The fruittree leafroller, Archips argyrospila (Walker), has recently reached out-break densities on a newly recorded host plant, baldcypress, Taxodium distichum (L.) Richard. We conducted a genetic analysis of the cypress population and one feeding on oaks in Louisiana. To obtain a geographic perspective on differentiation within the fruittree leafroller, we compared the Louisiana cypress population with a California oak population genetically and conducted cross-rearing studies on oak and cypress. A citrus population from California was also included for a host-associated perspective. Genetic data suggest the existence of three distinct taxa. One taxon feeds on oaks and citrus in California, one feeds on oaks in Louisiana, and a third feeds on baldcypress in Louisiana. Developmental cross-rearing studies indicate the cypress population is virtually unable to survive on Louisiana oaks, further supporting the existence of host-associated differentiation. Pheromone attraction studies conducted in Louisiana forests with California citrus and Louisiana cypress virgin females indicate California citrus females are not attractive to male fruittree leafrollers in cypress swamps. Differences in pheromonal response suggest evolutionary divergence in mating behavior on a geographic scale. Further studies are required to determine the degree of reproductive isolation between host associated and geographic populations, but genetic, developmental, and pheromonal studies suggest sibling species or host races, or both, exist.
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Goyer et al. (1995) studied this question.