Thermal requirements for development and resource partitioning in aphidophagous guilds
Dixon, A.F.G.(University of East Anglia, Norwich (United Kingdom). School of Biological Sciences)E-mail:[email protected] | Jarosik, V.(Karlova Univ., Prague (Czech Republic). Katedra Ekologie)E-mail:[email protected] | Honek, A.(Vyzkumny Ustav Rostlinne Vyroby, Prague (Czech Republic))E-mail:[email protected]
Two aphidophagous predatory guilds were studied in order to determine whether the temporal attack sequences of syrphids and coccinellids differ. The numbers of sycamore aphids and their natural enemies were monitored on 4 sycamore trees from 1963 to 1973 (system S), coccinellid and syrphid larvae were monitored in winter wheat in the summer of 2004 (system W). The immature stages of syrphids appeared before those of coccinellids in the system S in spring and in the system W in summer. In the system S the autumnal peak in abundance was on average larger than the spring one, and although attacked by more syrphids, it was not exploited by coccinellids. The lower developmental thresholds (LDT) of syrphids (4 deg C) enables them to develop faster between 10 and 27 deg C than coccinellids, whose LDT is 10 deg C. Thus, the niche shift between syrphids and coccinellids is possibly more a consequence of a phylogenetic constraint than a response to competition and/or intraguild predation.
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