Insect biotypes

Development of insect biotypes and their management

1. WELCOME

2. Course Seminar On Development of insect biotypes and their management Narendra Deva University of Agriculture & Technology, Kumarganj , Ayodhya – 224229 (U.P.)

3. Contents Introduction Concept of insect biotypes Evalution of biotypes Genetics of biotypes development Factors leading to development of biotype Importance Of Study Of Biotype Occurrence of Biotypes Methods of biotype detection Biotypes of some important insect pests Management Stratgies Conclusion References

4. INTRODUCTION We all know this thing that plants and insects have coexisted together for about 4 million years. Insect have own defense mechanism which deters the feeding of herbivores. On the other hand, talking about insects, the selective ability . In order to protect our crop plants from insect pests, what immediately clicks our mind is to go for chemical pesticides. The concept of using host plant resistance is of great advantage which is an essential component of integrated pest management.

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6. Concept of insect biotypes Biotype: A group of organisms having the same or nearly the same genotype, such as a particular strain of an insect species. A group of organism having an identical genetic constitution. The continuous growing of insect resistant varieties may lead to certain physiological and behavioural changes in insect pests so that they are capable of feeding and developing on the resistant variety. ( Dhaliwal and Arora 2009. )

7. More specifically, biotype refers to the populations within a species which can survive on and destroy varieties that have genes for resistance.( Heinrichs et., al 1985). Broadly speaking, the term biotype is an intraspecific category referring to insect population of similar genetic composition for a biological attribute. ( Saxena and Barrion,1987).

8. EVOLUTION OF BIOTYPES The continuous growing of insect resistant varieties. Failure to recognize the existence of insect biotypes. Genetic factors

9. GENETICS OF BIOTYPE DEVELOPMENT Genetics of biotype development can be understood with the help of Gene for Gene hypothesis proposed by Flor (1942). It is also known as Matching Gene Theory.

10. Isolation mechanisms or barriers pre mating isolating mechanisms Post mating isolation mechanisms Differences in habitat Seasonal differences Ethological isolation Mechanical isolation Gametic mortality Zygote mortality Hybrid inviability Hybrid sterility Factors leading to development of biotype

11. Factors influencing Selection of Biotypes in Insect pests: Selection pressure exerted by the resistant crop variety. E.g. BPH, GM. Monogenic resistance Combinations of antibiosis and antixenosis are less prone to biotype than individual. Improper management practices. Biotypes that possess an inherent genetic capability to overcome plant resistance. Some insect species with short life cycles, short generation times and high fecundities Conti…

12. Importance Of Study Of Biotype Breeding for insect resistant varieties of crops Better understanding of how to control manage by resistant varieties. Genetic control of insect pest population. The Entomologists and plant breeders to combat insect pest of crops and at same time maintain the genetic diversity of crops.

13. In 1970, biotypes were known to occur in eight species of insect pests affecting agricultural crops. Twelve species of the phytophagous insects are known to have biotypes of which seven come under Aphididae as reported by Wilbert in 1980 . Saxena and Barrion in 1987 reported that biotypes reportedly occur in 36 arthropod species belonging to 7 families of 6 order. Occurrence of Biotypes

14. Insect species Common name Crops Number of biotypes Acyrthosiphon pisum (Harris) Pea aphid Pea Alfalfa 4 Amphorophora idaei (Born) Raspberry aphid Raspberry 4 Eriosoma lanigerum ( Hausmann ) Apple woolly aphid Apple 3 Mayetiola destructor (Say) Hessian fly Wheat 16 Nephotettix virescens (Distant) Green leaf hopper Rice 3 Nilaparvata lugens ( Stal ) Brown plant hopper Rice 5 Orseolia oryzae (Wood-Mason) Gall midge Rice 6 Rhopalosiphum maidis (Fitch) Corn leaf aphid Corn 5 Schizaphis graminum ( Rondani ) Green bug Sorghum Wheat 5 7 Therioaphis maculata ( Buckton ) Spotted alfalfa aphid Alfalfa 6 Some examples of insect biotypes involved in host plant resistance to insects

15. Methods of biotype detection Morphological differences: Insects that exhibit measurably different traits with respect to host range, host plant adaption, physiological character. Figure: Three distinct biotypes of whitefly on the basis of morphological differences in cibarium .

16. Behavioural differences: Behavioral studies, especially mating behavior is used for distinguishing biotypes.   Biotype – host association: Understanding the interaction between host plant and biotype will help to understand the mechanism of evolution a virulent insect biotype. Genetics of biotypes: It helps to understand the mutation occurring single allele and expressing changes behavioral and physiological level. Conti…

17. 1. Brown Plant hopper Symptom of Damage Hopper burn or yellowing, browning and drying of plant. Circular patches of drying and lodging of matured plant. Nymphs and adults congregate at the base of the plant above the level. Affected plant dries up and gives a scorched appearance called hopper burn. It is vector of grassy student ragged stunt wilted stunt disease. BIOTYPES OF SOME OF THE IMPORTANT INSECT PESTS Symptom Insect

18. Biotype Region Countries Biotype 1 South East Asia Philippines, China, Japan, Malaysia, Taiwan, Thailand Biotype 2 South East Asia Philippines, Solomon Islands, Vietnam Biotype 3 South East Asia Philippines, Taiwan Biotype 4 South Asia India, Bangladesh, Sri Lanka Biotype 5 South East Asia Philippines Brown plant hopper biotypes existing world wide ( Source : Dhaliwal and Ram Singh, 2005)

19. 2. Rice Gall Midge Symptom of damage Maggot feeds at the base of the growing shoot. Causing formation of a tube like gall that is similar to onion leaf or Silver-shoot. Infested tillers produce no panicle. Symptom Insect

20. Germplasm Gene 1 2 3 4 5 6 W 1263 Gm 1 R S R S R R Phalguna Gm 2 R R S S R S RP 2068-18-3-5 Gm 3 R S R R R S Abhava Gm 4 R R R R R S ARC 5984 Gm 5 R R S S S S Dukong # 1 Gm 6 R S S S Not tested Not tested Reaction to biotypes for genes for resistance ( Source : Dhaliwal and Ram Singh, 2005)

21. White Fly Symptoms of Whitefly Infestation   and  Affected Plants. Common  noticeable  symptoms are an abundance of white,  waxy  material covering leaves and fronds, a sugary substance called "honeydew" produced by the  leaf -sucking insects, and  excessive dark sooty mold  on leaves or fronds that grows on the honeydew.

22. BIOTYPES OF WHITEFLY Sida race Jetropha race

23. MANAGEMENT STRATEGIES TO OVERCOME DEVELOPMENT OF INSECT BIOTYPES: 1. Systematic pest surveillance and monitoring :

24. 2. Sequential release of varieties with major genes: When a variety with a major gene becomes susceptible due to selection for a new biotype, another variety with new major genes for resistance should be released. 3 .Gene pyramiding: The incorporation of two or more major resistant genes in the same variety to provide resistance to two or more biotypes is known as gene pyramiding. Bph 1 + Bph 3 bph 2 + Bph 3 Bph 1 + bph 4 bph 2 + bph 4 Conti…

25. 4 . Horizontal resistance: One of the effective practices to manage biotype selection is the use of cultivar with a broad genetic base of resistance. 5. Gene rotation: A strategy where varieties with different resistance genes are used in different cropping season to minimize selection pressure on given resistant gene. 7. Varietal mixture: One should employ the use of varietal mixtures consisting of 80 – 90 % resistant plants and 10 – 20 % susceptible plants of similar varietal background. Conti…

26. Conclusion The threat of selection and spread of prolific insect biotypes cannot be avoided and ignored. At the same time there is a need for better understanding of insect plant interactions. There is a need for developing several short and long term strategies in breeding for insect resistance and the thrust should be to broaden the genetic base of resistance both in terms of major and minor genes. Also study the speciation of major factor responsible for speciation is reproductive isolation, which may be due to various barriers, like geographical isolation, reproductive incompatibility, differences in habitat, seasonal occurrence and behaviour. Presence of endosymbiont , like Wolbachia , present an all together different perspective to look at the problem of biotypes.

27. REFERENCES Barro , P.J. and Boykin, L.M. 2011. Bemesia tabaci : A statement of species status. Annual Review Entomology . 56:1-19. Claridge , M.F. and Hollander, J.D. 1983. The biotype concept and its application to insect pests of agriculture. Crop Protection . 2(1): 85-95. 3.David, B.V. and Ramamurthy, V.V. 2011. Elements of Economic Entomology. Namrutha Publications, Chennai. pp. 296-301. 4. Dhaliwal , G.S. and Arora Ramesh . 2009. Integrated Pest Management: Concept and Approaches. Kalyani Publishers, New Delhi. pp. 135-136. 5.Downie, D.A. 2010. Baubles, bangles and biotypes: A critical review of the use and obuse of the biotype concept. Journal of Insect Science 10(6): 176-179. 6. Pedigo , L.P. and Rice, M.E. 2009. Entomology and Pest Management. PHI Learning Private Limited, New Delhi. pp. 470-471. 7. Rawat , N., Neeraja , C.N. and Jagadish , S.B. 2012. Differential gene expression in gall midge susceptible rice genotypes revealed by suppressive substraction hybridization (SSH) c DNA libraries and microassay analysis. Rice . 5:8.

28. 8. Singh, B.D. 2005. Plant Breeding: Principles and Methods.Kalyani Publishers, New Delhi. pp. 515-519. 9. Yasala , A.K., Rawat , N. and Sundaram , R.M. 2012. In silico analysis for gene content in rice genomic regions mapped for the gall midge resistance . Plant Omics Journal 5(4): 405-413. 10. Zong , X.L., Xiao, P.Y., Jian , C. and Xu -Sung. 2004. Dynamics of Yeast like Symbiote and its relationship with the virulence of Brown Plant Hopper , Nilaparvata lugens Stal , to resistant rice varieties. Journal of Asia-Pacific Entomology 7(3): 317-323.