Insecticidal activity of sugar-apple (Annona squamosa L.) seed extracts from different locations and synergism of the most active extract with spiked-pepper (Piper aduncum L.) fruit extract against Crocidolomia pavonana (F.) (Lepidoptera: Crambidae) larvae

Abstract

Results of leaf-residue bioassays of methanolic sugar-apple (Annona squamosa L.) seed extracts from eight locations in Central Java and Papua showed that LC50 of the extracts against Crocidolomia pavonana larvae ranged from 27.6 to 374 ppm, whereas the range of LC95 was 160.8-6067.8 ppm. Sugarapple extract from Sumber Lawang-Blora, Central Java had the lowest LC50 value, while the extract from Cepu-Blora had the lowest LC95. The difference in the slope of probit regression of sugar-apple extracts resulted in the difference in LC95/LC50 ratio. Spiked-pepper (Piper aduncum L.) fruit extract (LC50 867 ppm and LC95 3122.7 ppm) was much less active than the most active sugar-apple extract. The mixture of sugar-apple seed extract and spiked-pepper fruit extract (1:10) (LC50 66.3 ppm and LC95 1686.9 ppm) had strongly synergistic joint action at LC50 level (combination index 0.30) but antagonistic at LC95 level (combination index 1.59). In a semifield experiment, addition of spiked-pepper extract, neem (Azadirachta indica) seed extract or an optical brightener did not significantly increase the effectiveness of sugar apple seed extract against C. pavonana larvae on polybagged chinese cabbage plants.

Ulat krop kubis, Crocidolomia pavonana (F.) (Lepidoptera: Crambidae), merupakan salah satu hama penting pada tanaman famili Brassicaceae seperti kubis, caisin, brokoli, petsai, sesawi, mostar, dan lobak. Di lapangan tidak ada musuh alami yang efektif untuk menekan populasi hama tersebut sehingga petani mengandalkan insektisida sintetik—yang dapat menimbulkan berbagai dampak negatif—untuk mengendalikan hama tersebut. Salah satu alternatif yang dapat digunakan untuk menggantikan sebagian peranan insektisida sintetik ialah insektisida nabati yang tidak merusak lingkungan dan relatif aman terhadap organisme bukan sasaran. Selain digunakan secara tunggal, insektisida nabati dapat digunakan dalam bentuk campuran, terutama bila campuran tersebut bersifat sinergis. Penelitian ini bertujuan menguji aktivitas insektisida ekstrak biji srikaya (Annona squamosa L. ) dari enam lokasi berbeda di Jawa Tengah dan dua lokasi berbeda di Papua terhadap larva C. pavonana di laboratorium; menguji sinergisme campuran ekstrak biji srikaya dan buah sirih hutan (Piper aduncum L.) terhadap larva C. pavonana di laboratorium; serta menguji efek residu sediaan ekstrak biji srikaya dan campurannya dengan ekstrak buah sirih hutan, ekstrak biji mimba (Azadirachta indica), dan optical brightener (OB) terhadap larva C. pavonana pada tanaman caisin pada skala semilapangan.