2 results
2 - Wood ant reproductive biology and social systems
-
- By Arnaud Maeder, Museum of Natural History, La Chaux-de-Fonds, Switzerland, Daniel Cherix, University of Lausanne, Lausanne-Dorigny, Switzerland, Christian Bernasconi, Museum of Zoology, Lausanne, Switzerland, Anne Freitag, Museum of Zoology, Lausanne, Switzerland, Samuel Ellis, University of York, Heslington, York,UK
- Edited by Jenni A. Stockan, Elva J. H. Robinson, University of York
-
- Book:
- Wood Ant Ecology and Conservation
- Published online:
- 05 June 2016
- Print publication:
- 07 July 2016, pp 37-50
-
- Chapter
- Export citation
-
Summary
Transmitting genes from one generation to the next is the fundamental basis of natural selection and evolution. Understanding the reproductive biology of a species is, therefore, fundamental to understanding how the species evolved and how it is adapted to its environment. In eusocial insects such as the wood ants (Formica rufa group), reproduction is invested in a specialised reproductive caste, which produces both the workers and the next generation of sexual individuals. This chapter introduces the reproductive biology of wood ants, and also gives a general view of the life cycle of a wood ant colony to put the reproductive biology in context.
Wood ant life cycle
The wood ant life cycle is strongly linked to seasonal changes in the environment. Wood ant colonies generally first become active, after winter quiescence, in early spring when the sun begins to heat the nest and, in some locations, melt the snow (Figure 2.1). The timing of the beginning of activity is strongly influenced by the local climate, altitude and nest location. In Switzerland, for example, significant colony activity usually begins in March or April (Cherix 1981; Chauternes 1988).
On warm and sunny days, early in spring, worker activity begins and the internal temperature of the nest begins to rise to between 25°C and 30°C. Nest temperature remains at this level for the entire active season, even when, during early spring, the outside temperature is close to freezing (discussed in detail in Chapter 4) (Rosengren et al. 1987). Workers gather in the warm nest core and their nutrient-producing glands become more active, converting lipids and protein into food ready to be fed to queens and future larvae (Bausenwein 1960). The queen(s) remain(s) in the warm nest core for several days and lay ‘winter eggs’. The larvae hatching from these eggs are fed by the overwintering workers, usually developing into sexuals in about 6 weeks (Otto 2005). The queen(s) then retire(s) to the lower nest chambers to start to produce ‘summer eggs’, which usually develop into workers (Otto 2005).
Reproduction generally takes place in early summer, with thousands of sexual individuals flying away from their nests and participating in nuptial flights (e.g. Cherix et al. 1991).
11 - Sampling and monitoring wood ants
-
- By Anne Freitag, Museum of Zoology, Lausanne, Switzerland, Jenni A. Stockan, James Hutton Institute, Aberdeen,UK, Christian Bernasconi, Museum of Zoology, Lausanne, Switzerland, Arnaud Maeder, Museum of Natural History, La Chaux-de-Fonds, Switzerland, Daniel Cherix, University of Lausanne, Lausanne-Dorigny, Switzerland
- Edited by Jenni A. Stockan, Elva J. H. Robinson, University of York
-
- Book:
- Wood Ant Ecology and Conservation
- Published online:
- 05 June 2016
- Print publication:
- 07 July 2016, pp 238-263
-
- Chapter
- Export citation
-
Summary
Wood ants (Formica rufa group) are the ecological centre of many temperate and boreal forest ecosystems, with influence over ecosystem processes and other organisms. Owing to their dominance and keystone role, there are many reasons why it may be desirable or necessary to sample or monitor wood ants. Most field-based studies are based on exploring the relationships between red wood ants and their environment, be it the effects wood ants have on their surroundings via their nesting or foraging activities, or the effect a changing environment has on the ants. Given their keystone roles with the ecosystem, red wood ants can be useful indicators of ecosystem health, environmental degradation or restoration, or climate change (Torossian 1977b; Sorvari and Hakkarainen 2007b). With many species in Eurasia threatened and those in North America little understood, there is often simply a requirement to assess whether a species is present or not, or whether introductions or translocations have been successful.
Unlike most other invertebrates, and indeed even other ant species, most red wood ants build conspicuous and long-lasting mound nests that facilitate their census. However, as for other ant species, this social living presents particular challenges for sampling and monitoring. Careful planning and the application of considered methods are needed to overcome these difficulties. This chapter provides an overview of the sampling methods and approaches that have been directly applied to wood ants, and the theory underpinning them. Where methods or approaches are ineffective or warrant further development, these are highlighted. The goal is to recommend a set of reliable and easy to use methods that can provide accurate and repeatable data, which are comparable between studies.
The challenges of studying red wood ants
Consideration of life cycle and seasonality
Effective sampling or monitoring of wood ants presents considerable theoretical and practical problems. Wood ants are social insects which are patchily distributed and territorial. Moreover, there are seasonal patterns to the abundance and presence of certain castes. The queen (or queens) and some workers are present throughout the year, though not always visibly so. Males and particular stages of brood are present only for part of the year and this can depend on factors such as colony size and age, food availability and local environmental variables.