Indigenous utilization of termite mounds and their sustainability in a rice growing village of the central plain of Laos

<p>Abstract</p> <p>Background</p> <p>The objective of this study was to investigate the indigenous utilization of termite mounds and termites in a rain-fed rice growing village in the central plain of Laos, where rice production is low and varies year-to-year, and to assess the possibility of sustainable termite mound utilization in the future. This research was carried out from 2007 to 2009.</p> <p>Methods</p> <p>The termites were collected from their mounds and surrounding areas and identified. Twenty villagers were interviewed on their use of termites and their mounds in the village. Sixty-three mounds were measured to determine their dimensions in early March, early July and middle to late November, 2009.</p> <p>Results</p> <p>Eleven species of Termitidae were recorded during the survey period. It was found that the villagers use termite mounds as fertilizer for growing rice, vegetable beds and charcoal kilns. The villagers collected termites for food and as feed for breeding fish. Over the survey period, 81% of the mounds surveyed increased in volume; however, the volume was estimated to decrease by 0.114 m³mound^-1year^-1on average due to several mounds being completely cut out.</p> <p>Conclusion</p> <p>It was concluded that current mound utilization by villagers is not sustainable. To ensure sustainable termite utilization in the future, studies should be conducted to enhance factors that promote mound restoration by termites. Furthermore, it will be necessary to improve mound conservation methods used by the villagers after changes in the soil mass of mounds in paddy fields and forests has been measured accurately. The socio-economic factors that affect mound utilization should also be studied.</p

Relative Role of Flower Color and Scent on Pollinator Attraction: Experimental Tests using F1 and F2 Hybrids of Daylily and Nightlily

The daylily (Hemerocallis fulva) and nightlily (H. citrina) are typical examples of a butterfly-pollination system and a hawkmoth-pollination system, respectively. H. fulva has diurnal, reddish or orange-colored flowers and is mainly pollinated by diurnal swallowtail butterflies. H. citrina has nocturnal, yellowish flowers with a sweet fragrance and is pollinated by nocturnal hawkmoths. We evaluated the relative roles of flower color and scent on the evolutionary shift from a diurnally flowering ancestor to H. citrina. We conducted a series of experiments that mimic situations in which mutants differing in either flower color, floral scent or both appeared in a diurnally flowering population. An experimental array of 6×6 potted plants, mixed with 24 plants of H. fulva and 12 plants of either F1 or F2 hybrids, were placed in the field, and visitations of swallowtail butterflies and nocturnal hawkmoths were recorded with camcorders. Swallowtail butterflies preferentially visited reddish or orange-colored flowers and hawkmoths preferentially visited yellowish flowers. Neither swallowtail butterflies nor nocturnal hawkmoths showed significant preferences for overall scent emission. Our results suggest that mutations in flower color would be more relevant to the adaptive shift from a diurnally flowering ancestor to H. citrina than that in floral scent

Soil Productivity after Decomposition of Waste Materials under Different Soil Moisture and Temperature

Productivity of the soil with waste material (WM), i.e., bagasse, coir dust, rice chaff and rice straw decomposed for two months at various temperatures and soil moisture were investigated by analyzing the chemical properties and growth of maize cultured on the soil for 45 days. The soil with decomposed WM (WM soil), tended to show lower pH values than the soil without WM soil (control) as a whole. The values of electric conductance were higher in WM soil, especially in the soil with decomposed rice chaff and rice straw referred to as rice-chaff and rice-straw soils, respectively. The total N content tended to be higher in the WM soil except for coir dust soil. The total C content tended to be higher in all WM soils. The difference in the content of total N and total C between WM and control soils was remarkable in bagasse soil. The change of the chemical properties of the soil did not apparently correlate with the rate of CO2 generation during incubation of WM soils, but pH, electric conductance, content of total N and total C contents were higher in the soils generating CO2 at a rate of 40 to 80 ppm min−1, in bagasse or rice straw soils. The dry matter production of maize on WM soils was positively correlated with the rate of CO2 generation. It was suggested that the WM soils generating little CO2, such as the soil with bagasse or rice straw decomposed in a dry condition, tended to inhibit maize growth owing to low pH and shortage of available nitrogen by rapid decomposition just after the start of maize growth. The wet WM soils generating CO2 format a rate of 40 to 80 ppm min−1, e.g., bagasse and rice straw soils might be favorable for dry matter production of maize

Effects of Soil Moisture and Temperature on Decomposition Rates of Some Waste Materials from Agriculture and Agro-industry(Agronomy)

The effect of soil moisture and temperature on decomposition of waste materials, bagasse, coir dust, rice chaff and rice straw, in soil were examined by measuring the decrease in weight of and CO2 generation from each waste material. The rate of the decrease in weight increased as temperature rose, and was highest in rice straw followed by bagasse, rice chaff and coir dust in this order, irrespective of soil moisture and temperature level. In all waste materials, the rate of decrease in weight was highest in the soil holding the water equivalent to field capacity (saturated soil) followed by submerged soil and dry soil in this order. CO2 generation rate was also highest in rice straw followed by bagasse, rice chaff and coir dust. It was highest in saturated soil followed by half-saturated or submerged soil and dry soil in this order. The rate of CO2 generation from rice straw in saturated soil was highest at the initial period of incubation and it decreased thereafter, but the rate in submerged soil was highest at 40 and 20 days after the start of incubation at 20 and 35ºC, respectively. The rate of CO2 generation from coir dust and rice chaff was very low at all soil moisture levels at either 20 or 35ºC. The content of total N in the waste materials was positively and significantly correlated with the rate of decrease in weight in saturated and submerged soils at a moderate temperature (Oct. – Dec.), and in submerged soil at a high temperature (Aug. – Oct.). It was also significantly correlated with CO2 generation rate in submerged soil at 20ºC. Holocellulose and hemicellulose contents were negatively and significantly correlated with CO2 generation rate in dry soil at 20ºC. Lignin content was also significantly and negatively correlated with CO2 generation in dry soil at 35ºC