Agricultural Entomology

Biology, Distribution and Management of Fall Armyworm, Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), on Maize (Zea mays L.) in Ethiopia

2026-06-22T06:56:20Z

Biology, Distribution and Management of Fall Armyworm, Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), on Maize (Zea mays L.) in Ethiopia Hailu Terefe, Tesfaye Fall armyworm (FAW) Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) is a polyphagous insect pest and has long been known as a serious economic pest in the tropical and subtropical regions of America. However, outside of the native range in North and South America, FAW was recently invaded different African countries and caused significant damage to maize. The invasive FAW first invaded Ethiopia in February 2017 and has since become established in many areas across the country and threatened food security of smallholder maize growing farmers. Maize, Zea mays L. is one of a strategic and staple crop that is prmarlly grown as a source of food in several Sub-Saharan Africa (SSA) countries including Ethiopia. In SSA, maize is essential for economic and food security for over 208 million people. In Ethiopia, maize occupies about 2.1 million hectares of land, of which, smallholder farms accounted for more than 95% of the total area and production. However, maize has a very low average grain yield in SSA due to a variety of abiotic and biotic constraints. Among the biotic constraint the damage caused by the recently introduced FAW is the most significant biotic component. Therefore, the present study aimed at determining the biological characters of FAW, their current distribution, damage level and its associated natural enemies which may provide further insights for future effective integrated management options. Recently, the damage caused by FAW has increased year after year. The current assessment of FAW distribution and infestation in different parts of Ethiopia confirmed that during the main season, the overall mean average infestation of FAW for the 2018/19 and 2019/20 crop seasons was 16.38 and 21.41%, respectively. Moreover, the dry season assessment recorded an average infestation of 42.5%. The results of natural enemy assessment revealed that six different types of indigenous natural enemies namely Entomopathogenic fungi (EPF), Entomopathogenic nematodes (EPN), Ladybird beetle, Earwig, Trichogramma sp., and Cotesia sp. that cause natural mortality on FAW were recorded and identified. The identified EPF and EPN were further screened against FAW to develop a biocontrol program against FAW. Among the EPN isolates, Steinernema sp. (Aso-Tes-287) and Heterorhabditis sp. (Am-Ger-Tes-74, Am-Adm-Tes-369, Z9) caused larval mortality within ten days under laboratory and lath house pot experiments. Particularly, based on the pot experiment, 74.7 (Aso-Tes-287), and 78.3% (Am-Ger-Tes-74) larval mortality were obtained at 600 IJ/ml. Most of the isolated EPF from different maize growing areas are virulent xxii against the 3rd instar larvae of FAW larvae and caused 50% mortality within 5.6 days. The four most virulent EPF isolates were further tested in a wire-house pot experiment for dose response at four different conidial concentration levels. Accordingly, two of the EPF isolates (ABe28 and SMe162) caused significant larval mortality at the higher conidial concentration (i.e., 1x109 conidia ml–1). Therefore, two EPN (Aso-Tes-287 and Am-Ger-Tes-74) and two EPF (ABe28 and SMe162) isolates, which caused higher mortalities within shorter periods, were promising bio-agents for the management of FAW. Future work would therefore be focused on field validation of these isolates against different stages of FAW in different agro-ecologies. The biology of FAW was studied in the greenhouse (usingr no-choice test) on different crops namely, maize, sorghum, chickpeas, barley, and wheat. Thus, the life cycle of FAW ranged between 31 to 38 days at rearing room temperature of 25.5 to 37.4°C and relative humidity of 35.33 to 45.46%. The highest number of days from egg to adult was recorded on sorghum and maize, while the lowest duration of on chickpea, barley, and wheat. The host preference study was also conducted using both choice and nonchoice tests on the major crops grown in Ethiopia. The host preference study result discovered that maize, sorghum, Swiss chard, teff, elephant grass, and cabbage were the most preferred hosts for egg-laying and larval development. 200

ECOLOGY AND MANAGEMENT OF THE WHITE MANGO SCALE, Aulacaspis tubercularis Newstead (HOMOPTERA: DIASPIDIDAE) IN ETHIOPIA

2023-03-21T12:59:45Z

ECOLOGY AND MANAGEMENT OF THE WHITE MANGO SCALE, Aulacaspis tubercularis Newstead (HOMOPTERA: DIASPIDIDAE) IN ETHIOPIA Temesgen Fita Gursha; Prof. Emana Getu (Ph.D.); Mulatu Wakgari (Ph.D.); Prof. Kebede Weldetsadik (Ph.D.) Mango is grown in more than 100 countries. However, many Arthropd insect pests attack mango, among which scale insects are the most devastating. Aulacuspis tubercularis Newstead (Homoptera: Diaspididae), commonly known as the white mango scale, is a serious insect pest of mango in many mango-growing countries, including Ethiopia. The ecology, host and cardinal direction preferences, presence of natural enemies (predators and parasitoids), and management aspects, including botanical extracts, are not well studied in Ethiopia. Therefore, the survey was conducted to determine the distribution, incidence, severity status, and knowledge of farmers’ occurrence and management practices of the pest in western, southwestern, northwestern, northeastern, central rift valleys, and eastern Ethiopia. The results of the field survey confirmed that the RAJ Agro Industry Loco mango commercial farm was the 1st locus of A. tubercularis accidental emergence and distributed to the neighboring administrative zones and regions of the country up to maximum air distances of 239, 277, 380, and 436 km in the western, southwestern, eastern and northern directions, respectively. Among the respondents, approximately 63% indicated that different cultural practices, such as tree smoking and pruning of heavily infested branches, are used for management practices. The incidence of A. tubercularis cluster (ATC) formation in the infested zones varied from 60 to 100% and was significantly (P<0.05) higher in the Assosa zone, followed by west Shewa. The lowest incidence was observed in the UAAI mango commercial farm in the East Showa zone, followed by the Bench-Sheko, Mizan Tepi & Kefa zones. The maximum average mean ATCs per leaf were recorded in the Assosa zone (39.24±7.56) and the minimum was recorded in the north Shewa zone (5.06 ± 0.66). The numbers of clusters and adult A. tubercularis females recorded per infested mango leaf showed large differences among the localities, with the maximum being 73 clusters and 821 adult females at the Algalea locality in the Homosha district of the Assosa zone, while the minimum was 5 clusters and 38 adult females at the UAAI locality. The results of the study on ecological aspects, cardinal direction preference and cluster population density confirmed that A. tubercularis were present in all sampled study areas throughout the study period with a fluctuating cluster population density. In all study areas, the highest population density of ATCs was significantly (0<0.05) concentrated on the upper side than on the underside of the infested mango leaves. The abundance and population density of ATCs were significantly higher at Bako than in the rest of the study areas (0<0.05). There was a marked increase in ATC population density from March to mid-June, with the general trend of slight to medium increased precipitation. Conversely, there was a swift decline in the ATC population from scarce to nonexistent from mid-June to September followed by prolonged heavy precipitation. The population fluctuation i.e., increase and decrease of the pest population may concides with the peak flowering and fruiting season so that the scale can exploit the peak time of photosynthesis, which needs future detailed study. The correlation coefficient between the ATC population and some basic weather factors, such as maximum and minimum temperature, rainfall, and relative humidity, showed weak to moderate positive correlations in the four study areas and a weak negative correlation with mean average temperature (TeM) in Nekemte city. The results of the study showed that ATC is distributed in all four cardinal directions with significant differences in population density (0<0.05), where the A. tubrcularis scale insect prefers the southern cardinal direction. Furthermore, the build-up and decline in ATCs were found to be affected by basic climatic factors, temperature and rainfall, and cardinal direction differences, whereas the other contributing factors need to be investigated further. The study on the presence of natural enemies was carried out in three study areas of the western and central rift valleys of Oromia and the Assosa zone of the Benishangul-Gumuze regional state. The specimens of A. tubercularis and associated natural enemies (predators and parasitoids) were collected and identified via DNA sequencing. The DNA sequences of the COI gene of all Ethiopian sampled scales were identical and confirmed as a single haplotype of A. tubercularis. This lack of genetic variation might be expected of an invasive species and suggests that a small number of insects instigated the invasion. Identifying the source xxiii of that invading population would be useful but is beyond the scope of the current study, that would needed a significant collection trip or some other way of acquiring many more samples of A. tubercularis, which in turn, this requires a significant source of funding. There are currently only three COI sequences available for A. tubercularis in public databases: one from the Philippines and two from Egypt. Three Coccinellidae (Coleoptera) predators of A. tubercularis were recovered from the specimens. These included two Coccinellidae, Rhizobius lopanthe (Blaisdell), Platynaspis species, and a third unidentified beetle species from the family Nitidulidae. The DNA sequences of the parasitoid specimens identified two species of Encarsia, E. lounsburyi Berlese & Paoli and E. citrina Craw (Hymenoptera: Aphelinidae). These natural enemies were identified for the first time as resident natural enemies of A. tubercularis in Ethiopia. During specimen collection, the newly associated adults and larvae of the predators were found to be voraciously feeding on live A. tubercularis. The parasitoids were found parasitizing all stages of sessile A. tubercularis. In addition, one newly associated Coccinellidae predator Twice-stabbed lady beetle, Chilocorus stigma, was identified morphologically. The beetle was observed preying voraciously on sessile A. tubecularis. The novel association of resident predators and parasitoid wasps with A. tubercularis has likely developed recently in Ethiopia. A host preference study on A. tubercularis was carried out on nine mango cultivars through 12 successive months at RAILMCF and MARC. The results of the study revealed that the pick maximum mean ATCs were recorded on local cultivars during the month of June at RAILMCF & MARC, with values of 50.97±4.62 and 49.22±5.13, respectively. The minimum mean average ATC aggregation was recorded on the Dodo cultivar (0.47±0.56) at RAILMCF and on the Apple cultivar (0.33±0.48) at MARC during the month of November. At both study sites, the mean annual minimum ATC formation was recorded on the Sabre (2.14±0.41) and Vandyke (2.29±0.33) cultivars, followed by the Dodo (4.26±0.63) and Apple (5.20±1.02) cultivars, which were more resistant to A. tubercularis. Overall, ATC populations on the tested mango cultivars showed statistically significant positive correlations (0<0.01) with Tmin, while all mango cultivars showed moderately positive correlations (p<0.05) with Tmax. RH had slight significant positive correlations, and Rf showed moderately significant positive correlations with ATC populations on all mango cultivars except Van Dyke, which had slight negative correlations. The experiment was carried out to test the efficacy of Azadirachta indica L. (A. Juss) seed powder water extract (SPWE) & leaf powder water extract (LPWE) against A. tubercularis under field conditions at two experimental sites in the Arjo Gudetu and Uke experimental sites of the East Wollega zone. The experiment was laid out in a randomized complete block design in four replications. The amount of neem seed & leaf powder required per liter of water was 5, 10 and 15g, which was for each parts of neem powder. The treatments were applied 3 times at 10-day intervals after complete infestation was observed. The mortality count was recorded 10 days after each of the 1st, 2nd, and 3rd-round treatment applications with different spray concentrations of 0.05, 0.1, and 0.15 mg/ml water. For field application 12 l of each concentrate was applied on one mango tree considered as a plot. The results of the study revealed that aqueous A. indica SPWE at a 0.15 concentration significantly (p<0.05) reduced the population of A. tubercularis at both experimental sites. Male adults and crawlers were more affected than females. A related study was conducted at the same study sites to test the potency of A. indica leaf powder water extract (LPWE) against A. tubercularis under field conditions. The results obtained revealed that water extracts of A. indica LPWE at 0.15 concentration significantly (p<0.05) reduced the population of A. tubercularis at both experimental sites. Crawlers and males were more affected than females. Hence, based on the findings, A. indica aqueous LPWE & SPWE could be useful as botanical insecticides in the management of A. tubercularis on mangoes. As a summary & conclusion, the current study concluded reviled that that A. tubercularis was spreading across all directions of the country from its first locus, present in all surveyed areas abundantly with higher infestation and damage level while temperature, relative humidity and rain fall affected and determine its population dynamics. The identified natural enemies (predators & parasitoids) and resistant cultivars as well as the results of neem botanical extracts are promising findings for planning future management practices by incorporating with IPM activities 243

EFFECT OF INTERCROPPING AND BOTANICAL EXTRACT ON POPULATION ABUNDANCE OF INSECT PESTS AND THEIR ASSOCIATED NATURAL ENEMIES ON TOMATO (Lycopersicon Esculentum (MILL.) IN EASTERN ETHIOPIA

2023-03-09T08:00:40Z

EFFECT OF INTERCROPPING AND BOTANICAL EXTRACT ON POPULATION ABUNDANCE OF INSECT PESTS AND THEIR ASSOCIATED NATURAL ENEMIES ON TOMATO (Lycopersicon Esculentum (MILL.) IN EASTERN ETHIOPIA Dabalo, Belachew; Wakgari, (PhD) Mulatu; Fite, (PhD) Tarekegn Tomato is one of the most important vegetable crops grown in Ethiopia. Its production is constrained by arthropod pests and diseases. Fruit borer (Helicoverpa armigera), Whiteflies (Bemisia tabaci), Aphids (Aphis spp), leafminer (Tuta absoluta), Serpentine leafminer (Liriomyza sp), Thrips sp and two spotted spidemites (Tetranchus urticae Koch) are the major economic pests recorded in the study area. The research was initiated to evaluate the potential of intercropping and plant extract to reduce pests on tomato and their associated natural enemies using irrigation systems from January to May 2021 at Haramaya University, Rare research station. The treatments, tomato - onion (Allium cepa L.), tomato - head cabbage (Brassica Oleracea), tomato - common bean (Phaseolus vulgaris) intercropping and sole tomato(control), tobacco (Nicotiana tabacum) leaf extract, and Karate 5% EC (Standard check) were used. The experiment was laid out in a randomized complete block design (RCBD) with four replications. Tobacco leaf extract was applied weekly for eight times whereas karate 5%EC was applied at ten days interval for six (6) times until the first fruit harvest. The data on the population of the insect pests were recorded weekly starting on the 21st day after transplanting for eight (8) weeks. The parasitoids population was recorded from samples in the laboratory after their emergence from the host. The over all result indicated that all intercropping systems and tobacco leaf extract significantly (P < 0.05) reduced the population of these insect pests compared to sole tomato. The highest population reduction was recorded on tobacco leaf extract followed by tomato – onion. The companion crops harbored the parasitoids of diverse species in the highest level, but tobacco extract was comparable to untreated control. Tomato onion intercropping and tobacco leaf extract raised the best economic performances upon high net benefits and benefit cost ratio. Therefore, tomato onion intercrops and tobacco leaf extract can be used as the first options in boosting tomato production as an alternative to karate 5%EC. Further study on the mechanisms of the effectiveness of botanical extracts with rate and frequency and also intercropping and detailed morphological and molecular-based parasitoid species identification and their ecological host ranges are of utmost importance in the sustainable IPM strategies in tomatoes 108p.

SPECIES DIVERSITY AND MANAGEMENT OF TERMITES USING ENTOMOPATHOGENIC NEMATODES IN GROUNDNUT (Arachis hypogaea L.) IN ETHIOPIA

2023-03-08T07:13:38Z

SPECIES DIVERSITY AND MANAGEMENT OF TERMITES USING ENTOMOPATHOGENIC NEMATODES IN GROUNDNUT (Arachis hypogaea L.) IN ETHIOPIA Kassaye Gurmu, Ashenafi; Getu, Prof. Emana; Wakgari, (PhD) Mulatu; Goftishu, (PhD) Muluken; Seid, (PhD) Awol First and foremost, I want to thank and praise God, the Almighty, for His graces, strength, sustenance, blessings, knowledge, and opportunities. His benevolence has made me excel and be successful in all my academic pursuits. I am deeply grateful to Prof. Emana Getu for his assistance at every stage of the research project and for his invaluable supervision and tutelage during the course of my PhD degree. Throughout the writing of this dissertation, I have received a great deal of support and assistance. I would like to offer my special thanks to Dr. Awol Seid for making the nematode molecular work possible at ILVO, Belgium. I also would like to sincerely acknowledge him for awarding me an internship on "Nematode Taxonomy" at Sophia Agrobiotech Institute, INRAe, Sophia Antipolis, France during my study. I very much appreciate his support in publishing the first manuscript of this PhD dissertation. I would like to express my sincere gratitude to Dr. Mulatu Wakgari for his insightful comments, suggestions on the manuscript, and valuable guidance throughout my studies. I am grateful for his unparalleled support and supervision during sample collection and fieldwork. I would like to extend my sincere thanks to Dr. Muluken Goftishu for his unwavering support and trust on me. You have played a massive role in my development as a researcher and inspired me to be a better researcher. I wish to express my thanks to Dr. Gillian Gile, Arizona State University, and Dr. Lieven Waeyenberge, ILVO Belgium, for their support in molecular identification of termites and nematodes, respectively. I would also like to extend my deepest gratitude to Mr. Gebissa Yigezu, who is a talented and dedicated colleague, for his support during data collection and laboratory work. I very much appreciate the support by Mr. Solomon Yielma in the identification and maintenance of the isolated nematodes at Ambo Plant Protection Research Center. I wish to express my thanks VIII to Dr. Temesgen Addis, e-nema Germany, for his support in providing valuable comments on the proposal and the manuscript on molecular identification of nematodes. I would like to acknowledge Azeb Tegenu, Habtamu Tadesse, Misrach Melese, Gebi Hussien, Haymanot Bizuneh, Yegele Gebremaryam Marta, and Addis. without whom I could not have completed this dissertation and would not have been able to do my laboratory experiments, field work and data collection. I’m extremely grateful to my loving and supportive wife, Kidist Tekle, who provides unending inspiration. She has been supportive of me throughout this entire process and has made countless sacrifices to help me get to this point. She is also acknowledged for the support she made to the family during much of my graduate studies. Without her tremendous understanding and encouragement in the past few years, it would have been impossible for me to complete my studies. My deep and sincere gratitude also goes to my family for their continuous and unparalleled love, help and support. Specially, I am grateful to my sister, Misrak Kassaye, for always being there for me 202p.