Energy Flow and Grazing Behavior of Conocephaline Grasshoppers in a Juncus Roemerianus Marsh

Abstract

At least three species of conocephaline grasshoppers (Tettigoniidae) form the major grazing herbivores on the leaves of the marsh black needlerush Juncus roemerianus Scheele. They ingested 105 kJ/m 2 of the 31.62 MJ/m 2 net annual aboveground production of Juncus. Assimilation of ingested Juncus tissue was 60.7 kJ · m-2 • yr-' and production of new tissue by the grasshoppers was 9.6 kJ · m-2 • yr-1 , which represents 0.03% of the net annual primary production. A secondary effect of grazing was manifested by the premature death of portions of the Juncus leaf distal to the grazed area. Subsequent mechanical breakage resulted in early deposition of broken-off leaf tips into the detrital mat on the marsh. This represented a maximum input into the decomposer trophic level of 246 kJ · m-2 • yr-' prior to the death and deposition of the entire Juncus leaf.The addition of Juncus to the diet of the conocephaline post-nymphal and adult stages is discussed in the light of the hypothesis that C 4 plants are nutritionally inferior to C 3 plants, based on comparisons of amino acid concentrations within different parts of the Juncus leaf and in comparison with Spartina cynosuroides.

Grasshopper (Orthoptera: Tettigoniidae) Species Composition and Size Across Latitude in Atlantic Coast Salt Marshes

“…O. fidicinium appears to be limited to the S. alterniflora zone. Given that O. concinnum was found much more frequently in the Juncus than the Spartina zone, it appears to be a specialist herbivore on J. roemerianus (Parsons and de la Cruz 1980), along with C. aigialus. These two tettigoniid species appear to be transient visitors to the S. alterniflora zone.…”

“…Studies with high-latitude tettigoniid assemblages, likely dominated by C. spartinae, have concluded that they feed mostly on seeds and flowers, and thus, influence plant communities by impacting sexual reproduction more than somatic growth (Bertness et al 1987;Bertness and Shumway 1992). In contrast, studies with low-latitude tettigoniid assemblages, likely dominated by O. fidicinium (Georgia S. alterniflora zone) and O. concinnum (Mississippi J. roemerianus zone), have focused on consumption of leaves (Smalley 1960;Parsons and de la Cruz 1980). These patterns were confirmed in our laboratory feeding assays using southern S. alterniflora and J. roemerianus.…”

“…Although no comparative studies have been conducted across broad geographic regions, ecological studies in New England (Bertness et al 1987;Bertness and Shumway 1992), Georgia (Smalley 1960), and Mississippi (Parsons and de la Cruz 1980) have focused on different tettigoniid grasshopper species (Conocephalus spartinae in New England, Orchelimum fidicinium in Georgia, and O. concinnum in Mississippi), which presumably were the most abundant grasshoppers at each site. Whether this reflects local site-to-site variation in species composition or a broader geographic pattern, however, is unclear.…”

Trophic Relationships of a Marsh Bird Differ Between Gulf Coast Estuaries

“…Additionally, the percent aerial cover of dominant vegetation types within 50 m of each nest site was estimated visually (methods described in Conway 2008). Prey items included gastropods (olive nerite Neretina usnea and marsh periwinkle Littorina irrorata), bivalves (ribbed mussel Geukensia demissa and common rangia Rangia cuneata; Bishop and Hackney 1987;LaSalle and de la Cruz 1985), tettigoniid grasshoppers (Parsons and de la Cruz 1980), blue crab (Callinectes sapidus), and gulf fiddler crab (Uca longisignalis; Mouton and Felder 1996). All materials were placed in individual plastic bags and frozen within several hours of collection.…”

Insect herbivory on an inland brackish wetland

“…Varley (1967) has shown that feeding by tissue-chewing lepidopteran larvae can reduce standing biomass of plants, and Weigert and Pomeroy (1981) speculate that the same is true for salt marsh plants. Other authors (Gallagher and Pfeiffer 1977, Crow and McDonald 1978, Parsons and de la Cruz 1980 have questioned whether significant portions of wetland standing crops are affected by herbivory.…”