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Time‐specific life tables for the pea aphid, Acyrthosiphon pisum ( Harris ), on alfalfa
Author(s) -
Hutchison William D.,
Hogg David B.
Publication year - 1985
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/bf02515463
Subject(s) - acyrthosiphon pisum , biology , aphididae , aphid , population dynamics , homoptera , population , pisum , coccinellidae , predation , fecundity , botany , predator , pest analysis , agronomy , ecology , demography , sociology
Summary Time‐specific life tables were constructed for three pea aphid, Acyrthosiphon pisum ( Harris ) (Homoptera: Aphididae), populations using a modification of Hughes' analytical procedure. All populations were studied on second‐growth alfalfa (mid‐June to mid‐July) in south central Wisconsin; data for two populations were collected during 1980, and data for the third population were collected during 1982. The intrinsic rate of increase ( r m ) estimated on a physiological time (day‐degree) scale under field conditions but in the absence of natural enemies, provided a reliable estimate of potential population growth rate and was used in preference to Hughes' approach of estimating potential population growth rates directly from stage structure data. Emigration by adult alatae and fungal disease were the major sources of A. pisum mortality in each of the three populations studied. These factors were most important because of their impact on reducing birth rates within the local population. Parasitism was never greater than 9 percent. Mortality attributable to predation ranged from 0.0 to about 30.0%; however, even at the highest predator densities A. pisum populations increased exponentially.