Project
Genetic diversity of Spodoptera frugiperda population
The fall armyworm (FAW) is a native agricultural pest in tropical and subtropical regions of America. Due to its rapid and long-distance migratory behavior, this polyphagous pest crossed the Atlantic Ocean and invaded more than 70 countries in Africa, Asia, and Australia within five years. In Ethiopia, it was first reported in 2017. In this project, we will describe the Ethiopian FAW population in terms of its host plant preference, resistance to chemical pesticides and Bt_protien, and predict its origin and migration pattern.
Background
The fall armyworm (FAW) (Spodoptera frugiperda) (J.E. Smith) (Lepidoptera: Noctuidae: Noctuinae) is an invasive noctuid pest native to the Americas. It was introduced to the old world through human activities and has become widespread, causing significant economic, ecological, and societal impacts in the areas it newly invaded. The adult moth can fly more than 100km per day; this long-distance flight behavior, coupled with human anthropological activities, have facilitated the pest’s rapid global dispersal. Early in 2016, initial report of the fall armyworm outside the American continent was made in West African countries Nigeria and São Tomé and Príncipe, and it has rapidly spread to the Sub-Saharan countries within two years of period. Since then, it has spread rapidly to the Near East, Asia and the Pacific areas including India, China, Indonesia, Japan and South Korea. The pest has continued invading new territories in Far East and detected in Northern part of Australia in 2020. More recently, the pest has been reported to reach New Zealand in early February 2022.
Spodoptera frugiperda is a polyphagous pest and the larvae of this pest can feed on more than 350 host plants beloning to 76 plant families. Because of it polyphagy, it can cause significant economic damage on major edible and commercial crops such as maize, sorghum, cotton, sugarcane, millet, and rice. The distribution of this pest into new geographic habitats away from its origin brings on major threats to the agricultural sector. In Africa, for example, FAW has caused yield reduction in maize ranging from 15 – 73%. FAW is a major alien invasive species known to cause the highest annual yield loss resulting up to USD 9.4 billion loss per annum.
Population studies provide the presence of two morphologically indiscriminate lineages of FAW: the Corn(C) strain that prefers large grasses such as maize, sugarcane and sorghum and the Rice(R) strain that is preferentially found in rice and various pasture grasses. The mitochondrial gene cytochrome oxidase subunit I gene (COI), a barcode region, is more reliable and widely used species identification techniques than the morphological approach. Genetic polymorphisms in the COI gene are also used to characterize strain identity into C or R. In addition to mitochondrial markers, the sex linked nuclear Triosephosphate isomerase (Tpi) gene, has been used for strain identity. More recently, whole genome sequencing is being utilized to described allele frequencies of specific point mutations that are associated with resistance to chemical pesticides and Bt-toxin and to investigate population dynamics. This study aspires to make use of these molecular tools to describe the FAW population in Ethiopia. Particularly, we want to figure out the crops that are under potential risk to this invasion and we also want to deliver effective intervention mechanisms that can be harmonized with the existing integrated pest management practices.
Project description
The aim of this project is to characterize the FAW population in Ethiopia. More specifically, we want to use molecular species identification to confirm the presence of this species in the region which was previously reported only through morphological techniques. This investigation also determines whether the Corn(C) or the Rice(R) strain or both strains are introduced into Ethiopia. It also examines if the Ethiopian population carries resistance alleles for important chemical pesticides and Bt-toxins. The study describes the potential source of entry and its migration pattern throughout the country as well.
To achieve the stated goals, we will carry out DNA barcoding using the COI gene. To determine the strain identity of the population second subunit of the mitochondrial cytochrome oxidase I (COB) gene and the nuclear triosephosphate isomerase (Tpi) gene will be sequenced. Likewise, whole genome sequencing will be done to investigate the genetic variation at genomic level. Finally, transcriptome analysis will be done to reveal the interaction of these pests to important chemical pesticides and Bt_proteins.