Antennal sensilla in Cyclocephala literata Burmeister, 1847 (Coleoptera: Scarabaeidae: Dynastinae)

Abstract

Adults of the beetle Cyclocephala literata Burmeister, 1847 are important pollinators to some Magnoliaceae. Is known that insects could find host plants by detecting volatiles through antennal sensilla. Cyclocephala has its three distal antennomeres lamellate, and the surface of each lamella has sensilla trichodea, chaetica, placodea, coeloconica, basiconica and ampullacea. Three kinds of sensilla placodea were found (type I, II and III), and two kinds of sensilla coeloconica were observed (type I and II). Females have on average 10,776 sensilla, of which 10,214 are sensilla placodea, 536 are sensilla coeloconica, and 26 are sensilla basiconica. Males have on average 10,386 sensilla, of which 9,873 are sensilla placodea, 464 are sensilla coeloconica, and 49 are sensilla basiconica. Males and females have similar quantities of sensilla, and sensilla placodea are predominant. The differences observed in the number of sensilla of males and females were found in other beetles and were attributed to the detection of cospecific sexual pheromones by one of the sexes, or to the detection of plant volatiles. The antennal sensilla of C. literata is described and quantified in present study, and some perspectives about the differences kind of chemical communication, pollination, and antennae dimorphism is discussed.

Antennal sensilla of two species of Gymnetis MacLeay, 1819 (Coleoptera: Scarabaeidae: Cetoniinae)

“…4A) and restricted the term sensilla basiconica to longer sensilla surrounded or not by a pit. The sensilla basiconica found on genera Cyclocephala (Dynastinae: Cyclocephalini; Saldanha et al, 2020;Nagamine et al, 2022) and Anomala (Rutelinae: Anomalini; Rodrigues et al, 2019) are not found in Cetoniinae genera of the tribe Gymnetini: Cotinis (described by Baker and Monroe, 2005), Gymnetis (by present study), and Hoplopyga (by Costa et al, 2021); and are also not found in other flower chafers as Osmoderma (Osmodermatini; by Zauli et al, 2016: sensilla basiconica sub-type 1 is here interpreted as a sensilla coeloconica variation) and Pachnoda (by Bengtsson et al, 2011).…”

“…These setae are designated here with sensilla chaetica, but other studies termed these setae as sensilla trichodea (as Bohacz et al, 2020). Despite the term used (see terminology in Material and Methods), the presence of this group of setae is a conspicuous character of Cetoniinae and part of Dynastinae (Bohacz et al, 2020;Costa et al, 2021), is inconspicuous to Rutelinae and part of Dynastinae (Cyclocephalini; Rodrigues et al, 2019;Saldanha et al, 2020;Nagamine et al, 2022), and is indistinct in Melolonthinae (Bohacz et al, 2020;Menis et al, 2021). In Rutelinae and Cyclocephalini, the outer side of proximal lamella has a sparse group of setae, and these setae are not evidently different from other setae present on lamellar edges (Rodrigues et al, 2019;Nagamine et al, 2022).…”

“…The inner side of proximal and distal lamella and both sides of medial lamella have two well defined area, a posterior homogeneous area mainly formed by sensilla placodea type II, and an anterior heterogeneous area with sensilla coeloconica (type I and II), and sensilla placodea (mostly type I). These areas are present in Cetoniinae, Dynastinae, Rutelinae, and Melolonthinae (Rodrigues et al, 2019;Bohacz et al, 2020;Costa et al, 2021;Menis et al, 2021;Nagamine et al, 2022). Larsson et al (2001) noted that the sensilla of homogeneous area is responsible to the sexual pheromone detection, and those of heterogeneous area are responsible to other volatiles detection in the ruteline Anomala cuprea (Hope, 1839).…”