PATOGENISITAS DUA ISOLAT LOKAL JAMUR Nomuraea rileyi (FARLOW) SAMSON TERHADAP Helicoverpa armigera HUBNER (LEPIDOPTERA: NOCTUIDAE)
Authors: INDRAYANI IGAA. , PRABOWO HERI , MULYANINGSIH SRI 
Published: June 2020

<p>ABSTRAK<br />Epizootik Nomuraea rileyi telah berkembang secara alami dalam<br />populasi lebih dari 30 spesies serangga inang, termasuk H. armigera.<br />Penelitian ini dilakukan di Laboratorium Patologi Serangga Balai<br />Penelitian Tanaman Pemanis dan Serat Malang mulai Januari hingga<br />Desember 2011, tujuannya untuk mengetahui patogenisitas dua isolat lokal<br />jamur entomopatogen N. rileyi terhadap larva H. armigera. Penelitian<br />terdiri atas dua faktor perlakuan, faktor 1 adalah dua isolat lokal N. rileyi,<br />yaitu ML 01 dan LG 02, dan faktor 2 adalah konsentrasi konidia, yaitu: 2,2<br />x 10 5 ; 4,5 x 10 5 ; 2,2 x 10 6 ; 4,5 x 10 6 ; 2,2 x 10 7 ; 4,5 x 10 7 ; 2,2 x 10 8 ; 4,5 x<br />10 8 konidia/ml, dan kontrol. Setiap perlakuan disusun dalam Rancangan<br />Acak Kelompok Faktorial dengan tiga kali ulangan. Aplikasi jamur pada<br />larva H. armigera dilakukan dengan metode kontaminasi permukaan<br />media yang berupa daun kapas muda (1cm 2 ) di dalam ruangan bersuhu<br />25±1⁰C dan kelembapan 75-80%. Parameter yang diamati adalah<br />mortalitas larva, LC 50 dan LT 50 , serta bobot larva. Hasil penelitian<br />menunjukkan bahwa tingkat patogenisitas isolat ML 01 terhadap larva H.<br />armigera lebih tinggi dibandingkan dengan isolat LG 02. Isolat ML 01<br />menyebabkan mortalitas larva H. armigera antara 51,13-85,56% (LC 50  =<br />2,5 x 10 2  Konidia/ml) dan isolat LG 02 antara 43,36-78,90%, (LC 50  =<br />5x10 6  Konidia/ml). LT 50 isolat ML 01 antara 5,2-5,5 hari, sedangkan isolat<br />LG 02 antara 6,8-7,0 hari, terutama pada konsentrasi 2,2-4,5 x 10 8<br />konidia/ml. Terdapat korelasi positif yang erat antara konsentrasi konidia<br />dan mortalitas larva baik pada isolat ML 01 (r=0,975) maupun LG 02<br />(r=0,980), demikian pula antara konsentrasi konidia dan kehilangan bobot<br />larva pada isolat ML 01 (r=0,982) dan LG 02 (r=0,972).<br />Kata kunci: Helicoverpa armigera, Nomuraea rileyi, patogenisitas, isolat,<br />mortalitas</p><p>ABSTRACT<br />The epizootic of the fungi Nomuraea rileyi has naturally developed<br />in more than 30 species of insect host population, including cotton<br />bollworm, H. armigera. A study on pathogenicity of two local isolates of<br />Nomuraea rileyi (Farlow) Samson fungi against Helicoverpa armigera<br />(Hubner) (Lepidoptera: Noctuidae) was conducted at Insect Pathology<br />Laboratory of Indonesian Sweeteners and Fibers Crops Research Institute<br />(ISFCRI) in Malang from January to December 2011 in order to find out<br />the pathogenicity of the isolates against H. armigera larvae. This study<br />consists of two factors as treatment. The first factor was N. rileyi isolates,<br />e.g. ML 01 and LG 02, and the second factor were eight conidia<br />concentrations, viz. 2.2 x 10 5 ; 4.5 x 10 5 ; 2.2 x 10 6 ; 4.5 x 10 6 ; 2.2 x 10 7 ; 4.5<br />x 10 7 ; 2.2 x 10 8 ; 4.5 x 10 8 conidia/ml, and one untreated control.<br />Treatments were arranged in Factorial Randomized Block Design with<br />three replications. Suspense of conidia was applied by surface<br />contamination method of cotton leaf as medium at 25±1⁰C of temperature<br />and 75-80% of humidity. Parameter observed were larval mortality, LC 50 ,<br />LT 50 , and larval weight. Result showed that ML 01 isolate was more<br />pathogenic against H. armigera larvae than LG 02 isolate based on larval<br />mortality, LC 50 , and LT 50 . Percentage of mortality of H. armigera larvae<br />due to ML 01 and LG 02 infection were 51.1- 85.56% and 43.36-78.90%,<br />respectively. The LC 50 of ML 01 and LG 02 isolates was 5.2-5.5 days and<br />6.8-7.0 days, respectively.There are closest positive correlation between<br />conidia concentration and percentage of mortality on ML 01 (r = 0.975)<br />and LG 02 (r = 0.980) isolates as well as between conidia concentration<br />and larval weight loss on ML 01 (r = 0.982) and LG 02 (r = 0.972)<br />isolates.<br />Key words: Helicoverpa armigera, Nomuraea rileyi, pathogenicity,<br />isolate, mortality</p>