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Movement, colonization, and establishment success of a planthopper of prairie potholes, Delphacodes scolochloa (Hemiptera: Delphacidae)

Authors


James T. Cronin, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, U.S.A. E-mail: jcronin@lsu.edu

Abstract

Abstract 1. Movement, and particularly the colonisation of new habitat patches, remains one of the least known aspects of the life history and ecology of the vast majority of species. Here, a series of experiments was conducted to rectify this problem with Delphacodes scolochloa Cronin & Wilson, a wing-dimorphic planthopper of the North American Great Plains.

2. The movement of brachypterous and macropterous planthoppers within and among host-plant patches was quantified. Also, an experiment was conducted to assess whether planthopper propagule size (i.e. number of colonists) influenced the presence of planthopper adults or eggs over time, planthopper population growth rate (R0), and abundance or impact of an egg parasitoid.

3. Delphacodes scolochloa movement was well described by a simple diffusion model. As expected, brachypters were less dispersive than macropters – mean displacement distances among patches were three times greater for macropters (2.8 m vs. 8.1 m per day).

4. Number of colonists of vacant patches increased with increasing patch size (both wing forms) and decreased with increasing isolation (brachypters only). At the scale of individual potholes (<38 m), brachypters were dispersal limited.

5. Establishment success was strongly influenced by propagule size. An Allee effect constrained the establishment of new populations, but low establishment success was not a result of mate limitations or the presence of natural enemies (i.e. egg parasitoids).6. These movement data reveal important insights regarding the spatial population structure and spread of D. scolochloa.

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