TY  - JOUR
A1  - Joschinski, Jens
A1  - Beer, Katharina
A1  - Helfrich-Förster, Charlotte
A1  - Krauss, Jochen
T1  - Pea Aphids (Hemiptera: Aphididae) Have Diurnal Rhythms When Raised Independently of a Host Plant
JF  - Journal of Insect Science
N2  - Seasonal timing is assumed to involve the circadian clock, an endogenous mechanism to track time and measure day length. Some debate persists, however, and aphids were among the first organisms for which circadian clock involvement was questioned. Inferences about links to phenology are problematic, as the clock itself is little investigated in aphids. For instance, it is unknown whether aphids possess diurnal rhythms at all. Possibly, the close interaction with host plants prevents independent measurements of rhythmicity. We reared the pea aphid Acyrthosiphon pisum (Harris) on an artificial diet, and recorded survival, moulting, and honeydew excretion. Despite their plant-dependent life style, aphids were independently rhythmic under light–dark conditions. This first demonstration of diurnal aphid rhythms shows that aphids do not simply track the host plant’s rhythmicity.
KW  - artificial diet
KW  - circadian clock
KW  - hourglass clock
KW  - Acyrthosiphon pisum
KW  - photoperiodism
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-168783
VL  - 16
IS  - 1
ER  - 
TY  - JOUR
A1  - Beer, Katharina
A1  - Steffan-Dewenter, Ingolf
A1  - Härtel, Stephan
A1  - Helfrich-Förster, Charlotte
T1  - A new device for monitoring individual activity rhythms of honey bees reveals critical effects of the social environment on behavior
JF  - Journal of Comparative Physiology A
N2  - Chronobiological studies of individual activity rhythms in social insects can be constrained by the artificial isolation of individuals from their social context. We present a new experimental set-up that simultaneously measures the temperature rhythm in a queen-less but brood raising mini colony and the walking activity rhythms of singly kept honey bees that have indirect social contact with it. Our approach enables monitoring of individual bees in the social context of a mini colony under controlled laboratory conditions. In a pilot experiment, we show that social contact with the mini colony improves the survival of monitored young individuals and affects locomotor activity patterns of young and old bees. When exposed to conflicting Zeitgebers consisting of a light-dark (LD) cycle that is phase-delayed with respect to the mini colony rhythm, rhythms of young and old bees are socially synchronized with the mini colony rhythm, whereas isolated bees synchronize to the LD cycle. We conclude that the social environment is a stronger Zeitgeber than the LD cycle and that our new experimental set-up is well suited for studying the mechanisms of social entrainment in honey bees.
KW  - Social entrainment
KW  - Foragers
KW  - Nurses
KW  - Locomotor activity
KW  - Temperature rhythms
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-188030
VL  - 202
IS  - 8
ER  -