Heteroptera research in Latin America and the Caribbean (Insecta, Hemiptera): status and perspectives in the 21st century.

Latin American and the Caribbean regions (LAC) harbor one of the most biodiverse areas of the world, the Neotropics. True bugs (Hemiptera: Heteroptera) are a diverse lineage of insects, with more than 45,000 species, particularly speciose in the Neotropical region. True bugs are fundamental in the dynamics of natural and modified ecosystems, with several species critical to agriculture and public health. We compiled Heteroptera research in LAC from 1998-2022 using bibliographic databases. Productivity, collaborative networks, and the main topics studied were analyzed. A total of 1,651 Heteroptera studies from LAC were found, with continuous growth being 2021 the most prolific. Four categories (Taxonomy of extant species, Faunistic inventories and new records, Pest species biology, and Community ecology) represent most of the published research. About 60 percent of the records evaluated correspond to five families (Pentatomidae, Reduviidae, Coreidae, Miridae, and Rhyparochromidae). We emphasize the need to keep working on Heteroptera taxonomy because it will allow further advances in other areas such as phylogenetic analyses, biogeography, ecology, and natural history, among others. The results of our analyses characterize the current state of heteropterology in the region, establishing a baseline for future studies and efforts to broaden the knowledge of the group.

Ecological drift during colonization drives within-host and between-host heterogeneity in an animal-associated symbiont.

Specialized host-microbe symbioses canonically show greater diversity than expected from simple models, both at the population level and within individual hosts. To understand how this heterogeneity arises, we utilize the squash bug, Anasa tristis, and its bacterial symbionts in the genus Caballeronia. We modulate symbiont bottleneck size and inoculum composition during colonization to demonstrate the significance of ecological drift, the noisy fluctuations in community composition due to demographic stochasticity. Consistent with predictions from the neutral theory of biodiversity, we found that ecological drift alone can account for heterogeneity in symbiont community composition between hosts, even when 2 strains are nearly genetically identical. When acting on competing strains, ecological drift can maintain symbiont genetic diversity among different hosts by stochastically determining the dominant strain within each host. Finally, ecological drift mediates heterogeneity in isogenic symbiont populations even within a single host, along a consistent gradient running the anterior-posterior axis of the symbiotic organ. Our results demonstrate that symbiont population structure across scales does not necessarily require host-mediated selection, as it can emerge as a result of ecological drift acting on both isogenic and unrelated competitors. Our findings illuminate the processes that might affect symbiont transmission, coinfection, and population structure in nature, which can drive the evolution of host-microbe symbioses and microbe-microbe interactions within host-associated microbiomes.

Binding properties of chemosensory protein 4 in Riptortus pedestris to aggregation pheromones.

In insects, chemosensory proteins (CSPs) play an important role in the perception of the external environment and have been widely used for protein-binding characterization. Riptortus pedestris has received increased attention as a potential cause of soybean staygreen syndrome in recent years. In this study, we found that RpedCSP4 expression in the antennae of adult R. pedestris increased with age, with no significant difference in expression level observed between males and females, as determined through quantitative real-time polymerase chain reaction (qRT-PCR). Subsequently, we investigated the ability of RpedCSP4 to bind various ligands (five aggregated pheromone components and 13 soybean volatiles) using a prokaryotic expression system and fluorescence competitive binding assays. We found that RpedCSP4 binds to three aggregated pheromone components of R. pedestris, namely, ((E)-2-hexenyl (Z)-3-hexenoate (E2Z3), (E)-2-hexenyl (E)-2-hexenoate (E2E2), and (E)-2-hexenyl hexenoate (E2HH)), and that its binding capacities are most stable under acidic condition. Finally, the structure and protein-ligand interactions of RpedCSP4 were further analyzed via homology modeling, molecular docking, and targeted mutagenesis experiments. The L29A mutant exhibited a loss of binding ability to these three aggregated pheromone components. Our results show that the olfactory function of RpedCSP4 provides new insights into the binding mechanism of RpedCSPs to aggregation pheromones and contributes to discover new target candidates that will provide a theoretical basis for future population control of R. pedestris.

Chromosome-level genome assembly of the predatory stink bug Arma custos.

The stink bug Arma custos (Hemiptera: Pentatomidae) is a predatory enemy successfully used for biocontrol of lepidopteran and coleopteran pests in notorious invasive species. In this study, a high-quality chromosome-scale genome assembly of A. custos was achieved through a combination of Illumina sequencing, PacBio HiFi sequencing, and Hi-C scaffolding techniques. The final assembled genome was 969.02 Mb in size, with 935.94 Mb anchored to seven chromosomes, and a scaffold N50 length of 135.75 Mb. This genome comprised 52.78% repetitive elements. The detected complete BUSCO score was 99.34%, indicating its completeness. A total of 13,708 protein-coding genes were predicted in the genome, and 13219 of them were annotated. This genome provides an invaluable resource for further research on various aspects of predatory bugs, such as biology, genetics, and functional genomics.

Begomovirus Transmission to Tomato Plants Is Not Hampered by Plant Defenses Induced by Dicyphus hesperus Knight.

Plants can respond to insect infestation and virus infection by inducing plant defenses, generally mediated by phytohormones. Moreover, plant defenses alter host quality for insect vectors with consequences for the spread of viruses. In agricultural settings, other organisms commonly interact with plants, thereby inducing plant defenses that could affect plant-virus-vector interactions. For example, plant defenses induced by omnivorous insects can modulate insect behavior. This study focused on tomato yellow leaf curl virus (TYLCV), a plant virus of the family Geminiviridae and genus Begomovirus. It is transmitted in a persistent circulative manner by the whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), posing a global threat to tomato production. Mirids (Hemiptera: Miridae) are effective biological control agents of B. tabaci, but there is a possibility that their omnivorous nature could also interfere with the process of virus transmission. To test this hypothesis, this study first addressed to what extent the mirid bug Dicyphus hesperus Knight induces plant defenses in tomato. Subsequently, the impact of this plant-omnivore interaction on the transmission of TYLCV was evaluated. Controlled cage experiments were performed in a greenhouse setting to evaluate the impact of mirids on virus transmission and vector acquisition by B. tabaci. While we observed a reduced number of whiteflies settling on plants exposed to D. hesperus, the plant defenses induced by the mirid bug did not affect TYLCV transmission and accumulation. Additionally, whiteflies were able to acquire comparable amounts of TYLCV on mirid-exposed plants and control plants. Overall, the induction of plant defenses by D. hesperus did not influence TYLCV transmission by whiteflies on tomato.

Different binding properties of odorant-binding protein 8 to insecticides in Orius sauteri.

Chemical sensing systems are vital in the growth and development of insects. Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is an important natural enemy of many pests. The molecular mechanism of odorant binding proteins (OBPs) binding with common insecticides is still unknow in O. sauteri. In this study, we expressed in vitro OsauOBP8 and conducted fluorescence competition binding assay to investigate the function of OsauOBP8 to insecticides. The results showed that OsauOBP8 could bind with four common insecticides (phoxim, fenitrothion, chlorpyrifos, deltamethrin). Subsequently, we used molecular docking to predict and obtained candidate six amino acid residues (K4, K6, K13, R31, K49, K55) and then mutated. The result showed that three key residues (K4, K6, R31) play important role in OsauOBP8 bound to insecticides. Our study identified the key binding sites of OsauOBP8 to insecticides and help to better understand the molecular mechanism of OBPs to insecticides in O. sauteri.

Identification and expression patterns of somatic piRNAs and PIWI genes in Riptortus pedestris (Hemiptera: Alydidae).

RNA interference (RNAi)-based gene silencing is a feasible and sustainable technology for the management of hemipteran pests by double-stranded RNA involvement, including small-interfering RNA, microRNA, and Piwi-interacting RNA (piRNA) pathways, that may help to decrease the usage of chemical insecticides. However, only a few data are available on the somatic piRNAs and their biogenesis genes in Riptortus pedestris, which serves as a significant pest of soybean (Glycine max). In this study, two family members of the PIWI gene were identified and characterized in R. pedestris, containing Argonaute3 (RpAgo3) and Aubergine (RpAub) genes with conserved protein domains, and their clusters were validated by phylogenetic analysis. In addition, they were widely expressed in all developmental stages of the whole body of R. pedestris and had lower expression levels in R. pedestris guts under different rearing conditions based on previous transcriptome sequencing. Furthermore, abundant clean reads were filtered to a total number of 45,998 piRNAs with uridine bias at the first nucleotide (nt) position and 26-32 nt in length by mapping onto the reference genome of R. pedestris according to our previous whole-transcriptome sequencing. Finally, our data revealed that gut bacterial changes were significantly positively or negatively associated with differentially expressed piRNAs among the five comparison groups with Pearson correlation analysis. In conclusion, these findings paved new avenues for the application of RNAi-based biopesticides for broad-spectrum hemipteran pest control.

Elucidating the ecophysiology of soybean pod-sucking stinkbug Riptortus pedestris (Hemiptera: Alydidae) based on de novo genome assembly and transcriptome analysis.

Food security is important for the ever-growing global population. Soybean, Glycine max (L.) Merr., is cultivated worldwide providing a key source of food, protein and oil. Hence, it is imperative to maintain or to increase its yield under different conditions including challenges caused by abiotic and biotic stresses. In recent years, the soybean pod-sucking stinkbug Riptortus pedestris has emerged as an important agricultural insect pest in East, South and Southeast Asia. Here, we present a genomics resource for R. pedestris including its genome assembly, messenger RNA (mRNA) and microRNA (miRNA) transcriptomes at different developmental stages and from different organs. As insect hormone biosynthesis genes (genes involved in metamorphosis) and their regulators such as miRNAs are potential targets for pest control, we analyzed the sesquiterpenoid (juvenile) and ecdysteroid (molting) hormone biosynthesis pathway genes including their miRNAs and relevant neuropeptides. Temporal gene expression changes of these insect hormone biosynthesis pathways were observed at different developmental stages. Similarly, a diet-specific response in gene expression was also observed in both head and salivary glands. Furthermore, we observed that microRNAs (bantam, miR-14, miR-316, and miR-263) of R. pedestris fed with different types of soybeans were differentially expressed in the salivary glands indicating a diet-specific response. Interestingly, the opposite arms of miR-281 (-5p and -3p), a miRNA involved in regulating development, were predicted to target Hmgs genes of R. pedestris and soybean, respectively. These observations among others highlight stinkbug's responses as a function of its interaction with soybean. In brief, the results of this study not only present salient findings that could be of potential use in pest management and mitigation but also provide an invaluable resource for R. pedestris as an insect model to facilitate studies on plant-pest interactions.

A synopsis of the genus Cylindrostethus Fieber 1861 (Insecta: Hemiptera: Gerridae).

Cylindrostethus Fieber, 1861 is one of the most striking genera of water striders (Insecta: Hemiptera: Gerridae) and has Pantropical distribution. Members of this group can be recognized by the very long, cylindrical body; the short antennomere IV; the short labium not reaching the mesosternum; and by characteristics of the abdomen of males and females. Although Neotropical representatives of the genus have been revised, there are pending taxonomic issues related to this fauna, and that of the Eastern Hemisphere has been barely studied in recent years. Here, we present a short note about the authorship of Cylindrostethus, an updated key to all species of the genus, a new synonymy, and the description of a previously unknown macropterous male of C. hungerfordi Drake and Harris.

Silicon applications in rice plants alter the stylet probing behaviors of Glyphepomis spinosa (Hemiptera: Pentatomidae).

The stink bug Glyphepomis spinosa Campos & Grazia (Hemiptera: Pentatomidae) is a potential rice pest in Brazil. This study evaluates the interaction between silicon sources and 3 rice cultivars (BRS Esmeralda, Canela de Ferro, and IRGA 417) and examines how increasing silicon levels affect the stylet probing behavior of G. spinosa. The experiment was set up in a completely randomized design with a 3 × 3 factorial scheme (silicon sources: calcium silicate, potassium silicate, a control, and 3 rice cultivars). Fertilizing rice plants with Si altered the probing behavior of the stink bug G. spinosa. The cultivar interaction by Si source was significant in a few variables. This was evidenced by longer periods without ingestion, prolonged time to the first stylet probe (initial probing), and less time spent in cellular maceration. This result supports the use of electropenetrography as a tool to evaluate resistance inducers in plants.

Diversity of true bugs (Insecta: Hemiptera: Heteroptera) from the El Impenetrable National Park, Argentina.

The study of the Heteroptera (Hemiptera) fauna of the El Impenetrable National Park, resulted in an inventory composed of: Alydidae (2 spp.), Aradidae (1 sp.), Belostomatidae (5 spp.), Berytidae (1 sp.), Blissidae (1 sp.), Coreidae (11 spp.), Corixidae (2 spp.), Geocoridae (1 sp.), Gerridae (1 sp.), Hebridae (1 sp.), Largidae (4 spp.), Lygaeidae (5 spp.), Miridae (17 spp.), Nabidae (1 sp.), Notonectidae (1 sp.), Oxycarenidae (1 sp.), Pachygronthidae (1 sp.), Pachynomidae (2 spp.), Pentatomidae (16 spp.), Pleidae (1 sp.), Pyrrhocoridae (1 sp.), Reduviidae (30 spp.), Rhopalidae (5 spp.), Rhyparochromidae (12 spp.), Saldidae (1 sp.), Scutelleridae (2 spp.), Tingidae (1 sp.), and Veliidae (1 sp.). These findings include six new records for the Argentinean fauna: Prytanes foedus (Stl), Saldula pallipes (Fabricius), Camirus brevilinea (Walker), Atopozelus opsimus Elkins, Doldina bicarinata Stl, Rocconota sextuberculata St and 39 new records for Chaco Province.

Effects of photoperiod and temperature on the developmental duration and diapause in Dolycoris baccarum (Heteroptera: Pentatomidae) from Hohhot, Inner Mongolia, China.

The shield bug, Dolycoris baccarum (L.) (Heteroptera: Pentatomidae), is widely distributed across Asia and Europe. At high latitudes, it overwinters, as adult in diapause, which then becomes the insect source for the following year. To fully understand the developmental duration and diapause characteristics of D. baccarum, the effects of photoperiod and temperature were studied in a population from Hohhot, Inner Mongolia, China. The results indicated that the developmental duration was significantly prolonged at temperatures of 20 or 25 °C, with a prolonged light period; however, when the light period was prolonged to 16L:8D and 18L:6D, the developmental duration was shortened significantly. Furthermore, the developmental duration was also shortened significantly with increasing temperature, when the photoperiod was 12L:12D for short days and 16L:8D for long days. All individuals entered diapause under short-day conditions of 10L:14D and 12L:12D at a temperature of 20 °C; however, the diapause rate decreased significantly under 14L:10D and 16L:8D photoperiods, and the diapause rate decreased significantly at a temperature of 25 °C with prolonged photoperiod. Interestingly, when the photoperiod was fixed at 12L:12D, the diapause rates at different temperatures (20, 25, 28, and 30 °C) exceeded 95%; while the effect of temperature on diapauses was nonsignificant under this photoperiod, it was still sensitive to the photoperiod; at a photoperiod of 16L:8D, the effect of temperature on the diapause rate was noticeable, and the diapause rate decreased significantly with increasing temperature.

Checklist and distribution of Nepomorpha (Hemiptera: Heteroptera) from China.

An updated catalog of the infraorder Nepomorpha from China is provided based on literature reports, museum specimens, and field collections. In total, 214 species of Nepomorpha are listed in 6 superfamilies, 11 families, and 37 genera, including: Aphelocheiridae (1 genus, 27 species), Belostomatidae (3 genera, 7 species), Corixidae (9 genera, 52 species), Gelastocoridae (1 genus, 3 species), Helotrephidae (5 genera, 25 species), Micronectidae (1 genus, 28 species), Naucoridae (7 genera, 12 species), Nepidae (5 genera, 21 species), Notonectidae (4 genera, 32 species), Ochteridae (1 genus, 2 species) and Pleidae (1 genus, 5 species). Paraplea liturata (Fieber, 1844) is reported from mainland China for the first time. Distribution maps are provided for most species and are based on museum specimens and our field collections.

Thirty-four new species of Rhagovelia (Heteroptera: Veliidae) from the East Papua Composite Terrane, far eastern New Guinea.

Thirty-four new species of Rhagovelia are described from the East Papua Composite Terrane of far eastern New Guinea. The new taxa described from this area are as follows: R. yela, R. woa, and R. mbo from Rossel Island; R. tagula, R. kolukolu, and R. riu from Tagula Island; R. bwagabwaga from Misima Island; R. suloga from Woodlark Island; R. torrenticola and R. elongata from Goodenough Island; R. awaetowa from Fergusson Island; R. dibuwa from Normanby Island; R. basima from Fergusson and Normanby islands; R. kalawai from Sideia and Basilaki islands; R. guiagoila from Basilaki, Sideia and Sariba islands; R. tufi, R. bowutu, R. obscura, R. upalai, R. antap, R. goilala, R. udabe, R. watuti, R. peninsularis, R. auga, R. aviavi, R. tekadu, R. sapoi, R. mimani, R. dinga, R. ivimkana, R. loriae, R. grisea, and R. cheesmanae from the Owen Stanley Range of eastern New Guinea. Redescriptions are also provided for five previously described species occurring in this portion of New Guinea: R. peggiae Kirkaldy, R. hirsuta Lansbury, R. priori Lansbury, R. caesius Lansbury and R. aureospicata Lansbury. A regional key is provided for these 39 species of Rhagovelia occurring in the Papuan Peninsula and adjacent island groups, accompanied by figures of the male parameres and other diagnostic morphological structures, and distribution maps for all species.

Studies in the New World tribe Anisoscelini Laporte, 1832 (Heteroptera: Coreidae: Coreinae): updated distributions, nomenclatural changes, and keys to the genera of the tribe and the species of Anisoscelis Latreille, 1829 and Bitta Osuna, 1984.

Ninety new country records are recorded for 44 species of Anisoscelini Laporte, 1832 (Heteroptera: Coreidae: Coreinae). Informal distributional records are recognized and included, and updated distributions are provided for all accounted species. The following new synonymy is proposed: Malvana Stl, 1865 (= Belonomus Uhler, 1869, n. syn.) and Malvana serrulata Stl, 1865 (= Belonomus annulaticornis Uhler, 1869, n. syn.). The rank of one genus is reinstated: Bitta Osuna, 1984, stat. resurr. (formerly a subgenus of Anisoscelis Latreille, 1829). The following new or restored combinations are proposed: Bitta affinis (Westwood, 1840), comb. reins., Bitta alipes (Gurin-Mneville, 1833), comb. reins., Bitta gradadia (Distant, 1881), comb. reins., Bitta hymeniphera (Westwood, 1840), comb. reins., Bitta lurida (Brailovsky, 2016), comb. nov., and Bitta podalica Brailovsky & Mayorga, 1995, comb. reins.. We also present dichotomous keys to the twenty-nine genera of Anisoscelini, and to the species of the genera Anisoscelis Latreille, 1829 and Bitta Osuna, 1984.

Xenobates indicus sp. nov. (Hemiptera: Gerromorpha: Haloveliidae) from India, the first species of the genus described from the Indian subcontinent.

Xenobates indicus sp. nov. is described from Tamil Nadu and West Bengal, India. It constitutes the first species of the genus from the Indian subcontinent. The new species can be identified by its large size when compared to its closely related species and the presence of setal fringe on the posterior margin of mediotergite VIII of female. Key to the species of Xenobates from South and Southeast Asia and the list of world species are provided (Table 1).

Taxonomic corrections on Oriental Anthocoridae (Hemiptera: Heteroptera) described by Bertil Poppius.

Five species of Oriental Anthocoridae (Hemiptera: Heteroptera) described by Robert Bertil Poppius are revised based on their type materials. The following new combinations and new junior subjective synonyms are proposed: Amphiareus constrictus (Stl, 1860) = Cardiastethus laeviusculus Poppius, 1915, syn. nov.; Lippomanus longiceps (Poppius, 1915), comb. nov. (transferred from Cardiastethus) = Lippomanus brevicornis Yamada & Hirowatari, 2004, syn. nov.; Alofa sodalis (B. White, 1878) = Cardiastethus minutus Poppius, 1909, syn. nov.; Physopleurella obscura Poppius, 1909 (recognized as valid species) = P. nigrifemora Yamada & Hirowatari, 2007, syn. nov. Lectotypes are designated for the following species: Cardiastethus laeviusculus Poppius, 1915; Cardiastethus pilosus Poppius, 1909.

Identity on Filchneria heteroptera (Wu, 1938) (Plecoptera: Perlodidae) with a new record of Paraleuctra cercia (Okamoto, 1922) from China.

Filchneria heteroptera (Wu, 1938) is rediscovered from Heilongjiang Province of northeastern China. A supplementary description and illustrations including aedeagal structures based on newly collected specimens are provided. Filchneria dongruihangi Chen, 2020 is considered here as a junior synonym of F. heteroptera (Wu, 1938). Paraleuctra cercia (Okamoto, 1922) is reported from Liaoning and Heilongjiang provinces, China for the first time.

Review of the genus Tetralicia (Hemiptera: Aleyrodidae) and description of two new species of whiteflies found on avocado trees in Peru.

Two new species, Tetralicia sawyeri n. sp. and Aleuroplatus martini n. sp. found on avocado (Persea americana) trees in Peru are described and illustrated. The synonymy of Aleuropleurocelus Drews & Sampson, 1956 n. syn. with Tetralicia Harrison, 1917 is proposed and a review and an illustrated key to the 39 species of Tetralicia of the world based on characteristics of the puparia is provided. Thirty-three species are transferred from Aleuropleurocelus to Tetralicia. A lectotype is designated for Aleurodes abnormis Quaintance, 1900. Aleurotrachelus gratiosus Bondar, 1923 is transferred to the genus Aleuroplatus. Paracarniella mexicana (Distant) and Adparaproba cf. yungensis Carvalho (Hemiptera: Miridae) are recorded for the first time in Peru and are important predators of both new whitefly species. Other natural enemies of these whiteflies found in the study include predatory species: Nephaspis isabelae Gonzlez (Coccinellidae), Chrysoperla sp., Ceraeochrysa sp. (Chrysopidae) and Gasteracantha cancriformis L. (Araneidae) as well as Encarsia brasiliensis Hempel, a common whitefly parasitoid in the Neotropics. A key to the New World genera of whiteflies similar to Aleuroplatus and Tetralicia is provided.