The toxicity and behavioural effects of neem limonoids on Cnaphalocrocis medinalis (Guenée), the rice leaffolder

Meliaceae plant products have been shown to exert pesticidal properties against a variety of insect species. In agricultural pest control programs, such products may have the potential to be used successfully as botanical insecticides. The effect of the neem (Azadirachta indica) limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione and deacetylnimbin on the biology and mortality of rice leaffolder larvae was investigated. In laboratory experiments, treatment with neem limonoids suppressed leaf folding behaviour of C. medinalis. Biological parameters (larval duration, pupal duration adult longevity and fecundity) were also affected by the treatment. Azadirachtin, salannin, and deacetylgedunin showed high bioactivity at all doses, while the rest of the neem limonoids were less active, and were only biologically active at high doses. Azadirachtin was most potent in all experiments and produced almost 100% larval mortality at 1 ppm concentration. These results indicate neem limonoids affect the larval behaviour. These effects are most pronounced in early instars.     

Correction to: Studies on the influence of natural resource utilization by humans on foraging behavior of honey bees at rural ecosystems

Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org10.1007/s11356-021-14573-3     

Effect of ultrasonic pretreatment on secondary sludge and anaerobic biomass to enhance biogas production

Journal of Material Cycles and Waste Management - Anaerobic digestion studies were carried out with tannery excess secondary sludge obtained from common effluent treatment plant. The excess sludge...     

Identification of source of faecal pollution of Tirumanimuttar River, Tamilnadu, India using microbial source tracking

Efficient management of deteriorating water bodies can be achieved by determining the sources of faecal pollution. Resourceful techniques for discrimination of the sources of Escherichia coli in surface water have recently been developed, including the use of river water to facilitate faecal indicator surveillance, identification of sources of faecal contamination and employing relevant management practices to maintain water quality. This study was conducted to employ microbial source tracking (MST) techniques for the determination of the sources of faecal pollution based on a water quality investigation of the physico-chemical characteristics and coliform count point of the Tirumanimuttar River. To accomplish this, an MST library-based antibiotic resistance analysis, serotyping and the genomic tool rep-PCR techniques were applied, and the obtained results were analysed statistically. Among 135 and 70 E. coli isolates present in the library and water samples collected from the river and nearby well water sources, respectively, most showed intrinsic, high or moderate resistance to antibiotics. Isolates from human and pig faecal sources were 92% homologous with the samples from the river, whereas isolates from sewage and dairy cattle showed 89% and 80% homology, respectively. These findings indicated that the Tirumanimuttar River is subjected to stress from anthropogenic activities and runoff contaminated with agricultural and human faecal contamination. The sources of faecal pollution identified in this study may facilitate the monitoring and management of the Tirumanimuttar River.     

Effect of neem limonoids on lactate dehydrogenase (LDH) of the rice leaffolder, Cnaphalocrocis medinalis (Guenée) (Insecta: Lepidoptera: Pyralidae)

Neem is derived from the neem tree Azadirachta indica A. Juss. (Meliaceae), and its primary insecticidal component is the tetranortriterpenoid azadirachtin and other limonoids. The effect of neem limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione and deacetylnimbin on enzyme lactate dehydrogenase (LDH) activity of the rice leaffolder (RLF) Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) larvae was investigated. There was a decrease in enzyme activity relative to the control at all concentrations tested. When fed a diet of rice leaves treated with neem limonoids in bioassays, gut tissue enzyme, LDH levels in rice leaffolder larvae are affected. These results indicate neem limonoids affect LDH activity. These effects are most pronounced in early instar larvae. Azadirachtin was the most potent in of all the limonoids in all experiments indicating strong enzyme inhibition. Clear dose-response relationships were established with respect to LDH activity.     

Influence of cover thickness in structural frames exposed to fire and service loads

Environmental Science and Pollution Research - This paper deals with the effect of cover thickness in a reinforced concrete columns of 3-D (three dimensional) frame structures under progressive...     

Performance studies of low GWP refrigerants as environmental alternatives for R134a in low-temperature applications

Environmental Science and Pollution Research - Climate change is an important environmental issue that is causing global temperatures to rise. The primary environmental targets are to reduce carbon...