Selection of Biotype Populations 2 and 3 of Nilaparvata lugens1 by Exposure to Resistant Rice Varieties

Abstract

The release of an insect pest-resistant variety and subsequent adaptation of the insect species to that variety through the process of biotype selection has occurred on many cultivated crops. The present study was designed to obtain detailed information on some of the processes involved in the selection of biotypes of Nilaparvata lugens (Stål) on two rice varieties with different major genes for resistance. The N. lugens population selected for the study, which had originally been collected in the field and reared on a susceptible variety for 12 years (ca. 140 generations), initially had a low survival on the resistant rice varieties Mudgo (Bph 1 gene) and ASD7 (bph 2 gene) and high survival on the susceptible variety, Taichung Native 1 (TN1). Monitoring the survival and length of the developmental period for seven generations indicated a progressive increase in the survival and shortening of the nymphal period in each generation on the heretofore resistant varieties until they were similar to those on TN1. The shift in the population to a more virulent biotype was also confirmed by the seedling bulk test. The selected populations reared on Mudgo or ASD7 were not able to kill Mudgo or ASD7, respectively, in the fifth generation but by the eighth generation were able to do so. In addition, adult longevity and fecundity on the resistant varieties increased during the selection process. Nilaparvata lugens (Stål) is one of the major insect pests of rice and has had a distinct economic effect on rice production in many Asian countries (Dyck and Thomas 1979). It is a monophagous pest, limited to feeding on Oryza sativa and wild rice species. The epidemic of outbreaks of N. lugens in 1972, 1973, and 1974 in several Asian countries including the Philippines stimulated rice scientists to accelerate the development of rice varieties resistant to this pest. Genetic analysis of several rice varieties resulted in identification of two

The Quantitative Genetics of Polyphagy in an Insect Herbivore. I. Genotype‐environment Interaction in Larval Performance on Different Host Plant Species

“…In so doing, estimates ofthe magnitude of quantitative genetic variation in host plant related characters were produced. These parametric estimates supplement the qualitative evidence, chiefly from population crosses and selection experiments, that characters associated with host plant use in herbivores and pathogens are indeed genetically based (Smith, 1941;Gallun et al, 1961;Hatchett and Gallun, 1970;Knerer and Atwood, 1973;Day, 1974;Groth and Person, 1977;Gould, 1979;Wasserman and Futuyma, 1981;Pathak and Heinrichs, 1982;Jaenike and Grimaldi, 1983;Futuyma et al, 1984). The study of genetic mechanisms of insect-host plant evolution requires quantitative estimates of several popu- The genotype-environment interaction estimated here in development time on different host plants (Table 3-5) demonstrates that genetic variation in the relative performance of individuals on different host plants can occur within a "generalist" species.…”

Planthopper Outbreaks in Different Paddy Ecosystems in Asia: Man-Made Hopper Plagues that Threatened the Green Revolution in Rice

“…Mass-rearing inbred BPH populations established on TN1, Mudgo, and ASD7 were designated as biotypes 1, 2, and 3 at IRRI (IRRI 1976;Pathak and Heinrichs 1982). So far as these biotypes 1, 2, and 3 concern, they show phenotypically a vertical virulence specific to the BPH resistance genes Bph1 and bph2, as if there were a gene-for-gene relationships between the virulence of biotypes and host plant resistance conferred by each BPH resistance gene (Gallun and Khush, 1980).…”

“…Selection experiments revealed that BPH populations could easily adapt to the resistance varieties carrying the Bph1 and bph2 genes within 5-10 generations under continuous inbred conditions (Clarige and Den Hollander 1982;Pathak and Heinrichs 1982;Sogawa and Kilin 1987). Heritability for BPH biotypes is estimated based on the data of selection experiments.…”

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“…Some differences between populations have been shown to be genetically determined (e.g., Hsiao, 1978;Tabashnik, ~ 1983;Thind & Muggleton, 1981;Rausher, 1982;Scriber, 1982;Bowers, 1986;Thomas et al, 1987). Nonetheless, only a few studies have demonstrated a genetic basis for within-population variation in oviposition preference (e.g., Jaenike & Grimialde, 1983;Thompson, 1988) or performance (e.g., Gallun et al, 1961;Gould, 1979;Pathak & Heinrichs, 1982;Tabashnik, 1983;Rausher, 1984a;Hare & Kennedy, 1986). Moreover, nearly nothing is known about how these aspects of host use covary genetically (Via, 1986).…”