Monday, December 11, 2006 - 9:23 AM

Fitness of Diabrotica barberi Smith and Lawrence x Diabrotica longicornis (Say) hybrids (Coleoptera: Chrysomelidae)

Laura A. Campbell, and Lance J. Meinke, University of Nebraska, Department of Entomology, 202 Plant Industry, Lincoln, NE

Diabrotica barberi Smith and Lawrence and Diabrotica longicornis (Say) (Coleoptera: Chrysomelidae) are sister species. D. barberi, the northern corn rootworm, is an important pest of corn in the U.S. Corn Belt; its range includes the entire Corn Belt and extends into the northeastern U.S. and Canada. D. longicornis is a nonpest species that occurs in grassland habitats in the southwestern U.S. The speciesí ranges overlap in eastern and central Nebraska and Kansas, and observational data suggest that some habitat overlap occurs as well. Hybrids have been created under lab conditions in previous studies, and hybridization between the two species may occur under field conditions, but fitness of hybrids is unknown. This study focuses on viability and fertility of hybrids. Eggs were obtained from parental crosses (hybrids) and parental lines in 2005; eggs were hatched in 2006, and various life history traits, which may contribute to overall fitness, were measured. Percentage egg hatch, total development time (neonate larva to adult emergence), and larval survival for each cross were recorded. Adult sex ratio, longevity, and fecundity were also documented. Female D. barberi x male D. longicornis crosses produced no viable offspring, but the reciprocal cross was viable. Hybrid adults were mated to other hybrid individuals or backcrossed to parental individuals. The life history traits characterized in this study were comparable between female D. longicornis x D. barberi hybrids and parental species. This suggests that hybrid individuals, if produced in the field, may have no significant fitness disadvantage when compared to the parent species.

Species 1: Coleoptera Chrysomelidae Diabrotica barberi (northern corn rootworm)
Species 2: Coleoptera Chrysomelidae Diabrotica longicornis

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