Perilaku Imago dan Penetasan Telur Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

Abstract

Spodoptera frugiperda (J.E. Smith) atau ulat grayak jagung (UGJ) merupakan hama kosmopolitan yang menyebabkan kerusakan berat pada pertanaman jagung di beberapa negara. Penelitian ini bertujuan mempelajari perilaku imago dan penetasan telur UGJ. Perilaku hinggap dan peletakan telur diamati pada pagi pukul 07:00 s.d. 09:00 dan sore pukul 16:00 s.d. 18:00 terhadap 223 imago jantan dan 366 imago betina yang dilepaskan di dalam sungkup kasa berukuran 1.5 m x 1.5 m x 2 m dengan sembilan tanaman jagung. Perilaku imago juga diamati setiap dua jam selama 24 jam terhadap kurang lebih 30 pasang imago. Proses penetasan telur dilakukan dengan mengamati dua puluh kelompok telur setiap dua jam sekali selama dua hari. Tidak terdapat perbedaan pola distribusi hinggap pada beberapa lokasi selama pengamatan pagi dan sore, dan juga diantara jenis kelamin. Sepertiga dari populasi imago hinggap pada tanaman jagung dan secara keseluruhan hinggap pada bagian permukaan atas (adaksial) daun jagung. Sebagian besar imago S. frugiperda meletakkan kelompok telur pada permukaan bawah (abaksial) daun jagung. Imago S. frugiperda aktif malam hari dan seluruh aktivitas bergerak/terbang, kawin, serta meletakkan telur terjadi antara pukul 18:00 s.d. 04:00. Telur S. frugiperda menetas antara pukul 02:00 s.d. 12:00 dan sekitar 75% kelompok telur menetas di antara pukul 02:00 s.d. 06:00.

The fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a cosmopolitan pest that may cause severe damages on corn in many countries. This research was to study FAW moth and egg hatching behavior. The perching and egg laying behaviors were observed in the morning (7–9 am) and late afternoon (4–6 pm) on 223 males and 366 females moths released inside a 1.5 m x 1.5 m x 2 m cage with 9 corn plants in it. The behaviors were also observed every two hours for 24 hours involving about 30 pairs of moths. Egg hatching processed were carried out by observing 20 egg clusters every 2 hours for 2 days. There were no differences on the pattern of moth perching locations during the morning and afternoon observations, and also between sexes. One third of the moths perched on the corn plants and almost all moths perched on upper surfaces of the corn leaves. About half numbers of egg clusters were laid on the corn plants, and most of them were laid at lower surfaces of the corn leaves. Fall armyworm moths were nocturnal and activities of moving/flying, mating and egg laying occurred between 6 pm to 4 am. Fall armyworm egg hatching occurred between 2 am to 12 am, and 75% of them hatched between 2 am to 6 am.