EFEKTIVITAS FORMULA JAMUR Beauveria bassiana DALAM PENGENDALIAN PENGGEREK BUAH KAPAS (Helicoverpa armigera)

ABSTRAK Jamur entomopatogen Beauveria bassiana sangat potensial mengendalikan berbagai serangga hama, namun potensinya terhadap penggerek buah kapas (Helicoverpa armigera) belum banyak diteliti. Tujuan penelitian adalah untuk mengetahui efektivitas B. bassiana terhadap H. armigera. Penelitian dilakukan di Laboratorium Patologi Serangga dan Kebun Percobaan Karangploso, Balai Penelitian Tanaman Pemanis dan Serat mulai Januari hingga Desember 2012. Penelitian terdiri atas dua kegiatan di lapangan, yaitu (1) uji efektivitas B. bassiana terhadap H. armigera di pot, dan (2) uji efektivitas B. bassiana terhadap H. armigera di lapangan. Kegiatan pertama terdiri dari delapan perlakuan konsentrasi B. bassiana, yaitu: (1) 3,7 x 10 4 ; (2) 7,7 x 10 4 ; (3) 1,2 x 10 5 ; (4) 1,5 x 10 5 ; (5) 1,9 x 10 5;  (6) 2,3 x 10 5;  (7) 2,5 x 10 5 ; (8) 3,0 x 10 5 konidia/ml; dan (9) kontrol. Perlakuan disusun dalam Rancangan Acak Kelompok dengan 3 kali ulangan. Parameter yang diamati adalah mortalitas dan bobot larva hidup. Kegiatan kedua terdiri dari empat perlakuan konsentrasi B. bassiana, yaitu: (1) 3,1 x 10 11 ; (2) 6,2 x 10 11 ; (3) 9,3 x 10 11 ; dan (4) 1,2 x 10 12 konidia/ha dengan dua pembanding (azadirachtin dan betasiflutrin), serta kontrol. Perlakuan disusun dalam Rancangan Acak Kelompok dengan tiga kali ulangan. Parameter yang diamati adalah populasi larva H. armigera dan laba-laba, kerusakan buah kapas, dan hasil kapas berbiji. Hasil uji efektivitas di pot menunjukkan hingga hari ke-7 setelah perlakuan B. bassiana masih efektif menyebabkan mortalitas larva H. armigera sebesar 46,7% dan meningkatkan kehilangan bobot larva hidup hingga 59,3%, terutama pada konsentrasi 2,3 x 10 5 konidia/ml. Di lapangan, perlakuan jamur B. bassiana efektif menurunkan populasi larva H. armigera sekitar 36-48%, tetapi menurunkan populasi laba-laba hingga 48,4%, sehingga kurang aman bagi musuh alami tersebut. Perlakuan B. bassiana dapat menurunkan kerusakan buah kapas 10,1- 10,3% dengan meningkatkan hasil kapas berbiji sekitar 12,1-29,7%. Kata kunci: Beauveria bassiana, Helicoverpa armigera, konidia, larva, mortalitas ABSTRACT Beauveria bassiana is the most common fungal entomopathogen against several of insect pests. Its potency, however, has not been tested on cotton bollworm, H. armigera. The objective of study was to know the effectivity of B. bassiana against H. armigera. This study had been conducted at Pathology Laboratory and Experimental Station of Indonesian Sweetener and Fiber Crops Research Institute (ISFCRI) from January to December 2012. The study consists of two field tests, e.g. test on B. bassiana effectivity against H. armigera (polybag testing) dan test on B. bassiana effectivity a against H. armigera (field testing). In polybag testing, eight concentrations of B. bassiana and one control were used as treatment, e.g. (1) 3.7 x 10 4 ; (2) 7.7 x 10 4 ; (3) 1.2 x 10 5 ; (4) 1.5 x 10 5 ; (5) 1.9 x 10 5;  (6) 2.3 x 10 5;  (7) 2.5 x 10 5 ; (8) 3.0 x 10 5  conidia/ml; and (9) control. Each treatment was arranged in Randomized Block Design with three replications. Parameters recorded were mortality and weight of survival larvae. The field testing consists of four concentrations of B. bassiana viz. 3.1 x 10 11 ; 6.2 x 10 11 ; 9.3 x 10 11 ; and (4) 1.2 x 10 12 conidia/ha which compared to azadirachtin and betacyfluthrin. Each treatment was arranged in Randomized Block Design with three replications. Parameter observed were population of H. armigera larvae and its natural enemy (spiders), boll damage, and seed cotton yield. Result showed that until the day seventh the mortality of H. armigera larvae reached 46.7% due to B. bassiana and loss 59.3% of larval weight at 2,3 x 10 5 conidia/ml in polybag testing. In field testing, B. bassiana proved to be relatively harmful to spiders because it reduced the their population as 48.4%. However, the B. bassiana reduced of 36-48% the population of H. armigera larvae as well as the cotton boll damage of 10.1-10.3% and increased the seed cotton yield ranged 12.1-29.7%. Key words: Beauveria bassiana, Helicoverpa armigera, conidia, larvae, mortality