INFLUENCE OF CORN PLANTING DATE ON THE SURVIVAL AND ON SOME REPRODUCTIVE PARAMETERS OF DIABROTICA-VIRGIFERA-VIRGIFERA (COLEOPTERA, CHRYSOMELIDAE)

The effects of three different planting dates of corn and three times of infestation on the survival and subsequent fecundity, egg viability, and longevity of Diabrotica virgifera virgifera LeConte were examined under field conditions in eastern South Dakota. Earlier planting and infesting dates resulted in greater survival of adults. Male-female survivorship was affected by the treatments because only the second infestation date, despite planting date, produced a 1:1 male/female sex ratio. When corn was planted and infested at the same time on the first or third date, the sex ratios were 1:1.5 and 2:1, respectively. Female longevity was significantly affected by the latest corn planting and infestation treatment. The various treatments had little effect on fecundity of individual adults derived from the treatment plots or on the viability of their eggs.