Nghiên cứu đặc điểm sinh vật học, sinh thái học của rệp sáp bột hồng phenacoccus manihoti (matile ferrero, 1977) (homopter pseudococcidaehại sắn và biện pháp quản lý theo hướng tổng hợp tt tiếng anh

MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE AND AND TRAINING RURAL DEVELOPMENT VIETNAM ACADEMY OF AGRICULTURE SCIENCES  - DO HONG KHANH RESEARCH ON BIOLOGY AND ECOLOGY OF THE CASSAVA MEALYBUG, Phenacoccus manihoti (Matile-Ferrero, 1977) (Homoptera: Pseudococcidae), ON CACSSAVA AND THEIR INTEGRATED MANAGEMENT Specialization: Plant Protection Code: 9.62.01.12 SUMMARY OF THESIS FOR THE DEGREE OF DOCTOR OF AGRICULTURE Ha Noi - 2019 The thesis was completed at Vietnam Academy of Agricultural Sciences (VAAS) Scientific Supervisor: Prof Dr Pham Van Lam Critic Commentator 1: ………………………………………… Critic Commentator 2: ………………………………………… Critic Commentator 3:…………………………………………… The dissertation will be protected at Council for Thesis Assessment before the Institute of Dissertation Boads meets at Institute level, held at Viet Nam Academy of Agricutural Sciences At hours 30’, date….monh… year 2019 This thesis can be referred to at: Vietnam National Library Library of Vietnam Academy of Agricultural Sciences Library of Plant Protection Institute INTRODUCTION Rationale The Cassava Mealybug, Phenacoccus manihoti (Homoptera: Pseudococcidae), was firstly detected on cassava in 1960 in Africa It spreads with cassava at speed of 300 km/year and enters 31 out of 35 cassava production countries in this continent by 1987 (Herren, 1990; Neuenschwander et al., 1990) This pest can cause a loss of 84% of cassava productivity (Nwanze, 1982) In Vietnam, the Cassava Mealybug was firstly found in July 2012 in Tay Ninh province To date, no researches have been conducted on this pest in Viet Nam while its biology and ecology are scientific basis for defining effective measures for sustainable management is urgently needed Therefore, the “Research on biology and ecology of the Cassava Mealybug, Phenacoccus manihoti (MatileFerrero, 1977) (Homoptera: Pseudococcidae), on cassava and their integrated management” is of great significance Purpose and requirements of the thesis 2.1 Purpose Determine the biological, ecological characteristics of P manihoti and propose the control measures base on IPM for sustainable development of the cassava industry in Vietnam 2.2 Requirements Recording the infestation of P manihoti on cassava-growing provinces/regions in Vietnam Determine biological and ecological characteristics of the Cassava Mealybug in laboratory conditions; Determining the occurrence, annual a population dynamics and environmental factors that related to outbreak of this sucking insect in cassava-growing areas of Vietnam Find out the feasible control measures for P manihoti on cassava production Scientific and practical significances of thesis 3.1 Scientific significances Thesis provides scientific data on invasion, establishment of the Cassava Mealybug populations in cassava-growing areas in Vietnam Providing new scientific data on biology and ecology of P manihoti as foundation for control measures in Vietnam 3.2 Practical significances Output of thesis as scientific foundation for IPM to control cassava mealybug populations in cassava Subject and scope of research 4.1 Research subject The Cassava Mealybug, P manihoti damaging cassava plants 4.2 Scope of research Thesis’s scientific data covered the invasive status, population setup, biological and ecological characteristic of P manihoti including life cycle, annual population density, ovipostion capacity The effectiveness of on-going IPM on P manihoti –infesting region in Vietnam (Tay Ninh, Dong Nai, Phu Yen, etc ) New contribution of dissertation - Providing the update reports on invasion of the Cassava Mealybug in cassava-growing areas of Vietnam - Proving the scientific data on life cycle, ecological characteristic of P manihoti in Vietnam - Providing the data on effectivenes of control measures including using Anagyrus lopezi Thesis structure This dissertation comprises 156 pages with 36 tables and 31 figures allocated into introduction, main thesis contents (3 chapters), conclusion and proposals The thesis cited 114 references including 30 papers in Vietnamese and 84 papers in English Chapter LITERATURE REVIEW 1.1 Scientific base of thesis The composition of cassava pests in each geographical cassavagrowing region is very different The Cassava Mealybug, with highly reproductive capacity, rapid dispersal, are emerging as highly environment-adapting insect pest all over the cassava-growing areas In order to control effectively this pest, understanding of biological, ecological, population dynamic as well as factors affecting the density of the Cassava Mealybug on cassava are necessary for building up IPM strategy in cassava plant protection 1.2 The status of cassava-cultivation in the world and Vietnam Cassava is cultivated mostly at tropical and subtropical areas with more than 100 countries in Asia, Africa and America Cassava considered as the fifth food crop (252.20 million tons) after corn, rice, wheat and potatoes (Nguyen Van Bo et al., 2013) In Vietnam, cassava is one of the importance food crops after rice and corn The cassava-growing areas in the period of 2011-2015, reached 551.1 - 566.5 thousand ha, cassava productivity 176.4 188.4 quintals/ha 1.3 Research on the Cassava Mealybug in the world 1.3.1 Species composition of cassava insect pests Cassava production is attacked by many insect pests, at South America nearly 200 species of arthropods are recorded (Bellotti, 1990) including 17 common pests on cassava (Bellotti and Schoonhove, 1999) 1.3.2 Research on the Cassava Mealybug Species composition of mealybugs damaging cassava According to Williams Granata de Willink (1992), 19 species of mealybugs (Pseudococcidae) have been discovered on cassava in the world The main Cassava Mealybugs have been studied in biology, ecology and measure of control Taxonomy, origin, distribution, damage of the Cassava Mealybug Cassava Mealybug, P manihoti belongs to the family of Pseudococcidae (Homoptera) It originated in the tropics of the Americas (Gutierrez et al., 1988; Löhn et al., 1990; ) In the 1970s, P manihoti accidentally introduced into western Africa, then spread to most cassava growing countries in Africa By 2008, it entered Asia (FAO-IPM, 2013; Herren, 1990; Parsa et al., 2012, Winotai et al., 2010) P manihoti is the most dangerous pest on cassava Cassava root yield could be reduced by 58-84% when severely damaged by Cassava Mealybug (Bellotti et al., 1999; Nwanze, 1982; Sartiami et al., 2015; ) Study on morphology of the Cassava Mealybug The morphological characteristics of P manihoti at each development phases of life cycle have been described in Parsa et al (2012) and some other authors Research on biology of the Cassava Mealybug Biological characteristics of P manihoti have been recoreded in publication of Barilli et al (2014), Le Rü and Fabres (1987), Nwanze (1978) and Parsa et al., (2012) Study on ecological characteristics of the Cassava Mealybugs The effects of food crops, climate, natural enemies on P manihoti populations have been refered in some publication of Barilli et al., (2014), Essien et al., (2013), Study on control measures of the Cassava Mealybug The cultivation, mechanical and biological methods to control P manihoti have been mentioned in many publications (Bennett and Greathead, 1978; Emehute and Egwuatu, 1990; Nwanze, 1978; ) 1.4 Study on the Cassava Mealybug, P manihoti, in Vietnam 1.4.1 Species composition of cassava insect pests No cassava pests have been listed via some crops surveys of pests and diseases Six species of cassava pests were recorded in studies of Nguyen Thi Chat et al., (2005), Pham Van Lam (2013), Plant Protection Research Institute (1976, 1999a, 1999b), 1.4.2 Study on the Cassava Mealybug, P manihoti Species composition of mealybugs on cassava in Vietnam On cassava in Vietnam, two species of mealybug were identified as Ferrisia virgata, Phenacoccus manihoti (Pham Van Lam, 2013) Invasion and damage of the Cassava Mealybug in Vietnam The Cassava Mealybug, P manihoti was first discovered in Tay Ninh province in July 2012 on an area of 169 By 2013, 10 provinces have recorded infested by the Cassava Mealybug on cassava with a total infected area of 1,350.037 (Plant Protection Department, 2013) Study on morphological characteristics of CM No publication on morphological characteristics of the Cassava Mealybug have been issueded yet Research on biological characteristics of the Cassava Mealybug Some studies on the biological characteristics of the Cassava Mealybug were conducted at Hue University (Tran Dang Hoa, Nguyen Thi Giang, 2014; Hoang Huu Tinh et al., 2018a, 2018b) Study on ecological characteristics of the Cassava Mealybug Ecological characteristics of the Cassava Mealybug were done at Hue University (Tran Dang Hoa, Nguyen Thi Giang, 2014; Hoang Huu Tinh et al., 2018a, 2018b) Study on measures to suppress the Cassava Mealybug The Plant Protection Department has instructed some control measures to suppress the Cassava Mealybugs An initial study of parasitic wasp Anagyrus lopezi was conducted (Hoang Huu Tinh et al., 2017) Chapter RESEARCH MATERIAL, CONTENT AND METHODOLOGY 2.1 Location and time of studies 2.1.1 Location Laboratories at Provincial Plant Protection Sub Departments, Regional Plant Protection Center and Plant Protection Research Institute Some main cassava-growing areas in Vietnam 2.1.2 Time of studies Time of studies from 2014 to 2017 2.2 Research materials Cassava varieties, tools, chemicals, equipment for rearing cassava mealybugs in the laboratory and conducting field experiments 2.3 Study contents Determine species composition of insect pests on cassava and the invasive situation of Phenacoccus manihoti in Vietnam Research on morphological, biological and ecological characteristics of the Cassava Mealybugs, Phenacoccus manihoti, in the laboratory Research on seasonal population dynamic and factors affecting the density of the Cassava Mealybug on cassava in some cassava growing area in Vietnam Research measures trending sustainable IPM to control the Cassava Mealybug, Phenacoccus manihoti 2.4 Methods 2.4.1 Determine species composition of pest of cassava and the invasive situation of P manihoti in Vietnam Method of survey on species composition of pest of cassava Base on the method of insect pest survey as described in publication of Plant Protection Research Institute (1997) Methods to determine the invasive situation of the CM According to the method of Plant Protection Research Institute (1997) and instruction described in QCVN 01-38: 2010/BNNPTNT issued by Ministry of Agriculture and Rural Development Sample of P manihoti were handled according to Watson (2007) Identification of P manihoti followed by Williams (2004) 2.4.2 Methods of laboratory research on morphological, biological and ecological characteristics of the Cassava Mealybug Maintained the Cassava Mealybug population in laboratory Pumpkin (from the garden does not spray pesticides) at the beginning of ripening stage and cassava (KM 98-7 variety) is grown in a plastic cup (25cm high, 15cm diameter) covered with net, without pesticides used as food to feed P manihoti P manihoti used in this study was collected in August-September 2015 in Quang Tri and Tay Ninh provinces Study morphological characteristics Description of shape, color, external structure, measurement of length/width and photograph of egg, nymphs, adult of the Cassava Mealybug under a microscope (number of samples observed for each phase/stage of development n = 30) Research on biological and ecological characteristics of CM P manihoti was kept in an ecological cabinet (RGX-400E brand) at 20oC, 25oC, 30oC, 62% RH, 16L:8D Monitor time for each development phases, life cycle, etc Life table parameters (rm, Ro, Tc, λ, DT) of P manihoti are calculated according to Birch (1948) and Kakde at el., (2014) The lower developmental threshold temperature was determined according to Blunk (1923) and Sanderson (1917) 2.4.3 Research on seasonal population dynamic and factors affecting the density of the Cassava Mealybug on cassava in some cassava growing area in Vietnam According to the method of Plant Protection Research Institute (1997) and instruction described in QCVN 01-38: 2010/BNNPTNT issued by Ministry of Agriculture and Rural Development 2.4.4 Research on measures trending sustainable IPM to control the Cassava Mealybug, Phenacoccus manihoti Manual control measures Compare the level of P manihoti infestation, cassava yield between control (no treatment) and manual-applying treatments which mainly rely on removing P manihoti- infesting shoot Evaluate the effectiveness of chemical combined with manual control Compare the level of P manihoti infestation, cassava yield between chemical spraying and combination of manual and chemical treatments Research on application of Anagyrus lopezi Compare the rate parasitism of wasp A lopezi on P manihoti in wasps-releasing regions and control (non- wasp releasing regions) 2.5 Data analysis Experimental data are processed by Excel software and statistical software of Statistix window, IRRISTAT CHAPTER RESEARCH RESULTS AND DISCUSSION 3.1 Cassava pests, invasion and hamful status of the Cassava Mealybug, Phenacoccus manihoti, in Vietnam 3.1.1 Species composition of cassava pests in Vietnam 10 species of insects and miters were recorded on cassava in the study areas The Cassava Mealybug, Papaya Mealybug and Two Spotted Red Mites were highlighted as key pests In this study, insect species have added into the list of cassava pests of Viet Nam which including termite Coptotermes sp., whitefly Aleurodicus disperses, common armyworm Spodoptera litura and cotton bollworm Helicoverpa armigera Base on updated information, the 12 species have been recorded in the list of cassava pests in Vietnam 3.1.2 The invasion status of the Cassava Mealybug (P manihoti) in Vietnam Invasive progress of the Cassava Mealybug in Vietnam The Cassava Mealybug was first discovered in Vietnam in 2012 By 2017, it has appeared in 53 cassava growing districts of 16 provinces especially Tay Ninh, Dong Nai and Phu Yen provinces have many invaded-districts (7-8 districts) (Table 3.3) Table 3.3 Occurrence of the Pink Cassava Mealybug at cassavagrowing regions in Vietnam by 2017 No Provinces Tay Ninh Dong Nai Long An Ba Ria-Vung Tau Hau Giang Son La Thanh Hoa Nghe An Quang Tri Districts recorded the occurrence of P manihoti Tan Chau, Tan Bien, Chau Thanh, Duong Minh Chau, Hoa Thanh, Go Dau, Ben Cau, Tp Tay Ninh Nhon Trach, Xuan Loc, Long Khanh, Long Thanh, Đinh Quan, Tan Phu, Trang Bom and Vinh Cuu Đuc Hoa Son Moc, Chau Đuc, Tan Thanh, Xuyen Moc and Đat Đo Chau Thanh Mai Son Nhu Xuan Thanh Ngoc, Thanh My, Thanh Lam, Thanh Khe and Thanh Chuong Huong Hoa, Vinh Linh, Gio Linh, Hai Lang and Cam Lo Appearance year 2012 2013 2013 2013 2013 2013 2013 2013 2013 (respectively) are different at a statistically significant level with a confidence level of P