Date of Award

1988

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Entomology

First Advisor

Thomas J. Riley

Abstract

Seasonal biology studies of the chinch bug, Blissus leucopterus leucopterus (Say), indicated movement out of overwintering sites in April in central Louisiana. Mass emergence appeared to be influenced by ambient temperatures of 26.7$\sp\circ$C or above. Overwintering populations attacked corn and wheat simultaneously and field invasions were predominantly by flight. Peak overwintering populations in Andropogon virginicus L. occurred in November and December. Overwintering populations decreased consistently beginning in January and culminated with spring emergence. Fall migrations back to overwintering sites began in September and peaked in October. Studies on the effect of temperature on the immature stages of this insect indicated faster development at 28$\sp\circ$C than at 22$\sp\circ$C. Males developed significantly faster than females at 22$\sp\circ$C but not at 28$\sp\circ$C. First and fifth stadia were the longest in duration for both males and females and at both temperatures. Egg survival was not affected by temperature; however, incubation period was shorter at 28$\sp\circ$C when compared to 22$\sp\circ$C. Greenhouse studies were conducted in which corn seedlings were infested at different stages of plant development with varying levels of chinch bug density. Results indicated a highly significant interaction between plant developmental stage and chinch bug infestation level. This suggests that the response of corn seedlings to chinch bug infestations is dependent on the stage of plant development. Persistent reductions in plant height were obtained two weeks after insect pressure was removed from the plants with 10 insects/plant for V1 plants, 15 insects/plant for V2 plants, and 20 insects/plant for V2.5 plants. Field studies were conducted in an effort to determine the long-term effect of chinch bug feeding in seedling corn. Corn plants were infested artificially at two stages of plant development with different chinch bug densities. In addition, plants damaged by a natural chinch bug infestation were rated into no damage, slight, moderate, and heavy damage classes at the time of damage and followed to maturity. Results indicated that young plants were most susceptible to damage and reduced performance of plants was evident with slight or greater levels of damage.

Pages

94

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