Tujuan penelitian ini untuk mengetahui 1) tingkat kepekaan kesebelas populasi P. xylostella terhadap emamektin benzoat agar diketahui tingkat kepekaannya, 2) faktor penyebab perbedaan tingkat kepekaan masing-masing populasi uji 3) metode yang dapat mendeteksi perubahan kecil frekuensi individu resisten, 4) mekanisme resistensi P. xylostella sehingga populasi menjadi resisten, dan 5) pewarisan sifat resistensi populasi P. xylostella terhadap emamektin benzoat. Uji hayati emamektin benzoat terhadap larva P. xylostella instar ketiga generasi kedua dilakukan dengan metode celup pakan ke dalam insektisida. Pengujian dengan enam seri konsentrasi yang berbeda untuk setiap populasi, dan perlakuan diulang tiga kali. Pengamatan mortalitas dilakukan 24 sampai 72 jam setelah perlakuan. Besarnya resistensi populasi serangga ditunjukkan dengan menghitung nilai resistance factor (FR). Populasi serangga dinyatakan resisten jika FR ≥ 4. Data dianalisis dengan probit analisis. Analisis biokimia dilakukan pada populasi serangga yang telah resisten terhadap emamektin benzoat. Analisis aktivitas asetilkolin esterase, dan esterase non-spesifik diukur dengan menggunakan ELISA reader Hasil uji kepekaan menunjukkan, bahwa populasi Puasan FR nya sebesar 3,97 kali, dan merupakan populasi dengan FR tertinggi, sedangkan terendah pada populasi Selo yang merupakan populasi paling peka. Hasil validasi konsentrasi diagnostik menunjukkan semua populasi uji nilai χ2 hitung < χ2 tabel, maka konsentrasi diagnostik yang ditetapkan (2443,99 ppb) efektif untuk monitoring resistensi P. xylostella terhadap emamektin benzoat. Perbedaan resistensi menggambarkan variasi alami dan tekanan seleksi karena pemaparan insektisida tersebut. Hasil uji biokimia menunjukkan adanya peningkatan detoksifikasi AChE, tetapi aktivitas esterase non-spesifik tidak mencerminkan aktivitas esterase. Hasil uji hayati pada F1 hasil perkawinan resiprok menunjukkan, resistensi P. xylostella bersifat resesif, tidak ada efek maternal, Analisis chi-square membuktikan bahwa sifat resistensi diturunkan secara monogenik.

The objectives of this research were (1) to know the susceptibility of eleventh P. xylostella populations to emamectin benzoate, (2) to know the sensitivity differences of P. xylostella to emamectin benzoate, (3) to know the monitoring method for detecting an individual of resistance the small change, (4) to know whether the process is connected to the emamectin benzoate into the body of insect, (5) to study of inheritance resistance to emamectin benzoate in P. xylostella. The leaf-dip bioassay were employed to determine the sensitivity of P. xylostella to emamectin benzoate. The third instars larvae of the second generation were used. The test used six different concentration series for each population, and each treatment was repeated three times. The mortality observation was conducted 24 to 72 h after treatment. Data was analyzed used probit analysis. Resistance factor was determined by comparing LC50 value of field population with standard population. Field population of P. xylostella was considered resistant if it had FR ≥ 4. Biochemistry analysis of resistance which was conducted to P. xylostella showed resistance. The analysis of acetylcholinesterase and esterase non-specific activities were done using ELISA reader method. The results of sensitivity assay show that the resistance factor value of Puasan population was 3.97 times and it was higher than of Selo population to represent the most sensitive population. The resistance difference represents natural variation and selection pressure to insecticide exposure. Results of validation the diagnostic concentration show that the χ2-count was smaller than χ2-table value so that the diagnostic concentration was considered (2443.99 ppb) to be effective to monitor resistance of P. xylostella (L.) to emamectin benzoate. The resistance could be explained by the reduced sensitivity of target enzyme to inhibition by insecticide, The non-specific esterase activity did not reflect the esterase activity. The results of the bioassay of F1 represent reciprocal and backcross mating showed that the P. xylostella (L.) resistance inherited resessive, not maternal effect. The chi-square analysis of monogenic model proved that the resistance was controlled by single genetic.

Kata Kunci : Plutella xylostella (L.), konsentrasi diagnostik, emamektin benzoat, resistensi, monogenik