Learning,retention and coding of nest-associated visual cues by the Australian desert ant, <Emphasis Type="Italic">Melophorus bagoti</Emphasis>

A variety of social insects use visual cues for homing. In this study, we examine the possible factors affecting the learning and retention of nest-associated visual cues by the Australian desert ant Melophorus bagoti and the manner in which such cues are encoded by foraging ants. We placed four prominent cylindrical landmarks around a nest and trained foragers from that nest to a food source. Ants were tested with the landmark array in a distant testing field after (1) a known number of exposures to the landmarks (1, 3, 7 or 15 trials, spread over a period of 1 day, 2 days or ≥3 days) and (2) after a known period of delay (0, 24, 48, 96 or 192 h). The results show that a combination of an increase in training trials and an increase in number of training days affected the acquisition of landmark memory. Moreover, once the landmarks were learnt, they became a part of long-term memory and lasted throughout the ants’ foraging lifetime. To examine visual cue encoding behaviour, ants trained under similar conditions for 4 days were tested with (1) an identical landmark array, (2) landmarks of the same size used in training, but placed at twice the distance from each other, and (3) landmarks whose dimensions were doubled and placed at twice the distance from each other. In conditions (1) and (3), the ants searched extensively at the centre of the four landmarks, suggesting that, similar to the Saharan ant (genus Cataglyphis) and the honeybee, M. bagoti too uses a snapshot to match the view of the landmarks around the nest. But contrary to the snapshot model, in condition (2), the ants did not search extensively at the centre of the landmarks, but searched primarily 0.5 m from the landmark, the distance from each landmark to the nest during training. We discuss how various search models fare in accounting for these findings.     

Organochlorine insecticide residues in Ganga river water near Farrukhabad,India

Multiple residues of organochlorine insecticides were monitored in Ganga river water in the district of Farrukhabad in northern Indian for one year (1991–1992). Almost all the samples were found to be contaminated with residues of HCH and DDT. Residues of aldrin, endosulfan and heptachlor were also detected in a larger number of samples. Alpha-HCH, pp-DDT and alpha-endosulfan were found to dominate over the other isomers of HCH, DDT and endosulfan, respectively. Enhanced percentage of beta-HCH suggests accumulation of this isomer in the aquatic environment. The average concentration of aldrin was more than that of dieldrin. Aldrin residues often exceeded the WHO guideline value for drinking water and the concentration of heptachlor occasionally exceeded the specified limits.     

Soy proteins as environmentally friendly sizing agents to replace poly(vinyl alcohol)

An environmentally friendly and inexpensive substitute to the widely used poly(vinyl alcohol) (PVA) has been developed from soy proteins for textile warp sizing. Textile processing is the major source of industrial water pollution across the world, and sizing and desizing operations account for nearly 30 % of the water consumed in a textile plant. PVA is one of the most common sizing agents used for synthetic fibers and their blends due to PVA’s easy water solubility and ability to provide desired sizing performance. However, PVA does not degrade and is a major contributor to pollution in textile effluent treatment plants. Although considerable efforts have been made to replace PVA with biodegradable sizing materials, the performance properties provided by PVA on synthetic fibers and their blends have been unmatched so far. Soy proteins are inexpensive, biodegradable, and have been widely studied for potential use in food packaging, as resins and adhesives. In this research, the potential of using soy proteins as textile sizing agents to replace PVA was studied. Polyester and polyester/cotton rovings, yarns, and fabrics sized with soy protein showed a considerably better improvement in strength and abrasion resistance compared to commercially available PVA-based size. Soy protein size had a 5-day biochemical oxygen demand /chemical oxygen demand ratio of 0.57 compared to 0.01 for PVA indicating that soy protein sizes were easily biodegradable in activated sludge. The total and ammonia nitrogen released from the proteins also did not adversely impact the biodegradability. Good sizing performance and easy biodegradability demonstrate that soy protein-based sizes have potential to replace PVA-based sizes leading to substantial benefits to the textile industry and the environment.     

Temporal variation in density and diversity of cyanobacteria and cyanotoxins in lakes at Nagpur (Maharashtra State), India

Toxic cyanobacteria (TCB) are known worldwide for the adverse impacts on humans and animals. Species composition and the seasonal variation of TCB in water bodies depend on interactions between physical and chemical factors. The present investigation delineates temporal variations in physico-chemical water quality parameters, viz. nutrients and density, diversity, and distribution of toxic cyanobacteria and cyanotoxins in Lake Ambazari (21°7′52″N, 79°2′22″E) and Lake Phutala (21°9′18″N, 79°2′37″E) at Nagpur (Maharashtra State), India. These lakes are important sources of recreational activities and fisheries. Toxic cyanobacterial diversity comprised Anabaena, Oscillatoria, Lyngbya, Phormidium, and Microcystis, a well-known toxic cyanobacterial genus, as dominant. Chlorophyll-a concentrations in the lakes ranged from 1.44 to 71.74 mg/m³. A positive correlation of Microcystis biomass existed with orthophosphate-P (p?<?0.05) and nitrate-N (p?>?0.05). Identification and quantification of microcystin variants were carried out by high performance liquid chromatography equipped with photodiode array detector. Among all the tested toxin variants, microcystin-RR (arginine–arginine) was consistently recorded and exhibited a positive correlation (p?<?0.05) with Microcystis in both the water bodies. Microcystis bloom formation was remarkable between post-monsoon and summer. Besides nutrient concentrations governing bloom formation, the allelopathic role of microcystins needs to be established.     

Frequency distribution of pollutant concentrations over Indian megacities impacted by the COVID-19 lockdown

Environmental Science and Pollution Research - The megacities experience poor air quality frequently due to stronger anthropogenic emissions. India had one of the longest lockdowns in 2020 to curb...     

Heavy metals in the polychaete Glycera longipinnis from the southwest of India

Metal concentrations in sediment and in whole tissue of the benthic polychaete Glycera longipinnis collected along the southwest coast of India were analysed. Relative seasonal accumulation of metals (Cu, Pb, Cr, Ni, Zn, Cd, Hg) was studied by categorising the habitat as less polluted or highly polluted based on metal contamination routed through industrial and urban sources. The metal content in tissues varied seasonally in the ranges, Cu: 2.21–27.08 μg·g^?1, Pb: 0.06–4.92 μg·g^?1, Cr: 1.73–29.20 μg·g^?1, Ni: 1.60–4.61 μg·g^?1, Zn: 14.72–82.30 μg·g^?1, Cd: 0.04–1.38 μg·g^?1and Hg: below decetable limits to 0.86 μg·g^?1. Concentration of heavy metals was found to be high in the whole body of G. longipinnis pooled from the polluted transects. The results of this study suggest that G. longipinnis may act as a useful biological indicator for heavy metal pollution along the southwest coast of India.     

Alkali Treated 3D Chitosan Scaffolds with Enhanced Strength and Stability

Journal of Polymers and the Environment - 3D chitosan scaffolds treated with alkali showed enhanced mechanical properties and stability in aqueous conditions. Chitosan is a preferred polymer for...     

Water and sediment quality of Ashtamudi estuary, a Ramsar site, southwest coast of India—a statistical appraisal

Ashtamudi estuary, situated on the southwest coast of India, is enormously affected by anthropogenic interventions. Physicochemical quality of water and sedimentological features of the estuary are evaluated during monsoon and nonmonsoon seasons to elucidate its quality variations and to link the same with existing environmental scenario. The whole data has been factorized using principal component analysis for extracting the total variability and linear relationships existing among a set of different physicochemical parameters of the backwater system. In PCA, high loadings were obtained for conductivity, salinity, fluoride, calcium, magnesium, sulfate, boron, and pH. The results were revealed that all the physicochemical processes depend upon seasonal fluctuation of freshwater input and seawater intrusion. Wide spatial concentration fluctuations of organic carbon and iron in bottom sediment have been noticed and both constituents reveal good correlation with sediment texture. The results showed high deterioration of the physicochemical quality of water during nonmonsoon season with respect to monsoon season.     

Assessment of flubendiamide residues in pigeon pea in different agro-climatic zones of India

Supervised field trials were conducted at the research farms of four agricultural universities located at different agro-climatic zones of India to find out the harvest time residues of flubendiamide and its des-iodo metabolite on pigeon pea (Cajanus cajan) during the year 2006-2007. Two spray applications of flubendiamide 20 WDG at 50 g (T(1)) and 100 g (T(2)) a.i./ha were given to the crop at 15-days interval. The foliage samples at different time intervals were drawn at only one location, however, the harvest time samples of pigeon pea grain, shell, and straw were drawn at all the four locations. The residues were estimated by HPLC coupled with UV-VIS variable detector. No residues of flubendiamide and its des-iodo metabolite were found at harvest of the crop at or above the LOQ level of 0.05 μg/g. On the basis of the data generated, a pre-harvest interval (PHI) of 28 days has been recommended and the flubendiamide 20 WDG has been registered for use on pigeon pea by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India and the MRL has been fixed by Ministry of Health and Family Welfare, Government of India under Prevention of Food and Adulteration as 0.05 μg/g on pigeon pea grains.     

Prallethrin induced biochemical changes in erythrocyte membrane and red cell osmotic haemolysis in human volunteers

Changes in biochemical composition in erythrocyte membrane, erythrocytic osmotic haemolysis, and nitrite and nitrate levels in plasma were analyzed in 12 human volunteers who were exposed regularly to prallethrin, a type I pyrethroid mosquito repellent. The results revealed a decrease in cholesterol (C) and phospholipid (P) moieties in erythrocyte membrane with no consequent change in C:P ratio. Further, a significant decrease in the content of phosphatidyl serine suggested that PS is a sensitive phospholipid species to the pyrethroid action. Significant decrease in membrane lipid peroxidation and enhanced levels of nitrite and nitrate in plasma and erythrocyte indicate that increased generation and availability of nitric oxide might have rendered tolerance to erythrocyte membrane by protecting the cells from haemolysis. Increased NO(2) and NO(3) may be due to increased activity of nitric oxide synthase (NOS) and/or expression of isoforms of NOS. A possible involvement of free radical scavenging and antioxidant effects of nitric oxide might have contributed to the observed decrease in lipid peroxidation in the present study.