Attraction of Adults of Cyclocephala lunulata and Cyclocephala barrerai (Coleoptera: Scarabaeoidea: Melolonthidae) towards Bacteria Volatiles Isolated from Their Genital Chambers

Abstract

In the study of the chemical communication of adults of the Melolonthidae family, bacteria have been observed in the epithelium of the genital chamber; possibly, bacteria are involved in the production of sex attractants in their hosts. Therefore, it is important to identify the volatile organic compounds from bacteria (VOCsB) released by these microorganisms and study the biological activity stimulated by VOBCs in adults of Melolonthidae. In this study, bacteria were isolated from the genital chamber of Cyclocephala lunulata and Cyclocephala barrerai, from which VOCsB were extracted using static headspace solid-phase microextraction (SHS-SPME) and dynamic headspace Super Q solid-phase extraction (DHS-SPE) and analyzed using gas chromatography-mass spectrometry. The effect of VOCsB on the hosts and conspecifics was evaluated utilizing an olfactometer and electroantennography (EAG). Two species of Enterobacteria were isolated from the genital chamber of each female species, and VOCsB derived from sulfur-containing compounds, alcohols, esters, and fatty acids were identified. An attraction response was observed in olfactometry studies, and antennal responses to VOCsB were confirmed in EAG bioassays. With these results, new perspectives on the relationship between these beetles and their bacteria emerge, in addition to establishing a basis for management programs in the future.

Reproductive Apparatus, Gonadic Maturation, and Allometry of Cyclocephala barrerai Martínez (Coleoptera: Melolonthidae: Dynastinae)

“…The presence of microorganisms in the female genital chamber agrees with a previous report [ 30 ] that identified Klebsiella oxytoca and Citrobacter freundii in C. barrerai wild females. The presence of microorganisms in lab-reared females indicates that these might be transferred by the mother or acquired during the larval period and not transferred by the male during mating.…”

“…The presence of microorganisms in lab-reared females indicates that these might be transferred by the mother or acquired during the larval period and not transferred by the male during mating. The architecture of the genital chamber and the presence of microorganisms suggest that they are relevant during attractant production [ 14 , 30 ].…”

“…The genital chamber and accessory glands of Cyclocephala jalapensis Casey are particular for this species, and the rest of its reproductive apparatus is very similar to that of other Melolonthidae [ 29 ]. Recently, Sanchez-Cruz et al [ 30 ] reported that the internal walls of the genital chamber of C. barrerai females show oval or round 2–10 μm long bacteria. The male reproductive apparatus has been described for C. jalapensis , Cyclocephala picta Burmeister, Cyclocephala sexpunctata Castelnau, Cyclocephala mafaffa Burmeister, Cyclocephala lunulata Burmeister, and Cyclocephala weidneri Endrödi, with the parameres showing the widest variation among these species [ 9 ].…”

“…There is no available management program for this pest. However, adults are attracted to volatiles produced by symbiotic bacteria from the female genital chamber [ 30 ].…”

Uncovering Active Bacterial Symbionts in Pollen-Feeding Beetles

“…In other hosts, Sodalis provision nutrients such as tyrosine, lysine, biotin and ribo avin [30], suggesting the potential for bene cial impacts. Another bacterium, Morganella -found in other insects and beetles [31,32] -was also active in the two generalist species (Fig. 1).…”