Proceedings of the Third International Conference on Invasive ...

Chapter 4: Spartina Control and Management<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaTable 1: Vacuum Survey Results: Number <strong>of</strong> salt marshes, <strong>of</strong> 13 sampled,inhabited by known Spartina herbivores by zone. Feeding Guilds: (LC)Leaf-chewer; (SS) Sap-sucker; (SB) Stem-borer.SpeciesFeedingGuildLowMarshZoneHighMarshOrchelimum spp. LC 2 5Prokelisia dolus SS 3 13Prokelisia marginata SS 10 10Trigonotylus uhleri SS 11 10Chaetopsis aenea SB 11 11Chaetopsis apicalis SB 12 10sampled once from mid July to late September using aHomelite ® gas-powered leaf blower/vacuum with a finemesh net fitted inside <strong>the</strong> intake tube. Samples were taken bywalking along transects (approximately 30 meters (m) atboth low and high marsh elevations) and sweeping <strong>the</strong>vacuum over S. alterniflora plants from base to tip. Sampleswere frozen prior to being sorted. Specimens <strong>of</strong> interest were<strong>the</strong>n mounted and identified.At a subset <strong>of</strong> five marshes, <strong>the</strong> frequency <strong>of</strong> damagedue to specific species or feeding guild was measured. Thetotal number <strong>of</strong> stems in a square meter quadrat was countedinitially. Fifty stems chosen at random were harvested aswell as every stem showing apical leaf damage. Fourreplicates were sampled at each site. Stem height anddiameter were recorded before <strong>the</strong> stem was scored forexternal feeding damage and <strong>the</strong>n dissected for stem-boringlarvae. Data were analyzed using Micros<strong>of</strong>t Excel andAnalyse-it ® supplementary s<strong>of</strong>tware.RESULTSSpecimens collected in vacuum samples representedfour genera <strong>of</strong> Spartina herbivores in three feeding guilds(Table 1; Fig. 2). Of <strong>the</strong> three guilds, sap-sucking and stemboringspecies were collected at all but a few sites, while <strong>the</strong>sole leaf-chewing genus, Orchelimum Serville (Orthoptera:Tettigoniidae), was recovered rarely. Prokelisia dolusWilson was also anomalous in that it was found much morefrequently at high marsh than at low marsh. Additionalspecies observed during stem dissections were not recoveredat all in vacuum samples.Harvested stem analysis revealed disparities in <strong>the</strong>infestation rates across species or feeding guild (Fig. 3).Number <strong>of</strong> Species8765432Leaf-chewerStem-borerSap-sucker10FoglandEmilie RueckerTouissetNagPondMarsh MeadowsSheffield CoveFox HillRome PointNarrow RiverGalileeSuccotashWest BeachLathropFig. 2: Composition <strong>of</strong> Spartina alterniflora herbivore feeding guilds based on vacuum samples collected at thirteen marshes.- 274 -