Antennal sensilla in Cyclocephala literata Burmeister, 1847 (Coleoptera: Scarabaeidae: Dynastinae) / Sensilas antenais em 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.

Resumo: Adultos do besouro Cyclocephala literata Burmeister, 1847 desempenham importantes funções de polinização em plantas da família Magnoliaceae. É conhecido que muitos insetos encontram plantas hospedeiras pela detecção de voláteis pelas sensilas antenais. Cyclocephala possui os três antenômeros distais lamelados e na superfície de cada lamela possuem sensila trichodea, caética, placódea, coelocônica, basicônica e ampulacea. Foram encontrados três tipos de sensilas placódeas (tipo I, II e III), e dois tipos de sensilas coelocônicas (tipo I e II). Fêmeas apresentam em média 10.776 sensilas, das quais 10.214 são sensilas placódeas, 536 são sensilas coelocônicas e 26 são sensilas basicônicas. Os machos apresentaram em média 10.386 sensilas, das quais 9.873 são sensilas placódeas, 464 são sensilas coelocônicas e 49 são sensilas basicônicas. Machos e fêmeas apresentam quantidades semelhantes de sensilas e as sensilas placódeas são predominantes. As diferenças encontradas nas quantidades de sensilas em machos e fêmeas também foram encontradas em outros besouros e foram atribuídas a detecção de feromônios coespecíficos por um dos sexos, ou para detecção de voláteis de plantas. A sensila antenal de C. literata é descrita e quantificada no presente estudo, e algumas perspectivas sobre as diferenças entre os tipos de comunicação química, polinização e dimorfismo antenal é discutido.

Description of mating behavior, life cycle, and antennal sensilla of Cyclocephala putrida Burmeister, 1847 (Coleoptera, Scarabaeidae, Dynastinae) / Descrição do comportamento de cópula, ciclo de vida e sensilas antenais de Cyclocephala putrida Burmeister, 1847 (Coleoptera, Scarabaeidae, Dynastinae)

Abstract The genus Cyclocephala is common in Brazil (Coleoptera, Scarabaeidae, Dynastinae). The adults of some species are important pollinators, and the larvae develop in the soil, feed on organic matter, and contribute to nutrient cycle, but immatures of some species feed on plant roots, and some were registered causing damage in crops. The mating process of some phytophagous scarab beetles has a chemical recognition step, and the antenna is the main structure involved in the detection of odorants associated with insect communication. In the present study the mating behavior, life cycle, and antennal sensilla of C. putrida are described. The study was conducted at the Universidade Estadual de Mato Grosso do Sul, Cassilândia, Brazil. Adults were collected by a light trap installed from January 2016 to December 2017 and were taken to the laboratory for studies. Adults swarms are brief and were registered from January to February, and specimens were mostly collected at 20:00 to 22:00h. Chemical recognition may occur at least during one of the mating steps, during which the couple kept their antennae moving and the lamellae open, while females select males. In laboratory, the mating process lasted 7.5 minutes on average. The antennae of females have about 3399 sensilla and males about 4229 sensilla. Sensilla placodea types I, II, and III are the most abundant, and sensilla ampullacea, basiconica, and coeloconica are also present. The embryonic period lasted 16.0 days; first, second and third instars lasted 16.0, 48.3, and 165.3 days, respectively. The pupal period lasted 24.0 days. The period between egg deposition and adult emergency is about 271.5 days.

Resumo O gênero Cyclocephala é comum no Brasil (Coleoptera, Scarabaeidae, Dynastinae). Os adultos de algumas espécies são importantes polinizadores, e a larva desenvolve-se no solo, alimenta-se de matéria orgânica e contribui para a ciclagem de nutrientes, mas imaturos de algumas espécies alimentam-se de raízes de plantas, e alguns são registrados causando danos em plantas cultivadas. O processo de cópula de algumas espécies de Scarabaeidae fitófagos, apresentam reconhecimento químico, e nas antenas aparecem várias estruturas responsáveis pela detecção dos odores envolvidos na comunicação. No presente trabalho o comportamento de cópula, ciclo de vida e sensilas antenais de Cyclocephala putrida são descritos. O estudo foi conduzido na Universidade Estadual de Mato Grosso do Sul, Cassilândia, Brasil. Adultos foram coletados com armadilha luminosa instalada de Janeiro de 2016 a Dezembro de 2017, e levados para laboratório para estudos. Os adultos revoam por curto período de janeiro a fevereiro, e os espécimes foram coletados em maior quantidade das 20:00 às 22:00 h. O reconhecimento químico possivelmente ocorre durante as etapas que envolvem o comportamento de cópula, no qual o casal mantém as antenas em movimento e as lamelas abertas e as fêmeas selecionam os machos. Em laboratório a cópula dura 7,5 minutos em média. As antenas das fêmeas possuem 3399 sensilas e os machos 4229 sensilas, e as sensilas placódeas dos tipos I, II e III, foram as mais abundantes e sensilas ampuláceas, basicônicas e coelocônicas também estão presentes. O estágio de ovo durou 16,0 dias; o primeiro, segundo e terceiro instar duraram 16,0, 48,3 e 165,3 dias, respectivamente. O período pupal durou 24,0 dias. O período entre deposição dos ovos e emergência dos adultos é de 271,5 dias em média.

Population dynamics and description of larva and pupa of Cyclocephala tucumana Bréthes, 1904 in West-Central Brazil, and remarks on immatures of other Cyclocephala species (Coleoptera: Scarabaeidae: Dynastinae)

ABSTRACT Some species of Cyclocephala Dejean, 1821 (Coleoptera, Scarabaeidae, Dynastinae, Cyclocephalini) were reported as crop or pasture pests. Within this genus, Cyclocephla tucumana Bréthes, 1904 was noticed in cultivated areas in South Brazil, 2009 − 2010. Other study found larvae of the species associated with pastures in Aquidauana, Mato Grasso do Sul State (MS), 2009. In the present study, larvae of C. tucumana were collected in pasture areas from August 2015 to July 2016, in Cassilândia, MS. The material was reared in laboratory for the description of immatures, and the regional population was studied to clarify its dynamics. Immatures were abundant throughout the years and are described for the first time. Taxonomic discussion, updated key to larvae and pupae, and a teratological note are also added.

Flight patterns and sex ratio of beetles of the subfamily Dynastinae (Coleoptera, Melolonthidae)

ABSTRACT Dynastinae is one of the most representative subfamilies of Melolonthidae (Scarabaeoidea) and has considerable ecological importance due mainly to interactions with plants of the families Araceae and Annonaceae. This relationship has led to the evolution of nocturnal activity patterns, which are influenced by environmental conditions. In the present study, abiotic factors were investigated to comprehend the influence on the flight patterns and identify the sex ratio of beetles from this subfamily. A study was conducted at Campo de Instrução Marechal Newton Cavalcanti in northeastern Brazil between December 2010 and November 2011. Thirteen species of Dynastinae were identified, most of which were from the genus Cyclocephala. Abundance and richness were greater in the dry season. Six species exhibited peak flight activity at specific periods of the night. More females than males were recorded for Cyclocephala distincta and C. paraguayensis. The present findings suggest that rainfall reduces the flight activity of these beetles and different time schedules may be related to mating behavior, foraging behavior and the avoidance of interspecific resource competition.

Biological aspects of Cyclocephala tucumana Brethes, 1904 and Cyclocephala melanocephala (Fabricius, 1775) (Coleoptera: Scarabaeidae) / Aspectos biológicos de Cyclocephala tucumana Brethes, 1904 e Cyclocephala melanocephala (Fabricius, 1775) (Coleoptera: Scarabaeidae)

The studies were conducted on the biological aspects of Cyclocephala tucumana Brethes, 1904 and C. melanocephala (Fabricius, 1775) in Aquidauana, MS, Brazil. From January to December 2009 a light trap was installed to make collections of adults of C. tucumana and from January 2010 to February 2011 for collections of adults of C. melanocephala, at the experimental farm of the Universidade Estadual de Mato Grosso do Sul. Adults were maintained in plastic containers with soil and complete plants of Brachiaria decumbens Stapf cv. Basilisk to oviposition and start biological studies. Adults of C. tucumana were collected from September to November in the field; the embryonic period lasted on average 14.7 days, and the first, second and third larval instars lasted 47.7, 66.1 and 78.6 days, respectively. Pre-pupa and pupa phases lasted 98.2 and 15.1 days, respectively, and longevity of the adults was 13.3 days. From the egg to adult stage of C. tucumana was a period of average 211.2 days. Adults of C. melanocephala were collected from September to October 2010 and February 2011. The embryonic period lasted 17.8 days, and larvae in the first, second and third instars lasted 22.3, 21.0 and 27.0 days, respectively. The pre-pupa stage lasted 11.3 days and pupa phase lasted 13.3 days. The longevity of adults was 26 days, and the cycle from egg to adult lasted 113 days.

Foram desenvolvidos estudos sobre os aspectos biológicos de Cyclocephala tucumana Brethes, 1904 e C. melanocephala (Fabricius, 1775) em Aquidauana, MS. Foi instalada uma armadilha luminosa de janeiro a dezembro de 2009 para obter adultos de C. tucumana e de janeiro de 2010 a fevereiro de 2011 para obter adultos de C. melanocephala, na fazenda experimental da Universidade Estadual de Mato Grosso do Sul. Adultos foram mantidos em recipientes de plástico, contendo solo e plantas de Brachiaria decumbens Stapf cv. Basilisk, para oviposição e início dos estudos biológicos. Os adultos de C. tucumana foram coletados de setembro a novembro no campo, o período embrionário durou em média 14,7 dias, e o primeiro, segundo e terceiro instar larval duraram 47,7, 66,1 e 78,6 dias, respectivamente. As fases de pré-pupa e pupa duraram 98,2 e 15,1 dias, respectivamente, e a longevidade dos adultos foi de 13,3 dias. A fase de ovo a adulto de C. tucumana durou em média 211,2 dias. Os adultos de C. melanocephala foram coletados em setembro e outubro de 2010 e em fevereiro de 2011. O período embrionário durou 17,8 dias, as larvas no primeiro, segundo e terceiro instar duraram 22,3, 21,0 e 27,0 dias, respectivamente. A fase de pré-pupa durou 11,3 dias a pupa durou 13,3 dias. A longevidade dos adultos foi de 26 dias, e o ciclo de ovo a adulto durou 113 dias.