RESUMO
Phlebotomus papatasi Scopoli is a medically important insect that has been successfully colonized in the laboratory, and blood feeding is critical for colony propagation. There has been much interest in developing established protocols for in vitro blood-feeding systems. The objective of this study was to determine if a Parafilm membrane and a hog's gut membrane could be successfully used with in vitro feeding systems. We evaluated percentages of P. papatasi females that blood fed on different blood-feeding systems (a mouse, a Hemotek feeder, or a glass feeder) used with either a Parafilm or a hog's gut membrane, with cohorts of 250 and 500 P. papatasi females, and with or without external exhalations. For all feeding system combinations, female P. papatasi blood fed in higher percentages when in cohorts of 500 individuals and in the presence of exhalations. Higher percentages of P. papatasi fed on a mouse, but this study also demonstrates that P. papatasi will readily feed with in vitro feeding systems using a Parafilm membrane or a hog's gut membrane. This study suggests that female P. papatasi may use an invitation effect to blood feed and are attracted to blood sources via chemical olfaction cues, both of which have been characterized in other blood-feeding arthropods. Our study demonstrates that a Parafilm membrane or a hog's gut membrane, in conjunction with the Hemotek or glass feeder system, is potentially a viable alternative to live rodents to blood feed a colony of P. papatasi.
RESUMO
Ecological zonation of salt marsh macrophytes is strongly influenced by hydrologic factors, but these factors are poorly understood. We examined groundwater flow patterns through surficial sediments in two saltmarshes in the southeastern United States to quantify hydrologic differences between distinct ecological zones. Both sites included tall- or medium-form Spartina alterniflora near the creek bank; short-form Spartina alterniflora in the mid-marsh; salt flats and Salicornia virginica in the high marsh; and Juncus roemarianus in brackish-to-fresh areas adjacent to uplands. Both sites had relatively small, sandy uplands and similar stratigraphy consisting of marsh muds overlying a deeper sand layer. We found significant hydrologic differences between the four ecological zones. In the zones colonized by S. alterniflora, the vertical flow direction oscillated with semi-diurnal tides. Net flow (14-day average) through the tall S. alterniflora zones was downward, whereas the short S. alterniflora zones included significant periods of net upward groundwater flow. An examination of tidal efficiency at these sites suggested that the net flow patterns rather than tidal damping controlled the width of the tall S. alterniflora zone. In contrast to the S. alterniflora zones, hypersaline zones populated by S. virginica were characterized by sustained periods (days) of continuous upward flow of saline water during neap tides. The fresher zone populated by J. roemarianus showed physical flow patterns that were similar to the hypersaline zones, but the upwelling porewaters were fresh rather than saline. These flow patterns were influenced by the hydrogeologic framework of the marshes, particularly differences in hydraulic head between the upland water table and the tidal creeks. We observed increases in hydraulic head of approximately 40 cm from the creek to the upland in the sand layers below both marshes, which is consistent with previous observations that sandy aquifers below fine-grained marsh soils act as conduits for flow from uplands to tidal creeks. This hydrologic framework supports relatively good drainage near the creek, increased waterlogging in the mid-marsh, and the development of hypersalinity adjacent to the freshwater upland. These hydrologic differences in turn support distinct ecological zones.
