Foraging activity and dietary spectrum of wood ants (Formica rufagroup) and their role in nutrient fluxes in boreal forests

Abstract

1. We monitored three different-sized wood ant ( Formica aquilonia Yarrow) mounds over a 3-year period in Finnish boreal forests dominated by Norway spruce ( Picea abies Karst.), to assess the seasonal temperature dependency of ant activity. Additionally, we also monitored Norway spruce trees around the mounds for descending honeydew foragers.2. The amount of collected honeydew and prey and its composition, as well as the carbon (C), nitrogen (N), and phosphorus (P) in honeydew and invertebrate prey was also investigated.3. The number of warm days (average temperature above 20 °C) and the amount of precipitation differed among the years. Ant activity at the mounds (but not on the trees) was highly correlated with air temperature throughout the ant-active season (May -September), but ant activity in spring and autumn was lower than in summer at similar temperatures. During all 3 years, honeydew played a major role in wood ant nutrition (78 -92% of dry mass). Invertebrate prey was mainly Diptera (on average 26.2%), Coleoptera (12.5%), Aphidina (9.3%), and Arachnoida (8.5%).4. The total amounts of C, N, and P input brought into the ant mounds in the form of food (both honeydew and prey) on the stand level were 12.6 -39.0, 1.6 -4.6 and 0.1 -0.4 kg ha -1 year -1 , respectively, which is equivalent to 2 -6%, 12 -33% and 27 -58% of the fluxes in annual needle litterfall in typical boreal Norway spruce forests. Thus, wood ants can play a significant role in short term and local N and P cycling of boreal forest ecosystems.

Sun Basking in Red Wood Ants Formica polyctena (Hymenoptera, Formicidae): Individual Behaviour and Temperature-Dependent Respiration Rates

“…polyctena workers (CO 2 production rates in microliters per hour) in the temperature range that wood ants encounter in nature, from 5°C to 35°C [33–35], to quantify the effects of a long-term exposure and so to characterize the temperature-dependence of respiration across the ranges of temperatures ants experience after overwintering. The range includes the maximal temperatures of sun-basking ants we measured in our experiments using the artificial hot spot, which varied between 23.8 and 31.6°C.…”

“…We measured respiration rates of red wood workers in a temperature range going from 5°C to 35°C, which are approximately the limits of wood ant activity in nature [33–35]. At low temperatures, between 5 and 10°C, respiration rates were low, and significantly increased with increasing temperatures.…”

“…Our aim was to quantify the CO 2 -production rate for F . polyctena ants as a function of temperature, starting from 5°C, which is the low temperature limit of ant activity, up to 35°C, which is the highest temperature limit [33–35]. Measurements of respiration rates in individual workers were performed at 5, 10, 20, 30 and 35°C.…”

Effects of sap-feeding insect herbivores on growth and reproduction of woody plants: a meta-analysis of experimental studies

“…For example, in boreal coniferous forests, aphids excrete as honeydew between one-quarter and one-half of the nitrogen and phosphorous contained in annual litterfall (Domisch et al 2009). However, in spite of the long history of research on pest species (including aphids, scales, and bugs), which can substantially weaken or even kill plants, ecosystem-level studies generally estimate losses of net primary production (NPP) due to insect herbivory on the basis of foliage eaten away by leaf chewers (Hodkinson and Hughes 1982;Cebrian and Lartigue 2004;Wolf et al 2008).…”

Fine‐scale variation in natural nitrogen isotope ratios of ants

“…This species suffers from a dearth of available biological information, but is likely similar in behaviour to other Palaearctic Formica species, which have mixed diets and are integral to forest ecosystem nutrient fluxes (Fielder et al, 2007;Domisch et al, 2009). This species suffers from a dearth of available biological information, but is likely similar in behaviour to other Palaearctic Formica species, which have mixed diets and are integral to forest ecosystem nutrient fluxes (Fielder et al, 2007;Domisch et al, 2009).…”