Annotated catalog and bibliography of the cyclocephaline scarab beetles (Coleoptera, Scarabaeidae, Dynastinae, Cyclocephalini)

Cuticular lipid profiles of selected species of cyclocephaline beetles (Melolonthidae, Cyclocephalini)

Neotropical cyclocephaline beetles, a diverse group of flower-loving insects, significantly impact natural and agricultural ecosystems. In particular, the genus Cyclocephala, with over 350 species, displays polymorphism and cryptic complexes. Lacking a comprehensive DNA barcoding framework, accessible tools for species differentiation are needed for research in taxonomy, ecology, and crop management. Moreover, cuticular hydrocarbons are believed to be involved in sexual recognition mechanisms in these beetles. In the present study we examined the cuticular chemical profiles of six species from the genus Cyclocephala and two populations of Erioscelis emarginata and assessed their efficiency in population, species, and sex differentiation. Overall we identified 74 compounds in cuticular extracts of the selected taxa. Linear alkanes and unsaturated hydrocarbons were prominent, with ten compounds between them explaining 85.6% of species dissimilarity. Although the cuticular chemical profiles efficiently differentiated all investigated taxa, only C. ohausiana showed significant cuticular profile differences between sexes. Our analysis also revealed two E. emarginata clades within a larger group of 'Cyclocephala' species, but they were not aligned with the two studied populations. Our research underscores the significance of cuticular lipid profiles in distinguishing selected cyclocephaline beetle species and contemplates their potential impact as contact pheromones on sexual segregation and speciation.

Egg development and viability in three species of Cyclocephala (Coleoptera: Scarabaeidae: Dynastinae)

Different species of Cyclocephala scarab beetles (Scarabaeidae, Dynastinae) perform key functional roles in both natural and agricultural systems, such as the cycling of organic matter and pollination, while also being known as destructive pests both as immatures and adults. Therefore, the identification of biological parameters is crucial for defining strategies for their conservation and efficient pest management. In a forest fragment within the Brazilian Atlantic Forest biodiversity hotspot, we field-captured adult individuals of Cyclocephala cearae, C. celata, and C. paraguayensis then reared and bred them under controlled temperature and humidity conditions. On a daily basis, we individually weighted eggs of all three species, from oviposition until hatching, and monitored egg development parameters (i.e., incubation duration, viability, and egg weight increase). Our findings provide novel empirical evidence showing (i) a positive correlation between egg weight and incubation duration, (ii) idiosyncratic characteristics on egg development, and (iii) a negative (involuntary) effect of manipulation on egg development and viability. Thus, the successful breeding and rearing of Cyclocephala spp. is correlated with egg integrity and the targeted species. Our analyses present a quantitative understanding of the egg phase and can assist in refining strategies for ovicidal activity and pest management of Cyclocephala spp. in agriculture systems. Moreover, they can provide a basis for new studies related to captivity breeding, pollinator management, and developmental biology for biodiversity conservation.

Methyl benzoate and nerolidol attract the cyclocephaline beetle Cyclocephala paraguayensis to trumpet flowers

Cyclocephaline beetles are flower visitors attracted primarily by major floral volatiles. Addressing the identity of these volatile compounds is pivotal for understanding the evolution of plant-beetle interactions. We report the identification and field testing of the attractant volatiles from trumpet flowers, Brugmansia suaveolens (Willd.) Sweet (Solanaceae), for the beetle Cyclocephala paraguayensis Arrow (Melolonthidae: Dynastinae). Analysis of headspace floral volatiles revealed 19 compounds, from which eucalyptol (57%), methyl benzoate (16%), and β-myrcene (6%) were present in the largest amounts, whereas E-nerolidol in much lesser amounts (1.8%). During a first-field assay, traps baited with Mebe alone or blended with the other two major compounds attracted more beetles than myrcene and eucalyptol alone, which did not differ from the negative controls. In a second assay, Mebe and nerolidol attracted more beetles as a blend than individually. Nerolidol was more attractive than Mebe, and all treatments attracted more beetles than negative controls. The number of attracted beetles in the Mebe-nerolidol blend was greater than the combined sum of beetles attracted to these compounds alone, suggesting a synergistic interaction. The attraction of C. paraguayensis by trumpet-flower volatiles supports the beetle's extended preference for sphingophilous plants, especially when cantharophilous (beetle-pollinated) flowers are lacking. This phenomenon, thus, might have contributed to the widespread occurrence of this beetle throughout the Brazilian biomes.

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

Simple Summary

Cyclocephala barrerai larvae feed on the roots of ornamental and commercial grasses. Most of their biology is still unknown, and there are no tools to manage their populations. The objective of this work was to study the reproductive system, gonadic maturation, and allometry of C. barrerai. This is the first report into the Melolonthidae family that characterizes the reproductive apparatus, gonadic maturation of both sexes, and allometric relationships of virgin F1 specimens. Adults do not feed, so gonadic maturation depends on larvae reserves. Females present sclerotized accessory glands and a genital chamber with muscular fibers and bacteria. The morphology of the parameres and the antennae are under sexual selection. This is the first report of two main differences among sexes: females are heavier while males have longer antennae. Males and females exhibit allometric relationships that can be used to predict the bodyweight of field-collected specimens.

Abstract

The Order Coleoptera provides good examples of morphological specializations in the reproductive apparatus, gonadic maturation, and allometry differing between the sexes. The female and male reproductive apparatus has been modified to ensure reproduction between individuals of the same species. The genus Cyclocephala has more than 500 species distributed in America, and Cyclocephala barrerai Martínez is an economically important species in the central part of Mexico. The objective of this work was to study the reproductive system, gonadic maturation, and allometry of C. barrerai. We used light, scanning electron, and laser scanning confocal microscopy to describe the reproductive apparatus and gonadic maturation of females and males. The relationship between adult weight and different parts of the body was established by linear regression. Regardless, the reproductive apparatuses of C. barrerai are like those of other Melolonthidae: the genital chamber, the type II accessory glands, and the ventral plaques of the female and the ejaculator bulb and genital capsule of the males are specific to C. barrerai. The gonads are fully developed when 18 d old. The weight of adult C. barrerai has a positive linear relationship with distinct parts of its body, while the antennae of males are larger than those of the females.

Actualización a la lista de coleópteros (Insecta: Coleoptera) de la región Piura, Perú

Con base en colectas, registros en la bibliografía y revisión de material depositado en colecciones entomoló-gicas se realiza una actualización a la lista de coleópteros de la región Piura en Perú, añadiendo nuevas especies y nuevos datos distribucionales. Se adicionan 72 especies, 52 géneros y 5 familias, con lo cual la cantidad de coleópteros para la región se eleva a 317 especies, 255 géneros y 38 familias, mientras que para 13 especies ya conocidas se reportan nuevos datos provinciales ampliando su distribución dentro de la región. Ahasverus advena (Waltl, 1834), Alaetrinus pullus (Sahlberg, 1823), Taeniotes marmoratus Thomson, 1865 y el género Coscinoptera Lacordaire, 1848 se citan por primera vez para Perú, mientras que Pagiocerus frontalis (Fabricius, 1801), Scymnobius ecuadoricus Gordon & González, 2005 y Rodolia cardinalis (Mulsant, 1850) son nuevas citas para la región Piura. Las especies consideradas en esta actualización se presentan a modo de listado fau-nístico comentado y se incluye lista actualizada de todos los coleópteros conocidos hasta el momento para la región con distribución por provincia y paisaje ecológico.

Revisiting pollinating Cyclocephala scarab beetles (Coleoptera: Melolonthidae: Dynastinae) associated with the soursop (Annona muricata, Annonaceae)

The soursop (Annona muricata L., Annonaceae) is an important fruit crop in several countries of South America, including Brazil, and the presence of the scarab beetles in this orchads can reduce pollination deficits and increase the productivity. For this reason, we report Cyclocephala celata Dechambre, 1980 as a flower visitor and potential pollinator of the soursop. Additionally, this work presents an updated list of Cyclocephala species found on A. muricata, corrects some misidentifications, and provides comments and an identification key for all taxa cited as floral visitors of this crop.

New tribal placement and review of Parapucaya Prell and Pucaya Ohaus (Coleoptera, Scarabaeidae, Dynastinae)

The dynastine scarab genera Parapucaya Prell and Pucaya Ohaus have been historically classified in Pentodontini; however, that tribal classification is not supported under the current tribal circumscriptions. A discussion justifying the transfer of the genera Parapucaya and Pucaya from Pentodontini into Cyclocephalini is presented. This research is based on morphological observations (mandible shape and wing characters among others) and molecular data (genes 28S, COI, and 16S/ND1). A review of both genera is included, providing descriptions, diagnoses, distribution data, illustrations, and keys to species. A revised key to the world genera of Cyclocephalini is also included.