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Tolerance Of The Rice Variety Triveni To The Brown Planthopper, Nilaparvata Lugens, D. T. Ho, E. A. Heinrichs, F. Medrano
Tolerance Of The Rice Variety Triveni To The Brown Planthopper, Nilaparvata Lugens, D. T. Ho, E. A. Heinrichs, F. Medrano
Department of Entomology: Faculty Publications
Seedling screening and survival and population growth studies on 30-day-old plants indicated similar degrees of susceptibility on Taichung Native 1 (TN1) and Triveni rice to Nilaparvata lugens (Homoptera: Dilphacidae). However, studies in the screenhouse and field indicated that at both the vegetative and mature stage, Triveni possesses tolerance to insect damage, expressed as the ability to survive and produce a higher percentage of productive tillers than TN1 at similar N. lugens populations. Yield reduction caused by feeding of N. lugens was ca. 40% when infested with 400 N. lugens on 35-, 50-, or 75-day-old plants, whereas it was almost 100% …
Effects Of Insecticides On Nilaparvata Lugens And Its Predators: Spiders, Microvelia Atrolineata, And Cyrtorhinus Lividipennis, W. H. Reissig, E. A. Heinrichs, S. L. Valencia
Effects Of Insecticides On Nilaparvata Lugens And Its Predators: Spiders, Microvelia Atrolineata, And Cyrtorhinus Lividipennis, W. H. Reissig, E. A. Heinrichs, S. L. Valencia
Department of Entomology: Faculty Publications
Thirty-five insecticides used on rice in Asia were tested in the field against Nilaparvata lugens. The most important predators of the pest, Cyrtorhinus lividipennis, Microvelia atrolineata, and predacious spiders, Lycosa pseudoannulata, Tetragnatha, and Araneus species, were also monitored in the test plots. Ten insecticides significantly reduced numbers of N. lugens, but propoxur and ethylan gave the most consistent and effective control. Most insecticides did not significantly reduce populations of spiders and M. atrolineata compared with untreated checks, but they did reduce numbers of C. lividipennis. Fifteen treatments caused resurgence of N. lugens, …
Resurgence Of Nilaparvata Lugens (Stål) Populations As Influenced By Method And Timing Of Insecticide Applications In Lowland Rice, E. A. Heinrichs, G. B. Aquino, S. Chelliah, S. L. Valencia, W. H. Reissig
Resurgence Of Nilaparvata Lugens (Stål) Populations As Influenced By Method And Timing Of Insecticide Applications In Lowland Rice, E. A. Heinrichs, G. B. Aquino, S. Chelliah, S. L. Valencia, W. H. Reissig
Department of Entomology: Faculty Publications
Resurgence of Nilaparvata lugens (Stål) after insecticide application is a common phenomenon in rice in South and Southeast Asia. Among other insecticides inducing resurgence, carbofuran, decamethrin, and methyl parathion were selected for this study. Of the various methods of carbofuran application tested, foliar sprays were most active in inducing resurgence. Extent of resurgence was highly influenced by time of insecticide application. Sprays of methyl parathion and decamethrin applied 50 and 65 days after transplanting (DT) induced resurgence in the third generation of N. lugens at ca. 90 DT, whereas earlier applications had little effect. The cause(s) for resurgence was not …
Selection Of Biotype Populations 2 And 3 Of Nilaparvata Lugens By Exposure To Resistant Rice Varieties, P. K. Pathak, E. A. Heinrichs
Selection Of Biotype Populations 2 And 3 Of Nilaparvata Lugens By Exposure To Resistant Rice Varieties, P. K. Pathak, E. A. Heinrichs
Department of Entomology: Faculty Publications
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 …
Insecticide-Induced Resurgence Of The Brown Planthopper, Nilaparvata Lugens, On Rice Varieties With Different Levels Of Resistance, W. H. Reissig, E. A. Heinrichs, S. L. Valencia
Insecticide-Induced Resurgence Of The Brown Planthopper, Nilaparvata Lugens, On Rice Varieties With Different Levels Of Resistance, W. H. Reissig, E. A. Heinrichs, S. L. Valencia
Department of Entomology: Faculty Publications
Three rice varieties, IR29, IR40, and IR42, which are, respectively, susceptible, moderately resistant, and resistant to Nilaparvata lugens Stål in the Philippines, were treated in the field with decamethrin, an insecticide known to cause resurgence. N. lugens populations increased to a significantly higher level in the treated plots than in untreated checks, but the degree of resurgence varied among varieties. The maximum population increases in the treated plots compared with the checks were ca. 74-, 50-, and 5-fold, respectively, for IR29, IR40, and IR42. Decamethrin was toxic to predators, and this reduction of natural enemies of N. lugens may …