TY  - JOUR
A1  - Beer, Katharina
A1  - Joschinski, Jens
A1  - Sastre, Alazne Arrazola
A1  - Krauss, Jochen
A1  - Helfrich-Förster, Charlotte
T1  - A damping circadian clock drives weak oscillations in metabolism and locomotor activity of aphids (Acyrthosiphon pisum)
JF  - Scientific Reports
N2  - Timing seasonal events, like reproduction or diapause, is crucial for the survival of many species. Global change causes phenologies worldwide to shift, which requires a mechanistic explanation of seasonal time measurement. Day length (photoperiod) is a reliable indicator of winter arrival, but it remains unclear how exactly species measure day length. A reference for time of day could be provided by a circadian clock, by an hourglass clock, or, as some newer models suggest, by a damped circadian clock. However, damping of clock outputs has so far been rarely observed. To study putative clock outputs of Acyrthosiphon pisum aphids, we raised individual nymphs on coloured artificial diet, and measured rhythms in metabolic activity in light-dark illumination cycles of 16:08 hours (LD) and constant conditions (DD). In addition, we kept individuals in a novel monitoring setup and measured locomotor activity. We found that A. pisum is day-active in LD, potentially with a bimodal distribution. In constant darkness rhythmicity of locomotor behaviour persisted in some individuals, but patterns were mostly complex with several predominant periods. Metabolic activity, on the other hand, damped quickly. A damped circadian clock, potentially driven by multiple oscillator populations, is the most likely explanation of our results.
KW  - circadian mechanisms
KW  - behavioural ecology
KW  - damped circadian clock
KW  - Acyrthosiphon pisum
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170020
VL  - 7
IS  - 14906
ER  - 
TY  - JOUR
A1  - Dainese, Matteo
A1  - Schneider, Gudrun
A1  - Krauss, Jochen
A1  - Steffan-Dewenter, Ingolf
T1  - Complementarity among natural enemies enhances pest suppression
JF  - Scientific Reports
N2  - Natural enemies have been shown to be effective agents for controlling insect pests in crops. However, it remains unclear how different natural enemy guilds contribute to the regulation of pests and how this might be modulated by landscape context. In a field exclusion experiment in oilseed rape (OSR), we found that parasitoids and ground-dwelling predators acted in a complementary way to suppress pollen beetles, suggesting that pest control by multiple enemies attacking a pest during different periods of its occurrence in the field improves biological control efficacy. The density of pollen beetle significantly decreased with an increased proportion of non-crop habitats in the landscape. Parasitism had a strong effect on pollen beetle numbers in landscapes with a low or intermediate proportion of non-crop habitats, but not in complex landscapes. Our results underline the importance of different natural enemy guilds to pest regulation in crops, and demonstrate how biological control can be strengthened by complementarity among natural enemies. The optimization of natural pest control by adoption of specific management practices at local and landscape scales, such as establishing non-crop areas, low-impact tillage, and temporal crop rotation, could significantly reduce dependence on pesticides and foster yield stability through ecological intensification in agriculture.
KW  - ecosystem services
KW  - agroecology
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158621
VL  - 7
ER  -