title: Resistance to the birch leafminer Fenusa pusilla (Hymenoptera: Tenthredinidae) within the genus Betula.
abstract: Thirteen Betula species were tested for resistance to the birch leafminer, Femusa pusilla (Lepeletier), using no-choice assays. Birch leafminers were able to oviposit into expanding leaves of all Betula individuals tested. Larvae did not survive within any of the tested individuals of three species, B. alleghaniensis (Britt.), B. grossa (S. & Z.), and B. lenta (L.). Leafminer eggs deposited into the leaves of these species hatched, and larvae fed for a short period before dying. These three species were classified as highly resistant to birch leafminer, based on very low percent of mines (0.6-3.1%) with a diameter >3 mm. Eight species, B. papyrifera (Marsh), B. pendula (Roth), B. turkestanica (Litvin), B. glandulifira (Regal), B. ermanii (Cham.), B. platyphylla variety japonica [(Miq.) Hara], B. populifolia (Marsh) and B. maximowicziana (Regal) were classified as susceptible, with percent of mines >3 mm diameter of 87-94%. Two species, B. costata (Trautv.) and B. davurica (Pall.), displayed intermediate and variable resistance. B. davurica exhibited a mechanism of resistance not observed in the other species, Eggs oviposited into the leaves of resistant B. davurica individuals became surrounded by an area of discolored and necrotic tissue, and died. This response resembles the programmed cell death associated with a hypersensitive response.
authors.affiliation: Department of Horticulture, University of Wisconsin-Madison, 53706, USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Hoch
authors.forename: E L
authors.initials: EL
authors.lastname: Zeldin
authors.forename: B H
authors.initials: BH
authors.lastname: McCown
mesh_terms: D000818:Animals; D005260:Female; D006927:Hymenoptera; D007814:Larva / Q000502:physiology; D010058:Oviposition; D010935:Plant Diseases; D018515:Plant Leaves; D013045:Species Specificity; D014197:Trees