Chemical diversity and potential biological functions of the pygidial gland secretions in two species of Neotropical dung roller beetles

Abstract

Dung roller beetles of the genus Canthon (Coleoptera: Scarabaeinae) emit an odorous secretion from a pair of pygidial glands. To investigate the chemical composition of these secretions, we used stir bar sorptive extraction (SBSE), coupled with gas chromatography-mass spectrometry (GC-MS) for analysis of extracts of pygidial gland secretions secreted by the dung roller beetles Canthon femoralis femoralis and Canthon cyanellus cyanellus. Chemical analyses of volatiles collected from pygidial gland secretions comprise a great diversity of the functional groups. Chemical profile comparisons showed high intra-and interspecific variability. The pygidial gland secretion of Canthon f. femoralis was dominated by sesquiterpene hydrocarbons, whereas the profile of Canthon c. cyanellus was dominated by carboxylic acids. The different pygidial secretions have a high diversity of chemical compounds suggesting a multifunctional nature involving some key functions in the biology. We discuss the biological potential of these compounds found in the pygidial glands of each species with respect to their ecological and behavioral relevance.

The Rolling of Food by Dung Beetles Affects the Oviposition of Competing Flies

“…Also, there are a number of exocrine glands located on the abdomens of Deltochilum species [ 18 ], which in Canthon sp. are known to serve several functions [ 8 , 9 ], so it is possible that secretions from several different glands may be applied during rolling.…”

“…The secretions deposited may act as allomones, directly affecting female fly oviposition behavior. However, during rolling the food may be contaminated with fungi and bacteria that negatively affect the beetle larvae [ 20 ] and chemical substances from abdominal exocrine glands help inhibit the growth of these microorganisms [ 21 ], including the pygidial glands [ 9 ]. Several fly species have been shown to preferentially lay eggs on substrates with bacteria rather than on sterile ones [ 22 , 23 , 24 , 25 , 26 ] as the bacteria may be essential dietary components for developing maggots [ 25 , 27 ] and/or may cause the release essential nutrients from the substrate though enzymatic action [ 25 , 28 ].…”

“…Favila [ 7 ] demonstrated that fresh male secretions, probably from the fifth abdominal sternite, were attractive to conspecific females, and secretions from different glands in Canthon species serve to deter competitors and predators [ 5 , 8 ], leading Cortez et al [ 9 ] to suggest that these secretions may serve multiple purposes. This idea is supported by studies on other dung beetles: for example, male secretions from glands situated on the first abdominal sternite of Kheper species are involved in mating [ 10 , 11 ], while adults of Oniticellus egregius (Klug, 1855) produce secretions from the lateral edges the anterior abdominal segments that play a role in defence [ 12 , 13 ].…”

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)

“…For analysis of the chemical compounds, the relative abundance value of the samples was calculated using the relative peak area of each compound, calculated by dividing the individual peak area by the total peak area of all compounds, and expressing the result as a percentage [ 36 ]. Similarity between the samples was calculated with a hierarchical clustering (CLUSTER) analysis using Whittaker’s index of association, which is appropriate for relative abundance data [ 37 ].…”

Nesting strategies and disease risk in necrophagous beetles

“…The characteristic upside-down position during rolling (Figure 1b) permits impregnation of secretions in the food ball (Bellés & Favila, 1983;Cortez-Gallardo & Favila, 2007;Favila, 1988;Pluot-Sigwalt, 1991), but the nature of these secretions remains poorly studied. Recently, a great diversity of compounds was identified (Cortez et al, 2015) in the secretion of the pygidial gland of the necrophagous roller beetle Canthon cyanellus cyanellus (Pluot-Sigwalt, 1988a,b, 1991. Some of the identified compounds have potentially defensive, preservative (retarding spoilage), and antimicrobial functions (Cortez et al, 2015;Cortez-Gallardo & Favila, 2007).…”