Details

Autor(en) / Beteiligte

• Szejner-Sigal, Andre
• Williams, Caroline M.

Titel

Aggregations reduce winter metabolic rates in the diapausing ladybeetle Hippodamia convergens

Ist Teil von

• Journal of insect physiology, 2022-02, Vol.137, p.104357-104357, Article 104357

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2022

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• [Display omitted] •Overwintering lady beetle aggregations reduce per capita metabolic rates.•Aggregations during winter show a hypometric metabolic-mass scaling relationship.•Locomotor activity partly explains metabolic savings, but only at low temperatures. Energy conservation is linked to survival and fitness of overwintering ectotherms, and is particularly critical in winter. Although many insects overwinter individually, some form aggregations with conspecifics. Aggregations cause metabolic suppression in some insects, but the effect of aggregations on metabolic rates and energy use in overwintering aggregations remains underexplored. The convergent ladybeetle (Hippodamia convergens) overwinters in massive aggregations, making it an ideal system for testing the effect of aggregation size on metabolic rates in overwintering insects. We measured metabolic rates of beetle aggregations of 1, 10, 25, and 50 individuals using stop-flow respirometry across two ecologically relevant temperatures, and measured locomotor activity as one possible driver of group effects on metabolic rate. Metabolic rates per beetle decreased with increasing aggregation size at both temperatures, but was more pronounced at low temperatures. Metabolic rates scaled hypometrically with mass, with deeper response at cool temperatures. Activity decreased with aggregation size, but only at low temperatures. These results suggest that individuals within aggregations enter a deeper metabolically inactive state that single individual beetles cannot achieve, which is partly but not completely explained by a reduction in locomotor activity. This group strategy for energy conservation may provide an additional selective advantage for the evolution of large overwintering aggregations.