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Overdispersion of Allothrombium pulvinum larvae (Acari: Trombidiidae) parasitic on Aphis gossypii (Homoptera: Aphididae) in cotton fields
Author(s) -
ZHANG Z.Q.,
CHEN P.R.,
WANG K.,
WANG X.Y.
Publication year - 1993
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.1365-2311.1993.tb01114.x
Subject(s) - biology , aphididae , aphis gossypii , aphid , alate , host (biology) , pest analysis , homoptera , acari , aphis , mite , entomophthorales , botany , zoology , ecology , biological pest control
.1 Dispersion patterns of the protelean parasite, Allothrombium pulvinum Ewing, among individuals of an aphid host, Aphis gossypii Glover, were examined during spring 1991 in several cotton fields in Jiangsu Province, China. 2 The variance‐to‐mean ratios (i.e. dispersion index) of larval mites per host were greater than 1, indicating that the mite parasites were overdispersed among aphid hosts. The variance increased with the mean according to the power law, variance = 1.51 mean 106 , which explained 99.7% of the variation in the data. 3 The negative binomial distribution adequately describes the patterns of larval mite dispersion among aphid hosts in eight out of ten populations. The degree of clumping (1/ k ) decreased curvilinearly with parasite density (mites per host). 4 Mites were more clumped among adult aphids than among immature ones. 5 Ecological and evolutionary consequences of mite overdispersion within host populations are discussed. The role of Allothrombium in pest control is also discussed.