded through treatment such as...     

Inactivation effect of pressurized carbon dioxide on bacteriophage Qβ and ΦX174 as a novel disinfectant for water treatment

The inactivation effects of pressurized CO2 against bacteriophage Qβ and ΦX174 were investigated under the pressure of 0.3–0.9 MPa, initial concentration of 107–109PFU/mL, and temperature of17.8°C–27.2°C. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 3.3-log reduction in bacteriophage Qβ was achieved by CO2, while a nearly 3.0 log reduction was observed for phage ΦX174. The viricidal effects of N2O(an inactivation gas with similar characteristics to CO2), normal acid(HCl), and CO2 treatment with phosphate buffered saline affirmed the chemical nature of CO2 treatment. The pumping cycle, depressurization rate, and release of intracellular substances caused by CO2 were its viricidal mechanisms. The results indicate that CO2 has the potential for use as a disinfectant without forming disinfection by-products.     

Novel enzymatic activity of cell free extract from thermophilic Geobacillus sp. UZO 3 catalyzes reductive cleavage of diaryl ether bonds of 2,7-dichlorodibenzo-p-dioxin

We characterized the ability of the cell free extract from polychlorinated dibenzo-p-dioxins degrading bacterium Geobacillus sp. UZO 3 to reduce even highly chlorinated dibenzo-p-dioxins such as octachlorodibenzo-p-dioxins in incineration fly ash. The degradation of 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) as a model dioxin catalyzed by the cell free extract from this strain implicates that the ether bonds of 2,7-DCDD molecule undergo reductive cleavage, since 4′,5-dichloro-2-hydroxydiphenyl ether and 4-chlorophenol were detected as intermediate products of 2,7-DCDD degradation.     

Effects of the reduction of pollution emissions on the economic performance of firms: an empirical analysis focusing on demand and productivity

This paper analyzes whether the reduction of pollution emissions improves a firm’s economic performance through the increase in sales to environmentally conscious customers and the cost reductions associated with the improvement in productivity. Because the selection of the control (end-of-pipe) or prevention (cleaner production) approach differently influences the effect through the improvement in productivity, this is also considered. Using panel data for Japanese manufacturing firms over the period 2002–2008, the findings indicate that firms that have reduced their pollution emissions can increase their economic performance through the increase in demand for their products and an improvement in productivity. However, the latter is conditional, and so the prevention approach is preferred.