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Methods

Ant collection

Ants were sampled according to the standardized A.L.L. protocol (Agosti & Alonso 2000). The A.L.L. protocol consists of a line-transect of 20 sampling points spaced at 10m intervals. One Winkler and one pitfall sample were taken at each point. For Winkler extractions, the leaf litter present inside a 1m²-quadrat was collected and sifted. The sifted litter was weighted and its fauna was extracted with a mini-Winkler apparatus (Fisher 1998). The Winkler extraction is based on the passive desiccation of the leaf litter, forcing the ants to find a more favourable environment and their nest mates (Krell et al. 2005). Standard extraction time was 24 hours. Pitfall traps consisted in 70mm-diameter drinking cups, containing water and a drop of detergent, operating for 24 hours. Our study showed that during drought periods pitfall traps were more cost-effective than the Winkler method (Delsinne et al. 2008).

Equipment needed for the Winkler method: from left to right: meshed bag in which the sifted leaf litter is placed and then hang into the Winkler extractor, sample bag (whirlpak), balance to measure the weight of the sifted leaf litter, sifter.	1m² quadrat delimiting the area where the leaf litter is collected, sifted and then placed in a cotton bag (hanging here in a tree) before to be extracted in the laboratory. Gloves are a necessary protection against cactus spines !
Ants and other arthropods fall at the bottom of the Winkler extractor.	Pitfall trap.
Up to 50 Winkler extractors are used simultaneously (here in Enciso National Park building).	Samples are collected along a 200m transect line.

(images by ML)

Database core: SIDbase

This website presents a subset of the data contained in SIDbase, a database system developed by Maurice Leponce (with a MS-Access database core) to manage biodiversity survey data and especially adapted to ecological inventories of social insects. Its main features are: (i) management of sample and specimen data through barcode printed labels (alcohol proof, to speed up data entry and facilitate loan management); (ii) quick storage and retrieval of numeric pictures on habitats and taxa; (iii) tools for specimen identification (computer keys linked with an image bank) and data entry (world checklist of ant genera); (iv) data analysis friendly (filters for sorting data with respect to taxon, site and sampling method; abundance matrices automatically exported to EstimateS format); (v) simultaneous data-entry by several users.

Digital imaging

A Leica Z6APO microscope with a Leica DFC290 digital camera is used to take the images with a 3 mega pixels resolution. To overcome the problem of limited depth of field encountered in microphotography, a series of images are taken at different heights. A montage software (Helicon Focus) is used to combine the focused area into a completely focused image. The system is operated by Yves Laurent.

Scanning Electron Microscope

A Philips XL 30 ESEM, operated by Julien Cillis, is used to capture the scanning electron micrographs. Generally ants are coated with gold (to enhance the contrast) before to take the image except in the case of unique specimens.

References

Agosti, D., and L. E. Alonso. 2000. The A.L.L. protocol. A standard protocol for the collection of ground-dwelling ants. In D., Agosti, J. D. Majer, L. E. Alonso, and T. R. Schultz. (eds): Ants: standard methods for measuring and monitoring biodiversity, pp. 204-206. Smithsonian Institution Press, Washington DC.

Delsinne, T.; Leponce, M.; Theunis, L.; Braet, Y.; Roisin, Y. 2008. Rainfall influence the ant sampling in dry forests. Biotropica, in press.

Fisher, B. L. 1998. Ant diversity patterns along an elevational gradient in the Réserve Spéciale Naturelle Intégrale d'Andringitra, Madagascar. Fieldiana Zool. (n.s.) 85: 93-108.

Krell, F.-T., A. Y. C. Chung, E. DeBoise, P. Eggleton, A. Giusti, K. Inward, and S. Krell-Westerwalbesloh. 2005. Quantitative extraction of macro-invertebrates from temperate and tropical leaf litter and soil: efficiency and time-dependent taxonomic biases of the Winkler extraction. Pedobiologia 49: 175-186.

Leponce, M. 2003. SIDbase. Royal Belgian Institute of Natural Sciences, internal technical report, 14p. (538KB)