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Developmental threshold, day‐degree requirements and voltinism of the aphid predator Episyrphus balteatus (Diptera: Syrphidae)
Author(s) -
HART A J,
BALE J S,
FENLON J S
Publication year - 1997
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1997.tb07672.x
Subject(s) - biology , aphid , predator , voltinism , degree (music) , zoology , predation , ecology , botany , larva , physics , acoustics
Summary Episyrphus balteatus is the dominant syrphid predator of aphids in the UK, reestablishment of populations each season is mainly by migration from warmer climes, as overwintering in this country is minimal with an uncertain level of success. The effects of temperature on the developmental rate of E. balteatus were investigated to determine the potential voltinism of this species in the UK. Estimates of the developmental threshold temperature from oviposition to adult emergence varied between 6.0d̀C and 7.1d̀C with a day‐degree (DD) requirement of between 256 and 280 depending on the method of analysis used. Using the DD requirement derived from a weighted linear regression (261 DD above a threshold of 6.8d̀C) in combination with the required value from adult emergence to first oviposition, suggests a total requirement of approximately 374 DD above 6.8d̀C per generation. These data, together with climate records, indicate that one to three generations are possible each year, depending on the available DD and origin of the population. The advantages and limitations of different approaches and models used to estimate developmental thresholds and DD requirements are discussed.