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Alternatives to key factor analyses for assessing the population dynamics of Hypera postica (Coleoptera: Curculionidae)
Author(s) -
Zahiri Babak,
Fathipour Yaghoub,
Khanjani Mohammad,
Moharramipour Saeid,
Zalucki Myron Philip
Publication year - 2014
Publication title -
population ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 59
eISSN - 1438-390X
pISSN - 1438-3896
DOI - 10.1007/s10144-013-0402-5
Subject(s) - hypera postica , weevil , biology , curculionidae , population , population dynamics , larva , population density , key (lock) , toxicology , ecology , botany , zoology , demography , fecundity , sociology
Abstract Key factors are those causes that are most responsible for the observed changes in population density between generations. Stage‐frequency of alfalfa weevil was modeled using Manly‐1997 model. Multiple decrement life table parameters from an 8 year‐field study were analyzed using traditional and λ contribution methods. In traditional method, the key factor was determined as k LII , the death of period‐two larvae from all mortality factors, whereas in λ contribution method, the key factor was determined as b 2&3 , oviposition rate of females per square meter. These differences result directly from the sensitivity of the population growth rate, λ , to variation of both k and b in various stages of the weevil. Among all mortality factors, only k LI‐Z , the death of period‐one larvae from the entomopathogenic fungus, Zoophthora phytonomi (Arthur) Batko (Zygomycetes: Entomophthoraceae), k LII and k LII‐Z , the death of period‐two larvae from Z. phytonomi , acted in a density dependent fashion. Remaining factors were independent of population densities affected. Using λ contribution method, life table approach still remains a major way of studying the dynamics of field populations for applied ecologists and population managers.