Presence after three decades of red wood ants (Formica rufa group; Hymenoptera: Formicidae) in forests in an agricultural landscape

Harry J.M Van Buggenum

doi:10.14411/eje.2022.009

Abstract

Conducting a repeat study of the presence of mound-building red wood ants (Formica rufa group) after a period of 30 years has rarely been done in Europe. From 1990 to 2020 such a study was done in an intensively used agricultural landscape with fragments of forest in the South-Eastern part of The Netherlands. In 1990, 280 nest mounds of three species of red wood ants and a hybrid were found in the forests and along forest edges. The highest occupancy was in forests of > 25 ha. The connectivity between the forest fragments mainly determined their presence. In 2020, only 160 nest mounds were found. The development of the colonies differed for Formica polyctena FĂśrster, 1850 (slight decrease), F. rufa Linnaeus, 1761 (substantial increase) and F. pratensis Retzius, 1783 (strong decrease). The differences between the species in this highly fragmented landscape may be due to differences in their colonization strategies of either nest splitting or producing swarms of young queens. Furthermore, the analyses show that the type of environment (in a forest or along a forest edge) determines the probability of extinction or settlement. There is a need to undertake management measures to prevent the extinction of species of red wood ants in the area studied. These measures include creating small clearings in dense forests, reducing shading due to overgrowing shrubs or herbaceous plants, and creating buffer zones around intensively manured fields. More long-term monitoring is needed in Europe to compare the circumstances in different regions, detect trends and evaluate the effects of protection measures.

Highlights

In recent decades, the number and distribution of many plants and animals have declined sharply in artificial landscapes, in The Netherlands and elsewhere
Dekoninck et al (2010) show that after 20 years, the West Flemish (Belgium) populations of F. rufa and F. polyctena have declined by more than 50%
The study area is in the central part of the province of Limburg (The Netherlands), east of the River Meuse

Summary

Introduction

The number and distribution of many plants and animals have declined sharply in artificial landscapes, in The Netherlands and elsewhere. Loss and fragmentation of habitat, pollution, climate change, invasive alien species and numerous other factors are mentioned as causes of recent declines (Sánchez-Bayoa & Wyckhuys, 2019; Jactel et al, 2020; Wagner et al, 2021). For several groups of insects, such declines are reported for a great diversity of insect in terms of both species and biomass (Hallmann et al, 2017). The question is, which species are more vulnerable to human influences and whether further decline can be prevented. The present research is limited to a few mound-building species of red wood ants (Genus: Formica; Subgenus: Formica) because their nests are relatively easy to find. There are indications that several species have decreased locally in Europe

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