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 Title: Phenology and Population Dynamics of the Squash Bug, Anasa Tristis Author(s): Fielding, Dennis Joseph Doctoral Committee Chair(s): Ruesink, William G. Department / Program: Entomology Discipline: Entomology Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Biology, Entomology Abstract: A computer model that simulates the population dynamics of the squash bug, Anasa tristis DeGeer (Heteroptera: Coreidae), was constructed and used to predict the effect of various management options and environmental factors on this pest of cucurbit crops. The life-history data required for the model were obtained by field and laboratory investigations into several processes that control the population dynamics of this species. These processes include: fecundity, mortality, developmental rates, and diapause induction.Female squash bugs continue to oviposit at a constant, temperature-dependent rate throughout most of their adult life unless diapause is induced. The mean oviposition rate in the field was 0.32 eggs per female per degree-day above a base temperature of 3.4$\sp\circ$C. Egg and nymphal mortality rates were estimated from successive counts of eggs and each instar on selected pumpkin plants.A degree-day model satisfactorily predicted rates of development for eggs in the field and under the alternating temperature regimes in the laboratory. A non-linear model fit to the rates of nymphal development at constant laboratory temperatures underestimated rates of development in the field and under the alternating temperature regimes in the laboratory. However, the degree of underestimation was consistent enough over a wide range of temperature regimes in the field for the model to be useful.The induction of diapause was shown to be determined by the combined effects of photoperiod, temperature, and age of the bugs. Squash bugs proved to be sensitive to photoperiodic induction of diapause at all times during their adult life.The effects of insecticide application schedules, planting dates, and various temperature regimes were evaluated using the model. Issue Date: 1988 Type: Text Description: 114 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988. URI: http://hdl.handle.net/2142/71112 Other Identifier(s): (UMI)AAI8823123 Date Available in IDEALS: 2014-12-16 Date Deposited: 1988
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