Distribution and Feeding Behavior of Omorgus suberosus (Coleoptera: Trogidae) in Lepidochelys olivacea Turtle Nests

Abstract

Omorgus suberosus (Fabricius, 1775) has been identified as a potential predator of the eggs of the turtle Lepidochelys olivacea (Eschscholtz, 1829) on one of the main turtle nesting beaches in the world, La Escobilla in Oaxaca, Mexico. This study presents an analysis of the spatio–temporal distribution of the beetle on this beach (in areas of high and low density of L. olivacea nests over two arrival seasons) and an evaluation, under laboratory conditions, of the probability of damage to the turtle eggs by this beetle. O. suberosus adults and larvae exhibited an aggregated pattern at both turtle nest densities; however, aggregation was greater in areas of low nest density, where we found the highest proportion of damaged eggs. Also, there were fluctuations in the temporal distribution of the adult beetles following the arrival of the turtles on the beach. Under laboratory conditions, the beetles quickly damaged both dead eggs and a mixture of live and dead eggs, but were found to consume live eggs more slowly. This suggests that O. suberosus may be recycling organic material; however, its consumption of live eggs may be sufficient in some cases to interrupt the incubation period of the turtle. We intend to apply these results when making decisions regarding the L. olivacea nests on La Escobilla Beach, one of the most important sites for the conservation of this species.

Checklist of the superfamily Scarabaeoidea (Insecta, Coleoptera) in an urban area of the Caribbean Colombia

“…Omorgus suberosus (Fabricius, 1775) Figure 5P Geographic distribution. America (Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Guatemala, Panama, Paraguay, Peru, Mexico, Nicaragua, and Venezuela) (Scholtz 1990, Deloya 2000, Ratcliffe 2002, Aballay et al 2008, Diéguez 2008, Correa et al 2013, Baena et al 2015, Salazar and Donoso 2015. In Colombia: Atlántico, Cesar, Chocó, Cundinamarca, Magdalena, and Norte de Santander (Scholtz 1990, Neita-Moreno 2011.…”

Identification and evaluation of semiochemicals for the biological control of the beetle Omorgus suberosus (F.) (Coleoptera: Trogidae), a facultative predator of eggs of the sea turtle Lepidochelys olivacea (Eschscholtz)

“…Furthermore, give that a turtle generation (~20 years) corresponds at least to 20 generations of the beetle O . suberosus (if we considered a generation per year, although it is possible that this species has several generations per year since the duration of its life cycle is of about 50 days only) [ 13 ] it is feasible to predict an exponential increase of beetle population since it has been reported in the last fifteen years [ 10 ]. Due to this particular scenario, predation of live and dead turtle eggs by O .…”

“…Due to this particular scenario, predation of live and dead turtle eggs by O . suberosus has clearly been observed in the form of shell mastication and also through the presence of beetle larvae and adults in the turtle embryos [ 9 , 11 , 12 , 13 ] ( Fig 2 ).…”

“…suberosus is normally necro–saprophagous in habit (adults and larvae feed on keratinose matter, mostly comprising animal materials, such as feathers, hair, skin, hair and bone in the final stages of decomposition, and carnivore droppings) [ 18 ]; however, it has also been reported as a facultative predator beetle of eggs of the turtle L . olivacea in Mexico [ 13 ], of the turtle Chelonia mydas (L.) in Costa Rica [ 14 ] and eggs and embryos in the Galapagos Islands (Ecuador) [ 16 , 17 ], even eating eggs of the grasshopper Schistocerca cancellata (Serville) in Argentina [ 19 ]. Furthermore, a close related species, Omorgus procerus (Harold), described as a predator of eggs of Schistocerca gregaria (Forskål) in Somalia [ 19 ], in 1966, was released on Sand Island in Honolulu to combat the invasive grasshopper S .…”

“…olivacea nests has favoured an exponential increase in the population of O . suberosus , which has been associated with a high percentage of the egg destruction at La Escobilla [ 13 ]. This study suggests that this beetle could be a considerable factor in the mortality of the embryos, thus affecting recruitment into the population of L .…”