Morphology of immature stages and mating behavior in Liogenys fusca (Blanchard) (Coleoptera, Melolonthidae, Melolonthinae)

ABSTRACT Liogenys fusca is a rizophagous insect pest in various crops of economic importance in Brazil. Here we investigated the morphology of immature stages and mating behavior of this species. The redescription of the 3rd instar larvae of L. fusca in this work allows identification and registration of occurrence independently of adults, which occur sporadically in a certain period of the year. Male and female of L. fusca remained confined in the soil during the day and exited between 19:00 and 23:30 h. The copulations occurred between 19:30 and 21:00 h, and were characterized by a typical behavioral sequence. Copulation durations in L. fusca lasted on average 512.23 s. Adults were observed feeding before the copulations on leaves and inflorescences of plant species belonging to the family Anacardiaceae, Myracrodruon urundeuva, Schinus terebinthifolius, Astronium fraxinifolium and Anacardium occidentale.

Biological aspects and mating behavior of Leucothyreus albopilosus (Coleoptera: Scarabaeidae) / Aspectos biológicos y comportamiento de apareamiento de Leucothyreus albopilosus (Coleoptera: Scarabaeidae)

AbstractThe genus Leucothyreus has been linked to some commercial plant crop pests. Eventhough several species have been described for this genus, information about this group is still scarce. This study investigated some biological aspects and mating behavior in Leucothyreus albopilosus. Studies were conducted at the State University of Mato Grosso do Sul, in the municipalities of Aquidauana and Cassilândia, MS, Brazil. For biological studies, adults were collected with light traps from February 2011 to February 2012, and for behavior analyses from September to December 2014. Biological studies were undertaken every three days and included the eggs inspection, and the separation of the newly hatched larvae to observe and describe their developmental stages; to monitor larval growth and differentiate larval instars, we measured the larvae cephalic capsule. Life cycle was determined starting from the newly laid eggs until adult death. For mating behavior studies, adults obtained with light traps were taken to the laboratory. As soon as they started flying in the evening, couples were formed and copulation steps were recorded. in the field, we observed that adults were mostly collected during warmer and wetter periods (from August to March). Our results showed that the embryonic period of L. albopilosus lasted 20.5 days, the 1st, 2nd and 3rd instars lasted 31.0, 33.1 and 85.6 days, respectively. The pupal stage lasted 20 days, and the egg to adult period was completed in 185.5 days; these results suggest that L.albopilosus can be characterized as a univoltine species. Observations of mating behavior in the laboratory showed that, after the sunset, adults projected a small portion of clypeus near the soil surface and flew off seeking a female to mate. The female could accept or reject the male for mating. When the female accepted the male, copulation occurred from 19:00 to 23:00 hours, and lasted 19.45 minutes on average. Sometimes females refused to mate, probably because the male or female were not sexually mature to perform copulation, and there might be a chemical communication between the adults. Adults were observed feeding on ripe bananas (Musa sp., Musaceae) and on mangaba flowers (Hancornia speciosa, Apocynaceae) in the laboratory. With this work we contributed with the description of mating behavior in the genus Leucothyreus and concluded that the biological cycle was completed in less than 200 days. Rev. Biol. Trop. 64 (2): 547-557. Epub 2016 June 01.

ResumenEn el género Leucothyreus se describen varias especies, sin embargo, hay poca información sobre este grupo. El presente trabajo tuvo por objetivo estudiar los aspectos biológicos y el comportamiento de copula de Leucothyreus albopilosus. Los estudios se realizaron en la Universidade Estadual de Mato Grosso do Sul, en los municipios de Aquidauana y Cassilândia, MS, Brasil. Fueron recolectados adultos con trampa de luz desde febrero 2011 hasta febrero 2012 para realizar estudios biológicos y desde septiembre hasta diciembre de 2014 para estudios de comportamiento. Para los estudios biológicos, se inspeccionaron los huevos cada tres días, y cuando las larvas eclosionaban, eran separadas para monitorear su desarrollo. Para supervisar el desarrollo y diferenciar las etapas larvarias fueron medidas las cápsulas cefálicas de las mismas. El ciclo de vida se determinó a partir de la ovoposición hasta la muerte de los adultos. Para realizar los estudios del comportamiento de la cópula, los adultos obtenidos con trampas de luz fueron llevados al laboratorio, y al atardecer cuando iniciaron el vuelo, se formaron parejas, permitiendo observar y registrar los pasos que involucran este comportamiento. En campo, se observó que los adultos fueron recolectados principalmente en los períodos más calientes y húmedos entre los meses de agosto y marzo. El período embrionario de L. albopilosus duró 20.5 días. La primera, segunda y tercera etapa duraron 31.0, 33.1 y 85.6 días, respectivamente. La etapa de pupa duró 20 días y el período desde huevo hasta adulto fue completado en 185.5 días. Estos resultados sugieren que L. albopilosus puede ser caracterizado como una especie univoltina. Con respecto al comportamiento de copula en el laboratorio, al iniciar la noche, los adultos primeramente proyectan una pequeña porción del clípeo próximo a la superficie del suelo, en seguida realizan el vuelo buscando una hembra para iniciar la cópula. La hembra puede aceptar o no al macho para realizar la cópula. Cuando la hembra aceptó al macho para la copula, esta ocurrió desde 19:00 hasta las 23:00 horas durando 19.45 minutos en promedio. Cuando la hembra rechazó al macho para la copula, se debió probablemente a que ella o el no estaban maduros sexualmente, ocurriendo un reconocimiento químico entre ellos. Se observó en el laboratorio que los adultos se alimentaban de plátanos maduros (Musa sp., Musaceae) y flores de mangabeira (Hancornia speciosa, Apocynaceae). En este trabajo se concluye que el ciclo biológico se completa en menos de un año y se describen las primeras etapas del comportamiento de copula del género Leucothyreus.

Biological aspects of Leucothyreus ambrosius Blanchard (Coleoptera, Melolonthidae, Rutelinae)

Biological aspects of Leucothyreus ambrosius Blanchard (Coleoptera, Melolonthidae, Rutelinae). Coleopterans of the family Melolonthidae comprise a large group of species that feed on different food sources, including plant roots, stems, and leaves, in addition to plant materials at different decomposition stages. Several species are found in the genus Leucothyreus, occurring in different regions of Brazil, including the various biomes in the country. Information on the biology of species of the genus Leucothyreus is scarce, therefore, we conducted studies on the biological aspects of Leucothyreus ambrosius Blanchard, 1850. The period of adult occurrence was determined with a light trap installed between a cropped and pasture area in the municipality of Aquidauana, Mato Grosso do Sul State, Brazil. Adults collected in the field were used to form insect pairs and the studies were initiated in the entomology laboratory as the adults began ovipositing. Adults were observed flying in the field from October to December. Eggs were obtained as pairs were formed and a colony was established, the embryonic period lasting 14.6 days on average. The larval period in the 1st instar lasted 21.6 days, in the 2nd instar 19.6 days, and in the 3rd instar, 85.6 days. The head capsule width was 1.48 mm in the 1st instar, 2.44 mm in the 2nd, and 3.83 mm in 3rd larval instar. The pupal stage had an average duration of 35.5 days. The egg to adult period lasted 173.3 days. Morphometric information for the larval and adult stages is presented in this study.