Abstract
Crocidolomia pavonana is an important pest of Brassicaceous vegetable crops. Botanical insecticides are potential alternatives for the control of C. pavonana pest. Insecticidal activity of Piper aduncum and Sapindus rarak fruit extracts as well as their mixtures was evaluated against C. pavonana larvae in the laboratory. Ethyl acetate P. aduncum (EtPa) extract as well as methanolic S. rarak (MeSr) and aqueous S. rarak (AqSr) extracts were tested separately and in mixtures against second-instar larvae C. pavonana by a leaf-residue feeding method. At the LC95 level - 72 hours after treatment (HAT), EtPa extract was about 14.5 and 12.8 times, respectively, more toxic to C. pavonana larvae than MeSr and AqSr extracts. At the LC95 level, EtPa + MeSr extract mixture (1 : 10 w/w) was about 1.64 times more toxic to the test larvae than EtPa + AqSr extract mixture (1 : 10 w/w). Based on combination index at 48, 72, and 96 HAT, EtPa + MeSr extract mixture at LC50 level as well as EtPa + AqSr extract mixture at LC50 and LC95 levels had additive joint action, whereas EtPa + MeSr extract mixture at LC95 was weakly synergistic. In addition to lethal effect, the treatment with all test materials delayed the development of C. pavonana larvae from second-instar to fourth instar. Thus, EtPa, MeSr, and AqSr extracts as well as the mixtures between EtPa and S. rarak extracts are potential alternatives for the control of C. pavonana pest.
Highlights
Crocidolomia pavonana is an important pest of Brassicaceous vegetable crops
Insecticidal activity of Piper aduncum and Sapindus rarak fruit extracts as well as their mixtures was evaluated against C. pavonana larvae in the laboratory
C. pavonana larvae than methanolic S. rarak (MeSr) and aqueous S. rarak (AqSr) extracts
Summary
Penelitian dilaksanakan di Laboratorium Fisiologi dan Toksikologi Serangga, Departemen Proteksi Tanaman, Fakultas Pertanian, Institut Pertanian Bogor (IPB), dari Januari sampai September 2012. Perbanyakan tanaman brokoli tanpa perlakuan pestisida dilakukan dengan cara seperti yang telah diuraikan oleh Abizar dan Prijono (2010). Daun dari tanaman brokoli yang telah berumur 2 bulan digunakan sebagai pakan larva C. pavonana. Larva C. pavonana diberi pakan daun brokoli bebas pestisida dan imagonya diberi pakan larutan madu 10% yang diserapkan pada segumpal kapas yang digantungkan di dalam kurungan plastik-kasa berbingkai kayu (50 cm x 50 cm x 50 cm). Larva dipindahkan ke dalam wadah plastik (35 cm x 26 cm x 6 cm) berjendela kasa dan diberi pakan daun brokoli bebas pestisida. Etil asetat dan metanol hasil penguapan yang diperoleh digunakan kembali untuk membilas residu pada perendaman dan kertas saring di corong kaca. Irisan daging buah lerak yang sudah ditimbang dan dicampur dengan air sesuai konsentrasi pengujian dihaluskan menggunakan blender. Hasil ekstrak disaring terlebih dahulu dengan pengayak kawat kasa berjalinan 0,5 mm
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