Observations on the seasonal incidence and diel oviposition periodicity of Haemagogus mosquitoes (Diptera culicidae) in Trinidad, W. I. II. Heamagogus equinus Theobald

Diel patterns of oviposition of sylvan Haemagogus equinus in the field in Trinidad, West Indies, were monitored weekly for 53 consecutive weeks using standard ovitraps. During the wet season (September to November 1981 and May to September 1982) a large well-defined unimodal peak (comprising 97 percent of all eggs laid and 89 percent of occurrences) occurred at 12.00-14.00 hours, four to six hours before sunset. During the dry season (December 1981 to May 1982), two small less-well-defined peaks occurred at 10.00-12.00 and 14.00-16.00 hours (comprising 4.9 percent of eggs laid and 14 percent of occurrences). A diurnal oviposition pattern was observed when the wet and dry season data were combined. The number of eggs and occurrences found during the wet season was significantly higher (P greater than 0.001) than that observed during the dry season. (AU)

Incidence and diel pattern of oviposition outdoors of the mosquito Aedes aegypti (L.) (Diptera: Culicidae) in Trinidad W. I. in relation to solar aspect

The incidence and diel patterns of oviposition of domestic Aedes aegypti in Trinidad, West Indies during the middle of the wet season (July and August) was compared, using modified ovitraps, in unshaded peridomestic outdoor sites facing east or west. Sites close to each other along a transect differed greatly in the total eggs they received, 18.2 percent of sites receiving 50.6 percent of the eggs. Sites receiving most eggs were close to other breeding sites. The incidence of oviposition in sites facing west, as measured by the number of eggs laid (>59 percent) and by the number of occurrences of eggs (>57 percent), was greater than in sites facing east. The diel pattern of oviposition was closely similar in sites facing east and west, indicating that the sun's azimuth at the moment of oviposition does not determine whether a female lays in sites facing east or west. The diel pattern of oviposition resembled an earlier study in being bimodal but differed from it in featuring a much larger morning peak (comprising more than 34 percent of eggs laid v. about 5 percent in the earlier study). This bimodal pattern closely resembles, the diel periodicity of landing on humans described previously by several authors and is probably close to the typical oviposition pattern for Ae. aegypti; an artefact may have modified the oviposition periodicity characterized earlier. In the evening significantly more eggs were laid facing east. These findings have implications for effective placement of ovitraps for surveillance or suppression of Ae. aegypti, and give rise to an hypothesis which invokes responses to microclimate to account for the form of the bimodal oviposition pattern (AU)

Diel patterns of oviposition indoors of the mosquito, Aedes aegypti L. Diptera: Culicidae in Trinidad, W. I.: a preliminary study

Diel patterns of oviposition of domestic Aedes aegypti were monitored early in the dry season in two situations indoors in Trinidad, West Indies. In kitchens, a large, well defined peak of oviposition (comprising more than 56 percent of eggs laid) occurred two to four hours before sunset and a smaller peak (about 16 percent of eggs laid)occurred within the two hours ater sunrise. In living rooms, the afternoon peak was better defined and larger (more than 86 percent of eggs laid) and occurred later, within the two hours before sunset; the morning peak coincided with its counterpart in kitchens but was much smaller (less than 2 percent of eggs laid); some oviposition (about 8 percent) occurred at night but only during the two hours after sunset. Peaks of oviposition corresponded with times of greater human presence or activity in the two kinds of room. Similarities and differences between these patterns and those of oviposition outdoors and of landing indoors are discussed in the context of possible determinants of oviposition behaviour.(AU)

Vitamin-D deficiency rickets in Jamaican children

Vitamin-D deficiency is not as rare in Jamaica as previously believed. 9 children with vitamin-D deficiency rickets have been seen at the University Hospital of the West Indies during the past 5 years. All were over 3 years of age at time of presentation. Both dietary deficiency of vitamin-D and lack of exposure to sunlight seem to be important causes. Children living in rural Jamaica seem to be more susceptible to the disease than those living in a city, due perhaps to more prolonged breast feeding and lack of fortified milk feeds on weaning.(AU)

Alkaline phosphatase in normal infants

Alkaline phosphatase was measured in plasma from children receiving vitamin D supplements in day nurseries in the London area, and from children exposed to sunlight in the West Indies. The distribution of values showed that there was no precise upper limit which could be used in the diagnosis of subclinical vitamin D deficiency. (AU)

Rickets in Jamaica

Florid rickets occuring in twins in Jamaica is described. Reasons are given for considering the rickets to be" simple". Although the patients were grossly malnourished, the most important causative factor is thought to be lack of sunlight. (AU)