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Population density, phenotype and mortality in the grasshopper Chorthippus brunneus
Author(s) -
WALL RICHARD,
BEGON MICHAEL
Publication year - 1986
Publication title -
ecological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.865
H-Index - 81
eISSN - 1365-2311
pISSN - 0307-6946
DOI - 10.1111/j.1365-2311.1986.tb00323.x
Subject(s) - biology , nymph , grasshopper , instar , population density , range (aeronautics) , mortality rate , population , density dependence , zoology , ecology , demography , larva , materials science , sociology , composite material
ABSTRACT.1 The patterns of mortality in laboratory populations of the grasshopper Chorthippus brunneus Thunberg are examined at a range of densities and at different stages of nymphal development with particular reference to the phenotypes of nymphs that die or survive. 2 Total mortality during nymphal development rises from density‐independence at the lowest densities to approximately compensating density‐dependence at the highest densities. 3 The greatest proportion of total mortality occurs in the first two instars. The stage broadly covering the second instar is the ‘key‐stage’ determining adult density. The mortality during these stages is largely density‐independent. There is relatively little mortality during stages broadly covering the final instar, but it is density‐dependent and also plays a significant part in determining final adult density. 4 As the mortality becomes more density‐dependent, either with density itself or with cohort age, the smallest individuals become increasingly disproportionately prone to mortality. 5 Males, which are smaller, are more susceptible to mortality than females, but their susceptibility relative to their size is less than that of females.