Judul: Pendugaan Kerapatan Populasi Hama Kutu Kebul (whitefly) pada Tanaman Sayuran Menggunakan Watershed Segmentation
Abstrak: Witheflies Bemisia tabaci and Trialeurodes vaporariorum are two important pests on vegetables. This research proposed a new method of estimating population density of whiteflies using watershed algorithm. Estimate of population density was obtained by counting the number of pests found on leaves. Watershed algorithm is highly appropriate for segmentation of whitefly, because this algorithm works properly on objects which has low gray level variation and overlapping areas. The research methodology consisted of image acquisition, image preprocess, image enhancement segmentation, calculation of whitely, calculation of infested leaf area, calculation of whitefly population density, and evaluation of infestation level estimates. Data used in this research were digital images of vegetable leaves infested by the whiteflies. Image pre-processing was used to reduce errors that might occur in the process of segmentation with watershed algorithm. Image enhancement with was aimed to reduce noises. Whitefly calculation was done after image segmentation. Infestation area was calculated by sampling leaf areas. The goal was to separate the non object areas so not to be included in the calculation process. The calculation results used to determine the level of pest population density. Whitefly densities were calculated using two methods: sampling area and leaf segmentation. The sampling area method was used when the observed images had a background difficult to separate from leaf objects, and the leaves were not in perfect condition such as folded, truncated, or blured. Whereas, the leaf segmentation method were used when the leaves images were in perfect condition, not bent or not blured, and the background was easy to separate. The process of testing was done using images grouped into three levels: low, moderate, and severe. Results of both methods then were with the estimates by expert. Our research showed that estimation of whitefly population density had an error of 12,5%. The sampling area method was chosen to estimate whitefly density because of its closeness to the expert estimates. Based on this method, the pest population infetations were grouped into three levels: low (≤ 10%), moderate (> 10% until ≤ 30%), and severe (> 30%). The system of estimating whitefly density developed through this research is expected to help pest observers in executing pest population monitoring.
Keyword: image processing, estimation of pest density, watershed segmentation

Judul: Keanekaragaman spesies dan kunci identifikasi kutukebul (Hemiptera: Aleyrodidae) pada tanaman pertanian di Jawa Barat
Abstrak: Whiteflies are one of the most important insect group of pests in agricultural crops which can cause direct and indirect damages to plants, i.e. disturb photosynthesis and plant aesthetics, and transmit plant viruses. Whiteflies have been reported in Indonesia since 1900’s. There are 37 whiteflies species that have been recorded in Indonesia, but it is believed that many more are unidentified. The aims of this research was to identify the whiteflies species in agricultural crops and study their diversity at different altitudes. Whiteflies were collected at five areas in West Java: Bogor, Cianjur, Sukabumi, Bandung, and Garut. The identification of whiteflies were using fourth instar nymph or known as pupa. Slide preparation followed Watson’s protocol that has been modified. Morphological characters for such species were recorded for identification. Identification key was constructed in the dichotomous and digital forms using Lucid Phoenix Key program. Diversity of whiteflies was analysed using Shannons’s (H’), Simpson’s (D) and Sorenson’s (C) diversity index. Whitefly natural enemies that were found in the field or parasitized whiteflies were identified. There were 38 whiteflies species found and 10 were still unidentified. About 89.5% whiteflies found were the member of subfamily Aleyrodinae. Whiteflies were more commonly found in the plants with complex architecture (fruit trees) than the plants with simple architecture (vegetables, ornamental plants, etc). Plant with complex architecture can provide more space and food for organism to live. Aleurodicus dispersus and Aleurodicus dugesii are cosmopolitan species that can be found in various types of plants and altitudes. Bemisia tabaci was commonly found in lower altitude, whereas Trialeurodes vaporariorum was mainly found in higher altitude. Both species are become important pests in vegetable crops and transmit plant diseases. The highest whitefly species richness and diversity was found in lowland (0-500 m above sea level (asl)) (H’=2.14; 1- D=5.53). Similarity analysis (C) showed that number of whitefly species found at lowland was 64% similar to midland (501-1000 m asl). The natural enemies that commonly found were coccinellid beetle, aphelinid, and encyrtid wasp.
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Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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