| Summary: | The more insects there are, the more food there is for insectivores and the higher the likelihood of insect-associated ecosystem services. Yet, we lack insights into the drivers of insect biomass over space and seasons, both for tropical and temperate zones. We used 245 Malaise traps, managed by 191 volunteers and park guards, to characterise year-round flying insect biomass in a temperate (Sweden) and a tropical (Madagascar) country. Surprisingly, we found that local insect biomass was similar across zones. In Sweden, local insect biomass increased with accumulated heat and varied across habitats, while biomass in Madagascar was unrelated to the environmental predictors measured. Drivers behind seasonality partly converged: In both countries, the seasonality of insect biomass differed between warmer and colder sites and wetter and drier sites. In Sweden, short-term deviations from expected season-specific biomass were explained by week-to-week fluctuations in accumulated heat, rainfall, and soil moisture, whereas in Madagascar, weeks with higher soil moisture had higher insect biomass. Overall, our study identifies key drivers of the seasonal distribution of flying insect biomass in a temperate and tropical climate. This knowledge is key to understanding the spatial and seasonal availability of insects — as well as predicting future scenarios of insect biomass change. Funding provided by: Knut and Alice Wallenberg Foundation Crossref Funder Registry ID: https://ror.org/004hzzk67 Award Number: To describe the large-scale distribution of flying insect biomass, we sampled insects during one year in a temperate (Sweden; latitude 55.3 to 69.1) and a tropical (Madagascar; latitude -25.6 to -12.0) country, across the full latitudinal and longitudinal gradient of each country. Sweden and Madagascar are comparable in their surface area, covering ~450,000 and ~590,000 km 2 respectively. The climate in Sweden ranges from oceanic to sub-Arctic, and in Madagascar from tropical humid to dry tropical. Insects were ...
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