Judul: Quantitative analysis of potency of acerophagus papayae noyes & schauff (Hymenoptera: Encyrtidae), parasitoid of the papaya mealybug
Abstrak: The papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae), was an invasive pest that invaded Indonesia in early 2008 and caused heavy damage on papaya. One of the natural enemies found in Bogor was parasitoid Acerophagus papayae Noyes and Schauff (Hymenoptera:Encyrtidae). The parasitoid was believed to have been fortuitously introduced into Indonesia. Research was conducted to evaluate the potency of A. papayae as biological control agent for the papaya mealybug. Studies included determining various biological parameters such as development time, host preference, functional response, and simulation model of host-parasitoid population dynamics. Parasitoids were obtained from the papaya fields by collecting the mummy of papaya mealybugs and enclosed individually in gelatin capsules. Adult parasitoids emerged were reared on the papaya mealybugs with Jatropha curcas as a host plant. Fitness and preference of the parasitoids were studied using papaya mealybug instar II dan III with a piece of papaya leaf in a test tube (d = 3 cm, h = 15 cm). Functional response of the parasitoids were studied at the host density of 2, 5, 10, 20, 30, 40, and 50 nymphs. Mummies were also collected from the fields, and the data were used to test the sensitivity and validate the model using Stella version 9.02 software. Our study revealed that the parasitoid preferred second-instar over the third-instar nymphs of P. marginatus. Immature developmental time was shorter and survival rate was higher of parasitoids developed on the second-instar nymps. Female parasitoid showed type II functional response with the increasing host density. Our simulation model indicated that the parasitoid had a good searching capacity and was able to regulate papaya mealybug population.
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Judul: Biologi perkembangan dan neraca hayati kutu putih pepaya, Paracoccus marginatus (Williams and Granara de Willink) (Hemiptera: Pseudococcidae) pada tiga jenis tumbuhan inang
Abstrak: The papaya mealybug, Paracoccus marginatus Williams & Granara de Willink (Hemiptera: Pseudococcidae), has been considered as a new invasive pest causing heavy damage on papaya in Indonesia since 2008. The pest is polyphagous with more than 55 host plant species. Study was conducted in laboratory with the objectives to determine developmental biology and life table parameters of the mealybug feeding on papaya, physic nut, and cassava leaves. Host plant species affected papaya mealybug performances. Egg stage lasted 7,25, 8,09, and 9,86 d on papaya, physic nut, and cassava, respectively. The shortest female nymphal developmental time was on papaya (18,91 d) and the longest on cassava (32,45 d). Longevity of adult males ranged from 1,09-2,85 d while females 12,29-14,93 d, respectively. When the mealybugs were reared on a seedling, the fecundity was higher on papaya (324,6) than those of physic nut (186,6) and cassava (157,5). No egg production occurred in virgin females. The sex ratio of P. marginatus favoured females, which comprised about 90% of population on papaya and cassava. The intrinsic rate of increase (rm) was significantly different among hosts, with the highest rate (0,117 female offspring/female/d) occured on papaya, followed by physic nut (0,079) and cassava (0,057). The maximum values of rm along with net reproductive rate (Ro) and finite rate of increase (λ), and the shortest mean generation time (T) and doubling time (DT) on papaya, indicating that papaya was the most favorable host plant for P. marginatus.
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Judul: Transformasi fasa pada pembuatan keramik alpha-alumina dengan proses sol-gel
Abstrak: Proses sol-gel merupakan proses terbaru yang dikcmbangkan untuk membuat keramik, termasuk alumina (Al2O3). Proses ini dapat mengontrol struktur mikro dan sifat keramik dengan jalan mengontrol parameter proses pcmbuatan, suhu pemanasan yang dibcrikan rclatif rendah, kcmurnian produk yang dihasilkan relatif tinggi, plastisitas gel dapat mcmbcrikan produk dalam bcntuk scrbuk, serat, lapisan tipis dan bentuk padat Hal yang menarik untuk diamati pada proses pembuatan kcramik alumina dengan proses sol-gel adalah te1jadinya transformasi fasa. Menurut bebcrapa pcnclili, fasa-fasa yang tc1jadi adalah alumina hidrat (dapat berupa diaspore atau boehmile), gamma-, delta-, theta-dan alpha-alumina. Masing-masing fasa tcrsebul mempw1yai sifat fisis yang berbcda. Satu mol serbuk aluminum /rifer/ butoxidc [(C21-15Cl-l(CI-13)O),Al] dicampur dengan 100 11101 air (H20). Campuran tersebut diaduk dengan magnetic stirer sampai homogcn. Setelah homogcn, pada suhu 90°C campuran tcrsebut dipeptisasi dengan katalis asam, 0,2 mol 1-JCI. Proses polimerisasi ini membentuk gel. Gel yang diperoleh dikeringkan pada suhu 90°C, kcmudian dibagi-bagi untuk dipanaskan pada beberapa suhu, yaitu 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, l000°C, 1100°C, 1200°C dan 1300°C, selama satu jam dalam ruang pemanas (furnace). Setelah itu, sampel segera dikeluarkan dari ruang pemanas dan didinginkan di udara. Evolusi termal diamati dengan analisis termal dari suhu kamar sampai suhu 1300°C, yaitu dijferential thermal analysis (DTA) dan lhermogravimetric analysis (TGA). Fasa-fasa yang te1jadi pada sctiap sampel ditentukan dcngan X-ray d/fji-actomelly (XRD). Idcntifikasi fasa dilakukan dengan menggunakan meta de Hanawalt secara manual dan analisis kuantitatif clilakukan pada pola difraksi sampel 1000°C, puncak 012 (fasa alpha) dan 004 (fasa theta) dengan menggunakan metode pcrbandingan langsung. Morfologi pennukaan sampel diamati dengan mikroskop optik (MO) dan scanning electron microscope (SEM). Sedangkan kerapatan sampel diukur dengan piknometcr. Dari basil penelitian diperoleh bahwa fasa-fasa yang terbentuk adalah fasa boehmite (antara suhu 90°C-300°C), fasa gamma-(antara suhu 400°C-800°C), fasa delta-(sekitar suhu 900°C), fasa theta­(sekitar suhu l000°C) dan fasa alpha-alumina (antara l 100°C-1300°C). Masing-masing fasa tersebut mempunyai sistem kristal, morfologi permukaan clan kerapatan yang bcrbcda. Pad a suhu 1000°C, secara kuantitatif, terbentuk fasa theta sebesar 50,18% dan alpha 49,82%. Transformasi tennal dari gamma-kc delta-, de/la-ke theta-tidak tcrdeteksi, baik dcngan DTA maupun TOA. Morfologi pcrmukaan gel alumina yang telah dipanaskan pada suhu 1300°C mcnunjukkan fonnasi kristalin. Kcrapatan fasa alpha­alumina adalah (400 ± 3) IO kg m-3•
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