Title: Inheritance of an extended diapause trait in the Northern corn rootworm, Diabrotica barberi (Coleoptera: Chrysomelidae) Authors
Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 9, 2012
Publication Date: August 24, 2012
Citation: French, B.W., Coates, B.S., Sappington, T.W. 2012. Inheritance of an extended diapause trait in the Northern corn rootworm, Diabrotica barberi (Coleoptera: Chrysomelidae). Journal of Applied Entomology. DOI: 10.1111/j.1439-0418.2012.01751.x. Interpretive Summary: Diapause is an adaptive trait that delays development or reproduction under adverse conditions. The northern corn rootworm (NCR) beetle, an economically important pest of corn, survives harsh winters in the egg stage. A two-year crop rotation of corn and soybean usually prevented damage to corn form NCR however, some NCR populations adapted to this crop rotation by delaying development for two years thus ensuring its favorite food would be available when development ensued. This extended diapause (ED) trait has increased in frequency and geographic distribution since first reported in Illinois in 1932. Our goal was to determine how this trait was inherited. Using reciprocal single pair crosses among laboratory beetles with the one-year egg diapause and two-year egg ED traits showed that this trait was primarily passed on to offspring through by the female and we believe that the maintenance of this trait in nature is related to the prominence of crop rotation.
Technical Abstract: Diapause is an adaptive trait that delays development or reproduction under unfavorable circumstances. The northern corn rootworm, Diabrotica barberi Smith & Lawrence, an important maize, Zea mays L., pest in the Diabroticite species complex, overwinters in diapause during the egg stage. Some NCR populations are adapted to crop rotation by expressing an extended diapause (ED) trait that delays embryonic development for two years. This ED trait has increased in frequency and geographic distribution since first reported in Illinois in 1932. Reciprocal single pair crosses among beetles from a laboratory colony with the ancestral one-year diapause trait and field collected beetles with the two-year ED trait indicated that ED females laid significantly more ED eggs than did females with the one-year diapause trait regardless of male genotype. The ED trait was highly heritable [realized heritability (h2) = 0.698 ± 0.314], with genetic dominance (D) of the trait strongly influenced by female genotype. Selection of the ED trait and maintenance of polymorphic diapause phenotypes within maize-soybean cropping systems is discussed in relation to response to a fluctuating environment and as a potentially advantageous life history adaptation.