Scielo RSS <![CDATA[Revista Brasileira de Entomologia]]> vol. 62 num. 3 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[Effects of cycloheximide on the mortality of <em>Atta sexdens</em> leaf-cutting worker ants]]> ABSTRACT Leaf-cutting ants live symbiotically with a fungus that they cultivate on the plant leaves that they cut. The innumerous studies on the plant selection mechanism used by leaf-cutting ants show the researchers’ interest in this issue. Many classical studies propose that plants are selected according to the fungus garden nutritional needs and the absence of potentially harmful substances. This hypothesis is corroborated by behavioral experiments using cycloheximide (fungicide) with citric pulp or forage plants greatly accepted by leaf-cutting ants. According to this hypothesis, under the action of a fungicide, the fungus emits an allomone that informs worker ants that some food is inadequate to its growth. Although some authors state that the cycloheximide “fungicide” used is specific and non toxic to ants, our findings are distinct. In our study, various concentrations of cycloheximide were administered orally to leaf-cutting worker ants in a citric pulp paste diet. After the ingestion period, the ants were isolated and offered the symbiotic fungus for 21 days and the mortality rate was evaluated. As expected, the treatment with 0.01% cycloheximide showed a low mortality rate (8.86%). At 0.1%, the mortality rate was mild (27.85%), and treatment with 1% cycloheximide resulted in moderate mortality (45.57%). In contrast, the positive control with 0.1% sulfluramid showed a high mortality rate (91.14%). Therefore, we concluded that the ingestion of high concentrations of cycloheximide results in a moderate mortality rate in leaf-cutting worker ants. <![CDATA[Sexual dimorphism in <em>Diabrotica speciosa</em> and <em>Diabrotica viridula</em> (Coleoptera: Chrysomelidae)]]> ABSTRACT Diabrotica speciosa (Germar) and Diabrotica viridula F. (Coleoptera: Chrysomelidae) are the two most abundant species of the genus in South America, and belong to the fucata and virgifera groups, respectively. Here, we characterize the dimorphism of the setae present on the basitarsi of males and females of these species. Dimorphism was confirmed in both species, and it was related to the presence of adhesive setae exclusively in males, which possess these structures on the basal tarsomeres of the pro- and mesothoracic legs. <![CDATA[Nomenclatural changes in the grass-feeding Mexican leafhopper genus <em>Cocrassana</em> Blocker & Larsen (Hemiptera: Cicadellidae: Deltocephalinae: Athysanini)]]> ABSTRACT Two nomenclatural changes are proposed in the tribe Athysanini (Cicadellidae: Deltocephalinae). Chlorotettix sexvarus DeLong, 1959, is newly placed in the genus Cocrassana Blocker &amp; Larsen and is a senior synonym of the type species of Cocrassana, C. riepmai Blocker &amp; Larsen, 1991, syn. nov. A revised diagnosis and illustration of the species are provided. <![CDATA[Trophic network of aquatic macroinvertebrates along an altitudinal gradient in a Neotropical mountain river]]> ABSTRACT Studies of trophic networks and the evaluation of processes that occur along altitudinal gradients in river systems are of great importance because they allow an understanding of energy flow dynamics and provide scientific tools for the planning and management of river ecosystems. This research describes the trophic network of aquatic macroinvertebrates along an altitudinal gradient of the Gaira River, a mountain Neotropical watercourse located in the Sierra Nevada de Santa Marta in northern Colombia. The organisms were collected in the upper, middle and lower reaches of the river during the rainy and dry seasons (between 2010 and 2013). Trophic relationships were evaluated through gut content analysis. The contents were determined and quantified using photographs and expert review, and a binary consumption matrix was used to determine the characteristics of the trophic network. We characterized the diet composition at each site for each season using discriminant analysis. Trophic networks during the dry seasons showed higher trophic species richness and linkage density, and the predominance of coarse particulate organic matter (CPOM) and fine particulate organic matter (FPOM) in the high and medium sections of the river. During the dry seasons the diets had a lower number of basal species, but in the low river section there was a high percentage of fungi and microalgae. During the rainy seasons, no patterns were observed for the percentage of resources. Results indicated a direct relation between periods of hydrologic stability and an increase of CPOM during dry seasons and an increase of resource diversity consumed by macroinvertebrates at all sites during the rainy season, showing that changes in trophic networks of the Gaira River were more important during seasonal periods than along the altitudinal gradient. <![CDATA[Spores of <em>Paenibacillus larvae</em>, <em>Ascosphaera apis</em>, <em>Nosema ceranae</em> and <em>Nosema apis</em> in bee products supervised by the Brazilian Federal Inspection Service]]> ABSTRACT Due to their ecological and economic importance, honey bees have attracted much scientific attention, which has intensified due to the recent population decline of these insects in the several parts of the world. Among the factors related to these patterns, infection by pathogens are the most relevant, mainly because of the easy dissemination of these microorganisms. Although no zoonotic diseases are associated with these insects, the presence of infectious agents in bee products should still be considered because they play a role as disease dispersers, increasing the risk to animal health. Because of the possibility of dispersion of pathogens via bee products, this work aimed to identify the presence of spores of the pathogens Paenibacillus larvae, Ascosphaera apis and Nosema spp. in samples of honey, pollen and royal jelly that are registered with Brazil's Federal Inspection Service (S.I.F.) and commercially available in the state of São Paulo. Of the 41 samples of bee products analyzed, only one showed no contamination by any of these pathogens. N. ceranae and P. larvae had the highest prevalence considering all the samples analyzed (present in 87.80% and 85.37% of the total, respectively), with N. apis present in 26.83% and A. apis present in 73.17% of the samples. These results provide support for the formulation of government regulations for sanitary control of exotic diseases by preventing dispersion of pathogens, including through illegal importation, since local and international trade and the transfer of colonies between regions play important roles in the dispersion of these microorganisms. <![CDATA[Selectivity of different biological products to the egg parasitoid <em>Telenomus remus</em> (Hymenoptera: Platygastridae)]]> ABSTRACT The selectivity of five entomopathogens and a chemical insecticide (positive control) to pupae and adults of the egg parasitoid Telenomus remus (Nixon) was evaluated in the laboratory under controlled environmental conditions according to protocols established by the International Organization for Biological Control. Baculovirus anticarsia (Baculovirus AEE®), Bacillus thuringiensis var. kurstaki (Thuricide®), Bacillus thuringiensis var. aizawai (Agree®), Beauveria bassiana (Boveril®), Metarhizium anisopliae (Metarril®) and Trichoderma harzianum (Trichodermil®) are harmless to T. remus pupae, and adults. Thus, our results suggest that the insect control strategies applied here are compatible since entomopathogens were classified as harmless to T. remus in most examined cases and therefore facilitate a joint application to control different pests. Bacillus thuringiensis var. kurstaki (Dipel®), despite being classified as slightly harmful in some of the evaluations, can still be considered compatible for use together with T. remus, especially when compared with chemical insecticides such as chlorpyrifos that might be considered harmful to the parasitoid survival. <![CDATA[Isolation, morphological and molecular characterization of <em>Bacillus thuringiensis</em> strains against <em>Hypothenemus hampei</em> Ferrari (Coleoptera: Curculionidae: Scolytinae)]]> ABSTRACT The coffee berry borer Hypothenemus hampei Ferrari, 1876 (Coleoptera: Curculionidae: Scolytinae) is considered the most serious pest of the coffee crop and is controlled primarily with the use of chemical insecticides. An alternative to this control method is the use of the entomopathogenic bacterium, Bacillus thuringiensis Berliner, 1911. Therefore, the objective of this work was to select strains of B. thuringiensis virulent against H. hampei and characterize them by morphological and molecular methods to identify possible genes for the production of genetically modified plants. To achieve this objective, 34 strains of B. thuringiensis underwent a selective bioassay to evaluate their toxicity to H. hampei first-instar larvae. Among the strains tested, 11 and the standard B. thuringiensis subspecies israelensis (IPS-82) caused mortality above 90%. Then, the median lethal concentration (LC50) was estimated for these strains followed by characterization using morphological, biochemical and molecular methods. The lowest LC50 was obtained for strain BR58, although this concentration did not differ significantly from that of the standard strain IPS-82 or from that of strains BR137, BR80 and BR67. The molecular characterization detected cry4A, cry4B, cry10, cry11 and cyt1 genes in 10 of the most virulent strains (BR58, BR137, BR80, BR81, BR147, BR135, BR146, BR138, BR139, BR140). Strain BR67 differed completely from the others and amplified only the cry3 gene. This strain was more virulent than BR135, BR146, BR138, BR139 and BR140, but it did not differ from BR58, BR137, BR80, BR81 and BR147. The protein profile revealed proteins of 28, 65, 70 and 130 kDa, and the morphological analysis identified spherical crystalline inclusions in all strains. The results showed that the 11 strains studied have potential for use as a gene source for insertion into coffee plants for the control H. hampei, especially the cry3, cry4A, cry4B, cry10, cry11 and cyt1 genes, that were repeated in the most virulent isolates. <![CDATA[Mating behavior and description of immature stages of <em>Cyclocephala melanocephala</em> (Fabricius, 1775) (Coleoptera: Scarabaeidae: Dynastinae), identification key and remarks on known immatures of Cyclocephalini species]]> ABSTRACT Mating behavior and description of immature stages of Cyclocephala melanocephala (Fabricius, 1775) (Coleoptera: Scarabaeidae: Dynastinae), identification key and remarks on known immatures of Cyclocephalini species. Some species of Cyclocephala Dejean, 1821 are regarded as rhizophagous crop pests and others as beneficial species. The objective of this work was to report the mating behavior and to describe the immature stages of C. melanocephala. The studies were developed at the Universidade Estadual de Mato Grosso do Sul in Cassilândia, Mato Grosso do Sul state, Brazil. Adults were collected with a light trap from September to December 2014 and 2015 to carry out studies of mating behavior, breeding, and descriptions of immature stages. Copulation lasted 10.4 ± 4.3 min and took place from 19:00 to 24:00 h. Some females refused males for mating and moved away from them. Regarding flight period, adults were collected in larger quantities from 20:00 to 23:00 h. Identification keys to immatures of three genera of Cyclocephalini, including several Cyclocephala species are presented. <![CDATA[<em>Myrciamyia pterandrae</em> (Diptera, Cecidomyiidae, Lopesiini), a new species of gall midge associated with <em>Pterandra pyroidea</em> A. Juss. (Malpighiaceae), an endemic plant in Brazilian Cerrado]]> ABSTRACT Myrciamyia pterandrae (Diptera, Cecidomyiidae), a new galling species associated with Pterandra pyroidea (Fabaceae), an endemic plant species in Brazilian Cerrado, is described based on larva, pupa, male and female. M. pterandrae galls were collected in the municipality of Quartel de São João, State of Minas Gerais, southeastern Brazil. Larvae were removed from the galls and pupae, and adults were obtained by rearing. The specimens were mounted on slides, and the diagnostic morphological characters were illustrated. M. pterandrae is compared to Myrciamyia maricaensis Maia, 1996 the unique, previously known species of the genus. <![CDATA[A new Costa Rican species of <em>Drosophila</em> visiting inflorescences of the hemi-epiphytic climber <em>Monstera lentii</em> (Araceae)]]> ABSTRACT Drosophila monsterae sp. nov. is described from 11 males and 13 females collected from the inside of closed inflorescences of Monstera lentii (Araceae) at 1810 m altitude in the Forest Reserve of Cerro de La Carpintera, Canton La Unión, Province of Cartago, Costa Rica. Although flies have been seen wandering and copulating inside the floral chambers of closed inflorescences during the floral female phase, eggs or larvae have not yet been found either in the spathe or in the fleshy spadix. The new species is related to Drosophila tristani Sturtevant, 1921, from San José, Costa Rica, from which it differs mainly by having smaller slightly circular compound eyes, distinctly broader genae (cheek index ca. 2.4 vs 5 in D. tristani), and the inner capsule of spermathecae with an unusual folded duct at basal half of its very wide introvert. This is the eighth species to be included in the New World, essentially Neotropical, subgenus Phloridosa. Photomicrographs of male and female terminalia are also provided. <![CDATA[<em>Diolcogaster flammeus</em> sp. nov. from Brazil, a new Microgastrinae wasp (Hymenoptera: Braconidae) of importance in biological control]]> ABSTRACT A new species of Diolcogaster (Ashmead, 1900) (Hymenoptera: Braconidae) is described and illustrated. Additionally, a key to all New World species formally published of the xanthaspis species-group (to which the new species belongs) is provided. The solitary larval parasitoid Diolcogaster flammeus sp. nov. was collected in Viçosa, Minas Gerais State, Brazil. This natural enemy was reared from caterpillars of Agaraea minuta (Schaus, 1892) (Lepidoptera: Erebidae) feeding on plants of spiked spiralflag ginger, Costus spicatus (Jacq.) Sw. and ginger spiral, Costus spiralis (Jacq.) Roscoe var. spiralis (Costaceae). The fauna of the xanthaspis group in the New World included just three published species prior to this publication. Diolcogaster flammeus sp. nov. is the only yellow-orange species of the xanthaspis group recorded in the New World thus far. <![CDATA[A revision of <em>Dichotomius</em> (<em>Homocanthonides</em>) Luederwaldt, 1929 (Coleoptera: Scarabaeidae: Scarabaeinae)]]> ABSTRACT The monospecific subgenus Dichotomius (Homocanthonides) is revised and its single species, Dichotomius (H.) smaragdinus (Perty, 1830) is redescribed and distinguished from other Dichotomius species. Dichotomius (H.) smaragdinus is a polymorphic species and its distribution comprises the Brazilian Cerrado. For the first time, morphological variation and male genital organ are described and illustrated. We believe that this species might be endangered due to extensive deforestation of Brazilian Cerrado by agricultural and pasture expansion. Thus, we highlight the importance of preserving this very unusual Dichotomius species. <![CDATA[Larva, pupa and DNA barcodes of the Neotropical geometrid moth <em>Glena mielkei</em> (Lepidoptera: Geometridae: Ennominae: Boarmiini)]]> ABSTRACT Glena mielkei Vargas, 2010 (Lepidoptera: Geometridae: Ennominae: Boarmiini) is a Neotropical geometrid moth native to the Atacama Desert of northern Chile whose larvae are folivorous on the shrub Trixis cacalioides (Asteraecae). The last instar and pupa are described and illustrated, and DNA barcode sequences are provided for the first time for G. mielkei. Descriptions are made based on larvae collected in the type locality. Comparisons with the available descriptions of congeneric species suggest that the chaetotaxy of the SV group of the abdominal segment and the morphology of the cremaster could be useful tools to species identification based on last instar and pupa, respectively. A search in BOLD (Barcode of Life Data System) showed that the only DNA barcode haplotype found in the two specimens sequenced was closest to Physocleora Warren, 1897 than Glena Hulst, 1896. These results coincide with the morphological peculiarities of the genitalia highlighted in the original description of G. mielkei, suggesting that a definitive assessment of the generic status of this geometrid moth deserves further integrative studies.