BIOKONTROL ULAT BAWANG MERAH (Spodoptera exigua Hubner, 1808) MENGGUNAKAN SENYAWA BIOAKTIF DAUN PANDAN WANGI (Pandanus amaryllifolius Roxb.)

Aras Beauty, Sukirno, S.Si., M.Sc., Ph.D. ; Prof. Dr. L. Hartanto N., M. Agr.

2023 | Tesis | S2 Biologi

Spodoptera exigua Hubner termasuk serangga hama yang dikenal sangat merugikan oleh para petani di dunia. Namun, pengaplikasian insektisida sintetik dapat menimbulkan dampak negatif terutama terkait resistensi, resurgensi, dan residu. Bioinsektisida mulai banyak dikaji sebagai alternatif pengganti insektisida sintetik karena lebih aman dan ramah lingkungan. Penelitian ini bertujuan untuk meneliti efektivitas ekstrak kasar dan fraksi Pandanus amaryllifolius sebagai bioinsektisida Spodoptera exigua serta mengungkap senyawa aktif utamanya. Proses ekstraksi dilakukan dengan cara maserasi menggunakan metanol 80%. Ekstrak kasar kemudian difraksinasi dengan kromatografi kolom vakum. Melalui fraksinasi diperoleh enam jenis fraksi yang selanjutnya digunakan dalam uji fraksi. Ekstrak kasar dan fraksi potensial yang diperoleh kemudian dilakukan analisis kandungan senyawa utamanya menggunakan teknik gas chromatography mass spectometry (GCMS). Uji histokimia dilakukan untuk mendeteksi kandungan golongan senyawa pada jaringan daun pandan wangi. Hasil uji insektisida terhadap ekstrak kasar diperoleh simpulan, yaitu metode racun kontak (LC90 = 18,51%) lebih toksik daripada racun perut (LC90 = 31,99%); ekstrak kasar berpengaruh signifikan terhadap daya hambat makan larva; serta terdapat penurunan rerata berat larva yang signifikan dengan metode racun perut sedangkan pada racun kontak terdapat penurunan berat larva meskipun tidak signifikan. Hasil uji fraksi potensial diperoleh simpulan, yaitu: Fraksi 2 adalah fraksi terbaik dalam uji mortalitas dengan LC90 = 3,56% (racun kontak) dan LC90 = 11, 46% (racun perut); fraksi 3 adalah fraksi terbaik dalam uji daya hambat makan; serta racun kontak menyebabkan penurunan berat larva yang signifikan, sementara racun perut menyebabkan penurunan berat larva meskipun tidak signifikan. Hasil uji histokimia menunjukkan reaksi positif terhadap kandungan alkaloid, flavonoid, fenol, tannin, dan terpenoid. Senyawa bioaktif potensial pada daun pandan wangi sebagai kandidat insektisida adalah 9,12,15-Octadecatrien-1-ol ; phytol ; 9,12-Octadecadienoic acid (Z,Z)- dan 9,12-Hexadiienoic acid, methyl ester.

Spodoptera exigua Hubner is an insect pest that is known to be very detrimental to farmers in the wold. However, the application of synthetic insecticides causes negative impacts, especially regarding resistance, resurgence, and residue. Bioinsecticide are starting to be widely studied as an alternative to synthetic insecticide because they are safer and environmentally friendly. This research aims to examine the effectiveness of crude extracts and fractions of Pandanus amaryllifolius as bioinsecticide for Spodoptera exigua and to reveal the main active compounds. The extraction process was carried out by maceration using 80% methanol. The crude extract was then fractionated by vacuum column chromatography. Through fractionation, six types of fractions are obtained which are then used in fraction tests. The crude extract and potential fraction obtained were then analyzed for the main compound content using gas chromatography mass spectometry (GCMS) technique. Histochemical tests were carried out to detect the content of compound groups in pandan wangi leaf tissue. The result of insecticide test on crude extract concluded that; the contact poison method (LC90 = 18.51%) was more toxic than stomach poison (LC90 = 31.99%); the crude extract had a significant effect on larval feeding inhibition; and there was a significant decrease in the average weight of larvae with the stomach poison method, while with contact poison the reduction in larval weight was not significant. The results of the potential fraction test concluded that; fraction 2 is the best fraction in  mortality test with LC90 = 3.56% (contact poison) and LC90 = 11.46% (stomach poison); fraction 3 is the best fraction in food inhibition test; as well as contact poison causes a significant decrease in larval weight, while stomach poison causes an insignificant decrease in larval weight. Histochemical test results showed a positive reaction to the content of alkaloids, flavonoids, phenols, tannins, and terpenoids. The potential bioactive compound as an insecticide candidate found in the two most potential fraction was 9,12,15-Octadecatrien-1-ol; phytol; 9,12-Octadecadienoic acid (Z,Z)- and 9,12-Hexadecadienoic acid, methyl ester.

Kata Kunci : Bioinsektisida, Pandanus amaryllifolius, Spodoptera exigua, racun perut, racun kontak