Title page for ETD etd-04112005-201256


Type of Document Master's Thesis
Author Patel, Dilipkumar Thakorbhai
Author's Email Address DPATEL1@LSU.EDU
URN etd-04112005-201256
Title Evaluation of Beauveria Bassiana and Host Plant Resistance for the Management of Rice Stink Bug in Rice Agro-Ecosystem
Degree Master of Science (M.S.)
Department Entomology
Advisory Committee
Advisor Name Title
James R. Fuxa Committee Chair
Michal J. Stout Committee Co-Chair
Richard N. Story Committee Member
Thomas E. Reagan Committee Member
Keywords
  • Oebalus pugnax
  • biological control
  • anthesis
  • fungal epizootics
  • milk stage
  • soft dough stage
  • disease prevalence
  • insecticide
  • Beauveria bassiana
  • rice fields
Date of Defense 2005-03-14
Availability unrestricted
Abstract
Isolates of Beauveria bassiana (Balsamo) Vuillemin were tested for biological control of rice stink bug, Oebalus pugnax (Fab.), in the laboratory, in small-plot field experiments compared with conventional insecticides, and in a large-plot experiment to determine the spread and persistence of the fungus. The soil-derived isolate LRC28 was more virulent to O. pugnax adults than the rice stink bug-derived isolate RSB in a laboratory experiment. The fungal isolates did not differ from one another in reducing insect numbers or in infecting rice stink bugs in the small-plot experiments. A single application of B. bassiana reduced rice stink bug nymphs on six of nine sampling dates and adults on two of nine sampling dates from two to 10 days after application, and prevalence of the fungus was higher in the B. bassiana treatment than in controls for nymphs on four dates versus none for adults. Mixtures of B. bassiana and insecticide provided better control of rice stink bug than a single application of either material alone. Fungal epizootics lasted 17-22 days after application. High temperatures probably were the major factor limiting B. bassiana epizootics. Thus, B. bassiana has potential for integrated management programs of O. pugnax in rice, since it was moderately effective against nymphs and had an additive effect with insecticides.

Greenhouse experiments were conducted to evaluate the effects of panicle age and grain maturity on quantitative and qualitative damage caused by stink bug infestations on rice. The effects were measured for two infestation levels (one and two bugs per panicle). Insect feeding during anthesis and the early milk stage of grain development caused substantially higher numbers of empty kernels than feeding during later grain development and the control. Average grain weights were lower in infestations during anthesis and milk stage than in infestations during later grain development and the control. Pecky rice was significantly higher during late milk and soft dough stages compared with remaining stages of grain development and the control. Damage was higher in the experiment in which panicles were infested with two bugs.

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