Native species of dung beetles in Chile according to nesting behavior.
Dung beetles are insects that provide a large-scale ecosystem service worldwide through their role in the decomposition of manure from livestock, thereby providing a series of environmental services, such as nutrients recycling, control of internal parasites of livestock whose eggs are in the feces, soil aeration, spreading of seeds and maintenance of ecological balance. Dung beetles are broadly classified according to their nesting behavior in three categories as telecoprids, paracoprids and endocoprids. Telecoprids are the rollers that make balls from feces and roll them into the ground; paracoprids are the tunnellers that bury the dung balls at different depths, forming galleries in the ground below or next to the food source and endocoprids, who are the dwellers that raise their larvae inside feces. There are 10 native species of dung beetles recorded in Chile, apart from 10 species of Aphodiinae, plus two introduced species, such as Onitis vanderkelleni and Onthophagus gazella. Dung beetles species were prospected in La Araucania Region and registered Homocopris torulosus, Frickius variolosus, Podotenus fulviventris and Aphodius pseudolividus. We found that species from genus Homocopris, Podotenus and Aphodius were distributed from 0 to 2000 m above sea level, while F. variolosus was distributed over an altitude of 350 m.
- dung beetles
Dung beetles (
The feeding habits of these insects bring significant environmental benefits and ecosystem services, such as recycling of soil nutrients, stimulation of plant development, spreading of seeds, biological control of parasite load in manure and indirect help in pollination [10–14].
In grasslands, the insects activity generates an increase in the rate of manure decomposition, allowing nutrient recycling, and also, the reuse of grassland, once feces have been cleared [15, 16]. The introduction of dung beetles has been used as a grassland management decision in other parts of the world. For example, in Eastern Island, the species
Dung beetles have received great attention in recent years due to their higher agro-ecological importance in crops and environmental management, especially due to their role in increasing soil fertility and parasites control in cattle. So much so that it is estimated that biological activity of dung beetles reaches an economic contribution to agriculture of US$380 million per year in the USA [19–21]. Dung beetles are also considered key important due to ecosystem services they provide worldwide by eliminating the remains of manure, derived from livestock production systems. These services are directly related to improving yields and crop sustainability; in addition, seeds dispersion become significant importance in reforestation, restoration and conservation of forests [19, 22–24].
Dung beetles have had great religious importance since ancient times, at such a point that have been considered as religious symbols in rituals or, as deities. Besides, beetles have been used as food, in medicine, and have played important roles in traditional culture and folklore (see Refs. [25–28]). Egyptians emphasized at that point, who observed dung beetles behavior and their ecology over 5000 years, and even compared a beetle with their deity, god Khepri. Beetles were considered sacred by Egyptians due to the role they played in the renewal, transformation and resurrection of life. There were four aspects that determined the relationship between facts and the biological-theological explanation : (1) beetles looking for droppings, something to what the Egyptians attributed a sacred character; (2) a beetle rolling a ball of dung and burying it in the ground; (3) the fact that most of their metamorphosis occurred underground; and (4) the fact that eggs hatch and restart the life cycle.
Dung beetles have been used as bio-indicators during the last three decades and also in biological models [23, 28, 29]. However, productive practices in croplands, prairies and even forests have lowered significantly the biodiversity of dung beetles, mainly due to the negative effects of chemical control against weeds and pests, such as herbicides and pesticides, as, for example, when controlling the horn fly (
A decline in the population of dung beetles in prairies has great importance in intensive livestock production systems, where the greatest accumulation of manure cannot be eliminated by native insects. In those cases, as a management measure, entomologists propose the introduction of exotic dung beetle species. However, previous to such decisions, it becomes necessary to carry out studies for assessing possible losses of native species, as it has already happened in other parts of the world, such as in Colombia where the release of
There are 10 native species identified in the literature as native species of dung beetles in Chile, four paracoprids and five telecoprids with no records of endocoprids . They are
|Endocoprids||Scarabaeidae||No records and there is not any species reported uncertain. |
There are few studies on both native and introduced dung insects in South Central Chile. One study in horse droppings was focused on the biology of
The sample was conducted in five agro-ecological areas of La Araucanía Region covering approximately 3,184,200 ha (see Ref. ). La Araucania Region is located in Southern Chile and corresponds to a transitional zone between a dry Mediterranean and climate. As most of South Central Chile, the region is divided into five different landscapes: (1) coastal rain fed area (CRF) that includes the coast (west side of coastal range) and the coastal range; (2) the interior rain fed area (IRF) that includes the dry east-side of the coastal range; (3) the central plain (CP) that includes the flat lands of the central valley; (4) the pre-Andean area (PA) that includes lands of the piedmont of the Andes Mountains; and (5) the vo1canic Andean area (VA) that corresponds to Andes Mountains. The Pluviometry varies from west to east, with notorious lower precipitations in the east side of the coastal range. Temperature decreases from west to east in the measure altitude increases to up in the Andes. The differences in temperature and altitude determine some vegetation differences. Therefore, in the coastal range and its east side will be dryer with sclerophyll vegetation; the central valley will be a transition between sclerophyll and rainy temperate and evergreen forests, with these temperate forests covering until the piedmont of the Andes and, with changes in species distribution, leaving space to species better adapted to low temperature. At higher altitude, forests of Chilean monkey puzzle trees (
In each agro-ecological area described above, we chose between 5 and 15 sampling areas based on the presence in pastures of manure from cattle and horses, and within native and exotic forests. The sampling areas were chosen and marked over the agroecologic map of the Araucanía Region .
At the same time, in each of these sampling areas, we chose as many as possible sampling points, where we sampled and measured the presence and abundance of insects in, over and around feces, and prepared a list of dung beetles. The sampling process was conducted during spring, summer and autumn, for 3 years (2008–2010). The observations were made during 30 minutes at each sampling place, and then samples with organic material were taken for analyses to laboratory. Once in the laboratory, the samples were compared against the material of reference (specimens) that are kept at Museum of Entomology, to assure a correct identification and classification of sample specimens. In a parallel procedure, the classification keys were examined in the literature. Insect samples were deposited in the Entomological collection at the Museum of Entomology.1 Each sampling place was georeferenced using a GPS devise “Garmin”.
In addition to the sampling areas, we had installed two light traps. Such light traps included a container to receive the insects. The traps were 1.1 m high and weighted approximately 5 kg each. The traps contained an ultraviolet illumination tube of 43 cm long and 20 W.
One in a farm located in the urban border of Temuco city, southern Chile and the second in the Experimental and Model Farm Maquehue, located at 38°50′27.20S 72°41′34.32″W at 12 km far from Temuco city. Both traps were set up for 10 years (year 2000–2010). The samples from each light trap were collected on daily basis and taken to the laboratory, for analysis and specimen classification.
3. Results and discussion
In our prospection performed in the sampling process (2008–2010) and during years 2000 and 2010 (light traps), we found four species of dung beetles in La Araucanía, which are detailed in Table 2.
We did not register the rest of dung beetles described in the literature nor the exotic ones. Apart of those detailed in Table 2, we would have expected to find in La Araucanía Region, the native species
From the four species recorded in the study,
Regarding the seasonal flight of the two species
Results indicate these species have completely unknown behavior in regards their univoltine life cycle. At least, one can know where they are when adults do not appear. It is interesting the fact that adults of both species coexist with adults of
Regarding the samples collected with the light traps (Figures 1 and 2), specimens of
It was found that
Regarding the distribution of species in La Araucanía Region (Figures 4–6), it should be noted that according to the sampling methodology, where the observations were made at different times, we were able to describe the sample distribution of
In Figure 4, we can see that both species are well distributed across the region, but
In regards the preference for a type of vegetation, samples were taken in both native forest and forestry plantations and, according to registered data, both specimens of
According to the present study, we found evidence that dung beetles are well distributed in La Araucania region, where we were able to collect specimens from four species. They are
All the species registered in this study are native. It is worth to mention that we did not find any specimen of those introduced species two decades ago. Besides, we could not find any record of previous studies that have found any specimen from such introduced species, which help in confirming our findings.
Also, we could not find any evidence, as mentioned in the literature, that dung beetles are present in higher frequency in manure located in native forests. We only could confirm that dung beetles are abundantly present in manure, independently of the type of cattle or type of forest (native or exotic) or vegetation cover, that is, they are present in forests, grasslands or any vegetation cover where there is manure that have been directly deposited over the ground by cattle. It is worth to note that dungs from wild animals like puma or foxes were not checked as part of this study.
The distribution of
Finally, in the particular case of
- Laboratory of Applied Entomology at the Faculty of Agricultural and Forest Sciences, University of La Frontera, Chile.