Factor from Swamp Water Induces Hatching in Eggs ofAnopheles diluvialis(Diptera: Culicidae) Mosquitoes

Abstract

Anopheles quadrimaculatus Say, An. smaragdinus Reinert, and An. diluvialis Reinert mosquitoes are recently described sibling species that occur in northern Florida where the adults are sympatric but larvae develop in different aquatic habitats. The hatching dynamics of these species showed that An. diluvialis utilizes a hatching stimulus that occurs in the substrate in intermittently flooded swamps. Most eggs of An. quadrimaculatus and An. smaragdinus hatch spontaneously in distilled water, but most eggs of An. diluvialis do not. Most An. diluvialis eggs hatch when placed in swamp water or when placed in an infusion of distilled water, leaf litter, and detritus from intermittently flooded swamps, suggesting the presence of an exogenous compound(s) as a hatching factor for this species. Percentage of egg hatch was largest in infusions made from swamp soil and in hexane extracts of swamp water, indicating that the hatching factor is a chemically stable organic substance. Because this phenomenon was not observed with water from lakes, ponds, springs, spring outlet streams, and rivers, An. diluvialis appears to require the hatching factor to facilitate egg hatch when intermittently flooded swamps are inundated. This article reports an exogenous compound being exploited as a hatching stimulus by an Anopheles mosquito.