Document Type
Thesis - University Access Only
Award Date
2004
Degree Name
Master of Science (MS)
Department / School
Plant Science
First Advisor
Dale Gallenberg
Abstract
Rootworm injury to maize, Zea mays L.., following soy, Glycine max (L.) Merr., has become one of the most significant insect pest problems for South Dakota farmers. In many areas rotational practices involving first-year maize has effectively controlled this insect pest complex for decades. However, increasing and unexpected rootworm damage shows evidence of a rotational resistance occurring. The two most likely ways rotational resistance could occur are extended diapause or variant egg laying behavior (oviposition in soybean rather than corn). To determine the mechanism of this resistance, sticky trap, sweep net, and emergence cages were employed to investigate the bionomics of rootworms in some problem fields. Beetle emerging were allowed to mate and egg hatch observations were conducted with the northern corn rootworm, Diabrotica barberi Smith and Lawrence and western corn rootworm, Diabrotica yirgifera virgifera Leconte.
Absence of D. v. virgifera from sweep net and sticky-trap samples of soy field during peak beetle oviposition helped in eliminating the behavioral variant as the cause of rotational resistance. Conversely, our data on the observations of egg hatch showed presence of extended diapause in D. v. virgifera populations of eastern South Dakota at 2% and 0.8% in first-year maize and continuous maize, respectively in 1998. In 1999, only one D. v. virgifera emerged from the first-year maize which limited our analysis of extended diapause. However, the extended diapause by D. v. virgifera in continuous maize was 0.9% in 1999.
In contrast, D. barberi had much higher levels of extended diapause at 24.2% and 42.3% in first-year maize and continuous maize, respectively in 1998 and 22.9% and 15 .4 % in 1999. In both years, there were some D. barberi eggs that hatched after the third chill period expressing multi-year diapause. However, the percentage of eggs viable under this multi-year diapause never exceeded 1.3% of the totals eggs; thus, this situation does not currently pose any immediate threat to farmers that opt for a 3 year rotation to manage rootworms. Therefore, the primary cause of first-year maize can be attributed to extended diapause in D. barberi.
Library of Congress Subject Headings
Northern corn rootworm -- South Dakota.
Western corn rootworm -- South Dakota.
Corn -- Diseases and pests -- South Dakota.
Publisher
South Dakota State University
Recommended Citation
Kadakia, Nimesh Dinkerlal, "Northern and Western Corn Rootworm (Coleoptera: Chrysomelidae): Investigation of First-Year Maize Damage in Eastern South Dakota" (2004). Electronic Theses and Dissertations. 1095.
https://openprairie.sdstate.edu/etd2/1095
Rights Statement
