The use of plant varieties can affect the presence and extent of pest attacks. Resistant varieties will cause a lower attack rate compared to susceptible varieties. It is not yet known which varieties of maize are resistant to Fall armyworm (S. frugiperda) (FAW) in the field, because this pest is an invasive pest and entered Indonesia one year ago. Research has been carried out to study the distribution, population, and level of S. frugiperda attack on maize varieties planted by farmers in the field. The research was conducted at the first location this pest was reported in West Pasaman district, West Sumatra, Indonesia. Survey on farmers’ corn with a sampling method: purposive random sampling. Samples were taken from different varieties of corn and showed signs of S. frugiperda attack. Observations were made on the varieties planted by farmers, symptoms, larvae population, and S. frugiperda attack rate. The results of the observations were that several trademarks of maize varieties grown by farmers were: Pioneer 32, Pertiwi, Bisi 18, NK7328, and NK212. The symptoms of this pest attack were the same for all varieties of maize, while the attack rate was significantly different at the 5% level. The attack rate ranged from 6.0 to 96.0%. The lowest attack percentage was on variety Bisi18, and the highest was on variety NK212. The population of S. frugiperda larvae was found in all varieties of maize with an average of 0.70 larvae per stem.

Botanical insecticide nanoemulsion formulation is an insecticide with spontaneous emulsion system. Nanoemulsion formulation is an oil phase-in-water dispersion stabilized by a surfactant molecule which has size ranging from 50 nm to 500 nm. The oil phase consists of Piper aduncum extracts and bioethanol, while the water phase consists of aqudest and emulsifiers. The experiment was conducted in Insect Bioecology Laboratory, Faculty of Agriculture, Universitas Andalas Padang from October 2018 to March 2019. The purpose of this research was to obtain nanoemulsion from P. aduncum extract and to observe the activity of P. aduncum nanoemulsion against C. pavonana. Nanoemulsion formulation was prepared using spontaneous emulsification method then followed by toxicity test against C. pavonana larvae. Nanoemulsion formulations with high insecticidal activity were analyzed using Zetasizer Nano (ZS) Malvern for particle size and zeta potential. The results showed that particle size of AT.1 and BA.1 nanoemulsions were 141.1 nm and 172.5 nm respectively, and they were categorized as nano particles. AT.1 and BA.1 nanoemulsions caused mortality of C. pavonana larvae with LC95 value were 0.85% and 0.76%, respectively. Besides the toxic effect, the AT.1 and BA.1 nanoemulsions were also interfered growth and development of C. pavonana larvae.

Nanoemulsion is a preparation consisting of an oil phase and a water phase with particle sizes in the range of 20-200 nm. The study aimed to obtain a mixed nanoemulsion from Piper aduncum fruit and Tephrosia vogelii leaves as an active botanical insecticide against larvae of Crocidolomia pavonana. Nanoemulsions were made using a low energy method, namely spontaneous emulsification using a magnetic stirrer and then followed by a toxicity test. The nanoemulsion toxicity test was carried out singly and in a mixture on C. pavonana larvae using the deep leaf method. The results showed that at the LC50 and LC95 nanoemulsion of mixture T. vogelii and P. aduncum extract was synergistic and showed higher activity than a single nanoemulsion of T. vogelii and P. aduncum.

Abstract. Nelly N, Hamid H, Lina EC, Yunisman. 2021. Distribution and genetic diversity of Spodoptera frugiperda J. E. Smith (Noctuidae: Lepidoptera) on maize in West Sumatra, Indonesia. Biodiversitas 22: 2504-2511. Fall Armyworm (FAW), Spodoptera frugiperda is a major maize pest, reportedly entering West Sumatra, Indonesia in early 2019. After a year of its discovery, there has been no information on the distribution and genetic diversity of this pest. In the present study, research has been carried out to obtain reliable information on the spread, incidence, and genetic diversity of this pest during July-October 2020 at the maize production center of West Sumatra, Indonesia. Sampling was then carried out using the purposive random sampling method, on maize fields in 5 districts (West Pasaman, Padang Pariaman, Solok, Limapuluh Kota and, Tanah Datar). The sample plots were determined with a size of 1x1m2 to observe the population and incidence, meanwhile, the observations were recorded on the larvae number and the percentage damage. Each district location's genetic diversity was analyzed based on the mitochondrial cytochrome c oxidase subunit I (COI) gene nucleotide variations amplified with specific primers. The observations show that S. frugiperda had attacked all maize planting sites in West Sumatra with the attacks ranging percentage from 12.78 to 41.25% and an average larval population of 0.26-1.05 larvae / 2 plants. The genetic diversity analysis results of the S. frugiperda West Sumatra population, on the phylogenetic tree, were divided into two groups, the first is group A which consisted of West Pasaman isolates, and Solok isolates. The second, Group B consisted of Padang Pariaman, Limapuluh Kota, and Tanah Datar isolates (The percentage genetic similirity 99.86-100%). The S. frugiperda population genetics in West Sumatra are similar to those isolates from several other countries in the world.

No abstract