EFEK KRONIS TOKSIN Bacillus thuringiensis Cry2Ab2 PADA LARVA Ostrinia furnacalis

A. DIMAS HAMDAYU RIZAL, Prof. Ir. Y. Andi Trisyono, M.Sc., Ph.D.; Dr. Suputa, S.P., M.P.

2014 | Skripsi | ILMU HAMA & PENYAKIT TUMBUHAN

Bacillus thuringiensis Cry2Ab2 dan Cry1A.105 merupakan insektisida protein yang terekspresi dalam jagung pipil dan jagung manis MON 89034 untuk mengendalikan beberapa jenis Lepidoptera. Efek kronis protein B. thuringiensis telah dilaporkan pada beberapa spesies serangga. Penelitian ini bertujuan untuk menentukan efek kronis toksin protein B. thuringiensis Cry2Ab2 terhadap konsumsi dan pemanfaatan pakan, pertumbuhan dan perkembangan larva Ostrinia furnacalis. Penelitian menggunakan Rancangan Acak lengkap (RAL) dengan tiga perlakuan 0 ppm (kontrol); 0,093 ppm (LC15); dan 4,328 ppm (LC50), masing-masing dengan enam ulangan menggunakan sepuluh larva per ulangan. Parameter untuk menentukan efek kronis diantaranya Waldbauers Indexes; mortalitas; Larvae Growth Index (LGI); Standarized Insect-growth Index (SII); lama hidup; berat larva; rasio jenis kelamin; abnormalitas; dan fekunditas. Perlakuan konsentrasi sublethal Cry2Ab2 menghambat pertumbuhan dan perkembangan larva O. furnacalis. Efek tersebut diduga disebabkan adanya gangguan pada sistem pencernaan (midgut) yang diindikasi oleh tingginya Consumption Index (CI) dan Approximate Disgestibility (AD) pada larva yang dipapar dibandingkan larva kontrol, namun Efficiency of Convertion of Ingested Food to Body Substance (ECI) dan Efficiency of Convertion of Disgested Food to Body Substance (ECD) larva yang dipapar lebih rendah daripada larva kontrol. LGI dan SII larva yang dipapar lebih rendah daripada larva kontrol. Efek kronis juga menyebabkan penurunan fekunditas betina O. furnacalis yang berkembang dari larva yang dipaparkan pada Cry2Ab2.

Bacillus thuringiensis Cry2Ab2 and Cry1A.105 are insecticidal proteins expressed in the field and sweet corn MON 89034 for controlling several Lepidoptera. Chronic effects of B. thuringiensis protein on several insects have been reported. This research was intended to determine the chronic effect of B. thuringiensis Cry2Ab2 againts consumption and diet utilization, growth, and development of Ostrinia furnacalis larvae. The experiment employed a Completely Randomized Design (CRD) with three treatments 0 ppm (control); 0.093 ppm (LC15); and 4.328 ppm (LC50) with six replications using ten larvae per replicate. Parameters used to determine the chronic effects were Waldbauer�s Indexes, mortality, Larvae Growth Index (LGI), Standardized Insect-growth Index (SII), life longevity; sex ratio; weight of larvae and pupae, and fecundity. Exposure ofO. furnacalis to sublethal concentration of Cry2Ab2 inhibited growth and development of larvae. There effects might be due to damage in the midgut as indicated by high Consumption Index (CI) and Approximate Disgestibility (AD) in the treated larvae compared to the control larvae, but the Efficiency of Convertion of Ingested Food to Body Substance (ECI) and Efficiency of Convertion of Disgested Food to Body Substance (ECD) of the treated larvae were less than those of the control larvae. The LGI and SII of the treated larvae were lower than those of control larvae. These chronic effects might have resulted a lower fecundity O. furnacalis females produced from treated larvae than those developed from the control larvae.

Kata Kunci : Bacillus thuringiensis, efek kronis, Cry2Ab2, Ostrinia furnacalis.