A Guide to Biological Control of Fall Armyworm in Africa Using Egg Parasitoids

Fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), a voracious agricultural pest native to North and South America, was first detected on the African continent in 2016 and has subsequently spread throughout the continent and across Asia. Fall armyworm (FAW) is known to feed on over 350 plant species and it has been predicted to cause up to $US 13 billion per annum in crop losses throughout sub-Saharan Africa, thereby threatening the livelihoods of millions of poor farmers. Since the occurrence of FAW in Africa, synthetic chemical insecticides have been widely used as emergency responses to halt distribution of the pest and minimize damage in maize fields. Most smallholder farmers in Africa and Asia, however, cannot afford frequent insecticide applications. Furthermore, dependence on chemical insecticides results in the development of resistance to major classes of insecticides, effects on nontarget organisms, as well as other adverse effects to humans and the environment. This highlights the need for the development of integrated pest management (IPM) strategies that are suitable to African smallholder farmers. Biological control using egg parasitoids particularly from the genus Trichogramma and Telenomus remus is part of the IPM approach presently underway to control FAW in North and South America. The approach involves mass rearing and release of these egg parasitoids to control FAW. These egg parasitoids are reared on factitious and natural hosts. Various species of both parasitoids are already present in Africa. After identifying the species/strain that best suit the local condition, the parasitoid wasps can be mass reared and used against FAW and other lepidopteran pests. Therefore, the purpose of this book is to provide guidelines on mass rearing systems for both the egg parasitoids and their hosts. The book describes the methods used to mass produce FAW (S. frugiperda), rice meal moth (Corcyra cephalonica (Stainton), Lepidoptera: Pyralidae), egg parasitoids - (Trichogramma chilonis Ishii, Hymenoptera: Trichogrammatidae) and (Telenomus remus Nixon, Hymenoptera: Platygastridae) in the facilities at icipe- Kenya and ICRISAT-Niger. This guide is primarily intended for biological control practitioners at universities, research institutes and commercial laboratories particularly involved in managing FAW and other lepidopteran pests. The information in this document is also intended to assist those who are relatively new at rearing FAW, rice meal moth, and the parasitoid wasps and to those who wish to improve existing rearing systems. The document covers virtually all aspects of information on the rearing techniques of each species such as colony establishment, stock culture maintenance, diet preparation, mass rearing, storage, quality control and field release. Each section is interrelated, contains step-by-step procedures, and is supported by colour pictures. The guide produced jointly by the International Centre of Insect Physiology and Ecology (icipe), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Haramaya University, and Virginia Tech through support provided by the Feed the Future Innovation Lab for Integrated Pest Management, funded by the of the US Agency for International Development (USAID) under the Cooperative Agreement No. AID-OAA-L-15-00001. International Centre of Insect Physiology and Ecology (icipe) is an international scientific research institute, headquartered in Nairobi, Kenya that works towards improving lives and livelihoods of people in Africa. The center’s main objective is to research and develop alternative and environmentally friendly pest and vector management strategies that are effective, selective, non-polluting, non-resistance inducing, and which are affordable to resource-limited rural and urban communities. icipe's mandate extends to the conservation and use of the rich insect biodiversity found in Africa. Today, icipe is the only international center in sub-Saharan Africa working primarily on arthropods. icipe focuses on sustainable development using human health as the basis and the environment as the foundation for sustainability (http://www.icipe.org/). International Crops Research Institute for the Semi-Arid Tropics (ICRISAT): is a non-profit, non-political organization that conducts agricultural research for development in the drylands of Asia and sub-Saharan Africa. Covering 6.5 million square kilometers of land in 55 countries, the semi-arid or dryland tropics has over 2 billion people, and 644 million of these are the poorest of the poor. ICRISAT and its partners help empower these poor people to overcome poverty, hunger and a degraded environment through better agriculture. ICRISAT is headquartered in Hyderabad, Telangana State, in India, with two regional hubs (Nairobi, Kenya and Bamako, Mali) and country offices in Niger, Nigeria, Zimbabwe, Malawi, Ethiopia and Mozambique. ICRISAT is a member of the CGIAR system Organization (https://www.icrisat.org/). Virginia Polytechnic Institute and State University, commonly known as Virginia Tech, is a public, land-grant research university with its main campus in Blacksburg, Virginia (https://vt.edu/). The university houses the Feed the Future Innovation Lab for Integrated Pest Management, which aims to improve the livelihoods of smallholder farmers by implementing sustainable crop solutions in the developing world. Haramaya University is a public academic and research university with its main campus in Haramaya, located at about 510 km East of Addis Ababa, Ethiopia. The university offers 264 academic programs of which 113 are undergraduate programs, 131 are second degree (M.Sc./M.Ed./MPH) and 20 are PhD level training programs. In addition, the university has been actively involved in research activities, primarily in the fields of agriculture

Biology of barley shoot fly Delia flavibasis Stein (Diptera: Anthomyiidae) on resistant and susceptible barley cultivars

The biology of barley shoot fly Delia flavibasis was studied using resistant (Dinsho and Harbu) and susceptible (Holker) barley cultivars at Sinana Agricultural Research Center, Ethiopia. A higher number of eggs was laid on Holker (17 eggs/female) than on Dinsho (11 eggs/female) or Harbu (12 eggs/female). However, there were no differences between cultivars in preoviposition and total reproductive periods. The shortest time required to complete larval, pupal and total developmental stages from egg to adult emergence occurred when the insect was reared on the cultivar Holker. Pupal weight, adult emergence and adult longevity did not differ between cultivars. The female to male sex ratio was 1:1. This study enabled us to understand the duration of each of the life stages of D.flavibasis, which will undoubtedly aid researchers and growers to design a sustainable management strategy against barley shoot fly

Diversity and abundance of lepidopteran stem borers and their host plants in Ethiopia

Lepidopteran stem borers are among the most important insect pests of maize, sorghum and sugarcane in sub-Saharan Africa. Except for Chilo partellus, the other stem borer pests in Ethiopia are indigenous to Africa and are assumed to have coevolved with some native grasses and sedges in the natural habitat. In addition to pest species, natural habitats harbour diverse non-economic stem borer species, some of which are new to science. However, with the growing threats to natural habitats, some non-economic stem borer species may switch or expand their host ranges to include cultivated crops and evolve as new pests. Besides host switch, some of the unknown species currently limited to natural habitats may disappear. We examined the diversity, abundance and interactions of lepidopteran stem borers and their wild host plants in five different vegetation mosaics in Ethiopia. The stem borer species diversity varied among vegetation mosaics and host plants. Forty-four stem borer species belonging to 14 different genera in the families of Noctuidae, Crambidae, Pyralidae and Tortricidae were recorded from 34 wild host plants and through light trap. Among these families, Noctuidae was the highest in species richness in which 31 species were identified, out of which 15 species and two genera were new to science. This paper discusses the ecological interpretation of host plant-stem borer species interactions, particularly in relation to habitat disturbances

Phylogeography of Sesamia cretica Lederer (Lepidoptera : Noctuidae)

The greater sugarcane borer, Sesamia cretica Lederer (Lepidoptera: Noctuidae) is an important pest of maize, sorghum and sugarcane in Africa, the Middle East, and Mediterranean Europe. However, the population genetics and phylogeography of this pest are unknown. Some insect pests exhibit genetic differentiation congruent with their geographical location and ecological conditions. To evaluate this, a molecular analysis was conducted on populations of S. cretica collected from Ethiopia, Eritrea, Kenya, Cameroon and Iran, using the cytochrome c oxidase subunit I (COI) region of the mitochondrial genome. Phylogenetic analyses based on neighbor joining tree separated the 22 specimens into two clades, the Ethiopian and Afro-Asian. The clades diverged long before the domestication of sorghum and the introduction of sugarcane in Africa. Analysis of molecular variance (AMOVA) indicated significant genetic differentiation among the clades. The observed genetic variation between the clades was further accompanied by restricted gene flow. The results of mismatch distribution analyses were consistent with the demographic expansion of the clades

Diversity and abundance of lepidopteran stem borer natural enemies in natural and cultivated habitats in Botswana

Lepidopteran stem-borers in Africa are attacked by diverse natural enemies in natural and cultivated environments. Field surveys of stem-borer natural enemies and associated host plants were conducted during the austral summers of 2014/15 and 2015/16 on natural and cultivated habitats across Botswana to determine their diversity and relative abundance. In cultivated habitats, the most common parasitoids of larvae were Cotesia flavipes Cameron, C. sesamiae (Cameron), and of pupae, Pediobius furvus Gahan and Gambroides nimbipennis Seyrig. In natural habitats, the larval parasitoids Chelonus curvimaculatus Cameron and Goniozus indicus Ashmead were recorded, along with the pupal parasitoid, Dentichasmias busseolae Heinrich. Furthermore, the predatory ants Linepithema humile Mayr, Crematogaster peringueyi Emery and Aenictus species were recorded in both cultivated and natural habitats. The major cultivated plants hosting stem-borers and related natural enemies were maize, sorghum, sweet sorghum, and the major wild plants were Echinochloa pyramidalis, Typha latifolia, Schoenopkctus corymbosus and Cyperus dives. Chilo partellus Swinhoe and Sesamia spp. were the major hosts for parasitoids, with C. partellus predominating in cultivated habitats and Sesamia jansei Tams & Bowden in natural habitats. Larval parasitism ranged from 2.1 to 34.7% and 3.3 to 14.3% in cultivated and natural habitats respectively, whereas pupal parasitism ranged from 6.1 to 10.6% and 6.7 to 9.1%, respectively. Parasitoid percentage abundance ranged from 1.1 to 41.6% and 4.8 to 38.1% in cultivated and natural habitats respectively, with C. flavipes dominating in cultivated and C. curvimaculatus in natural habitats. Our results show that cultivated and natural environments in Botswana harbor a diverse natural enemy community worthy of conserving for stem-borer biological control

Phylogeography and population structure of the Mediterranean corn borer, Sesamia nonagrioides (Lepidoptera : Noctuidae), across its geographic range

Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae), is a widespread insect pest in Africa, the Middle East, and Europe. However, its pest status varies across its distribution range. It is a major pest of maize in Europe and of sugarcane in Iran. In Africa, it is a major pest of maize in West Africa but not considered as a pest in East Africa. Recent surveys conducted in 2015 recorded S. nonagrioides to be a major pest of sugarcane in Ethiopia and reported the species for the first time in Botswana, outside its known geographic range. The genetic relationship of these records with the previously recorded population of S. nonagrioides was investigated using the cytochrome oxidase subunit I region of the mitochondrial genome. In total, 113 individuals across the geographic range of the species were analyzed and 63 haplotypes were identified. Phylogenetic analysis separated the populations into two clades with no distinct geographic distribution pattern. The genetic differentiation was also not associated with host plants and geographic distances. Results of the molecular analysis revealed the long-time establishment of S. nonagrioides population in Botswana and identified the newly recorded sugarcane population from Ethiopia as part of the wild host population in the country. The phylogeographic patterns observed among population of S. nonagrioides have probably been shaped by Pleistocene's climatic oscillations and geographic range expansions from different refugia with secondary contact and admixture. Possible reasons for the host-plant expansion by the Ethiopian population are discussed

Toward an understanding of the systematics and evolution of the genus Acrapex Hampson, 1894 (Lepidoptera : Noctuidae : Apameini : Sesamiina) : molecular phylogenetics of the genus and review of the species-rich Acrapex aenigma group

With a species count reaching almost 100 species, the genus Acrapex is themost diverse genus of sesamiine stemborers (Lepidoptera: Noctuidae: Noctuinae: Apameini: Sesamiina). Acrapex species are mostly distributed in the Afrotropics and consist of several large clades corresponding to distinct species complexes. In this study, 45 morphologically similar species of Acrapex from sub-Saharan Africa are reviewed, including 22 new species that are described: Acrapex alemura n. sp., A. barnsi n. sp., A. capelongo n. sp., A. congoensis n. sp., A. elgona n. sp., A. elisabethiana n. sp., A. eucantha n. sp., A. grandis n. sp., A. igominyi n. sp., A. inexpectata n. sp., A. ketoma n. sp., A. lilomwi n. sp., A. mafinga n. sp., A. makete n. sp., A. marungu n. sp., A. mazoe n. sp., A. mlanje n. sp., Acrapexmuchinga n. sp., A. ngorongoro n. sp., A. obscura n. sp., A. ruiru n. sp. and A. wittei n. sp. Supplemental descriptions for previously described species are provided as well. These 45 species are assigned to the newly defined Acrapex aenigma species group. We also conductmolecular phylogenetic analyses and molecular species delimitation analyses on a multimarker (four mitochondrial and two nuclear genes) molecular dataset encompassing 304 specimens (including 256 Acrapex specimens from 54 species of which 16 species belong to the A. aenigma group). Molecular phylogenetics analyses recover well-supported relationships within Acrapex and support the monophyly of the newly defined group. Results of molecular species delimitation analyses are mostly congruent and tend to corroborate the status of the sampled Acrapex species. Consistent with what has been previously found in other studies, the comparison of results from distinct methods and settings for molecular species delimitation analyses allows us to assess species boundaries with more confidence