Category Archives: Volume 35 No. 2 (2013)

Using Stable Carbon and Nitrogen Isotopes to Evaluate Parrotfish Diet

Authors: Maria Elisa B. Gerona1 and Florence C. Evacitas2


With limited inconclusive data provided by gut content analysis, stable isotope analysis has recently emerged to validate trophic position and dietary intake. In this study, a dual isotope approach was used to reveal parrotfish feeding. Comparisons of δ13C and δ15N values of muscle and liver among yellow barred (Scarus dimidiatus), rosy cheek (S. psittacus), and blue-barred (S. ghobban) parrotfishes from Canigao Island, Matalom, Leyte were made to track dietary shifting and to compare dietary carbon intake. Trophic assignment was based on the assumption that consumers are enriched by a factor of 3-4‰ for δ15N, relative to their diet. The δ13C values of muscle tissues of the three species of parrotfish were significantly higher (p=0.001) than those of their liver suggesting dietary shifting. The δ13C values of both muscle and liver tissues of S. dimidiatus were significantly (p<0.001) higher than those of S. psittacus and S. ghobban, but δ13C values of muscle and liver of S. psittacus and S. ghobban did not vary significantly. These mean that S. dimidiatus have different long term and recent dietary carbon intake compared to the other two species, while S. psittacus and S. ghobban have relatively the same dietary carbon intake. Considering the 1‰ δ13C trophic enrichment of consumers relative to their diet, possible dietary carbon sources of the sampled parrotfish include Dendronephthya spp., Ulva reticulata, Sargassum oligocystum, Dictyota sp., Digenea sp., Chlorodesmis sp., and Sargassum muticum suggesting that parrotfishes are generalist consumers. Mean stable isotope nitrogen ratios of S. dimidiatus (5.9‰), S. psittacus (6.9‰) and S. ghobban (6.7‰) together with their carbon isotope ratios confirmed that all sampled parrotfish species are generalist primary consumers.

Keywords: δ13C, δ15N, Canigao Island, diet, trophic position

Annals of Tropical Research 35(2):108-123(2013)
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Comparative Carbon Storage of Lanzones (Lansium domesticum) – fruit tree and Falcata (Paraserianthes falcataria) – forest tree based Agroforestry Systems

Authors: Samuel L. Malayao1 and Teodoro C. Mendoza2


Two agroforestry systems, a fruit tree-based with lanzones (Lansium domesticum) as dominant fruit tree and a forest tree-based with falcata (Paraserianthes falcataria) as dominant wood tree, were studied to compare their total carbon stocks in the above ground biomass (upperstorey and understorey), floor litters and soil and to determine any differences of soil organic carbon(SOC) in three soil depths: 0-30, 31-60 and 61-100 cm. Each site representing one agroforestry systems was grouped according to vegetation stand. For each vegetation stand, representative samples were taken from upper storey and under storey above ground biomass, floor litters and soil. Samples were analyzed for carbon content at International Rice Research Institute’s (IRRI) Analytical Service Laboratories(ASL), Los Baños, Laguna using Dumas Combustion Method.
The SOC in the soil depths (0-30, 31-60 and 61-100 cm) did not vary significantly in the two agroforestry systems. The above ground upperstorey biomass had the most carbon followed by the carbon stored in the soil, then, above ground understorey biomass and lastly, floor litters. The above ground upperstorey biomass of the fruit tree-based agroforestry system had slightly higher carbon stock at 38.92 tC ha-1 compared with the forest tree-based agroforestry system at 34.66 tC ha-1 due to the lanzones fruit tress. The 4 – year old falcata-based agroforestry systems had higher annual C sequestration of 14 tC ha-1 yr-1 while the lanzones-based agroforestry system had 1.8 tC ha-1 yr-1. Nevertheless, whatever is the main tree component, agroforestry performs ecological services as in carbon sequestration and at the same time provides financial benefits.

Keywords: carbon stocks; agroforestry systems; carbon density; biomass; soil organic carbon; floor litter

Annals of Tropical Research 35(2):88-107(2013)
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Social Impacts of the Abaca Bunchy Top Disease and Adaptive Strategies of Farm Households: A Case in Leyte, Philippines

Author: Jedess Miladel C. Nuñez


The abaca industry is in crisis because of the bunchy-top disease which has destroyed thousands of hectares of abaca ( Musa textilis Nee). While government and research efforts are focused on the eradication of the disease, this study brings attention to the changes in people’s livelihoods and conditions due to the decline of their agricultural and economic productivity as well as their adaptive responses to these impacts and explanations for these. The income loss experienced by households when their crops were destroyed by the combination of the abaca bunchy top disease (ABTD) and inappropriate use of herbicides had secondary impacts to businesses in and near the village. The loss of income led to flow-on impacts on households’ food security, education, health and even psychosocial well-being. However, small landowning households (less than 10ha) were more affected than those with medium-sized farms (10-30ha) in that the changes they experienced were more severe in terms of the quality and quantity of their food and budget for their children’s education. Moreover, households’ access to resources influenced the kind of strategies they employed, with small landowners generally engaged in wage labor, credits and loans and small enterprises to earn income. Medium landowners were generally independent of loans and one such land owner was able to engage in a profitable new enterprise (furniture-making). This case study’s focus shifted from the disease to the affected population and their adaptive responses. Moreover, it looked at the affected population as a stratified society affected by and responding to a disaster differently according to their access to resources.

Keywords: crop disease, cropping pattern, enterprise

Annals of Tropical Research 35(2):69-87(2013)
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Assessment of Insect Spectrum, and Insect-Induced Damage at Different Growth Stages of Cucumber (Cucumis sativus L.) In A Rainforest Transition Zone Of Nigeria

Authors: Olufemi Olutoyin Richard Pitan and Caroline Oyindamola Filani


In Nigeria, published information on the range and relative importance of different pests on cucumber is scanty. Studies were therefore carried out in a survey to determine the insects associated with cucumber, and on-field to quantify insect induced damage at different crop growth stages. Surveys were carried out in five cucumber fields each at Ibadan, Oyo State, and Abeokuta, Ogun State, Nigeria. In the field experiment, cucumber plants were protected at different stages: pre-flowering, flowering, post-flowering/fruiting, or all growth stages with lambd-acyhalothrin sprayed weekly at 25ga.i/ha. The control plots were without insecticide protection. Insects recorded from the surveys included: Zonocerus variegatus, Podagrica uniforma, Aphis gossypii, Myzus persicae, Bemisia tabaci, Thrips tabaci, Epilachna chrysomelina, and fruit flies Bactrocera invadens and Dacus ciliatus. Other insects found were Cheilomenes lunata and Chelisoches flavipennis, which are natural enemies of whiteflies and aphids, respectively, and the honey bees, Apis meliferae, which is a pollinator. Significantly higher number and heavier fruits, which were not statistically different from those recorded in full protection plots, were produced when cucumber was protected at post-flowering stage. Fruit fly damage in unprotected plots was 60% and 55%, while that of the Epilachna beetle was 55% and 46% in 2004 and 2009, respectively. Yield was significantly higher by 50% in plots sprayed at post-flowering stage over the control. Epilachna beetle and the fruit flies attacking at the post-flowering/fruiting stage are therefore, important in cucumber production, and the fruiting stage is the most critical where insect pest control measures must be applied.

Keywords: control, cucumber, lambda-cyhalothrin, insects, damage, Epilachna chrysomelina, Dacus spp., and Bactrocera spp.

Annals of Tropical Research 35(2):60-68(2013)
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Influence of Variety and Sulfite on Controlling Browning Within Four Months of Storage of Dehydrated Jackfruit (Artocarpus heterophyllus Lam.) Pulp

Authors: Lorina A. Galvez1, Remberto A. Patindol2 and Linda B. Mabesa3


The main problem of the dehydrated jackfruit developed by the Visayas State University (VSU) is that it develops browning after one to two month seven if the product is packed in a good packaging material. This study was conducted to determine the effects of variety and sulfite in controlling browning within 4 months of storage of dehydrated jackfruit pulp. Two recommended jackfruit varieties (AES Jak 1 and AES Jak 2) and two levels of sulfite (0.1 and 0.2% w/w) were used in the study. Treatments were laid out in CRD with three replications. Data were analyzed using SPSS version 16 and HSD was used to test the significance between treatments. Different parameters on physico-chemical properties and functional components of the product were investigated at 0, 2 and 4 months of storage.
Results revealed that utilization of AES Jak 1 variety and either 0.1 or 0.2% w/w sulfite can be used in dehydrated jackfruit processing with least browning during storage. Correlation analysis showed that as pH and TTA increase, DB decreases which indicates that pH and TTA can be used as control in minimizing browning. The weak correlation of TP and TC on DB implies that browning of stored dehydrated jackfruit is caused by non-enzymatic reaction.

Keywords: Physico-chemical properties, dehydrated jackfruit, functional components.

Annals of Tropical Research 35(2):40-59(2013)
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Potential of Root Crops as Source of Electrical Energy

Authors: Daniel Leslie S. Tan1, Julie D. Tan1, Mark Anthony R. Atanacio1 and Ruel B. Delantar2


Energy from edible and inedible root crop roots and tubers using galvanic cell and processing waste waters through microbial fuel cell (MFC) technology was harnessed. Electrolyte in the roots and tubers was tapped for galvanic cell and the microorganisms from waste waters act as catalyst in MFC. In galvanic cell, the optimized responses of badiang, cassava and sweetpotato were greatly affected by the surface area and distance between anode and cathode electrodes. An increase of nata-de-coco membrane size in MFC increased the voltage and current by 4.94 and 11.71 times, respectively. Increasing the width of anode also enhanced the responses. Different types of microorganisms were isolated from the biofilm anode of MFC. Their growth and proliferation which corresponded to the generation of electricity were also demonstrated in this study. A total of 54 bacterial isolates were collected from the biofilm at the anode of single-chamber MFC (SCMFC). The generated electricity observed using light emitting diodes (LED) showed potential both for galvanic and microbial fuel cell. The generated regression models are reliable tools in predicting desired outputs for future applications. These promising results demonstrated basic information on the electrical energy recovery from rootcrop waste waters and roots/tubers.

Keywords: energy, galvaniccell, rootcrop, microbial fuel cell, biofilm, nata-de-coco membrane

Annals of Tropical Research 35(2):22-39(2013)
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Physicochemical Properties, Nutritional and Sensory Quality of “Batuan” [Garcinia binucao (Blco.) Choisy] Fruits

Authors: Elizabeth S. Quevedo1, Antonio C. Laurena2 and Florinia E. Merca3


The physicochemical properties and nutritional profile of the different parts and stages of maturity of “batuan” [Garcinia binucao (Blco.) Choisy] fruits in the Visayas State University (VSU) were determined using standard analytical methods to validate their use as a safe food ingredient. Sensory evaluation on the acceptability of the dry, powdered “batuan” fruits as souring agent in fish stew dish was also conducted.
Proximate composition, physicochemical properties and nutrient composition between parts and fruit maturity varied to some level. The pulp which constituted the biggest part of the fruit and the immature ones contained high moisture and acidity that decreased as the fruit matured. Ash, protein, sugar, starch, total carbohydrates, total soluble solids, and sodium content were low in “batuan” fruits. The seeds contained high crude fat, crude protein, and tannin. “Batuan” fruits were also found high in vitamin C, potassium, phosphorus, calcium, magnesium, iron, and trace levels of zinc, copper and manganese. Crude fiber and vitamin A were concentrated in the peel, pulp and ripe fruit. Based on the 9-point Hedonic scale for sensory evaluation, the fresh and the dry, powdered “batuan” fruits were comparable to one another in terms of color, mouth feel, taste and general acceptability as souring agent for fish stew.
Results showed that “batuan” fruits have good physicochemical properties and nutrient contents which are comparable or even higher than some conventional fruits used as souring agents. The powdered “batuan” fruit is a potential ready-to-use souring agent for domestic consumption, food industry, and other applications.

Keywords: batuan, Garcinia binucao (Blco.) Choisy, minerals, vitamin content, general acceptability

Annals of Tropical Research 35(2):1-21(2013)
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