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Spodoptera frugiperda (Lepidoptera: Noctuidae) has successfully invaded and spread to almost all provinces of Indonesia which may cause significant impacts on corn production. Local natural enemies could play an important role in managing this invasive insect, and more diverse ecosystems would benefit natural enemies. This study aimed to assess parasitization rates of S. frugiperda eggs by local egg parasitoids in three different corn ecosystems (agroforestry, rice field, and rainfed field) in East Java. Sentinel egg masses were used for this study by exposing eight-hour-old egg masses collected from the laboratory mass-rearing and left for 24 hours in corn plantations aged 7, 14, and 28 days after planting. Telenomus sp. was more abundant in the three ecosystems compared to Trichogramma sp. The egg mass parasitization varied from 15.6 to 52.5%. The number of egg masses parasitized was consistently higher in agroforestry, followed by rice fields and rainfed fields in all three different sampling times. Interestingly parasitization rates on egg masses were not different, and they ranged from 43.7 to 81.6%. These findings provide evidence on the importance of local egg parasitoids for managing S. frugiperda and some insights related to plant diversity to improving the services by these parasitoids.

Spodoptera litura is one of the important insect pest of maize besides the notoriously damaging corn borer, Ostrinia furnacalis. S. litura has been the target of various controls including the use of Bacillus thuringiensis (Bt) toxin Cry1A.105 and Cry2Ab2. This study was conducted to evaluate the acute effect of Bt toxin Cry1A.105 and Cry2Ab2 on the growth and development of S. litura from larval to adult stages. Two sublethal concentrations were used; 0.1875 and 0.0469 ppm for Cry1A.105, and 0.0008 and 0.0003 ppm for Cry2Ab2. The bioassay using diet dipping was carried out on a CRD with three experiments and five repetitions. The observation was carried out on the mortality and survival rates of S. litura. The mortality reached 28% when the larvae were treated with 0.1875 ppm and 20% with 0.0469 ppm of Cry 1A.105. The exposed larvae and pupae were smaller than control. Larval and pupal weight were 117.0 and 165.6 g with 0.1875 ppm, while control were 212.9 and 211.2 g. Cry1A.105 also longer the larval stage, larval stage with higher and lower concentration were 24.5 and 22.3 day, while control was 20.5 day. The resulted pupae from larve which exposed by Cry1A.105 were less than control; there were 40% at concentration 0.1875 ppm and control 61%. The two concentration of Cry2Ab2 produced similar mortality of 20%. Similarly, Cry2Ab2 affected pupal to adult stages development. The longevity of pupal stage with concentration 0.0003 ppm was 9.5 days, followed by 0.0008 ppm (9.1 days) and control (10.1 days). The adult emerge on the highest concentration was 47.4% while control only 34.6%. There results showed that both Cry1A.105 and Cry2Ab2 were detrimental to the survival of S. litura which is the non-target insect of transgenic Bt maize. INTISARI Spodoptera litura merupakan salah satu hama penting yang menyerang tanaman jagung, selain Ostrinia furnacalis. Belakangan ini O. furnacalis diketahui telah menjadi target dari berbagai macam cara pengendalian termasuk penggunaan toksin Bacillus thuringiensis (Bt) Cry1A.105 dan Cry2Ab2. Penelitian ini dilakukan untuk mengetahui efek akut toksin Bt Cry1A.105 dan Cry2Ab2 terhadap pertumbuhan dan perkembangan S. litura dari larva sampai imago. Dua konsentrasi subletal yang akan digunakan adalah; 0,1875 dan 0,0469 ppm untuk Cry1A.105, dan 0,0008 dan 0,0003 ppm untuk Cry2Ab2. Pengujian dilakukan dengan menggunakan metode celup pakan dan Rancangan Acak Legkap dengan tiga perlakuan dan lima ulangan. Pengamatan dilakukan terhadap mortalitas dan kelangsungan hidup S. litura. Mortalitas mencapai 28% pada larva yang dipaparkan dengan 0,1875 ppm dan 20% dengan 0,0469 ppm Cry 1A.105. Larva dan pupa yang terkena toksin berukuran lebih kecil. Berat larva dan pupa yang terpapar toksin dengan konsentrasi 0,1875 ppm, masing – masing 117,0 dan 165,6 g, sedangkan kontrol masing – masing 212,9 dan 211,2 g. Cry1A.105 juga dapat memperpanjang stadia larva. Lama stadia larva dengan konsentrasi tertinggi dan terendah adalah 24,5 dan 22,3 hari, sedangkan kontrol 20,5 hari. Jumlah pupa yang berhasil terbentuk dari larva yang terpapar toxin Cry1A.105 lebih sedikit dibandingkan dengan kontrol; pada konsentrasi 0,1875 ppm sebesar 40%, sedangkan kontrol sebesar 61%. Kedua konsentrasi dari toksin Bt Cry2Ab2 menyebabkan mortalitas yang sama yaitu 20%. Cry2Ab2 juga berpengaruh terhadap lama stadia pupa dan tingkat keberhasilan pembentukan imago. Lama stadia pupa dengan konsentrasi 0,0003 ppm adalah 9,5 hari, diikuti dengan konsentrasi 0,0008 ppm (9,1 hari) dan kontrol (10,1 hari). Jumlah imago terbanyak terdapat pada perlakuan dengan konsentrasi 0,0008 ppm sebesar 47,4% sedangkan pada kontrol hanya 34,6%. Hal ini menunjukkan bahwa toksin Bt Cry1A. 105 dan Cry2Ab2 juga berpengaruh terhadap kelangsungan hidup S. litura yang merupakan serangga bukan sasaran dari tanaman jagung transgenik Bt.

A field study was conducted to determine the distribution of egg masses of Ostrinia furnacalis on corn leaves and within corn field. The corn field was divided into three regions: the inner edge closed to other crops and outer edge closed to main road and the middle region. The numbers of egg masses laid were recorded entirely in all corn plants existed (census method). Egg laying period lasted for 34 days, with 11 days from initiation of egg laying to the peak of oviposition and 23 days from the peak to termination of egg laying. The egg masses laid on corn leaves were distributed in aggregation pattern. During eight-opened-leaf to twelve-opened-leaf stages, there were 847 egg masses found, and 80.9% was laid on the sixth-to-ninth leaves. From tasseling to blister stages there were 491 egg masses found of which approximately 80.7% was laid on the seventh-to-11 32.8, and 29.8% of those were found in the inner edge, middle, and outer edge of corn field, respectively. leaves. Egg masses laid within corn field varied, in which 37.4, 32.8, and 29.8% of those were found in the inner edge, middle, and outer edge of corn field, respectively. Kajian lapang dilaksanakan untuk mengetahui pola sebaran peletakan kelompok telur ngengat Ostrinia furnacalis pada daun tanaman jagung dan penyebarannya pada lahan pertanaman jagung. Lahan penelitian dibagi menjadi tiga kelompok yaitu lahan pinggir dalam berdekatan dengan pertanaman lain, bagian tengah lahan, dan lahan pinggir luar berdekatan dengan jalan raya. Pengamatan kelompok telur dilakukan pada seluruh tanaman jagung (sensus). Periode peletakan telur berlangsung selama 34 hari, dengan periode inisiasi hingga puncak 11 hari dan periode setelah puncak hingga akhir peletakan telur 23 hari. Peletakan telur O. furnacalis pada daun tanaman jagung menyebar secara berkelompok. Pada fase 8 hingga 10 daun telah terbuka sempurna ditemukan sebanyak 847 kelompok telur, 80,9% diantaranya ditemukan pada daun ke 6–9. Pada fase VT (bunga jantan) hingga fase R2 (bunga betina telah kering) ditemukan sebanyak 491 kelompok telur, 80,7% diantaranya ditemukan pada daun 7–11. Penyebaran kelompok telur pada bagian lahan terjadi secara berkelompok. Jumlah kelompok telur tertinggi berturut-turut dari bagian lahan pinggir dalam, bagian tengah lahan, dan bagian lahan pinggir luar masing-masing 37,4; 32,8; dan 29,8%.

Increasing the reproductive capacity through increasing plant growth and nutrition is one plausible mechanism of resurgence. This research was intended to determine the effect of deltamethrin on plant vigor and nutrition contents. The experiment was carried out outdoor. The treatments tested were deltamethrin (50 ppm), buprofezin (100 ppm), and control (water). Insecticide applications were applied one time (at age 26 d or 50 d) and two times (at age 26 and 50 d). Deltamethrin applications as many as two times did not increase the total chlorophyll and the photosynthesis rate, nutrients (total nitrogen, total protein, total sugar, total reducing sugar at aged 26 d, and sucrose), growth (plant height and number of tillers), and yield (number of panicles). However, application of deltamethrin at aged 26 d increased the amount of asparagine. Asparagine is known to be associated with the feeding rate of Nilaparvata lugens stimulation. Therefore, increasing level of asparagine after application of deltamethrin at sublethal concentration was considered as one of the factors that might be involved in the mechanism of N. lugens resurgence. Salah satu mekanisme resurjensi adalah peningkatan reproduksi hama melalui peningkatan nutrisi dan pertumbuhan tanaman. Penelitian ini dimaksudkan untuk melihat pengaruh deltametrin terhadap kandungan nutrisi dan vigor tanaman. Pengujian dilakukan di lapangan. Perlakuan yang diuji adalah deltametrin 50 ppm, buprofezin 100 ppm, dan kontrol (air). Aplikasi insektisida dilakukan satu kali masing-masing pada umur tanaman 26 dan 50 hst dan dua kali pada umur 26 dan 50 hst. Aplikasi deltametrin sebanyak dua kali tidak meningkatkan total klorofil dan laju fotosintesis, nutrisi (total nitrogen, total protein, total gula, total gula reduksi pada 26 hst, dan sukrosa) kecuali asparagin, pertumbuhan (tinggi tanaman dan jumlah anakan), dan hasil (jumlah malai) tanaman. Oleh karena asparagin berperan sebagai pemacu laju makan Nilaparvata lugens, maka peningkatan kadar asparagin tanaman setelah aplikasi konsentrasi subletal deltametrin diduga sebagai salah satu faktor yang terlibat dalam mekanisme resurjensi N. lugens