86 © 2020 Adama Science & Technology University. All rights reserved Ethiopian Journal of Science and Sustainable Development e-ISSN 2663-3205 Volume 7 (2), 2020 Journal Home Page: www.ejssd.astu.edu.et ASTU Research Paper Evaluation of Some Insecticides against White Mango Scale, Aulacaspis Tubercularis Newstead (Hemiptera: Diaspididae) on Mango in Ethiopia Ofgaa Djirata  Department of Applied Biology, School of Applied Natural Science, Adama Science and Technology University, P. O. Box 1888, Adama, Ethiopia Article Info Abstract Article History: Received 7 May 2020 Received in revised form 15 Jun 2020 Accepted 20 Jun 2020 Mango (Mangifera indica L.) has been cultivated in Ethiopia at small scale level so far, but very few large scale farms have started to join the sector in recent days. Mango production in Ethiopia is currently constrained by white mango scale (Aulacaspis tubercularis). This study was performed to evaluate the efficacy of three formulations, i.e. Folimat, Closer 240 and D- C-Tron Plus, against white mango scale (WMS) on mango from mid-May 2016 to end of July 2016 in west Oromia. The experiment was laid in a Randomised Complete Block Design (RCBD) with three replications. Volume of water enough for complete coverage of a mango tree was calibrated and repetitive treatment and response recording were conducted. The insecticides were applied by manual Knapsack sprayer, every 14 days for a total of three times. A total of ten leaves were picked randomly from the treatments and the untreated control one day prior to each treatment and on the 5th and 10th days after each treatment. Live crawler; male and female WMSs were counted by the use of stereo microscope and recorded as number of live WMS. Folimat showed maximum pest population reduction followed with Closer 240. However, some non-target insects were found dead on trees treated with Folimat, an observation to be confirmed by further investigation. Incorporating the less toxic insecticide, Closer 240 SC which showed a certain degree of the pest population reduction, in to Integrated Pest Management to control the white mango scale infestation on big trees of mango landrace is recommended. Keywords: Gudetu Arjo Landrace Mango scale Mortality 1. Introduction Mango (Mangifera indica L.) is grown across the world in tropical and sub-tropical countries. It is the third most important fruit crop in the tropics next to citrus and banana (Louw et al., 2008). Mango is consumed as a fresh fruit and in different forms of beverages (Griesbach, 2003; Nabil et al., 2012). Mango possesses anti-oxidant, cardiotonic, hypotensive, anti-inflammatory and antispasmodic properties, and as a result plays vital role in Ethnopharmacology and various chemical industries (Wauthoz et al., 2007; Kayode and Sani,  Corresponding author, e-mail: ofgaa.djirata@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.239 2008; Masibo and He, 2008; Nwinuka et al., 2008; Shah et al., 2010). Moreover, mango is a significant foreign currency generating crop for many countries across the globe (UNCTAD, 2016). In Ethiopia mango is produced mainly at small scale level primarily for family consumption and local fresh fruit markets (Alemayehu Chala et al., 2014). However, large scale mango productions for juices and export markets are currently being introduced in to the sector (Wiersinga and Jager, 2009; Yilma Tewodros, 2009). http://www.ejssd.astu.edu/ mailto:ofgaa.djirata@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx http://www.unctad.org/ Ofgaa Djirata. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 87 Mango being a crop of such vital economic importance, its production is constrained by a variety of pests and pathogens. Medina and García (2002) depicted that over 492 species of insects, 17 species of mites and 26 species of nematodes were reported to have been damaging mango plantations. Mango pests include insects such as fruit fly complex, mango seed weevil, thrips, mealy bugs and scale insects; and non-insect pests such as mites, among others. Moreover, pathogenic fungi and bacteria cause diseases to the crop (USDA, 2006). Likewise, mango production in Ethiopia is challenged by a variety of pests and diseases (Alemayehu Chala et al., 2014, Ayantu Tucho et al., 2014). Tewodros Bezu et al. (2014) reported that, pertaining to poor management of mango production, thrips, fruit flies, termites, and various fungal diseases constrain the crop in Ethiopia. White mango scale is a noxious pest which has been reported to affect commercial values of mango in many countries (Labuschagne et al., 1995; Pena et al., 1998; Nabil et al., 2012; Mazzeo et al., 2014). In Ethiopia, white mango scale was reported to have posed severe threat to mango production since its first record in 2010 (Mohammed Dawd et al., 2012). White mango scale is a phytophagous insect. It inserts its stylets in leaf, fruit and other young mango parts and sucks the sap and results in discolouration of the leaves and the fruits, brings about dieback of the tree and in severe cases causes total death of young mango trees (Abo-Shanab, 2012; Juárez-Hernández et al., 2014). Various methods, such as cultural method, biological control and chemical insecticide applications have been implemented to control the damages inflicted by white mango scale to mango in different mango growing countries. In line with this, pruning as a cultural method, was practiced and found to have considerably decreased population of white mango scale in Mexico (Bautista- Rosales et al., 2013). Regarding the possible role of bio agents in controlling the pest, Ofgaa Djirata et al. (2017) reported from a field experiment in Ethiopia that larvae of predatory ladybird beetle were found aggressively preying on it, even though whether they could control the pest or not has not been reported so far. Moreover, it was stated that ladybird beetles, and green lacewings and tiny parasitic wasps may be used to suppress scale insect populations (Muralidharan, 1994; Buss and Turner, 2006). Chemical insecticides and mineral oils such as deltametrine, pyrethrin, super masrona and Diver were also proposed for the control of mango scales in Egypt and Kenya (Findlay, 2003; Abo-Shanab, 2012). In Ethiopia, however, there has been no sufficient report regarding insecticide efficacy test for control of white mango scale, for which this study was conducted with the core objective of evaluating the most effective insecticides that could help control the pest. 2. Materials and Methods 2.1. Description of the study area This study was performed at Arjo Gudetu mango orchard (09° 03´N and 036° 17´E) found in Diga District, East Wollega Administrative Zone of Oromia National Regional State at a distance of 370 km west of Addis Ababa, from mid-May to end of July 2016. The area receives a mean annual rainfall of 1649 mm and characterized by maximum and minimum monthly temperatures of 31°C and 16°C, respectively (Ethiomet, 2016).The orchard was found on a gentle slope with altitudes ranging between 1326 and 1379 m a.s.l. The study farm was entirely composed of local mango landraces grown by the orchard owner for the last 25 years. The plantation was spaced at an average distance of nine to ten metres away from each other. However, since no pruning has been practiced to the mango trees in the farm, most of the trees were tall and bushy, and moreover, their branches were highly interlocked in most instances. There has been no insecticide application to the mango farm for pest control so far (personal communication with Fayissa Dhuguma, owner of the orchard). The farming population of the study area grows mango as the major income generating crop next to maize and peanut. Cattle fattening is another source of income in the area. 2.2. The experimental design The field experiment was laid in a Randomised Complete Block Design (RCBD) with three replications. Allocation of each treatment and the untreated control within each replication was done randomly. In the meantime, three mango trees were allocated for each insecticide and to the untreated control. After the allocations, each mango tree assigned to each treatment and that of the untreated control were tagged accordingly for repetitive spray and response Ofgaa Djirata. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 88 record from the same tree. Before application of the formulations, the volume of water enough to completely cover a mango tree was calibrated. Mean volume of water enough per tree was found to be 20 litres. The mango trees being tall and bushy, telescopic extension lance of 3.2 meters long was fixed to the sprayer knapsack. Spraying was effected with the spray man being supported by scaffold fixed on a tractor back for ease of accessing all parts of each mango tree. Treatments were applied every 14 days for a total of three times. A total of ten leaves were plucked from top, middle and lower canopies of each treatment tree and the untreated control, one day prior to each treatment and on the 5th and the 10th days after each treatment. The leaves from each tree were placed in a separate cloth bag, labelled, kept in a plastic bag and taken to a temporary laboratory established around the trial area. Live crawler, male and female white mango scales were counted by the use of stereo microscope and recorded as number of live white mango scale. 2.3. Insecticides evaluated Field experiment was carried out to evaluate efficacy of three insecticides against white mango scale. These were Closer 240 SC (Sulfoxaflor), D-C-Tron (mineral oil) and Folimat 500SL. Closer 240 SC (Sulfoxaflor) was registered for the control of cabbage aphids on cabbage in Ethiopia (Federal Democratic Republic of Ethiopia Ministry of Agriculture and Natural Resources, 2016). It was obtained from Chemtex Plc, Addis Ababa, Ethiopia. Closer 240 SC was applied with the rate of six ml/tree in this study. The remaining two candidates, D- C-Tron (mineral oil) and Folimat 500SL (Omethoate 500g/L or 47.5% m/m) were registered in Kenya (Pest Control Product Board, 2016). D-C-Tron Plus was used for the control of leaf miners and scales in coffee, mites and aphids in flower and aphids in beans in Kenya. It was bought from Caltex Oil (K) ltd, Nairobi-Kenya and imported to Ethiopia for the purpose of this evaluation only. D-C-Tron Plus was applied with the rate of 100ml/tree in this study. Folimat 500SL was used for the control of aphids on coffee, citrus and flowers, and mealy bugs on coffee in Kenya. Like D-C-Tron Plus, Folimat 500SL was also bought from a legal company known as Arysta Lifescience Corporation (K) in Nairobi, Kenya, and imported to Ethiopia for the purpose of screening in this study. Folimat 500SL was applied at the rate of 25ml/tree in this study. Closer 240 is systemic in its action but Folimat serves as both systemic and contact insecticidal agent. D-C-Tron Plus is, however, suffocant oil. 2.4. Data analysis Sum of live crawler, female and male white mango scale was taken as white mango scale count data and subjected to analysis. Proc ANOVA of SAS software v9 was applied for data analysis. Significant means were separated by Fisher’s Least Significant Difference (LSD) at 5% error level. Percentage reduction in white mango scale population over control was worked out after each treatment using Henderson and Tilton (1955) formula of mortality correction. Mortality Correction = (1 − N1 ∗ N2 N3 ∗ N4 ) ∗ 100 where, N1, N2, N3 and N4 are white mango scale populations in control before treatment, in treated after treatment, in control after treatment and in treated before treatment, respectively. 3. Results Mean numbers of white mango scale counts per 10 leaves just before the initial treatment and in the two successive records following the first treatment are shown in Table 1. Table 1: White mango scale population counts before insecticide application and during the two successive recordings after initial application Treatment/Control Record before initial spray First record after initial spray Second record after initial spray D-C-Tron 297 300 298 Closer 333 330 320 Folimat 1084 1070 1066 Control 155 157 158 Ofgaa Djirata. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 89 Noticeable declines were observed in the counts of live white mango scale among the records starting from post second spray, mainly for Closer and Folimat, while population build up was recorded in cases of the untreated control. Mean numbers of live white mango scale per 10 leaves from pre-second spray onward are indicated by the following figures (Figures 1and 2). Figure1: White mango scale populations just before and after second round insecticide application Figure 2: White mango scale population just before and after third round insecticide spray The result of evaluating the three insecticides revealed that Folimat (49.52 ± 15.74) was found to be the most effective insecticide in reducing the population of white mango scale on mango with significant different (p0.05) compared to Closer (18.72 ± 5.32) and D-C-Tron (5.90 ± 2.15) at 5% error level (LSD=29.15). In the course of recording live white mango scales following each treatment, dead bodies of non-target insects, including Chilocorus sp. larvae (Coleopteran) were frequently encountered on mango leaves treated with Folimat, while no dead body of those insects was found on the leaves treated with the rest two insecticides, in most observed cases. Percent corrected mortality showed marked progress from the first to the third application of the insecticides, mainly in Folimat and Closer. Reduction in white mango scale population in response to the insecticides applied during the three phases (A and B for first and second responses after initial spray, C and D for first and second responses after second round spray, and E and F denoting first and second responses after the third round (final) spray, respectively) is shown in Figure 3. Figure 3. White mango scale percentage reduction in response to successive treatments 4. Discussion Population count started to noticeably decrease only after the second round spray in Folimat and Closer treatments. This is probably because as the mango trees under the experiment were tall, bushy and characterized by dense foliage, there might be some probabilities of uncertainties to have fully addressed each mango scale through only one round spray. Chin et al. (2010) underlines that keeping mango tree sizes at a manageable stature through pruning is very essential for ease of insecticide spray for the desired response in the control of pests and diseases. Reddy et al. (2018) also states that pruning is an essential management practice in the control of scale insect infestation on mango. On the other hand, the apparent population decrease following repeated applications of the insecticides might account for cumulative effects of the successive sprays. The principle of applying systemic insecticide to control sucking insects arises from the fact that they diffuse through the soft parts of the host plant and reach the pest. Therefore, the rate at which it gets in contact with the pest may not be as fast as contact insecticides. Gashawbeza Ayalew et al. (2015) screened Methidathion Ofgaa Djirata. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 90 and Movento on white mango scale on mango trees in Central Rift Valley, Ethiopia and found that population counts after the first treatment were similar between the treatments but differences were observed after the second spray, a report in agreement with the current trial. Population build-up was observed in the untreated control, indicating that the period of insecticide application in this trial took place during the period of continuous growth of white mango scale population. Ofgaa Djirata et al. (2018) stated that white mango scale population on mango began to build from February and attained its peak sometime before July. Folimat 500SL was found to exhibit over 90% pest population reduction with marked difference from Closer 240, which also performed well. It was reported that mango farmers in central and eastern Kenya were using this product to have controlled white mango scale (Ofgaa Djirata, et al., 2016). Folimat is both systemic and contact insecticide. The white mango scale first instars are naked and as a result Folimat can exterminate them upon contact, which could probably increase its efficacy in addition to its indirect action on the armoured adult scales which are sap sucking. Non-target insects were found dead on leaves treated particularly with Folimat. This probably demonstrates its strong toxicity which renders it worrisome profile to be considered for white mango scale control in the context of this study. However, whether the death of the non-target insects was purely due to Folimat had not been evaluated in this study. It was indicated that Folimat serves as both systemic and contact insecticidal agent while Closer 240 works only by translaminar and systemic activity. Therefore, it is arguable that Closer 240 could cause similar deaths of non- target insects, which were particularly not sucking insects. 5. Conclusion Folimat was found to exhibit considerable efficacy in reducing white mango scale population on mango. However, such highly toxic insecticides should not be used for white mango scale control purposes from ecological concern points of view. Complete coverage of the indigenous tall and bushy mango trees with insecticide during the spray was almost impossible. It is concluded, therefore, that controlling white mango scale on big mango trees by manual spraying, mainly at small scale farmer level after heavy infestation is highly challenging. As a result, it is advisable to practice consistent pruning and maintain general stature of the plantation at manageable size and make Integrated Pest Management an integral component in the control of white mango scale infestation on mango. Acknowledgment Mr. Fayissa Dhuguma, the owner of Gudetu Arjo mango orchard has allowed me to use his farm for this study and supported the investigation through providing his tractor with fuel throughout the study period and hence deserves due acknowledgement. I thank Chemtex PLC Insecticide Supplier PLC and Mr. Yemenu Jembere, general manger of the PLC; and Mr. Yordanose Ameyu, agronomist of the PLC, for the material, logistic and professional supports they gave me during this study. I would thank Professor Emana Getu for the technical support he gave me in the course of this study. Reference Abo-Shanab, A.S.H. (2012). Suppression of white mango scale, Aulacaspis tubercularis (Hemiptera:Diaspididae) on mango trees in El-Beheira Governorate. Egyptian Academic Journal of Biological Science, 5:43-50. Alemayehu Chala, Muluken Getahun, Samuel Alemayehu & Mekuria Tadesse (2014). Survey of mango anthracnose in southern Ethiopia and in-vitro screening of some essential oils against Colletotrichum gloeosporioides. International Journal of Fruit Science, 14:157-173. Ayantu Tucho,Fikre Lamessa & Gezahegn Berecha (2014). Distribution and occurrence of mango anthracnose, Colletotrichum gloiesporioides Penz and Sacc) in humid agro-ecology of southwest Ethiopia. Plant Pathology Journal, 13(4): 268-277. Bautista-Rosales,P.U., Ragazzo-Sánchez,J.A., Calderón-Santoyo, M., Cortéz-Mondaca, E. & Servín-Villegas,R.(2013). Aulacaspis tubercularis Newstead in mango orchards of Nayarit, Mexico, and relationship with environmental and agronomic factors. Southwestern Entomologist, 38(2):221-230. Buss, E.A. & Turner, J.C. (2006). Scale Insects and Mealybugs on Ornamental Plants. Arrington: University of Florida. Chin, D., Browm, H., Conde B., Neal M., Hamilton, D., Hoult, M., Moore, C., Thistleto, B., Ulyatt, L. & Zhang, L. (2010). Field Guide to Pests, Beneficials, Diseases and Disorders of Mangoes. Darwin: Northern Territory Government, department of resources. Ofgaa Djirata. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 91 Ethiomet, National Meteorology Agency of Ethiopia (2016). Agrometeorological Bulletin, http://www. ethiomet.gov.et/ bulletins/dekadal/_agricultural_bulletins (assessed 23 August 2019). Federal Democratic Republic of Ethiopia Ministry of Agriculture and Natural Resources (2016). www.moa.gov.et/65, Ministry, Plant Health Regulatory Directorate (assessed 19 February 2017). Findlay, J. (2003). Pesticide Evaluation Report and Safer Use Action Plan (PERSUAP) for the Kenya Business Development Services Program. Nairobi: Kenya Business Development Services Program. Gashawbeza Ayalew, Abiy Fekadu and Birhanu Sisay (2015). Appearance and chemical control of white mango scale (Aulacaspis tubercularis) in Central Rift Valley. Science, Technology and Arts Research Journal, 4:59-63. Griesbach, J. (2003). Mango Growing in Kenya. Nairobi: World Agroforestry Centre (ICRAF). Henderson, C.F. & Tilton, E. W. (1955). Tests with acaricides against the brow wheat mite. Journal of Economic Entomology, 48:157-161. Juarez-Hernández, P., Valdez-Carrasco,J., Valdovinos-Ponce, G. , Mora-Aguilera, A.J., Otero-Colina, G., Téliz-Ortiz, D., Hernández-Castro, E., Ramírez-Ramírez, I. and González-Hernández, V.A. (2014). Leaf penetration pattern of Aulacaspis tubercularis (Hemiptera: Diaspididae) stylet in mango. Florida Entomologist, 97:100-107. Kayode, R.M.O. & Sani, A. (2008).Physicochemical and proximate composition of mango (Mangifera indica) kernel cake fermented with mono-culture of fungal isolates obtained from naturally decomposed mango kernel. Life Science Journal, 5:1-9. Labuschagne, T.I., Hamburg, H.V. & Froneman, I.J. (1995). Population dynamics of the mango scale, Aulacaspis tubercularis (Newstead) (Coccoidea: Diaspididae), in South Africa. Israel Journal of Entomology, 29: 207-217. Louw,E. C. Labuschagne & Swart, SH.(2008). Developing a mango programme for optimum mango yield and quality. South African Mango Growers’ Association Research Journal, 28:1-11. Masibo, M. & He, Q.(2008). Major mango polyphenols and their potential significance to human health. Comprehensive Reviews in Food Science and Food Safety, 7:309-319. Mazzeo, G., Longo, S., Pellizzari, G., Porcelli, F., Suma, P.& Russo, A.(2014). Exotic Scale insects (Coccoidea) on ornamental plants in Italy: a never-ending story. Acta Zoologica Bulgarica Supplementum, 6:55-61. Medina, J.D.L.C., & García, H.S. (2002). Mango: Post-Harvest Operations. http://www.fao.org/3/a-av008e.pdf (assessed 27June 2019). Muraudharan,C.M. (1994). Biology and feeding potential of black beetle (Chilocorus nigritus), a predator on date palm scale (Parlato ria blallchardii). Indian Journal of Agricultural Sciences, 64 (4): 270-271. Nabil, H. A., Shahein, A. A., Hammad, K.A.A. & Hassan, A.S. (2012) .Ecological studies of Aulacaspis tubercularis (Diaspididae: Hemiptera) and its natural enemies infesting mango trees in Sharkia Governorate. Egyptian Academic Journal of Biological Sciences 5: 9-17. Nwinuka, Nwibani M., Monanu, Michael, O., Nwiloh & Barine I. (2008). Effects of aqueous extract of Mangifera indica L. (mango) stem bark on haematological parameters of normal albino rats. Pakistan Journal of Nutrition, 7:663-666. Mohammed Dawd, Belay H/Gebriel, Lemma Ayele, Konjit Feleke, Seyoum Hailemariam & Teshome Burka (2012). White mango scale: a new insect pest of mango in western Ethiopia, In: Proceeding of 3rd Biennial Conference of Ethiopian Horticulture Science Society, pp.257-267(Eshetu Derso,Asfaw Zelleke,Lemma Dessalegn,Zemedu Worku,Hailemikael K/Mariam,Getachew Tabor and Yehenew Geachew,eds.). Addis Ababa. Ofgaa Djirata, Emana Getu & Ruth, K. G. (2016). Trend in mango production and potential threat from emerging white mango scale, Aulacaspis tubercularis (Homoptera: Diaspididae) in central and eastern Kenya. Journal of Natural Sciences Research, 6(7): 87-94. Ofgaa Djirata, Emana Getu & Ruth, K. G. (2017). Association of a native predator Chilocorus sp. (Coleoptera: Coccinelidae) with a new exotic mango pest, Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) in Ethiopia. Israel Journal of Entomology, 47: 1–8. Ofgaa Djirata, Emana Get & Ruth, K. G. (2018). Population dynamics of white mango scale, Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) in Western Ethiopia. African Journal of Agricultural research, 13(31):1598-1605. Pena, J.E., Mohyuddin, A.I. & Wysoki, M. (1998). A review of the pest management situation in mango agroecosystems. Phytoparasitica, 26: 129-148. Pest Control Product Board (2016). Products Registered in Crop Production in Kenya, http://www.pcpb.or.ke/ (assessed 19 February 2020). Reddy, P.V.R. Gundappa. B., & Chakravarthy, A.K. (2018). Pests of Mango. Springer nature, doi.org/10.1007/978-981-10- 8687-8_12. Shah, K.A., Patel, M.B., Patel, R.J. & Parmar, P.K. (2010). Mangifera indica (Mango). Pharmacogn Review, 4(7):42-48. Tewodros Bezu, Kebede Woldetsadik & Tamado Tana (2014). Production scenarios of mango (Mangifera indica L.) in Harari Regional State, Eastern Ethiopia. Science, Technology and Arts Research Journal, 3:59-63. UNCTAD, United Nations Conference on Trade & Development (2016). Mango: an INFOCOMM commodity profile, http://unctad.org/en/ Publications Library/ INFOCOMM_cp07_Mango/ (assessed 30 January 2019). http://www.moa.gov.et/65,%20Ministry http://www.fao.org/3/a-av008e.pdf http://www.pcpb.or.ke/ http://www.unctad/ http://unctad.org/en/%20Publications%20Library/%20INFOCOMM_cp07_Mango/ Ofgaa Djirata. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 92 USDA, United States Department of Agriculture. (2006). Importation of Fresh Mango Fruit (Mangifera indica L.) from India into the Continental United States: a Qualitative, Pathway-Initiated Pest Risk Assessment. Raleigh: Center for Plant Health Science and Technology, Plant Epidemiology and Risk Analysis Laboratory. Wauthoz, N., Balde, A., Balde, E.S., Damme, M.V. & Duez, P. (2007). Ethnopharmacology of Mangifera indica L. bark and pharmacological studies of its main C-Glucosylxanthone, mangiferin. International Journal of Biomedical and Pharmaceutical Sciences, 1:112-119. Wiersinga, R.C. & Jager, A.D. (2009). Business Opportunities in the Ethiopian Fruit and Vegetable Sector. Wageningen: Report 2008 075.LEI. Yilma Tewodros (2009). United Nations Conference on Trade and Development Expert Meeting of Ldcs in Preparation For the 4th United Nations Conference on the Least Developed Countries: Case Study on Ethiopia: United Nations Conference on Trade and Development.