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Media type:
E-Article
Title:
Temperature Regulation and Energetics of the Solitary Bee Centris pallida during Foraging and Intermale Mate Competition
Contributor:
Chappell, Mark A.
imprint:
University of Chicago Press, 1984
Published in:Physiological Zoology
Language:
English
ISSN:
0031-935X
Origination:
Footnote:
Description:
<p>Solitary bees (Centris pallida Fox; Hymenoptera: Anthophoridae) were observed during diurnal activity in a hot desert environment. Females foraged throughout the day in flowering paloverde trees; males divided their time between foraging and hovering in search of receptive females. Thoracic temperatures (<tex-math>$T_{th}$</tex-math>) of both sexes were high. Foraging males and females had<tex-math>$T_{th}$</tex-math>averaging 44-46 and 43-45 C, respectively. The<tex-math>$T_{th}$</tex-math>of hovering males averaged about 44 C in the early morning and 47 C from midmorning until activity ceased. Thoracic temperatures of both sexes changed by 3-4 C over an ambient temperature (<tex-math>$T_{a}$</tex-math>) range of 25-40 C. Abdominal temperature (<tex-math>$T_{ab}$</tex-math>) was consistently about 4.5 C above<tex-math>$T_{a}$</tex-math>, and there was no indication of augmented heat transfer between thorax and abdomen at high<tex-math>$T_{th}$</tex-math>. Maximum tolerable<tex-math>$T_{th}$</tex-math>was 50-51 C. Evidence for evaporative heat loss was equivocal for artificially heated bees, but free-flying animals showed little indication of use of evaporative cooling. Energy metabolism (measured as oxygen consumption) during flight (1. 1 W/g thorax) resembled that of other endothermic insects of similar mass; mass-specific thermal conductance (0.034 W/[g thorax - C]) was slightly larger than predicted from body mass. Centris pallida probably controls body temperature by reducing flight at high<tex-math>$T_{a}$</tex-math>. Nevertheless, hovering males often attain<tex-math>$T_{th}$</tex-math>within 2-3 C of lethality.</p>