Mark D. Lyle

Document Type

Thesis - Open Access

Award Date

1973

Degree Name

Master of Science (MS)

Department / School

Entomology

Abstract

The western corn rootworm, Diabrotica virgifera LeCcnte, has caused great economic loss to the com producers of the Midwest. That economic loss is twofold: first, the loss of revenue due to insect damage and second, the cost of control measures. It has been estimated that in South Dakota in 1972, approximately $9,000,000 were lost to the insect. The rootworm complex in South Dakota is composed of the western and northern, D. longicomis, corn rootworms. In later years the western has become the primary pest in the complex. The resistance to chemicals by corn rootworms has compounded the problem of holding in check one of the major pests of com in South Dakota. Cultural controls, especially crop rotation, were first recommended for control of the insect. Ball and Weekman stated that in the early l950's, aldrin, chlordane, and heptachlor were recommended for control of the insect larva. By 1959 ineffective control of the rootworm larvae was noted where there were corn-on-corn growing practices, irrigation, and continual use of the chlorinated hydrocarbon insecticides. The western com rootworm had become resistant to these chemicals. With the development of the resistance to the chlorinated hydrocarbon insecticides new chemicals were sought; diazinon, an organophosphate insecticide, was one of these. However, Ball in Nebraska soon reported that rootworms were becoming resistant to diazinon. From 1963 to 1967 an increase of 66.1% in dosage was needed to obtain the same control. Since the western corn rootworm had become resistant to chemical insecticides and more entomologists were monitoring resistance, the Entomological Society of America in 1970 published a tentative method for detection of insecticide resistance. In 1972, the same organization published a second paper setting standard methods for detection of resistance in Diabrotica and Hypera beetles. In both publications it was noted that limited data was available concerning the possibility of resistance occurring in both the larvae and the adults. It is the purpose of this research to determine if any differences do occur in LD50 values for a carbamate and an organophosphate insecticide on adults and larvae of the western corn rootworm, and to investigate the possibility of the western corn rootworm becoming resistant to these same chemicals.

Library of Congress Subject Headings

Northern corn rootworm

Insecticides

South Dakota State University Theses

Format

application/pdf

Number of Pages

34

Publisher

South Dakota State University

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