Dung Beetles of Chile, with Emphasis in La Araucania Region

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

Virtual Screening of Plant Volatile Compounds Reveals a High Affinity of Hylamorpha elegans (Coleoptera: Scarabaeidae) Odorant-Binding Proteins for Sesquiterpenes From Its Native Host

Indexación: Web of ScienceHylamorpha elegans (Burmeister) is a native Chilean scarab beetle considered to be a relevant agricultural pest to pasture and cereal and small fruit crops. Because of their cryptic habits, control with conventional methods is difficult; therefore, alternative and environmentally friendly control strategies are highly desirable. The study of proteins that participate in the recognition of odorants, such as odorant-binding proteins (OBPs), offers interesting opportunities to identify new compounds with the potential to modify pest behavior and computational screening of compounds, which is commonly used in drug discovery, may help to accelerate the discovery of new semiochemicals. Here, we report the discovery of four OBPs in H. elegans as well as six new volatiles released by its native host Nothofagus obliqua (Mirbel). Molecular docking performed between OBPs and new and previously reported volatiles from N. obliqua revealed the best binding energy values for sesquiterpenic compounds. Despite remarkable divergence at the amino acid level, three of the four OBPs evaluated exhibited the best interaction energy for the same ligands. Molecular dynamics investigation reinforced the importance of sesquiterpenes, showing that hydrophobic residues of the OBPs interacted most frequently with the tested ligands, and binding free energy calculations demonstrated van der Waals and hydrophobic interactions to be the most important. Altogether, the results suggest that sesquiterpenes are interesting candidates for in vitro and in vivo assays to assess their potential application in pest management strategies.http://jinsectscience.oxfordjournals.org/content/16/1/3

<i>Steinernema australe</i> Enhanced Its Efficacy against <i>Aegorhinus</i> <i>nodipennis</i> (Coleoptera: Curculionidae) Larvae in Berry Orchards after an Artificial Selection Process

The entomopathogenic nematode (EPN) Steinernema australe was isolated from Isla Santa Magdalena in Chile and identified as a good alternative for controlling Aegorhinus nodipennis (Coleoptera: Curculionidae) larvae. This weevil is native to the south of Chile and some regions in Argentina, causing the decline and ultimate death of plants in berry orchards. The major problem brought about by the weevil is caused by the larvae, which spend between nine and eleven months below ground, feeding inside the roots of the plants. This study seeks to increase S. australe’s efficacy through an artificial selection process using an odor stimulus. We selected infective juveniles (IJs) that followed the stimulus in order to reach larvae at a depth of 30 cm to achieve this objective. Larvae infected with selected IJs and IJs from the original stock were compared under laboratory, greenhouse, and field conditions. The results showed a 20% increase in the efficacy of selected IJs compared with IJs from the original stock. We observed a higher proportion of selected IJs that reached the larvae faster during the first four days post-application. Moreover, larvae treated with selected IJs were depleted, with a mix of nematode stages emerging from the cadaver. Finally, a potential trade-off with regard to the recycling of nematodes into the soil is proposed