Abstract
Females of Psorophora confinnis (Lynch-Arribalzaga) deposit their eggs in a variety of microhabitats that exist in the Texas riceland environment. These microhabitats include ones associated with: (1) rice field and pasture levee slopes and lands; (2) cattle hoofprints in fallow rice fields used as pastures and (3) various types of tire tracks that are made in the soil by equipment during the act of harvesting rice. Moisture content of the soil appears to be one of the more important factors in determining whether or not and to what extent P. confinnis females will use these sites for egg deposition. Soil that is relatively muddy (i.e., 75%-above field capacity) is very attractive to gravid females of this species. Soil moisture conditions on levee slopes, as influenced by fluctuations in the depths of standing water, appear to play an important role in determining the location and dimensions of P. confinnis egg horizons on levee slopes in Texas ricelands. When water levels are relatively stable, the eggs tend to be congregated in rather narrow horizons on muddy soil just above the high water lines on the levee slopes. However, when wide fluctuations in water levels occur, several egg horizons may be located at different elevations on the levees. In general, P. confinnis egg horizons may occur at any point on rice field levee slopes to include ones at the uppermost elevations. In contrast, egg horizons on pasture levee slopes tend to be confined to the lower elevations. Among the other oviposition sites available to P. confinnis populations in Texas ricelands, fresh hoofprints of cattle and combine tire tracks in recently harvested fields appear to be the most important. Results of the studies described herein indicate that the presence of combine tire tracks in recently harvested rice fields, coupled with the movement of cattle into the rice fields after harvest, make this type of field a particularly important source of oviposition sites for fall populations of P. confinnis. Preliminary egg longevity studies indicate that eggs deposited by P. confinnis females in the fall tend to survive quite well under field conditions for at least 7 months; and some can survive up to 15 months. Extended periods of high temperatures and low rainfall, such as occurred in the summer of 1974, appear to drastically affect the survival rate of P. confinnis eggs.
Meek, Chester Lamar (1975). Bionomics of Psorophora confinnis (Lynch-Arribalzaga) in Texas ricelands: oviposition sites and egg longevity. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -183500.