Acute Toxicity of Synthetic Pyrethroid Cypermethrin on the Common Carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.) Embryos and Larvae

In this study, the toxic effects on the embryos and larvae of the common carp were used as a model to investigate the synthetic pyrethroid pesticide, cypermethrin, which contaminates aquatic ecosystems. Data obtained from the cypermethrin acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The control and eight test experiments were repeated five times. The number of dead embryos significantly increased in response to cypermethrin concentrations 0.0001, 0.001, 0.01, 0.1, 1, 2, 4 and 8 μg l⁻¹ (p<0.05 for each case). The 48 h LC₅₀ value (with 95% confidence limits) of cypermethrin for common carp embryos was estimated at 0.909 (0.256–5.074) μg l⁻¹. Dose–response decreases in hatching success were recorded as 87.4, 85.0, 80.2, 71.4, 56.3, 48.6, 38.8 and 23.5%, respectively. The lowest concentration of cypermethrin (0.0001 μg l⁻¹) produced a significant increase in the number of dead larvae compared to the control group (p<0.05). The number of dead larvae significantly increased with increasing cypermethrin concentrations exposed for 1–96 h (p<0.05). The highest concentration (8 μg l⁻¹) showed the highest larvae mortality. The 96 h LC₅₀ value (with 95% confidence limits) of cypermethrin for common carp larvae was estimated at 0.809 (0.530–1.308) μg l⁻¹. The results of the study suggest that low levels of cypermethrin in the aquatic environment may have a significant effect on the reproduction and development of carp.     

The mtDNA legacy of the Levantine early Upper Palaeolithic in Africa

Sequencing of 81 entire human mitochondrial DNAs (mtDNAs) belonging to haplogroups M1 and U6 reveals that these predominantly North African clades arose in southwestern Asia and moved together to Africa about 40,000 to 45,000 years ago. Their arrival temporally overlaps with the event(s) that led to the peopling of Europe by modern humans and was most likely the result of the same change in climate conditions that allowed humans to enter the Levant, opening the way to the colonization of both Europe and North Africa. Thus, the early Upper Palaeolithic population(s) carrying M1 and U6 did not return to Africa along the southern coastal route of the "out of Africa" exit, but from the Mediterranean area; and the North African Dabban and European Aurignacian industries derived from a common Levantine source.     

Impact of cold storage on the performance of entomophagous insects: an overview

Mass rearing for commercial production of high quality beneficial insects is considered as an important tool for biological control programmes worldwide, especially those based on augmentative releases. Low temperature storage is a valuable method for increasing the shelf life of entomophagous insects. Insect predators and parasitoids are used extensively in biological control programmes and, because of this, studies on cold storage started over 90 years ago. The ability to store reared biocontrol agents at low temperatures for certain duration provides an opportunity to accumulate or stockpile sufficient number of entomophagous insects for field release at proper weather conditions and make them available during high demand periods to the concerned farmers. Cold stored natural enemies can be synchronously released in the fields during critical stages of pest outbreaks. Cold storage also helps to keep viable stock of natural enemies when not needed and to minimize laboratory operations by prolonging their survival and delaying eclosion. Cold storage tolerance is highly plastic trait influenced by a range of biotic and abiotic factors experienced before, during and after cold exposure. These factors ultimately affect the development, longevity, fecundity, parasitization, sex-ratio and other fitness parameters along with morphology, behaviour and physiology of entomophagous insects. For the successful implementation of a cold storage project, knowledge of these diverse factors that cause storage and post-storage effects is essential. The potential of cold storage protocols in improving mass rearing and commercial production of bioagents is thus reviewed to access the strategies, innovations, techniques, devices and wisdom involved in the process of cold storage of entomophagous insects worldwide.     

Factors influencing biomass and carbon storage potential of different land use systems along an elevational gradient in temperate northwestern Himalaya

We observed the influence of five different altitudes and prevailing agro ecosystems on biomass and carbon sequestration potential in Kullu district of Himachal Pradesh, India. The study area had five prevailing land uses viz., agriculture, agro-horticulture, horticulture, silvi-pasture, and forest at four elevations representing about 1 °C temperature change. The results showed that maximum total biomass of 404.35 Mg C ha^?1 was accumulated by forest landuse and followed a decreasing trend in the order as forest > silvi-pasture > agro-horticulture > horticulture > agriculture. Similar trends were also seen with respect to biomass carbon (C) density and C-sequestration potential of different land uses. Biomass and carbon density potential enhanced with the increase in the altitudinal ranges from 1100–1400 to 2000–2300 m a.s.l. But, the rate of C-sequestration potential enhanced from 1100 to 2000 m and declined at 2000–2300 m a.s.l. Maximum carbon density (393.29 Mg C ha^?1) of both plant as well as soil was displayed by the forest-based land use systems situated at an altitudinal gradient of 2000–2300 m a.s.l. The rate of C-sequestration was maximum (2.17 Mg ha^?1) in the agro-horticulture at 2000–2300 m a.s.l. This study brings out the potential of different land use systems influenced by varying factors on their C-sequestration potential in western Himalayan elevation gradient, thereby providing useful information for effective management in a climate change mitigation and carbon budget.     

Quantification of organic carbon and primary nutrients in litter and soil in a foothill forest plantation of eastern Himalaya

The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four forest tree species(Lagerstroemia parviflora, Tectona grandis, Shorea robusta and Michelia champaca) in the Chilapatta Reserve Forest of the Cooch Behar Wildlife Division in the Terai zone of West Bengal, India. The most litter(5.61 Mg ha~(-1))was produced by T. grandis plantation and the least(4.72 Mg ha~(-1)) by L. parviflora. The material turnover rate to the soil through decomposition from total litter was fastest during the first quarter of the year and subsequently decreased during the next two quarters. The material turnover rate was only 1 year, which indicates that more than90% of the total litter produced decomposed within a year.The available primary nutrient content in litter varied across the four plantations over the year. The plantations generally did not significantly influence the soil physical characteristics but did significantly influence the availability of primary nutrients and organic carbon at two depths(1–15 and16–30 cm) over the year. The availability of soil primary nutrients in the four plantations also increased gradually from the first quarter of the year to the third quarter and then decreased during the last quarter to the same level as in the first quarter of the year at both depths. The availability for soil organic carbon in the plantations followed a similar trend. The amount of litter produced and the material turnover in the soil in the different plantations differed, influencing the nutrient availability and organic carbon at the plantations. The amount of soil organic carbon was highest for T. grandis(2.52 Mg ha~(-1)) and lowest for L. parviflora(2.12 Mg ha~(-1)). Litter is the source of soil organic matter,and more the litter that is produced by the plantations, the higher will be the content and amount of soil organic carbon in the plantation.     

Insecticidal activity of (2<Emphasis Type="Italic">n</Emphasis>-octyl<Emphasis Type="Italic">cyclo</Emphasis>prop-1-enyl)-octanoic acid (I) against three Coleopteran stored product insects from <Emphasis Type="Italic">Sterculia foetida</Emphasis> (L.)

The insecticidal activities of the extracts, fractions, and pure compound of Sterculia foetida (L.) seeds were investigated against three major stored product pests, namely, Sitophilus oryzae (L.), Callosobruchus chinensis (L.), and Tribolium castaneum (H.), through contact and fumigation bioassay. Responses varied with test chemicals, insect species, exposure times, and doses individually. The biologically active constituent of the S. foetida seeds was characterized as a cyclopropene fatty acid structurally elucidated as (2n-octylcycloprop-1-enyl)-octanoic acid (I) by spectroscopic analysis. The filter paper application of, (2n-octylcycloprop-1-enyl)-octanoic acid (I) at 0.2 mg/cm² caused 100% mortality to all test insects 2 days after treatment (2 DAT). Among the chromatographic fractions, only the pure hexane-eluted fraction caused 100% mortality at 0.3 mg/cm² to S. oryzae and C. chinensis 2 DAT, while the dose required to obtain the same percentage of mortality with the crude seed extract was 0.6 mg/cm². Under all treatment conditions, T. castaneum exhibited less susceptibility, taking longer than the other insects to show symptoms of toxicity. In terms of fumigant activity, the compounds appeared to be more effective in a vapor form against all the three insects in closed containers compared with open containers. These results suggest that the insecticidal activities of the test compounds were attributable to contact mode of action, although there was also significant fumigant toxicity. The results indicate that the bioactive compound isolated from S. foetida could act as a potent insecticide against S. oryzae, C. chinensis, and T. castaneum populations.