Eggshells as an index of aedine mosquito production. 1: Distribution, movement and sampling of Aedes taeniorhynchus eggshells.

The distribution of Aedes taeniorhynchus eggshells in Florida mangrove basin forests was determined and used to design a sampling plan. Eggshells were found in 10/11 sites (91%), with a mean +/- SE density of 1.45 +/- 0.75/cc; density did not change significantly year to year. Highest densities were located on the sloping banks of hummocks, ponds and potholes. Eggshells were less clumped in distribution than eggs and larvae and thus required a smaller sample size for a given precision level. While eggshells were flushed from compact soil that was subject to runoff during heavy rain, mangrove peat, the dominant soil of eggshell-bearing sites, was less dense and had little runoff or eggshell flushing. We suggest that eggshell surveys could be used to identify Ae. taeniorhynchus oviposition sites and oviposition patterns.

Eggshells as an index of aedine mosquito production. 2: Relationship of Aedes taeniorhynchus eggshell density to larval production.

To test if eggshell density could be used as an index of aedine mosquito production, we compared eggshell density with the larval production of Aedes taeniorhynchus in Florida mangrove basin forests. Quantitative (n = 7) and categorical (n = 34) estimates of annual larval production were regressed against the number of eggshells per cc of soil. Significant regressions were obtained in both instances. Larval production was concentrated in zones with the highest eggshell density. We suggest that eggshell density and distribution can be used to identify oviposition sites and the sequence of larval appearance.

Collection and separation of Aedes taeniorhynchus eggshells from mangrove soil.

Two methods to separate eggshells of Aedes taeniorhynchus from mangrove soil were compared. Selective sieving, using nested sieves with 0.185 and 0.170-mm screen openings, and water flotation both removed over 99% of the soil. However, water flotation recovered a significantly greater percentage of eggshells (62% vs. 34%). There was no significant difference in the recovery rate of viable eggs and new and old eggshells using water flotation.