Population Dynamics of the Australian Plague Locust, Chortoicetes Terminifera (Walker) in Central Western New South Wales. Ii. Factors Influencing Natality and Survival.

Abstract

Unrealized natality and mortalities at successive development stages were measured during synchronized breeding by populations of the Australian plague locust. Studies were made over a 3-y period, covering nine generations, on small plots situated in pastures derived originally from savannah woodland in central western New South Wales. Variations in natality and mortalities were influenced more by variation in soil moisture, primarily through its effect on pasture conditions, than by the effects of natural enemies; these variations were closely correlated with seasonal rainfall. Unidentified losses, independent of known variables, were recorded in the hopper stage and were highest in the hatchling. Such losses invariably exceeded 60% even under the most favourable conditions encountered in the field during the study period. The quantitative relationships established in this study between the plague locust and its natural enemies and other environmental factors suggest that prospects for the biological control of this pest by either native or introduced species are poor.