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Photoperiodic determination of gynoparae and males of damson‐hop aphid Phorodon humuli
Author(s) -
Campbell Colin A. M.,
Tregidga Emma L.
Publication year - 2005
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1111/j.1365-3032.2005.00447.x
Subject(s) - biology , offspring , parthenogenesis , aphid , hop (telecommunications) , embryo , andrology , botany , pregnancy , genetics , computer network , medicine , computer science
. Sexual morph production in Phorodon humuli is controlled by daylength. Wingless aphids reared from birth in short‐day conditions (LD 12 : 12 h) and transferred when adult to long‐day conditions (LD 18 : 6 h) produce only gynoparae and males until death some 7 weeks later, whereas those reared in long days and transferred to short days produce 20% wingless parthenogenetic females, 50% gynoparae and 30% of males in an overlapping sequence. No winged morph capable of re‐infesting hop is produced. Less mature embryos are more sensitive to short days than older embryos because 100% of the former became gynoparae after 4 days of exposure of their mothers, and 59% when their mothers were exposed for the 4 days immediately preceding the birth of their offspring. Two days of exposure to short days switches 94% of young embryos from wingless to gynopara production when mature. The response to short days is irreversible. Wingless aphids reared from birth to adult in short days produce 30% fewer offspring than those reared to the same stage in long days and are male‐biased, with 76–78% of their offspring being male.