Use of degree-days to time aerial spraying in west-central Colorado.

Seasonal fluctuations in Culex and Aedes were followed from 1984 to 1987 using degree-days (degree Days). The annual population maxima of a "mosquito season" can be predicted. Culex first becomes a problem at about 1,550 degree Days and disappears at 2,675 degree Days. Aedes are present at 525 degree Days, experience a midsummer decline at 900 degree Days, then resurge at 2,400 degree Days to mostly disappear at 2,700 degree Days. This timing appears to work in the arid western valley of Grand Junction, Colorado, due to the dependence by the mosquito on breeding sites related to local irrigation systems, which are dry in the winter and rehydrated at the same time each year.

Occurrence of Cryptosporidium in home daycare centers in west-central Colorado.

Thirty white middle-class 5 yr olds from home daycare centers were examined for Cryptosporidium. Five fecal samples were collected from each child, over a 3-wk period, concentrated by sedimentation, and stained by a modified acid-fast technique. Nine children were positive (30%), 6 of these were asymptomatic (5 of these were under 2 yr old). Two girls and 1 boy, under 2 yr old, had mild diarrhea within 3 wk prior to fecal collection.

Effect of Temperature on the Development of Thelastoma bulhoesi (Oxyurata, Thelastomatida) and Other Nematodes.

Embryonation of Thelastoma bulhoesi was monitored at eight temperatures between 0 and 35 C. Cell division did not occur below 15 C or at 35 C. Development was most rapid at 25 and 36 C. The effect of temperature on the rate of embryological development of T. bulhoesi at different stages was measured using the temperature coefficient, Q. The developmental temperature response curve obtained for T. bulhoesi was similar to enzyme temperature response curves. Our evidence supports the thesis that nematode embryonation, as affected by temperature, varies between species and between stages of development.

Development of Thelastoma bulhoesi (Oxyurata: Thelastomatida) and the Effect of Thiabendazole on the Unembryonated Egg.

The embryological and postembryological development of Thelastoma bulhoesi was determined. Initial cleavage was into unequal cells and occurred within 1-2 hours at 25 C. Cell division was holoblastic but no true morula is formed. Gastrulation occurred at approximately 48 hours by epibolic synectic mechanisms. First-stage larvae were fully developed at 96 hours. The molt to second-stage larvae was initiated in the egg and was completed at hatching. Second-stage larvae were first observed in the host at 11 hours postinfection, third-stage larvae at 18 hours, and fourth-stage larvae at 192 hours. Adult female worms were observed at 32 days. Thiabendazole, in even the lowest concentrations, inhibited the developmem of unembryonated ova.