The Coleopterists Bulletin, 70(2): 407–408. 2016.
SCIENTIFIC NOTE
FIRST REPORT AS A
LATRODECTUS GEOMETRICUS KOCH (ARANEAE: THERIDIIDAE) PREDATOR OF DIGITONTHOPHAGUS GAZELLA (FABRICIUS) (COLEOPTERA: SCARABAEIDAE) OF
JORGE ARI NORIEGA Laboratorio de Zoología y Ecología Acuática Universidad de Los Andes, Bogotá, COLOMBIA
[email protected]
was 1.1 cm. Two other dung beetle species were in the webs: Dichotomius cf. belus (Harold, 1880) and Canthon cf. juvencus (Harold, 1868) (they were in very bad condition, so it was not possible to confirm the species identification). This suggests that D. gazella is not a target prey for this spider. In addition, spider webs were not specifically located near dung piles, but in the vicinity of them there was abundant dung from cows, donkeys, and goats. The need to study and quantify the potential importance of this predation on the beetle’s population dynamics (see Noriega and Navarrete-Heredia 2013) is highlighted since the quantification of predation has not been fully recorded in detail. Collecting data is: COLOMBIA, Huila Department, Villavieja municipality, Tatacoa desert (surrounded by secondary fragments of Tropical Dry Forest), 450 m, 3°13′52″ N, 75°08′56″ W, 20.VII. 2014, A. Rueda, EANDES. Specimens are deposited in the Entomological Collection of the University of Los Andes. This is the most southern record for D. gazella in Colombia (Noriega et al. 2011), demonstrating the invasive power of this species to colonize new areas, even in extremely dry regions.
The Scarabaeinae (Coleoptera: Scarabaeidae) are a very important group in many ecosystems because they fulfill key functional rolls (Nichols et al. 2008). However, little is known about the importance of their predators (Halffter and Matthews 1966; Hanski 1991). Some authors have reported predation on dung beetles without specifying the precise taxonomic identity of the predator and/or prey species (Hanski and Hammond 1986; Hanski 1987). Recently, there was published a literature review of known predators, but there are several taxonomic inconsistences and few references related to invertebrates, especially arachnids (Young 2015). There are accurate records of a burrowing scorpion, Cheloctonus jonesii Pocock, 1892 (Harington 1978), a whip scorpion, Mastigoproctus colombianus Mello-Leitão, 1940 (Noriega and Botero-Trujillo 2008), and a spider, Argiope argentata (Fabricius, 1775) (Robinson and Robinson 1970), as predators of dung beetles. On the other hand, records show that the dung beetle Digitonthophagus gazella (Fabricius, 1787) is prey for eight anuran species (Blanco et al. 2013), one toad, Rhinella marina (Linnaeus, 1758) (Macqueen 1975), and one bird, Threskiornis aethiopicus Latham, 1790 (Davis 1977). Here I present a new record of an arachnid predator of a dung beetle. During a sampling project (November 2009 – August 2013) to characterize the food preferences of Latrodectus geometricus Koch, 1841 (the brown widow spider), eight individuals (3♂ and 5♀) of D. gazella were collected from six (2%, two webs with two individuals apiece and four webs with one specimen each) of 300 spider webs of L. geometricus that were sampled in the field. All webs were located in open field in the desert, constructed close to rocks or small shrubs, near the soil 20–40 cm above ground. All beetles were wrapped in spider silk directly on the web. The average size of the adult spiders was 4.1 cm for females and 1.3 cm for males, and the average size of the dung beetle
ACKNOWLEDGMENTS Thanks to Alexandra Rueda, Emilio Realpe, and the Laboratory of Zoology and Aquatic Ecology (LAZOEA) – University of Los Andes for their valuable information and support, to David Morris and Javier Santos for kindly checking the English version of the manuscript, and to an anonymous reviewer for comments on the manuscript.
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