Erratic hatching in aedes eggs: a new interpretation

Publisher Website
Google Scholar
Abstract
Erratic hatching of eggs in A. aegypti (and other aedine mosquitoes) has long been something of an enigma, although the temporal scatter it provides, when coupled with drought resistance, is advantageous to species utilizing small, temporary breeding places. Eggs of Aedes hatch when the amount of dissolved O2 (PO2) in the surrounding water is lowered, as when the medium becomes contaminated with bacteria. But erratic hatching in small installments may occur in the absence of any obvious stimulus. This problem was re-examined postulating that the eggs themselves harbor microbial colonies and that these, by lowering the PO2 in the microenvironment of each egg, quantitatively influence hatching. The eggs are sterile when laid, but each acquires surface colonies of bacteria which they pick up from the environment. Rearing each egg in isolation showed that the number of bacteria acquired in a given time differs markedly from egg to egg and, as predicted, those with the highest counts hatched first. Under natural conditions, with eggs of different ages massed together, the 1st larvae to hatch browsed over the surfaces of the remaining eggs, presumably consuming the bacteria and thus lowering the likelihood of further hatching. In this simple fashion, and not, it seems, by means of some hypothetical pheromone (as previously suggested), the 1st eggs to hatch influence the prospects of the other eggs, ensuring that a proportion of them remain unhatched, thus serving as a reserve for the future.