AUTOGENOUS EGG PRODUCTION IN THE SALT-MARSH MOSQUITO, AEDES TAENIORHYNCHUS

¹ Florida Medical Entomology Laboratory, P. O. Box 520, Vero Beach, Florida 32960

1. A total of 17 populations of Aedes taeniorhynchus were examined for the occurrence of autogeny. Every population contained some autogenous as well as some anautogenous females. In general, populations from the tropics and subtropics had higher rates of autogeny than did temperate zone populations. A major exception to this pattern was a Panama strain where less than 1% of the females were autogenous.

2. Autogenous and anautogenous females occurred in the same reproductive populations. The progeny derived from individual, wild-caught females often contained both reproductive types.

3. The mean fecundity was often less than 30 eggs per autogenous female in those populations where the occurrence of autogeny was rare or infrequent. In contrast, significantly higher levels of fecundity were associated with all populations that contained mostly autogenous females. Geographical variation in autogenous fecundity appears to be regulated by polygenic factors.

4. We compared the blood-feeding characteristics and requirements of two mosquito populations in southern Florida. At Flamingo, Florida, only 8.1% of the females collected with power aspirators were engorged, whereas at Big Pine Key, Florida the engorgement rate was 20.9%. Approximately 80% of all females from the Flamingo collections were at a stage where they could be considered "blood-thirsty" mosquitoes. In contrast, only about 60% of the Big Pine Key females were in this category. Both the frequency and the fecundity of autogenous females were significantly greater at Flamingo.

5. The higher engorgement rate for the Big Pine Key population when compared to the Flamingo population can be readily attributed to the differences in the availability of a single host species, the Key deer.

6. Our findings support the hypothesis that autogenous females are abundant in some populations of A. taeniorhynchus because hosts are either unavailable or available on a very limited basis.