EFEKTIVITAS NEMATODA ENTOMOPATOGEN Steinernema sp. PADA HAMA UTAMA BEBERAPA TANAMAN PERKEBUNAN DAN HORTIKULTURA

Abstract

ABSTRAK Nematoda  entomopatogen  Steinernema  sp.  telah  banyak dimanfaatkan sebagai agens hayati untuk mengendalikan serangga hama di luar negeri, namun di Indonesia masih terbatas. Tujuan penelitian adalah mengevaluasi efektivitas 3 strain Steinernema sp. lokal terhadap beberapa hama utama tanaman perkebunan dan hortikultura. Penelitian ini dilakukan di Laboratorium Entomologi dan Kebun Percobaan, Balai Penelitian Tanaman Tembakau dan Serat Malang, Jawa Timur, mulai April 2001 sampai Mei 2002. Tiga strain nematoda lokal, yaitu BT02, ML07, dan AB05 diuji masing-masing pada konsentrasi 50; 100; 200; 400; dan 800 Juvenil infektif (JI)/ml dan satu kontrol (tanpa JI). Sembilan spesies serangga hama yang diuji yaitu Helicoverpa armigera, dan Pectinophora gossypiella (hama kapas), H. assulta dan Myzus persicae (tembakau), Plutella xylostella, dan Crocidolomia binotalis (kubis), Spodoptera exigua (bawang merah), Liriomyza sp. dan S. litura (bunga krisan). Setiap spesies serangga mewakili satu unit pengujian. Setiap perlakuan dalam unit disusun dalam rancangan acak lengkap (RAL) dengan empat ulangan. Aplikasi perlakuan dilakukan dengan metode vial, kultur sel, dan sumuran, tergantung perilaku serangga uji dan menggunakan spray chamber. Di laboratorium, parameter yang diamati adalah sublethal (LC 25 ) dan lethal concentration (LC 50 ), sublethal and lethal time (LT), dan produksi JI. Di lapang, hanya satu perlakuan tunggal yang digunakan yaitu LC 50 dari setiap strain nematoda. Sebanyak masing-masing 20 inang serangga dipajankan daun atau bagian tanaman yang telah disemprot dengan suspensi nematoda di lapang, kemudian serangga uji diamati di laboratorium hingga mati. Hasil penelitian menunjukkan bahwa ketiga strain nematoda menunjukkan efektif membunuh C. binotalis (BT02), P. xylostella, M. persicae (ML07), dan P. gossypiella (AB05), tetapi kurang efektif terhadap H. armigera (AB05), S. exigua dan S. litura (ML07), dan Liriomyza sp. (BT02). Waktu efektif yang diperlukan nematoda untuk membunuh inang (Lethal Time) pada ketiga strain berkisar antara 1-4 hari. Selain efektif membunuh stadia larva, Steinernema sp. juga efektif terhadap prepupa dan pupa. Kata kunci : Tanaman  perkebunan,  hortikultura,  Steinernema  sp., Helicoverpa armigera, Pectinophora gossypiella, H. assulta, Myzus persicae, Plutella xylostella, Crocidolomia binotalis, Spodoptera exigua, S. litura, Liriomyza sp., juvenil infektif, mortalitas ABSTRACT Effectiveness of entomopathogenic nematode Steiner- nema sp. against major insect pests of plantation and horticulture Entomopathogenic nematode of family Steinernematidae is a prospective agent for biological control of insect pests. It has been known that many species of insects can be infected by nematode and sometimes showed different levels of infection. Laboratory and field study on the effectiveness of Steinernema sp. against major insect pests of plantation and horticulture was carried out in Laboratory of Entomology and Experimental Station of Indonesian Tobacco and Fiber Crops Research Institute (IToFCRI), Malang, East Java. The objective was to find out the effectiveness of three local strains of Steinernema sp. to any different major of insect pests of plantation and horticulture. Three local strains of nematode tested as BT02, ML07, and AB05 which each consist of five level concentrations of IJ, viz. 50, 100, 200, 400 and 800 IJ/ml and one untreated with IJ as control were tested against nine species of insect, viz. H. armigera, P. gossypiella (cotton), H. assulta and M. persicae (tobacco), P. xylostella and C. binotalis (cabbage), S. exigua (red onion), Liriomyza sp. and S. litura (chrysanthemum). Each species of insect was tested as one unit of test and treated with the same level of concentration. Each treatment in every unit of test was arranged in randomized complete design with four replications. Application method of treatment used were vial, cell culture plate, and well, depends on insect behaviour. Nematode suspension was applied by using spray chamber. Parameters observed were sublethal and lethal concentration, sublethal and lethal time and IJ production. In field study, only one single treatment LC 50 was used to observe the insect mortality. In this study, twenty of insect hosts were fed on treated-sample leaves collected from the field and observed till death. The result showed that all strains of Steinernema sp. were more pathogenic and effective against C. binotallis (BT02), P. xylostella and M. persicae (ML07), and P. gossypiella (AB05), but less pathogenic against H. armigera (AB05), S. exigua and S. litura (ML07), and Liriomyza sp. (BT02). Time needed (LT) to kill the insect host was ranged from one to four days. Strains of nematode tested were not only effective against larvae but also effective to kill prepupae and pupae of insect host. Key words : Estate crops, horticulture, Steinernema sp., H. armigera, P. gossypiella, H. assulta, M. persicae, P. xylostella, C. binotalis, S. exigua, Liriomyza sp, S. litura, infective juvenile, mortality