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Sex‐ratio bias in an aphid parasitoid‐hyperparasitoid association: a test of two hypotheses
Author(s) -
MACKAUER M.,
LARDNER R. M.
Publication year - 1995
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.1365-2311.1995.tb00437.x
Subject(s) - parasitoid , biology , aphid , sex ratio , offspring , host (biology) , zoology , pupa , instar , ecology , toxicology , botany , larva , demography , population , pregnancy , genetics , sociology
.1 We tested the hypothesis that biased sex ratios in the aphidiid parasitoid, Aphidius ervi , are the result of sex‐specific mortality of immatures due to hyperparasitism. The solitary hyperparasitoid, Dendrocerus carpenteri , deposits its eggs on the prepupa or pupa of the primary parasitoid after its pea‐aphid host is mummified. 2 In dichotomous choice tests, females of D.carpenteri accepted immatures of both sexes of A.ervi with equal frequency. Independent of the sex of the primary parasitoid, the probability of a mummified pea aphid being hyperparasitized did not differ between large (adult at the time of death) and small (fourth nymphal instar) mummies. 3 As predicted by‘host quality’models of offspring sex allocation, D.carpenteri produced a higher proportion of female than male offspring in large mummies. These laboratory results were supported by field data. 4 Because hyperparasitism by D.carpenteri is random with regard to host sex, it should have no influence on optimal sex allocation by the primary parasitoid.