Category Archives: Volume 24 No. 2 (2002)

Life history of yam scale, Gonaspidiotus hartii Cockerell (Hemiptera:Diaspididae)


Author(s): Erlinda A. Vasquez and Melecio A. Buyser

Abstract

Yam scale, Gonaspidiotus hartii Cockerell, is one of the most important insect pests attacking stored yam in the Philippines. In this study, G. hartii was investigated on greater yam Dioscorea data (var Kinampay). The insect underwent three developmental stages: egg, nymph and adult, The total developmental period from egg to adult stage lasted 53-62 (58.77) days for the male and 58-66 (61,74) days for the female. Each female laid 9-196 (89.85) eggs during its entire oviposition period of 3-7 days with 95-100 percent hatchability. A male to female ratio of 1:4.43 was recorded. Adult male lived shorter (1-4 days) than the female (14-22) days.

Keywords : yam scale insect, Gonaspidiotus hartii Cockerell, life history

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Mora grass in contour hedgerow: A technology for a sustainable upland farming system


Author: Zosimo M. de la Rosa

Abstract

The study was conducted on six adjacent upland farms usually planted to native corn under a few old coconut trees. The site had a slope ranging from 9 – 17% and had a clayey soil. The following were the objectives of the study: a) to determine the feasibility of using “mora” or vetiver grass (Vetiveria zizanoides) as foundation for establishing contour hedgerows, b) to determine the physical and chemical changes of the soil in the farm site in terms of color, slope, crop yield over time and the kind of vegetation and crops planted in between the contour strips, and c) to document farmer-cooperators’ responses and feedback on the effectiveness of “mora” used as contour hedgerow,
Farmer-users of “mora” grass as contour hedgerow claimed that the grass adapted well in the upland, checked soil erosion, stabilized the farm, and improved soil fertility. The consistent increase in the values of extractable phosphorus, potassium, calcium, and organic matter of the soil was believed to have caused the ramarkable increase in the yield of corn during the last two cropping seasons. Apparently, lesser soil erosion, improved soil fertility, and availability of moisture in the soil have contributed to the increase in productivity and profitability of the contour farms. The technology on the use of “mora” as foundation for contour hedgerows in upland corn fields has helped sustain crop productivity and supports current thrust on sustainable agriculture.

Keywords : “mora” grass, contour hedgerow, soil erosion, fallow-rotation farming

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Hunting pattern and pressure of communities inside protected areas in Leyte


Author: Teofanes A. Patindol

Abstract

The study was conducted to describe the hunting pattern and determine the factors associated to hunting pressure inside protected areas in Leyte.
The primary motivation to hunt inside protected areas is for both subsistence and commercial use. Because of low economic opportunities, hunting respondents hunt despite legal restrictions to augment income. Some non-hunting respondents are indirectly involved in hunting by participating in the wildlife trade.
The hunting pattern is characterized by preference for big game although hunting success is low because of the large amount of meat per unit catch. Hunting efficiency is improved with the use of homemade explosives and acquisition of air rifles. Wild pig is the most sought game and the improvement of hunting technology is geared toward increased harvest of this animal. The improvement of technology and the preference for big game made this group of animals highly vulnerable to overhunting. Equally vulnerable are doves, pigeons and parrots, which are considered secondary hunting targets for their meat and for pet trade.
The result of the correlation analysis showed that hunting effort is negatively associated with education, farm and total income of the respondents, and number of years the respondents availed of livelihood projects.
The overall scenario illustrates a classic interaction wherein pressure is continuously exerted on a limited resource in a fragile biological system by economically depressed sector of society. This therefore calls for urgent implementation of integrated conservation program in protected areas that would address both the biological diversity resources under constant pressure and the seemingly obligate users exerting the pressure.

Keywords : hunting pattern, hunting methods, wildlife management and conservation

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Fish length measurements using artificial neural networks


Author(s): C. M. Orofeo, R. U. Cruzet, M. P. B. Kindica, B. Zuidberg* and K. Karremans

Abstract

An existing stereoscopic technique employing neural networks has been used to measure the length of fishes. Prior to the actual measurements, certain parameters that might affect the accuracy of the measurement were investigated. The influence of the index of refraction of water (depending on salinity) and the orientation of the object relative to the cameras on the accuracy of the measurement was examined.
Results showed that the salinity of water and the orientation of the object with respect to the. cameras have negligible effect on the measurements. With a total error of less than 2 mm, the method presented in this paper is far better than conventional techniques.

Keywords : fish length, artificial neural networks, fish measurement accuracy

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The Ichthyofauna of Lake Manguao, Taytay, Palawan, Philippines


Author: Joie D. Matillano

Abstract

The fish fauna of Lake Manguao was investigated during two sample events last June and September 2002. The study was conducted in order to ascertain whether the unique fish fauna first catalogued by Day (1914) and later by Davies and Green (1990) is still present in the lake after the introduction of Oreochromis niloticus in 1992. This study also tried to find out whether there are two endemic species of Puntius in the lake, as described by Day (1914) and Herre (1924), or just one assumed by Davies and Green (1990), and if indeed a lake-endemic catfish is present in the area and to determine the local uses of the lake fishes
Six types of fishing gears were used and a total of eight sampling stations were sampled representing both the littoral and open water zones of the lake.
A total of 11 fish species from ten genera belonging to eight families including Anabantidac, Channidae, Cichlidae, Clariidae, Cyprinidae, Eleotridae, Hemiramphdae, and Siluridae were caught from the lake. In addition to the species previously accounted. for, a new fish species was recorded, Clarias macrocephalus, a native catfish of the Philippines. The two species of Puntuis collected by Day (1914) were also collected, as well as the silurid catfish described by Herre (1924) as Penisilurus palavanensis. Apparently, fishery focuses mainly on Tilapia and of secondary fishery importance are the other introduced species.

Keywords : ichthyofauna, fish species, Lake Manguao

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Survey of ultraviolet radiation-absorbing mycosporine-like amino acids in adult females of planktonic copepods


Author(s): Dorothy G. Lacuna

Abstract

The presence of UV-absorbing rnycosporine-like amino acids (MAAs) from nine planktonic calanoid copepod species were investigated. MAA concentrations from methanol extracts of adult females were analyzed by High Performance Liquid Chromatography (HPLC). A total of 4 MAAs were identified, namely mycosporine-glycine, palythine, porphyra-334 and shinorine. Although all the experimental copepods had MAAs, the occurrence of these compounds varied among species. For Acartia omorii, Calanus Sinicus and Pontella spinicauda, 4 MAAs were identified; Pontellopsis tenuicauda and P yamadae, had 3 MAAs while Acartia sinjiensis, Centropages abdominalis, Paracalanus sp. and Sinocalanus tenellus had only one MAA. Concentrations of total MAAs were also assessed. Total MAA concentrations ranged from 3.53 mgC-1 (Pontella spinicauda) to 0.003 µg mgC-1 (Sinocalanus tenellus). Since UV-absorbing MAAs act as a biochemical defense or sunscreen against the harmful wavelengths of UVB, increase content of these compounds, specifically MAAs with UVB-absorbing properties, in all neustonic copepods (Pontella spinicauda, Pontellopsis tenuicauda and P. yamadae) may suggest a physiological adaptation to high UV exposure which is the natural condition in neustonic environment.

Keywords : UV-absorbing compounds, copepods, mycosporine-like amino acids, neuston, plankton

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