Bronze Bug Thaumastocoris Peregrinus Carpintero and Dellapé (Hemiptera: Thaumastocoridae) on Eucalyptus in Brazil and its Distribution

The bronze bug Thaumastocoris peregrinus Carpintero & Dellape (Hemiptera: Thaumastocoridae) was detected infesting Eucalyptus trees in Brazil in 2008, in the states of São Paulo, Rio Grande do Sul and Minas Gerais and in 2009 was found in the state of Espirito Santo, Mato Grosso do Sul, Rio de Janeiro and Parana. Details about geographical spread, means of introduction, impact in Eucalyptus plantations and natural enemies observed in the field are discussed.

Association of the stilt bug Jalysus ossesae Henry (Hemiptera : Heteroptera : Berytidae) with myrmecophytic plants of the genus Maieta (Melastomataceae) in an upland forest area in central Amazon, Brazil

Maieta guianensis Aubl. and M. poeppigii Mart. ex. Triana (Melastomataceae) are among the most common myrmecophytic plants in the Amazonian forest understory. These myrmecophytes are colonized exclusively by the ants Pheidole minutula Mayr or Crematogaster sp. and usually host two other arthropods, the spider Faiditus subflavus Exline and Levi and the recently described stilt bug Jalysus ossesae Henry. In this study, the association between J ossesae and the myrmecophytic plants M. guianensis and M. poeppigii in an upland forest area in central Amazon, Brazil, is described. The presence of the stilt bugs on M. guianensis and M. poeppigii and on plants around these myrmecophytes was recorded in five transects. The number and position of the stilt bugs on the leaf surface (upper or lower) and leaf type (with or without domatia) of these myrmecophytes, as well as their behavioral acts, were recorded. Jalysus ossesae was found only on the myrmecophytic plants M. guianensis and M. poeppigii. The stilt bug occurred at similar frequencies on M. guianensis and M. poeppigii, and the number of leaves significantly influenced the presence and number of stilt bugs on these myrmecophytes. Feeding, agonistic interaction between males, and mating were observed. Our data indicate that J. ossesae uses the myrmecophytes M. guinanensis and M. poeppigii as reproductive and foraging sites.

Nonpreference of the lace bug Leptopharsa heveae Drake & Poor (Heteroptera: Tingidae) for rubber tree clones

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Esterase patterns in species of the triatome bug Rhodnius

The aim of the present study was to analyse esterase patterns in three triatomine species of Rhodnius genus. Four loci, Est 1, Est 2, Est 3 and Est 4, were found. The corresponding enzymes were characterized as carboxylesterases (E.C. 3.1.1.1) or cholinesterases (E.C. 3.1.1.8) based on inhibitory experiments, using eserine sulphate, malathion, mercury chloride, p-chloromercuribenzoate (pCMB) and iodoacetamide. Low genetic variability was observed: Est 1, Est 2 and Est 3 were monomorphic in Rhodnius domesticus, Rhodnius robustus and Rhodnius neivai, whereas locus Est 4 was polymorphic in the first two species. The UPGMA analysis based on esterase genotypic frequencies indicated greater similarity between R. domesticus and R. robustus when compared with R. neivai. The present study expands our knowledge about genetic variability among triatomines and accords with the hypothesis that R. domesticus is a species derived from R. robustus.

First record of infection by entomopathogenic nematodes of the grass bug Collaria scenica Stal (Hemiptera: Miridae).

NARANJO N, MONTERO DAV, SAENZ APONTE A. 2011. First record of infection by entomopathogenic nematodes of the grass bug Collaria scenica Stal (Hemiptera: Miridae). ENTOMOTROPICA 26(3): 117-125. The study was aimed to test the pathogenicity of Steinernema sp. and Heterorhabditis sp. in Collaria scenica. The effect of different concentrations of infective juveniles (IJ) were tested on nymphs and adults of C. scenica. For this purpose, the bugs were inoculated with 5 000 JI of each nematode species in a factorial design (3x2), and seven concentrations were tested in a JI factorial design (7x2x2). The bugs showed 100% mortality and symptoms of pathogenicity. Infection was found with both species of nematodes and penetration was assumed to be through the spiracles and anus. A higher capacity of pathogenicity was observed with Steinernema sp. Based on the results Heterorhabditis sp. and Steinernema sp. could constitute an efficient tool to control populations of C. scenica in pastures.

Alpha-glucosidase promotes hemozoin formation in a blood-sucking bug: An evolutionary history

Background: Hematophagous insects digest large amounts of host hemoglobin and release heme inside their guts. In Rhodnius prolixus, hemoglobin-derived heme is detoxified by biomineralization, forming hemozoin (Hz). Recently, the involvement of the R. prolixus perimicrovillar membranes in Hz formation was demonstrated. Methodology/Principal Findings: Hz formation activity of an α-glucosidase was investigated. Hz formation was inhibited by specific α-glucosidase inhibitors. Moreover, Hz formation was sensitive to inhibition by Diethypyrocarbonate, suggesting a critical role of histidine residues in enzyme activity. Additionally, a polyclonal antibody raised against a phytophagous insect α-glucosidase was able to inhibit Hz formation. The α-glucosidase inhibitors have had no effects when used 10 h after the start of reaction, suggesting that α-glucosidase should act in the nucleation step of Hz formation. Hz formation was seen to be dependent on the substrate-binding site of enzyme, in a way that maltose, an enzyme substrate, blocks such activity. dsRNA, constructed using the sequence of α-glucosidase gene, was injected into R. prolixus females' hemocoel. Gene silencing was accomplished by reduction of both α-glucosidase and Hz formation activities. Insects were fed on plasma or hemin-enriched plasma and gene expression and activity of α-glucosidase were higher in the plasma plus hemin-fed insects. The deduced amino acid sequence of α-glucosidase shows a high similarity to the insect α-glucosidases, with critical histidine and aspartic residues conserved among the enzymes. Conclusions/Significance: Herein the Hz formation is shown to be associated to an a-glucosidase, the biochemical marker from Hemipteran perimicrovillar membranes. Usually, these enzymes catalyze the hydrolysis of glycosidic bond. The results strongly suggest that α-glucosidase is responsible for Hz nucleation in the R. prolixus midgut, indicating that the plasticity of this enzyme may play an important role in conferring fitness to hemipteran hematophagy, for instance. © 2009 Mury et al.

Characterization of antibiosis to the redbanded stink bug Piezodorus guildinii (Hemiptera: Pentatomidae) in soybean entries

Stink bugs are among the major pests of soybean [Glycine max (L.) Merrill] worldwide. Piezodorus guildinii [Westwood] (Hemiptera: Pentatomidae) is one of the predominant pest species, causing more severe damage in many regions than other stink bugs. Its attack reduces yield and quality of the beans. Plant resistance is a valuable strategy in integrated pest management that can reduce insect populations below economic injury level. Here, we report the resistance of 17 soybean entries to P. guildinii. PI 229358, PI 274454, L1-1-01, IAC 19, PI 171451, PI 227687, IAC 100, IAC 78-2318, PI 274453, and IAC 74-2832 caused high nymphal mortality (greater than 90 %), indicating the expression of antibiosis. IAC 100, IAC 74-2832, PI 274453, and IAC 24 also increased the length of the nymphal stage of P. guildinii, showing the same mechanism of resistance. Our findings may be useful for breeding programs that focus on the resistance of soybeans to insects.

Effect of Egg Rearing Temperature and Storage Time on the Biological Characteristics of the Predatory Stink Bug Podisus nigrispinus (Hemiptera: Pentatomidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diploid chromosome set of kissing bug Triatoma baratai (Hemiptera, Triatominae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

De novo transcriptome assembly for a non-model species, the blood-sucking bug Triatoma brasiliensis, a vector of Chagas disease

High throughput sequencing (HTS) provides new research opportunities for work on non-model organisms, such as differential expression studies between populations exposed to different environmental conditions. However, such transcriptomic studies first require the production of a reference assembly. The choice of sampling procedure, sequencing strategy and assembly workflow is crucial. To develop a reliable reference transcriptome for Triatoma brasiliensis, the major Chagas disease vector in Northeastern Brazil, different de novo assembly protocols were generated using various datasets and software. Both 454 and Illumina sequencing technologies were applied on RNA extracted from antennae and mouthparts from single or pooled individuals. The 454 library yielded 278 Mb. Fifteen Illumina libraries were constructed and yielded nearly 360 million RNA-seq single reads and 46 million RNA-seq paired-end reads for nearly 45 Gb. For the 454 reads, we used three assemblers, Newbler, CAP3 and/or MIRA and for the Illumina reads, the Trinity assembler. Ten assembly workflows were compared using these programs separately or in combination. To compare the assemblies obtained, quantitative and qualitative criteria were used, including contig length, N50, contig number and the percentage of chimeric contigs. Completeness of the assemblies was estimated using the CEGMA pipeline. The best assembly (57,657 contigs, completeness of 80 %, < 1 % chimeric contigs) was a hybrid assembly leading to recommend the use of (1) a single individual with large representation of biological tissues, (2) merging both long reads and short paired-end Illumina reads, (3) several assemblers in order to combine the specific advantages of each.

Interactions of Bacillus thuringiensis bioinsecticides and the predatory stink bug Podisus nigrispinus to control Plutella xylostella

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Comparing de novo and reference-based transcriptome assembly strategies by applying them to the blood-sucking bug Rhodnius prolixus

High Throughput Sequencing capabilities have made the process of assembling a transcriptome easier, whether or not there is a reference genome. But the quality of a transcriptome assembly must be good enough to capture the most comprehensive catalog of transcripts and their variations, and to carry out further experiments on transcriptomics. There is currently no consensus on which of the many sequencing technologies and assembly tools are the most effective. Many non-model organisms lack a reference genome to guide the transcriptome assembly. One question, therefore, is whether or not a reference-based genome assembly gives better results than de novo assembly. The blood-sucking insect Rhodnius prolixus-a vector for Chagas disease-has a reference genome. It is therefore a good model on which to compare reference-based and de novo transcriptome assemblies. In this study, we compared de novo and reference-based genome assembly strategies using three datasets (454, Illumina, 454 combined with Illumina) and various assembly software. We developed criteria to compare the resulting assemblies: the size distribution and number of transcripts, the proportion of potentially chimeric transcripts, how complete the assembly was (completeness evaluated both through CEGMA software and R. prolixus proteome fraction retrieved). Moreover, we looked for the presence of two chemosensory gene families (Odorant-Binding Proteins and Chemosensory Proteins) to validate the assembly quality. The reference-based assemblies after genome annotation were clearly better than those generated using de novo strategies alone. Reference-based strategies revealed new transcripts, including new isoforms unpredicted by automatic genome annotation. However, a combination of both de novo and reference-based strategies gave the best result, and allowed us to assemble fragmented transcripts.

Towards biological control strategies for the bronze bug, Thaumastocoris peregrinus, on eucalyptus plantations in South America

The bronze bug is an invasive Australian pest that has reached eucalypt production areas worldwide in <10 years. The fi rst record in South America was in 2005 in Argentina. Collaboration in the region towards a unifi ed strategy for the management of the bronze bug started soon after the dispersal of the pest into Brazil and Uruguay was confi rmed. Here, we present the main achievements of this collaboration in four main topics: 1) biology of the pest, 2) monitoring, 3) biological control, and 4) cooperative networks. Two mass rearing procedures have been implemented in the region with relative success, allowing basic biological studies on the pest. Continuous monitoring in the region for >5 years has provided a reasonable knowledge on seasonal patterns of T. peregrinus. Biological control strategies developed include the use of local natural enemies of T. peregrinus, the development of biopesticides, and the introduction of Cleruchoides noackae, an egg parasitoid of T. peregrinus from Australia. We review the main achievements in each country. Finally, a regional network of institutions, researchers, and students has strengthened in the region, providing a solid background for future collaboration.

Biological control of the bronze bug, Thaumastocoris peregrinus, in eucalyptus plantations in Brazil

The bronze bug Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae) was detected in Brazil in 2008 and infested >180 000 ha of eucalyptus plantations in 2011. The bronze bug can cause a reduction of 10–15% in wood productivity after 2 years of heavy infestation. Although there is not an effective control method known, biological control is the main control strategy studied. An exotic egg parasitoid, Cleruchoides noackae (Hymenoptera: Mymaridae), was imported from Australia in 2012, reared in a laboratory and released in three Brazilian regions. Parasitoids were recovered at release points after 20–30 d. In 2013, preliminary evaluations demonstrated parasitoid establishment in these areas, and the parasitoid was recovered in adjacent areas after 1 year of release. Bioassays confi rmed egg parasitism of 15–20% by C. noackae. Other native natural enemies were studied. We found green lacewing Chrysoperla externa and predatory bugs Supputius cincticeps and Atopozelus opsimus preying on nymphs and/or adults of T. peregrinus. Another promising possibility is entomopathogenic fungi. Commercial formulations of Beauveria bassiana were tested with success in lab and fi eld conditions. Fusarium proliferatum and Paecilomyces cateniannulatus caused mortality of T. peregrinus in natural epizooties. After 5 years of research, it is possible to develop an integrated pest management system (IPM) for eucalyptus plantations based on biocontrol strategy for bronze bug.