Observations and Experiments on Aëdes concolor, Tayl. (Dipt. Culic.)

Abstract

The mosquitos of the Australian region have been extensively studied from the taxonomic aspect, and a number of workers, including Taylor (1914, 1928, 1929, etc.) Mackerras (1926), Cooling (1924), and Hill (1922), have recorded in general terms the types of water in which the larvae of various species are found. With the exception of the work carried out by Hamlyn-Harris (1927–28–30–33), however, no detailed studies have been made of the possible chemical, physical, or biological factors which may limit particular species of larvae to the special type of water in which they develop.The most important pest species in the Sydney district are probably Culex fatigans, Wied., Aëdes (Ochlerotatus) vigilax, Skuse, Aëdes (Finlaya) notoscriptus, Skuse, Aëdes (Mucidus) alternans, Westw., Aëdes (Finlaya) alboannulatus, Macq., and in restricted localities Aëdes (Pseudoskusea) concolor, Taylor. Of these A. vigilax, A. alternans and A. concolor breed commonly in various concentrations of sea-water. A. concolor was selected for study owing to its strict limitation to a particular habitat, in the hope that some information might be gained as to the factors responsible for this limitation. In addition nothing has so far been published on the bionomics of this species, which is a particularly interesting one from the ecological and physiological aspects. A discussion of the general position with regard to mosquito ecology is hardly necessary here, since numerous authors have given excellent summaries and bibliographies up to the time of publication of their work, and original papers are appearing at frequent intervals. The majority of the work on mosquito ecology, with certain notable exceptions, has so far been carried out by means of water analysis (both chemical and biological) and field observations, correlated with the occurrence of different species of larvae. While it is recognised that any ecological generalisations, if they are to be accepted, must agree with the observed conditions in the field, nevertheless laboratory experiments, in which a single factor only is varied, should yield considerable information. It is mainly along these lines that the present investigation has been commenced. While the information so far obtained as to the factors limiting the occurrence of A. concolor has been largely negative, still it is hoped that the data obtained are of sufficient general interest to warrant publication. The work will be continued if possible over a number of years.