COMMUNITY STRUCTURE and PEST STATUS of PHYTOPHAGOUS WHITEGRUB SPECIES in SOUTH AFRICAN FORESTRY by DERIAN ECHEVERRI-MOLINA RESE
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COMMUNITY STRUCTURE AND PEST STATUS OF PHYTOPHAGOUS WHITEGRUB SPECIES IN SOUTH AFRICAN FORESTRY by DERIAN ECHEVERRI-MOLINA RESEARCH DISSERTATION Submitted in fulfilment of the requirements for the degree of MASTER OF SCIENCE in BIOLOGY in the FACULTY OF HEALTH SCIENCES (School of Pathology and Pre-Clinical Sciences, Department of Biology) at the UNIVERSITY OF LIMPOPO (MEDUNSA Campus) Supervisor: Prof. P. GOVENDER (Ph.D.) 2012 Table of Contents Page Declaration iv Acknowledgements v Preface vii Chapter 1 1 Community structure and species composition of whitegrubs attacking Acacia mearnsii seedlings in the Natal Midlands of South Africa Abstract 2 Introduction 3 Materials and Methods 6 Species identification 6 Community analysis 7 Results 8 Discussion 11 Community structure pattern 11 References 15 Table 1 21 Table 2 22 Figure 1 23 Figure 2 24 Figure 3 25 Figure 4 26 ii Table of Contents (Continued) Page Chapter 2 27 Pest status of whitegrubs attacking Acacia mearnsii seedlings in the Natal Midlands of South Africa Abstract 28 Introduction 29 Materials and Methods 32 Data analysis 33 Results 35 Whitegrub morphospecies: abundance and distribution 35 Whitegrub morphospecies: group contribution to the community structure pattern 37 Whitegrub morphospecies: individual contribution to the community structure pattern (analysis of typification and discrimination) 37 Discussion 39 Group contribution of whitegrub morphospecies to the community structure pattern 40 Contribution of individual whitegrub morphospecies to the community structure pattern 41 References 43 Table 1 46 Figure 1 47 Summary of Results 49 iii Declaration I, Derian ECHEVERRI-MOLINA, declare that the research dissertation hereby submitted to the University of Limpopo – MEDUNSA Campus, for the degree of Master of Science in Biology has not previously been submitted by me for a degree at this or any other university; that it is my work in design and in execution, and that all material contained herein has been duly acknowledged. Derian Echeverri M. 16 May 2013 D. ECHEVERRI-MOLINA (Mr.) Date Student Number: 201118049 iv Acknowledgements I do believe that faith in God gives meaning and purpose to human life; a life given to me by my dear parents, Gilberto de Jesús Echeverry Cano and María Victoria Molina Hurtado. I thank you both for giving me life, support, love and the best education with the strongest family values. You also gave me a brother, Carlos Gilberto Echeverry Molina who has been there for me unconditionally. Carlos, I have never told you before but you were my very first dearly-wished gift. You also gave me a nephew, Emanuel Echeverry Gómez. The feeling of being an uncle makes me super happy and forever grateful. One of the characteristics of being a Latino and Colombian is that families are usually big and close; characteristics that I treasure because the family is always there for you and makes you never feel alone. Therefore, to all of you, in the Echeverry Cano, Molina Hurtado and extended families, thank you. Marija Kvas, you caught my attention without intention. Your love, company, encouragement and support make me proud and lucky of having found a beautiful diamond like you in South Africa. I love you! Remember that I also love an important person in your life, our lives, your mother, Irena Kvas. Thanks to all my international friends and colleagues wherever you are, especially to and in no particular order: Leonardo López, Claudia Hurtado, Claudia Vélez, Gabriela Jiménez, Gonzalo Agudelo, Sandra Serrano, Carlos Suárez, Razia Cassim, Dr. María Noël Cortinas, Dr. Sari Mohali, Dr. Serena Santolamazza Carbone, John Jairo Escobar, Tanja, Berislav and Lazar Savi čevi ć, Saša Suboti ć, Rebeka Gluhbegovi ć, Roshantha Kolapen, Pranitha Dawlal, Dylan Pillay, Lilias Makashini and Vusi Masiba, Tshepo Thlaku, Vladimir Krsti ć, Gifty Naa Ayeley Hammond, v Dr. Draginja Pavli ć Zupanc, Darko Zupanc, Vinka and Branko Bunjevac, Horacio Mones Ruiz and his family. Also, thanks to my Junior Chamber International (JCI), Linkedin and Facebook friends. The success of this M.Sc. dissertation would not have been a reality without the professional support of Prof. Pramanathan (Prem) Govender. I do not have enough words to thank you for your friendship, supervision, mentorship, empowerment, endless and rich science discussions, and for giving me the opportunity to begin my path in science. Please know that it has been a real pleasure and privilege working with you. Just to let you know that you are my hero. I extend my gratitude to your family as well because I know that you function as one. Thanks are extended to the various forestry companies and private growers for funding and supporting this study and especially the forestry staff that assisted with the sowing and maintenance of the trials. The use of the map of KwaZulu-Natal showing the location of the trials in this study (Chapter 1) was made with permission. This research project (No. MREC/P/140/2012: PG) was scientifically and ethically approved by the MEDUNSA Research Ethics Committee of the University of Limpopo. I thank the University of Limpopo, MEDUNSA Campus, for financial support and hosting me as a student, the Electron Microscope Unit of the Medunsa Campus for the arrangement to use the stereo microscope facilities. I promise to fulfil my duties as an ambassador and alumni of this University to the best of my abilities, wherever I will be in the future. vi Preface Acacia mearnsii De Wildman (Mimosaceae) is known in South Africa as black wattle. This tree species is native to Australia. Wattles were introduced into South Africa around the late eighteen hundreds. Since then, wattle has become the third most important commercial tree species used by the South African forestry industry after pines and eucalypts. Wattles are used for, amongst others, tannin extracts, production of pulpwood, mining poles and charcoal. The wattle industry employs numerous people due to its labour intensive silvicultural activities, hence the creation of jobs in South Africa. Since its introduction the expansion of wattle production has encounter different challenges such as: limited access to land due to the strong competition with agricultural crops; appearance of stricter planting permits, policies and regulations (e.g. Forestry Stewardship Council – FSC) to be able to plant in new areas and export and the appearance of pests and diseases that limit the production or make it less profitable. Today, the industry has no other choice but to become more efficient in increasing productivity. There are new technologies available to increase productivity, for example, the development and improvement of plant breeding techniques with the use of genetically modified organisms. The improvement of silvicultural practices such as: land preparation; fertilization; correct matching tree species with the locality; implementation of integrated weed and pest management (IPM). One of the most expensive and labour intensive activity in forestry is the preparation and planting of the site. There are many factors that limit the establishment of wattle seedlings. It has been reported that soil invertebrates, whitegrubs (Coleoptera: vii Scarabaeidae) in particular, are the most important pests that affect the survival rate of newly planted wattle seedlings and young saplings. This increases establishment costs because foresters have to implement control measures or incur expenses with the uncertainty of success. One of the preferred control measures is the prophylactic use of pesticides. However, most pesticide use is restricted by the FSC. A particular challenge with whitegrubs is the limited knowledge about them. Whitegrubs are generally associated with pest species. The family Scarabaeidae is one of the most prolific families in terms of diversity and abundance of species. These scarabs are very important for the environment and they also contain the group of dung beetles which are very beneficial. This dissertation aimed to plug the knowledge gap on the management factors that could allow a better understanding of the composition and community structure of these various whitegrub species on previous wattle sites in the Natal Midlands (South Africa) (Chapter 1). The abundance and distribution of whitegrubs that attacked black wattle seedlings during their establishment in the Natal Midlands of South Africa was assessed in Chapter 2, where their pest status and their contribution to the whitegrub community structure patterns were established. The results of this study can contribute towards the improvement and development of new whitegrub control strategies. This, in the end, will contribute to the success of wattle seedlings survival in the field. However, the impact of this study does not end in the forestry domain. This knowledge will impact the agricultural sector because these insects are also pests in other important crops like sugarcane and potatoes. Other agricultural crops are often rotated with wattle plantations in the Natal Midlands of South Africa and these crops can also benefit from the findings of this research. viii Chapter 1 Community structure and species composition of whitegrubs attacking Acacia mearnsii seedlings in the Natal Midlands of South Africa Manuscript prepared for submission to Southern Forests: a Journal of Forest Science 1 Abstract Whitegrubs (Coleoptera: Scarabaeidae) are the most important establishment pests attacking Acacia mearnsii De Wildman (black wattle) seedlings in South Africa. This study determined