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Characterization of selected life history traits of western corn rootworm, Diabrotica virgifera virgifera, LeConte populations resistant and susceptibile to methyl-parathion

Jenny Stebbing, University of Nebraska - Lincoln

Abstract

Research was conducted to characterize the relative fitness of organophosphate resistant versus susceptible western corn rootworm populations. Tethered flight behavior was similar among resistant and susceptible beetles with the exception that susceptible beetles flew more frequently than resistant beetles. Average fecundity per female was significantly greater in susceptible than resistant populations, but female longevity and egg viability were similar. Net replacement rate was significantly greater in a susceptible population than a resistant population and fecundity appeared to be the key factor affecting net replacement rate. Results of resistant by susceptible reciprocal cross experiments indicate that fecundity and net replacement rate were negatively influenced in a sex-linked fashion by the resistant population. The mean developmental time from neonate larva to adult was similar across parental and reciprocal crosses. ^ After sub-lethal exposure to methyl parathion, resistant beetles exhibited both trivial and sustained flight behaviors, however, mean total flight time, mean total trivial flight time, and mean number of flights per beetle significantly declined. Resistant females maintained fecundity at a similar level in insecticide and insecticide-free environments; however, age and reproductive state at the time of insecticidal exposure significantly affected reproductive potential. ^ Data collectively indicate that in the absence of insecticide, the relative fitness of susceptible beetles is greater than that of resistant beetles. In spite of this, fitness costs incurred when western corn rootworms are resistant to organophosphate insecticides do not appear to be severe enough to prevent movement, colonization, and reproduction to occur at levels that enable population densities to be maintained in either insecticide or insecticide-free environments. Data from this study complement what is known about the mechanisms and inheritance of resistance which increases our general understanding of the evolution and geographic spread of resistance in Nebraska. ^

Subject Area

Agriculture, Agronomy|Biology, Entomology

Recommended Citation

Stebbing, Jenny, "Characterization of selected life history traits of western corn rootworm, Diabrotica virgifera virgifera, LeConte populations resistant and susceptibile to methyl-parathion" (2003). ETD collection for University of Nebraska - Lincoln. AAI3117808.
http://digitalcommons.unl.edu/dissertations/AAI3117808

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