Farmer's behavior in pesticide use: Insights study from smallholder and intensive agricultural farms in Bangladesh.

Since independence and over the years, pesticides have become a dominant feature of Bangladesh agriculture. To protect farmers' health, environment and to improve sustainability of chemical pest control quantitative understanding of farmers' behavior in pesticide use is critical. However, study on the levels of knowledge and awareness of farmers and the practices of pesticide use are often limited. We conducted a broad analysis on the effects of knowledge and awareness of farmers as well as the influence of the different associated stakeholders such as pesticide retailers and the government, on farmers' behavior in pesticide use from a detailed survey of 917 agricultural households in different regions of Bangladesh. Within eight protective behaviors (PBs) or PPEs were largely influenced by the crops growers and regions. Never discarding empty pesticide containers in the field, never applying pesticides more than prescribed by DAE or the instruction manual, selecting new types of pesticides recommended by DAE and purchasing low toxicity pesticides were the most adopted practices. Most farmers from the South-East region were adopting the PB of wearing mask, gloves and long sleeved clothes when spraying and farmers from South trusted the recommendations of pesticides by village leaders and neighbors. Majority of vegetables growers were well informed that pesticides were very harmful to the quality of agricultural products, the environment, and human health but not rice or mixed crops growers. Generally, PBs were positively affected by the perception of the consequences of farmers' behavior and knowledge of pesticide use but negatively influenced by action of governments and trust of retailers. It is important to recognize the differences that exist among different crops growers and locations. Attempt needs to bridge the gap among crop growers, locations and different stakeholder such as government agencies and retailers to develop policy.

Plant composition changes in a small-scale community have a large effect on the performance of an economically important grassland pest.

BACKGROUND: The grasshopper Oedaleus asiaticus Bey-Bienko (Acrididae: Oedipodinae) is a dominant and economically important pest that is widely distributed across the Mongolian plateau. This herbivore pest causes major damage to the grassland of the Inner Mongolian steppe in China. The population dynamics of herbivore pests is affected by grassland management practices (e.g., mowing and heavy livestock grazing) that alter plant community structures and stoichiometric characteristics. For example, O. asiaticus outbreak is closely associated with plant preference changes caused by nitrogen loss from heavy livestock grazing. However, the manner by which small-scale variation in vegetation affects grasshopper performance and promotes outbreak is poorly characterized. To address this question, we investigated the relationship between small-scale (1 m2) vegetation variability and measures of O. asiaticus performance associated with plant stoichiometric characteristics. RESULTS: We found that food preferences of O. asiaticus varied significantly, but maintained a specific dietary structure for different plant compositions. Notably, small-scale changes in plant community composition significantly affected grasshopper food preference and body size. Partial least-square modeling indicated that plant proportion and biomass affected grasshopper body size and density. We found that this effect differed between sexes. Specifically, female body mass positively correlated with the proportion of Stipa krylovii grass, whereas male mass positively correlated with the proportion of Artemisia frigida grass. Further analyses indicated that grasshopper performance is closely associated with plant stoichiometric traits that might be responsible for the pest's plague. CONCLUSIONS: This study provides valuable information for managing grasshoppers using rational grassland management practices.

Molecular Ecological Basis of Grasshopper (Oedaleus asiaticus) Phenotypic Plasticity under Environmental Selection.

While ecological adaptation in insects can be reflected by plasticity of phenotype, determining the causes and molecular mechanisms for phenotypic plasticity (PP) remains a crucial and still difficult question in ecology, especially where control of insect pests is involved. Oedaleus asiaticus is one of the most dominant pests in the Inner Mongolia steppe and represents an excellent system to study phenotypic plasticity. To better understand ecological factors affecting grasshopper phenotypic plasticity and its molecular control, we conducted a full transcriptional screening of O. asiaticus grasshoppers reared in four different grassland patches in Inner Mongolia. Grasshoppers showed different degrees of PP associated with unique gene expressions and different habitat plant community compositions. Grasshopper performance variables were susceptible to habitat environment conditions and closely associated with plant architectures. Intriguingly, eco-transcriptome analysis revealed five potential candidate genes playing important roles in grasshopper performance, with gene expression closely relating to PP and plant community factors. By linking the grasshopper performances to gene profiles and ecological factors using canonical regression, we first demonstrated the eco-transcriptomic architecture (ETA) of grasshopper phenotypic traits (ETAGPTs). ETAGPTs revealed plant food type, plant density, coverage, and height were the main ecological factors influencing PP, while insect cuticle protein (ICP), negative elongation factor A (NELFA), and lactase-phlorizin hydrolase (LCT) were the key genes associated with PP. Our study gives a clear picture of gene-environment interaction in the formation and maintenance of PP and enriches our understanding of the transcriptional events underlying molecular control of rapid phenotypic plasticity associated with environmental variability. The findings of this study may also provide new targets for pest control and highlight the significance of ecological management practice on grassland conservation.

Determination of traces of molybdenum and lead in foods by x-ray fluorescence spectrometry.

An Energy Dispersive X-ray Fluorescence (EDXRF) method using X-ray emitting isotopes in combination with pre-concentration by carbonization was developed to determine the levels of Mo and Pb accumulated in foods. The samples were carbonized at temperatures range of 150-400°C for 15 min to 2 h for powdering. The powder was then quickly formed into a pellet for EDXRF analysis. This analytical method (detection limit, 0.08 mg/kg) was used to determine levels of Mo and Pb in several kinds of foods from the local kitchen markets. The analytical results indicated that higher concentration of Mo (2.51 ± 0.09 mg/kg) and Pb (0.62 ± 0.13 mg/kg) was present in pulse. The maximum lead concentration is also found in pulses with the mean value of, which is far below the maximum permissible limit (ASP, pp 235, 1980) of Pb in food (1-5 mg/kg). The possibility of determination of traces of Mo and Pb in foods by x-ray fluorescence after carbonization is evaluated by comparative studies of standard reference materials. The method enables fast and direct analysis to be carried out without lengthy sample pretreatment and thereby minimizing sample contamination on a routine basis for food monitoring. No loss (<5%) of Mo and Pb is observed and a significant matrix reduction is achieved. Our findings highlighted that this method could be used for monitoring the levels of heavy metals (like Mo and Pb) accumulation in foods within short time and people can avoid health risk due to toxic effect of food.