Showing papers by "College of Tropical Agriculture and Human Resources published in 2006"

Biological control of invasive species: solution or pollution?

Abstract: Biological control of invasive species using co-evolved natural enemies has long been considered a safe, cost effective, and environmentally benign tool for pest management. However, recent work has questioned the extent to which these imported natural enemies have negative impacts on populations of non-target species. The result has been a vociferous debate about the safety and proper role of biological control, often without convincing evidence on either side. The issues are particularly well focused in Hawaii, with its high numbers of both endemics and invasive pest species. We review the data concerning environmental impacts from past biocontrol projects, discuss the patterns and generalizations that emerge from retrospective analyses, and consider some new techniques for risk assessment. We then emphasize the need for a federal regulatory framework that is rational, efficient, transparent, and ecologically meaningful.

Tourism’s Forward and Backward Linkages

Abstract: This article proposes linkage analysis as a complement to the traditional tourism-impact analysis to examine tourism’s economic imprints on a destination’s economy. The starting point of tourism-impact analysis is final demand; impact analysis measures the direct and indirect impacts of tourist spending on the local economy. The starting point of linkage analysis is the tourism sector; the analysis examines the strengths of the inter-sectoral forward (FL) and backward (BL) relationships between the tourism sector and the nontourism industries. The FL measures the relative importance of the tourism sector as supplier to nontourism industries in the economy, whereas the BL measures its relative importance as demander. Directly applying conventional linkage analysis to tourism is not straightforward because tourism is not a defined industry. Thus, we develop a methodology to calculate tourism’s forward and backward linkages using national, regional, or local input-output tables and demonstrate its utility by...

Advances in Crop Water Management Using Capacitive Water Sensors

Abstract: Advances in microelectronics during the last decades resulted in the development of several dielectric‐based soil water monitoring techniques, that is, time‐domain reflectometry, single and multisensor capacitance probe (MCP) systems. These techniques have simplified the real‐time determination of water content at fine spatial and temporal scales. In this chapter, single and MCP systems will be referred to as capacitance. Because of their relatively low cost and ease of operation, capacitance has enjoyed widespread acceptance among researchers, growers, and consultants. This chapter gives an overview of the principle of operation of capacitance soil water content measuring systems. Installation and calibration procedures of these systems were also covered. The applications of capacitance are diverse. They have been used extensively as an essential part of many irrigation scheduling programs for different crops. We used real‐time logging capabilities of capacitance to give more detailed information about plant water uptake, effective rainfall, and also to determine some soil physical properties. Results of these types of studies demonstrate that considerable improvement in efficient water use can be made by collecting high‐resolution soil water content data in the soil, around the crop. Despite their success, the capacitance system showed some temperature and salinity effects for different soil types. Further research is needed to eliminate these salinity and temperature effects if these capacitance systems are to take their place as some of the leading soil water monitoring sensors.

Spatial Distribution of Soil Properties in Water Conservation Area 3 of the Everglades

Abstract: The need to integrate environmental responses at the landscape scale is a reoccurring theme in biogeochemistry and ecology. This linkage can be addressed by using geostatistics to examine spatial patterns and then assessing the relationships of these patterns to known ecosystem drivers. In this study, we used a stratified random sampling design to collect soil cores from 388 sites to quantify the spatial distribution of soil properties in a 233000 ha subtropical wetland, Water Conservation Area 3 (WCA-3). To reflect hydrologic boundaries within the system, WCA-3 was divided into three zones: 3AN, 3AS, and 3B. Interpolated maps indicated that the highest levels of bulk density were located in western 3AN, whereas the highest total phosphorus (TP) values were located in northern 3AN and in areas adjacent to a canal bisecting the area. Twenty-five percent of 3AN had TP concentrations in the 0- to 10-cm layer . 500 mg kg 21 , indicating enrichment beyond historic levels. Only 5% of 3AS and 6% of 3B showed TP . 500 mg kg 21 . Total nitrogen (TN) and carbon (TC) were lowest in western 3AN, whereas the rest of WCA-3 had higher and more homogenous TN and TC distributions. Overall, distributions of soil properties were more homogeneous in 3AS than they were in 3AN or 3B. The approach used in this study provides a model for assessing current impacts to WCA-3, supplies baseline conditions against which future restoration efforts can be evaluated, and could be used in other landscape-scale wetland restoration projects.

Lipid lowering effects of Momordica charantia (Bitter Melon) in HIV-1-protease inhibitor-treated human hepatoma cells, HepG2

Abstract: 1. Hyperlipidemic effects of HIV-1-protease inhibitors (PI) are associated with increased hepatic production of triglyceride (TG)-rich lipoproteins, rather than lipoprotein clearance. PI are known to increase apolipoprotein B (apoB) secretion, apoC-III mRNA expression and decrease apoA-1 secretion. Nutritional therapy remains an important strategy to manage PI-associated hyperlipidemia. 2. This study investigated the in vitro efficacy of Asian vegetable, Momordica charantia or bitter melon (BM) to ameliorate PI-associated apoB and lipid abnormalities in HepG2 cells. 3. Our study demonstrates that bitter melon juice (BMJ) significantly reduced apoB secretion and apoC-III mRNA expression and normalized apoA-I expression in PI-treated HepG2 cells. BMJ also significantly reduced cellular TG and microsomal TG transfer protein, suggesting that lipid bioavailability and lipidation of apoB assembly may play a role in decreased apoB secretion. 4. Identifying molecular targets of BM may offer alternative dietary strategies to decrease PI-associated hyperlipidemia and improve quality of life among HIV-1-infected patients.

Two new species of Apoloniinae (Acari: Trombiculoidea: Leeuwenhoekiidae) from African small mammals, with a key to the species of the world.

Abstract: The genus Liuella Wang et Bai, 1992 is transferred from Trombiculidae to Apoloniinae and a new species Liuella monosetosa sp. n. described from specimens taken in Morocco from the hosts Gerbillus sp. and Meriones libycus Lichtenstein. A new species of Straelensia Vercammen-Grandjean et Kolebinova, 1968, Straelensia variocula sp. n. is described from specimens taken in Morocco and Burkina Faso from the hosts Genetta thierryi Matschie, Gerbillus sp., M. libycus and Elephantulus rozeti (Duvernoy). A list of species, hosts and localities and a key to the species of the Apoloniinae of the world are presented.

Lichen Sulfur Contents as Bioindicators of Crop Sulfur: Deficiency or Luxury Uptake

Abstract: The most important, immediate source of sulfur (S) for agricultural crops is the soil, but the soil supply is augmented by anthropogenic and natural S additions. In either case, lichen S contents provide a means for evaluating the effective S supply. Thus, lichen S content may be a way of determining locations where S emissions are large and extensive and why soil levels may vary from sufficient to deficient. Lichen S and phosphorus (P) contents were determined in two contrasting areas of the North Central United States, one east and one west of the Mississippi River. Mean contents were in µg g−1 S 4100 and P 1550 in Area East and S 2100 and P, 1660 in Area West. Population density and S emissions are much greater in Area East. Sulfur deficiencies are not generally recognized there. Area West includes regions that range from severely S deficient to adequate in soil S, with regions that are borderline predominating. Lichen S in the Gulf Coast Plain area and northwest of the Great Lakes was in the ...

Using participatory rural appraisal and participatory research and extension in a post-independence environment: a case from East Timor

Abstract: A participatory rural appraisal (PRA) conducted in East Timor in 2004 as part of an agricultural development project provided the basis for a number of community-based participatory extension initiatives. The PRA involved several communities throughout a watershed and also served as a training exercise for local agriculture ministry staff. Despite the poverty of many of the communities involved, and in contrast to published literature on the local agricultural situation, farmers clearly expressed their need for more marketable crops and alternative sources of livelihoods. Their desires contrasted with the project's initial assumption that the major need was for increased production of staple crops to alleviate food scarcity. The project consequently branched out from concentrating on basic agronomy of staple crops into developing marketable crops, improving livestock production and facilitating development of a local business. Farmers' groups were set up to allow farmers to develop their own agricultural ...