DOI: 10.5061/dryad.2280gb5w3
title: Crickets as indicators of ecological succession in tropical

description: Cricket (Ensifera, Grylloidea) are not commonly used as ecological
 indicators in contrary to other Orthoptera (e.g. grasshoppers and
 katydids). However, they are sensitive to environmental changes and
 abundant in tropical regions. To evaluate if crickets are relevant
 bioindicators of tropical ecosystems, we investigated cricket assemblages
 along a tropical ecological gradient. We collected crickets during both
 day and night in southern New Caledonia for three stages of an ecological
 succession: open shrubland, preforest and forest. Simultaneously, we
 measured several environmental variables, such as temperature and relative
 humidity, at each sampling site. Cricket species assemblages showed a
 clear response to ecological succession. The highest and lowest species
 richness and abundances of individuals were respectively found in forest
 and shrubland, with species specialized in each ecological stage revealing
 the conservation value of each of these stages. Similar results were found
 when considering only the part of cricket communities with ability to
 acoustically communicate. This work is part of a larger research program
 about Neocaledonian crickets and contributes to support the use of
 acoustic approaches to monitor tropical environments. In conclusion, these
 findings highlight the potential value of crickets as an environmental
 indicator in tropical ecosystems. The results also contribute to the
 discussion of the intrinsic conservational value of shrublands in New
 Caledonia and similar ecotypes.
description: Cricket
 communities were studied in the southern region of Grande Terre, the main
 island of New Caledonia, an archipelago located in the Southwest Pacific
 Ocean. Sites were selected along the same geological ultramafic substrate
 at low altitude (231 ± 66 m). To study ecological succession on cricket
 fauna, three vegetation stages—forest, preforest and shrubland—were
 considered. Four sites were chosen within each stage for a total of twelve
 sites. Crickets were collected between November 2013
 and April 2014. In each of the twelve sites selected, two squared parcels
 with 10 m sides were delimited. Sampling was performed under clear sky
 meteorological conditions from hours 0900 to 1700 by day, and 1900 to 0000
 by night. On each parcel, crickets were collected using a same collection
 method of ten 30 minute sessions, with five total collections by day and
 five by night. Crickets
 were located using both sight and song cues in the field only based on
 human perceptions, which is the most appropriate sampling method for
 crickets. For each individual, activity (e.g. singing,
 eating, mating, resting) and microhabitat (e.g. trunk, leaf litter,
 vegetation, rocks, height from ground) were noted before the capture.
 Specimens are deposited in the Museum national
 d’Histoire naturelle de Paris with a reference collection in the Nouméa
 IRD center in New Caledonia. Species identifications were performed in lab
 by comparison to the specimens in the deposited collections and using the
 classification derived from the extensive molecular phylogeny of crickets
 (Chintauan-Marquier et al., 2016). Based on previous taxonomic description
 including acoustic production (i.e. Desutter-Grandcolas et al. 2016 and
 Anso et al. 2016b), we were able to attribute to each species a presence
 or absence of singing abilities. Of the 1,030 individuals collected, 54 were
 discarded. These specimens were not identifiable to the species level
 because of their destruction due to unfavorable conservation conditions
 (56%) or from the absence of morphological information for crickets in the
 juvenile development stage (44%). 
 During cricket sampling,
 environmental attributes were measured in each parcel, including: the
 percentage of bare ground, the percentage of three vegetation layers
 (herbaceous, shrub and tree), the number and diameter (dbh) of stems, the
 vegetation height, and the plant species richness. Canopy openness was
 extracted from photos taken with a 180° hemispherical (fisheye) lens in
 each parcel corner and in its center. From the photos, canopy openness was
 then calculated using the Gap Light Analyzer software (version 2.0, Simon
 Fraser University, Cary Institute of Ecosystem Studies) by estimating the
 percentage of light in the forest overstorey (Frazer et al., 1999). Daily
 temperature (°C) and relative humidity (%) were recorded every 30 minutes
 during 15 days at a 50 cm height above the ground using waterproof
 thermo-hygrometer sensors (HOBO U23 Pro v2; HOBOware software).
 Table
 S1: Crickets inventory. Details of species identification, time, date and
 location of collected specimens as well as their position in the
 vegetation at the moment of their collection. “NA” indicates an unknown
 information associated to the sex or the stage of development of the
 specimen. Table S2: Environmental data with the following
 abbreviations: HER for Herbaceous layer, SHR for shrub layer, TRE for tree
 layer, BAR for bare ground, VH for vegetation height, DN for number of
 stems, DBH for number and diameter of stems, CO for canopy openness, RI
 for vegetation richness, MT for mean temperature, HT for maximum
 temperature, LT for minimum temperature, DT for daily temperature
 variation, MH for mean humidity, LH for minimum humidity, and DH for daily
 humidity variation. Table S3: List of complete name species of crickets
 identified during the taxonomic inventory.
description: The tables 1 and 2 are in csv and can be open with several
 software including Libre office or Excel. Tha table 3
 is a docx and can be open by Word or Libre office Writter.