An evaluation of the Porac River irrigation system

An irrigation water management research programme was implemented by Hydraulics Research in collaboration with the National Irrigation Administration of the Philippines on the Porac Area of Porac Gumain Rivers Irrigation System. The objectives of the study are to monitor the response of the main canal network to changes in water availability and assess its capability to deliver crop water requirements to sub-areas jointly managed by National Irrigation Administration staff and existing Irrigator Associations. This paper presents an analysis of the response of the main system to the varying irrigation demands, and assesses the conjunctive use of groundwater with surface water and the potential of computer models to assist management with the preparation of the annual irrigation schedules.     

Visits to the U.S. Bureau of Reclamation from South Asia and the Middle East, 1946–1990: An indicator of changing international programs and politics

International study programs have contributed to the diffusion of modern irrigation technologies, approaches, and problems. But the patterns and processes of international travel have received little attention to date. This paper examines foreign visits to the US Bureau of Reclamation (USBR) from South Asia and the Middle East from 1946 to 1990. Using data from the Foreign Activities Branch of the USBR, we compare the participation rates from 16 countries in South Asia and the Middle East. India, Turkey, and Egypt had the highest rates of participation, followed by Pakistan, Iran, and Israel. The frequency of visits is influenced by political, economic, cultural, and institutional factors. But the most important factors appear to be foreign relations and geopolitics. Given the problems faced by national irrigation bureaucracies around the world, there is a need to focus more directly on political factors than in the past.     

Cell death localization in situ in laboratory reared honey bee (Apis mellifera L.) larvae treated with pesticides

In this study, cell death detected by DNA fragmentation labeling and phosphatidylserine (PS) localization was investigated in the honey bee (Apis mellifera L.) midgut, salivary glands and ovaries after treating larvae with different pesticides offered via an artificial diet. To do this, honey bee larvae reared in an incubator were exposed to one of nine pesticides: chlorpyrifos, imidacloprid, amitraz, fluvalinate, coumaphos, myclobutanil, chlorothalonil, glyphosate and simazine. Following this, larvae were fixed and prepared for immunohistologically detected cellular death using two TUNEL techniques for DNA fragmentation labeling and Annexin V to detect the localization of exposed PS specific in situ binding to apoptotic cells. Untreated larvae experienced ∼10% midgut apoptotic cell death under controlled conditions. All applied pesticides triggered an increase in apoptosis in treated compared to untreated larvae. The level of cell death in the midgut of simazine-treated larvae was highest at 77% mortality and statistically similar to the level of cell death for chlorpyrifos (65%), imidacloprid (61%), myclobutanil (69%), and glyphosate (69%) treated larvae. Larvae exposed to fluvalinate had the lowest midgut columnar apoptotic cell death (30%) of any pesticide-treated larvae. Indications of elevated apoptotic cell death in salivary glands and ovaries after pesticide application were detected. Annexin V localization, indicative of apoptotic cell deletion, had an extensive distribution in the midgut, salivary glands and ovaries of pesticide-treated larvae. The data suggest that the tested pesticides induced apoptosis in tissues of honey bee larvae at the tested concentrations. Cell death localization as a tool for a monitoring the subclinical and sub-lethal effects of external influences on honey bee larval tissues is discussed.     

Removing an exotic shrub from riparian forests increases butterfly abundance and diversity

Invasive plants are one of the greatest threats to endangered insect species and a major threat to Lepidoptera in eastern North America. We investigated the effects of the invasive shrub Chinese privet (Ligustrum sinense) and two methods (mulching or hand-felling) of removing it from riparian forests on butterfly communities and compared them to untreated, heavily invaded control plots and to “desired future condition” forests that never had extensive privet cover. Privet mulching resulted in nearly twice as many butterflies as privet felling and both treatments had more butterflies two years after privet removal than untreated control plots. Butterfly communities on control plots differed from those on the two treatments and the desired future condition forests. A number of forest characteristics were evaluated but only herbaceous plant cover (excluding privet) was positively correlated with butterfly abundance, diversity and evenness. The Carolina satyr, Hermeuptychia sosybius, was the best indicator of forests where privet had never invaded. Removing Chinese privet from riparian forests in the southeastern United States greatly improved forest habitats for butterflies and evidence suggests that butterfly communities in other temperate forests could benefit from removal of extensive shrub layers dominated by a single species.     

Distribution and nest site selection of red-shouldered hawks (Buteo lineatus) in forests of northeastern Wisconsin (USA)

Red-shouldered hawks (Buteo lineatus) are threatened in Wisconsin and when nest sites are found during the cruising or marking stage of timber harvesting, the harvest is altered to accommodate the hawks. If nest site locations are known before initiation of timber harvest, foresters can employ a proactive approach to manage red-shouldered hawks while maintaining timber production. We searched for red-shouldered hawks nest sites on Marinette County Forest (MCF) which encompasses 94,000 ha in northeastern Wisconsin and is the second largest county forest in the state. We used a comparative modeling approach to evaluate distribution and habitat relationships of red-shouldered hawk nest sites in relation to a suite of environmental variables in MCF. Models were used to develop forest management recommendations for red-shouldered hawks in Wisconsin. During the spring of 2006 and 2007, we broadcasted conspecific calls to survey 1121 calling stations along forest roads and trails. We located 20 and 25 active nesting territories in 2006 and 2007, respectively (11 of which were active in both years). To understand nest site selection, we measured 22 habitat variables within 0.04-ha plots at active nest sites (n = 34) and at stratified random sites (n = 61). Logistic regression with information-theoretic model selection identified a model including greater tree species richness and closeness to forested wetland as the best-approximating model. Variable selection with Discriminant Function Analysis (DFA) indicated that nest selection was best explained by greater number of tree species, closer distance to forested wetlands, greater volume of downed woody debris, fewer small sawlogs, and increased proximity to streams. Univariate comparisons identified four of the five aforementioned variables in the DFA model as significant. Red-shouldered hawks are likely more common in Wisconsin than their state status suggests. Forest management for red-shouldered hawk nest sites should focus on increasing tree species richness, increasing down woody debris volume, and protecting forested wetlands. These recommendations may assist property managers to locate and plan for continued persistence of this species on MCF.     

Efficacy of spinosad and methoprene,applied alone or in combination,against six stored-product insect species

Efficacy of the insecticides spinosad and methoprene, applied alone or in combination to wheat, was evaluated against six stored-product insect species, Rhyzopertha dominica, Sitophilus oryzae, S. granarius, Cryptolestes ferrugineus, Oryzaephilus surinamensis, and Liposcelis bostrychophila. The concentrations of the insecticides were 0.1 and 0.5 ppm for spinosad and 1 and 5 ppm for methoprene. Parental mortality of R. dominica was 100% on wheat treated with either rate of spinosad, with no progeny production in any combination treatment. Parental mortality of S. oryzae did not exceed 62%, and progeny production was not reduced by any insecticide treatment. All S. granarius adults exposed on wheat treated with spinosad alone at 0.5 ppm were killed, but parental mortality was reduced when methoprene was added. Progeny production was reduced in treatments containing spinosad. Mortality of adult C. ferrugineus was 97% or greater in treatments containing spinosad, but adult mortality of O. surinamensis and L. bostrychophila was not reduced by insecticide treatments. The specific combinations of spinosad and methoprene evaluated in our study would have no benefit over spinosad used alone for control of any of the six species tested.     

Maintaining Genetic Resources of Peach Palm (<Emphasis Type="Italic">Bactris gasipaes</Emphasis> Kunth): The Role of Seed Migration and Swidden-fallow Management in Northeastern Peru

Knowledge of the effects of farmer practices on population genetic parameters of peach palm (Bactris gasipaes Kunth) is relevant to the improvement and conservation of the palm’s genetic resources. Microsatellite markers were used to assess genetic diversity and population structure of peach palm in swidden-fallow agroforestry systems in northeastern Peru. The study covered eight communities, comprising two study areas 160 km apart – one occupied by indigenous Amerindians and the other by mixed race campesinos. Simultaneous analysis of an ex situ peach palm germplasm collection provided a means to compare population genetic parameters. Farmers who were surveyed on seed selection practices for peach palm reported that an average of only four palms (4.3 for campesino and 1.5 for indigenous populations) were used to provide seed for the establishment of the forest gardens sampled. As expected, inbreeding coefficients observed within communities were relatively high (f = 0.105 − 0.210), however, observed heterozygosities within communities were also high (0.625–0.741). A metapopulation approach was used to describe migration within and among regions, implying a hierarchical structure of gene flow which maintains relatively high levels of genetic diversity. Seed migration was found to occur over longer distances (≤600 km) and at a higher frequency (46% of palms sampled) in the indigenous study area, and a proportionally greater number of alleles was found (49 vs. 43 over three loci) with twice as many private alleles occurring only in the indigenous populations. The farmers’ practice of preserving remnant palms through successive swidden generations may have contributed to the maintenance of alleles by reducing the severity of founder effects. Although the campesino study area exhibited a significant (20% of the variation; p < 0.01) isolation-by-distance relationship across 35 km distance, in general, both study populations had relatively limited genetic structure (θ = 0.012–0.03), which is believed to have resulted from the exchange of seeds over long distances and periods of time.     

Sources of variation in nutrient intakes among men in Shanghai, China

BACKGROUND AND OBJECTIVE: Random errors, from any source, will attenuate epidemiological risk estimates. Before we launched the Shanghai Men's Health Study (SMHS), a large population-based cohort study investigating the diet-cancer association among Chinese men, a dietary calibration study was conducted among 96 men aged 40-75 years (mean age 56.5 years), with biweekly 24-hour dietary recalls (24HDRs) implemented over a 1-year period. Data from this study were analysed to evaluate the nature and magnitude of variances for intake of 26 nutrients among SMHS participants, to compare variance ratios of 26 nutrients among Chinese men and women and individuals in other studies, and to estimate the number of 24HDRs required for future dietary calibration studies in similar populations. DESIGN: Ninety-six healthy, free-living men in Shanghai were administered biweekly 24HDR interviews 24 times over a 1-year period. To assess between-individual and within-individual contributions to variance, a mixed effects model was fitted and ratios of within-individual to between-individual (sigma(w)(2)/sigma(b)(2)) dietary intake variances were computed. SETTING: Shanghai, China. RESULTS: In agreement with reports from studies conducted in the USA and many other countries, we found that within-individual variances were usually larger than between-individual variances in dietary intake for all nutrients. The sum of all other variation (e.g. weekday and weekend, seasonal, interviewer) accounted for less than 5% of total variation. Ratios of within- to between-individual variances (for log-transformed data) ranged from 1.25 for carbohydrate intake to near 8 for delta-tocopherol intake. CONCLUSIONS: The results of this study suggest that among middle-aged and elderly Chinese men in Shanghai, within- and between-individual variation account for more than 95% of the total variation for 26 nutrients. Further dietary validation studies in the same population could be adequately carried out with only 12 days of dietary recalls, if 100 participants were enrolled.