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What changed the demography of an introduced population of an herbivorous lady beetle?
Author(s) -
Ohgushi Takayuki,
Sawada Hiroichi
Publication year - 1998
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1046/j.1365-2656.1998.00225.x
Subject(s) - fecundity , population density , coccinellidae , biology , population , predation , natural population growth , ecology , biological dispersal , herbivore , density dependence , population ecology , population size , demography , predator , sociology
1. The population dynamics of an introduced population of Epilachna niponica (Lewis) (Coleoptera: Coccinellidae) was investigated for a 7‐year period following its introduction to a site outside of its natural range. A population from Asiu Experimental Forest was introduced to Kyoto University Botanical Garden, 10 km south of its natural distribution. 2. Arthropod predation was much lower in the introduced than in the source population. As a result of the lower predation in the Botanical Garden, larvae reached densities five times higher than in the Asiu Forest and host plants were frequently defoliated. Food shortage caused larval deaths from starvation and increased dispersal. 3. The density of the introduced population was much more variable than that of the source population. The variation in population density in both the introduced and source populations is limited by density‐dependent reduction in fecundity and female survival. However, variation in the introduced population's density was increased due to host plant defoliation that resulted in overcompensating density‐dependent mortality. In years with high larval density plants were defoliated and this increased adult mortality during the prehibernation period. Besides, the density‐dependent regulatory mechanisms that produce population stability were weaker in the introduced population than in the source population.