Nitidulidae Latreille, 1802

Berx, Peter, Bosmans, Bart, Dekoninck, Wouter, Janssen, Marc, Stassen, Eugène & Crevecoeur, Luc, 2023, Faunistic survey of myrmecophilous and other ant-associated beetles and spiders in the Belgian province of Limburg (Araneae, Coleoptera, Hymenoptera: Formicidae), Belgian Journal of Entomology 141, pp. 1-61 : 23-25

Nitidulidae Latreille, 1802

This large family of sap or pollen beetles is represented in the province of Limburg by 54 species. The number of specimens in our database amounts to 16,187 beetles belonging to the cosmopolitan genus Glischrochilus Reitter, 1873 . At only one location (Kolmontbos FS7130 Tongeren) 5,429 individulas of the saproxylic species G. hortensis (4.0-7.0 mm) ( Fig. 20B )

correlated ant species on specific point locations in the province of Limburg.

were collected using a trap baited with a mixture of water, alcohol, glycerol and acetic acid. The trap was installed in a dead oak tree, and beetles were captured from 21-06-2008 until 03-08-2008. Less abundant in both species numbers and occupancy of UTM grids (Annex) is Amphotis marginata (3.8-5.8 mm) ( Fig. 20A ). Although the niche occupancy of the latter may be significantly lower compared to the occurrence of G. hortensis , the attention given to this beetle in publications on myrmecophily is even greater. In this relationship, the ant L. fuliginosus appears to be the exclusive partner.

Once the shining black ant L. fuliginosus has found a suitable shelter, the workers start building a carton nest. Usually, the nest is built inside a cavity at the root of a decaying tree, and partly due to the labour-intensive cost of this enterprise, this settlement can be observed in the same location for years. From this permanent residence, hundreds of workers migrate incessantly, day and night, to nearby aphid colonies to feed on the excreted nectar of the aphids. These foraging paths, which can be up to a few dozen meters, will remain in use season after season. The nitidulid beetle Amphotis marginata ( Fig. 20A ) has found an easily accessible food source in the ants that return to the nest with a full social stomach. Hidden in a shelter during the day along the foraging trail, the beetles line up at dusk and during the night to beg the homing ants for food. They approach the food-carrying ants, imitate the food-begging behaviour of their nestmates and obtain the supplied honeydew through trophallaxis. The relationship between these beetles and the ants is mainly attributed to food solicitation and although no adult beetles have been observed in the ant nest, it cannot be ruled out that their larvae hibernate and develop inside the ant nests ( HÖLLDOBLER et al., 2017).

Lasius fuliginosus is a common ant, and the number of grids (156) where the species was recorded in the surveyed province contrasts sharply with the eight grids where A. marginata was observed. An explanation may be that the dispersal pattern of this nitidulid beetle is not distinctly large, and they prefer to stay close to an established colony of L. fuliginosus with a guaranteed food supply. However, this assumption is not supported by our observations (Annex). Eleven beetles were collected in just two grids when screening rotten wood from a tree ( Quercus sp. ) in which a nest of L. fuliginosus was located (Tongeren FS7130 – 2008 and Sint-Truiden FS5427 – 2012). In the other six grids, the beetles were caught in flight - one specimen was caught with a butterfly net, one specimen with a light trap and five specimens (in four grids) with a vehicle-mounted net. Therefore, from our data, we cannot offer an acceptable explanation for the scant presence of this beetle in a region where the host is a common species. Other unknown conditions need to be explored to better understand the ant-beetle association for A. marginata ( HÖLLDOBLER et al., 2017) .

Based on their observations of Lasius neglectus van Loon, Boomsma & Andrasfalvy, 1990 in Barcelona, Espadaler and Bernal (2007) make mention of Amphotis marginata as a guest but later this was corrected into the very similar species Amphotis martini Brisout, 1878 (LENCINA et al., 2011). This shows us that the related species within the genus Amphotis exhibit a similar behaviour towards a variety of host ants.

Figures

Fig.20. A, Amphotis marginata (Fabricius, 1781) (5.7mm; range 3.8-5.8mm). B, Glischrochilus hortensis (Geoffroy, 1785) (6.7mm; range 4.0-7.0mm). © U. Schmidt.