Judul: Sinergisme Ekstrak Piper aduncum dan Tephrosia vogelii terhadap Penggerek Batang Padi Kuning Scirpophaga incertulas
Abstrak: Rice (Oryza sativa) is one of the important staple food commodities in the world. One of the important pests on rice is the yellow rice stem borer (YRSB) Scirpophaga incertulas. Various control measures have been implemented to maintain rice production. One of the alternative control techniques that can be applied is by using botanical insecticides. The purpose of this study was to determine the synergism between Piper aduncum and Tephrosia vogelii extracts against YRSB larvae. P. aduncum and T. vogelii extracts, either tested separately or in mixtures with concentration ratios of 1:1, 2:1, and 1:2, were effective against YRSB larvae. The treatments with these extracts caused death in YRSB larvae at 72 hr after treatment in which the affected larvae showed internal tissue damage symptom. The most toxic test material to YRSB larvae was P. aduncum and T. vogelii extract mixture with a concentration ratio of 1:2. LC50 and LC95 P. aduncum extract were 0.175% and 0.126%, respectively, while those of T. vogelii extract were 1.620% and 2.075%, respectively. P. aduncum and T. vogelii extract mixture with 1:1 ratio had LC50 0.056% and LC95 0.143%, while those with 2:1 ratio had LC50 0.025% and LC95 0.149%. LC50 and LC95 of the mixture with 1:2 ratio were 0.016% and 0.083%, respectively. P. aduncum and T. vogelii extract mixtures at the three concentration ratios were more effective than P. aduncum and T. vogelii extracts applied separately and synergistic to YRSB larvae.
Keyword: Tephrosia vogelii., synergism, Scirpophaga incertulas, Piper aduncum, botanical insecticide

Judul: Kesesuaian Ekstrak Piper spp. (Piperaceae) untuk Meningkatkan Toksisitas Ekstrak Tephrosia vogelii terhadap Ulat Krop Kubis, Crocidolomia pavonana
Abstrak: Crocidolomia pavonana is one of major pests of Brassica vegetable crops. One of the viable control alternatives against this pest is the use of botanical insecticides. This study was conducted to determine the suitability of extracts of Piper spp. (P. aduncum, P. betle, P. cubeba, P. retrofractum, and P. sarmentosum) to increase the toxicity of Tephrosia vogelii leaf extract against C. pavonana larvae. Plant materials were extracted separately with ethyl acetate and the resulting extracts were tested against second instar larvae C. pavonana using a leaf-dip feeding method. Extract-treated cabbage leaves were provided to the test larvae for 48 hours then the larvae were fed untreated leaves for the following 48 hours. The number of dead larvae was counted daily until day 4 then larval mortality data were subjected to probit analysis. At 96 hours after treatment (HAT), LC50 of T. vogelii, P. aduncum, and P. retrofractum extracts was 0.046%, 0.105%, and 0.125% respectively. The treatment with extracts of P. betle 1%, P. cubeba 0.6%, and P. sarmentosum 1% caused low larval mortality at 72 HAT, i.e. 16.7%, 10%, and 34.4%, respectively. LC50 and LC95 of mixtures of T. vogelii extract with P. aduncum and P. retrofractum extracts were smaller than those of each extract tested separately and the mixtures had synergistic joint action against C. pavonana larvae. Addition of P. sarmentosum extract 0.2% or boiled P. betle aqueous extract 10% somewhat increased the toxicity of T. vogelii extract. Thus, P. aduncum and P. retrofractum extracts are potential to be used in mixtures to increase the toxicity of T. vogelii extract, especially for controlling C. pavonana.
Keyword: Tephrosia vogelii., Piperaceae, synergistic joint action, botanical insecticide mixtures, Crocidolomia pavonana

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf