Research Methods in Toxicology and Insecticide Resistance ...

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Preface Rice planthoppers are developing resistance to insecticides very rapidly. Publications by several authors have reported that the brown planthopper (BPH) has acquired as much as 1,000-fold resistance to imidacloprid in some areas in China. High resistance to fi pronil, fenobucarb, and buprofezin has also been reported. However, the methods used by different authors differ signifi cantly, thereby making data comparison between different countries and sites diffi cult and meaningless. In order to make toxicological data across countries comparable, Matsumura and his colleagues have collected live planthoppers at sites in Asia and cultured them in the laboratory in Kyushu, where tests are carried out ex situ. We have adopted an approach of developing a common standardized methodology and national training program for partners to conduct appropriate and meaningful in situ toxicological tests. Collaborators in a resistance monitoring network meet at least once a year to review methods, data, and interpretations. In addition to collecting standardized data sets that can be compared, this approach also develops local capacity and the skills of national scientists in insecticide toxicology. This book describes the standardized methodology we developed with step-by-step illustrations wherever appropriate. The initial two chapters provide readers with an introduction to insect toxicology involving insect biochemistry, genetics, and physiology related to insecticide mode of action and resistance. Chapter 3 discusses quantal response data and toxicological statistics. Here, we draw heavily from the works of Finney (1977), Busvine (1971), and Robertson et al (2005) to provide readers with some basics in quantal response data and toxicological statistics. Chapter 4 describes the whole process involved in collecting specimens from the fi eld, rearing them in an insectary, and preparing standardized test insects. In Chapter 5, preparation of a stock solution from technical-grade insecticide based on active ingredient and the test solutions used for insecticide application are discussed. Also discussed are topical application, the use of recovery cages, and posttreatment conditions for test insects. Probit analysis was developed by Finney to estimate the median lethal dose (LD 50 ) and associated statistics to be used for comparisons. Professor Finney’s program was subsequently modifi ed and developed by Robertson and coworkers into PoloPlus©, which is now the authoritative software for probit analysis in toxicology. In Chapter 6, the step-by-step use of PoloPlus© is discussed in detail with screen-shot illustrations and interpretations. Mixing two or more active ingredients either in a commercial product or by growers in spray tanks is a common practice in rice production in Asia. In Chapter 7, the use of PoloMix©, a program to determine whether a particular mixture has a vii
synergistic, antagonistic, or no added effect, is discussed. Step-by-step procedures are provided to help readers use the program. In reporting the toxicological experiments, it is important to provide suffi cient information so that other scientists can use it to make meaningful comparisons. There are several ways to document toxicological data and Chapter 8 discusses one way of presenting the data in tables and in probit line plots. The Reference section contains the references cited in the chapters and some additional useful sources from textbooks and Internet links. Although this book specifi cally describes toxicological methods for rice planthoppers, the basic principles involved in the determination of median lethal doses (LD 50 s) are the same. The general techniques and processes can be applied to other insects. viii
Page 2 and 3: Research Methods in Toxicology and
Page 4 and 5: Contents Foreword v Preface vii Ack
Page 6: Foreword By 2020, the world will re
Page 11 and 12: CHAPTER 1: Introduction to insect t
Page 13 and 14: Toxicology (derived from two Greek
Page 15 and 16: ogy can be subdivided into many sub
Page 17 and 18: Step 8: 3-phosphoglycerate is isome
Page 19 and 20: Each pyruvate molecule when complet
Page 21 and 22: H + H + H + H + NADH Cytochrome c d
Page 23 and 24: Insect physiology Mitochondria A mi
Page 25 and 26: of sodium channels allowing sodium
Page 27 and 28: ) Cytosol Pretranslation Masking, d
Page 29 and 30: CHAPTER 2: Insecticide toxicology R
Page 31 and 32: An insecticide is a pesticide used
Page 33 and 34: 2. Application technique, for examp
Page 35 and 36: nant in insects. In the neurons, th
Page 37 and 38: 30 g/kg, and fenoxycarb, LD 50 16.8
Page 39 and 40: tive feedback of acetylcholine rele
Page 41 and 42: Metabolic resistance via detoxifica
Page 43 and 44: 5. pen—a recessive gene that decr
Page 45 and 46: 1. Use of an appropriate synergist,
Page 47 and 48: CHAPTER 3: Quantal response data an
Page 49 and 50: Insecticide research generally invo
Page 51 and 52: esponse to probits is available in
Page 53 and 54: CHAPTER 4: Rearing and preparation
Page 55 and 56: As discussed in Chapter 3, for expe
Page 57 and 58:
4.3 4.4 Fig. 4.3. Aluminum rearing/
Page 59 and 60:
Preparation of standardized test in
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CHAPTER 5: Preparation of test solu
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The median lethal dose (LD 50 ) of
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Fig. 5.3. Recovery cage preparation
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Fig. 5.6. Treated planthoppers are
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CHAPTER 6: Analyz ing quantal respo
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In Chapter 3, we discussed probit a
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3. There is a need to further forma
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Using PoloPlus© The quantal respon
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Fig. 6.1. Output results. Research
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The values of the variance-covarian
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The lethal dose ratio on lines 95-9
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8. Then, Paste the Excel data sets
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3. For the fi rst population, open
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5. Highlight and Copy the Probit va
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9. Right-click the y-axis, and clic
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CHAPTER 7: Analyzing joint action o
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PoloMix© is another software devel
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c. Lastly, on the File menu, the Sa
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Fig. 7.2. PoloMix© output. Researc
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CHAPTER 8: Presenting results Resea
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The previous chapters provide the m
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References Abbott WS. 1925. A metho
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Sudderudin KI, Tan KH. 1973. Some h
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Appendix A Table 1. Transformation
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Appendix Table B1. Raw data recordi
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Appendix C Table 1. The distributio
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