Parasitoids as taxonomists: how does the parasitoid Chouioia cunea distinguish between a host and a non-host?

BACKGROUND: How parasitoids distinguish hosts from non-hosts remains an unknown question. Chouioia cunea Yang (Eulophidae) is an important fall webworm parasitoid that attacks many forest and agricultural pests. To study the differences in the chemical clues used by C. cunea to distinguish host and non-host plants, we used gas chromatography-mass spectrometry (GC-MS) to identify volatile compounds of two C. cunea hosts (Hyphantria cunea and Helicoverpa armigera) and two non-hosts (Spodoptera exigua and Spodoptera frugiperda). Additionally, we used behavioral assays to compare the attraction of C. cunea to various compounds. RESULTS: The two natural host species were more attractive than the two non-host species, in the following order: Hyphantria cunea > Helicoverpa armigera > S. exigua = S. frugiperda. The pupae of the natural hosts contained 1-dodecene, which was not produced by the two natural non-hosts. When the 'attractants' based on the difference between the species-specific blend emitted by pupae and the optimal blend were sprayed onto the natural non-host pupae, they significantly improved the attraction of C. cunea to the non-host pupae. CONCLUSION: These results revealed that specific host-produced volatile compounds guide C. cunea to distinguish between natural hosts and non-hosts. Overall, this study provides a foundation for developing a behavior-modifying strategy to re-direct C. cunea attacks to control important non-host pests. © 2023 Society of Chemical Industry.

Characterization of two new Pylorgus mitogenomes (Hemiptera, Lygaeidae, Ischnorhynchinae) and a mitochondrial phylogeny of Lygaeoidea.

Lygaeidae is a large family of Hemiptera (Heteroptera) currently separated into three subfamilies, Ischnorhynchinae, Lygaeinae, and Orsillinae. In this research, the complete mitogenomes of the iscnorhynchines Pylorgusporrectus Zheng, Zou & Hsiao, 1979 and Pylorgussordidus Zheng, Zou & Hsiao, 1979 were sequenced, and the phylogeny of Pylorgus and the Lygaeidae with known complete mitogenomes were examined. The mitogenomes are 15,174 bp and 15,399 bp in size, respectively, and comprised of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a control region (D-loop). Nucleotide composition is biased toward A and T, and the gene order is identical to that of the putative ancestral arrangement of insects. Eleven PCGs begin with a typical ATN, and the remaining two PCGs begin with TTG (cox1 and nad4l). All tRNAs had a typical cloverleaf secondary structure, but some of them had individual base mismatches. The phylogenetic analyses based on the concatenated nucleotide sequences of the 13 PCGs, using Bayesian inference and maximum likelihood, support the monophyly of Lygaeidae. The results show that P.porrectus and P.sordidus clustered with nine other Lygaeidae. This study includes the first complete sequencing of the mitochondrial genomes of two Pylorgus species, which will provide important data for studying the phylogenetic position of Lygaeidae in Lygaeoidea and reconstructing the phylogenetic relationships within Pentatomomorpha.

Out of East Asia: Early Warning of the Possible Invasion of the Important Bean Pest Stalk-Eyed Seed Bug Chauliops fallax (Heteroptera: Malcidae: Chauliopinae).

The short stay at the beginning of the invasion process is a critical time for invasive species identification and preventing invasive species from developing a wider distribution and significant economic impact. The stalk-eyed seed bug Chauliops fallax is an important agricultural pest of soybean and was first reported to occur outside East Asia. Here, we reported the native evolutionary history, recent invasion history, and potential invasion threats of C. fallax for the first time based on population genetic methods and ecological niche modelling. The results showed that four native East Asian genetic groups (EA, WE, TL, and XZ) were well supported, showing an east-west differentiation pattern consistent with the geographical characteristics of three-step landforms in China. Two main haplotypes existed: Hap1 might have experienced a rapid northwards expansion process after the LGM period, and Hap5 reflected local adaptation to the environment in southeastern China. The Kashmir sample was found to come from the recent invasion of populations in the coastal areas of southern China. Ecological niche modelling results suggested that North America has a high risk of invasion, which might pose a serious threat to local soybean production. In addition, with future global warming, the suitable habitat in Asia will move towards the higher latitude region and gradually deviate from the soybean planting area, which indicates the threat of C. fallax to soybean production in Asia will decrease in the future. The results could provide new insights into the monitoring and management of this agricultural pest in the early invasion stage.

Revision of the genus Urvaschia Hopp (Hemiptera, Lygaeoidea, Oxycarenidae), with descriptions of two new species from China and Nepal.

The species of Urvaschia Hopp, 1987 are reviewed. The following taxonomic change is proposed: Urvaschiaobscuripennis (Kiritshenko, 1914), comb. nov. (transferred from Microplax Fieber, 1860). The genus Urvaschia Hopp is newly recorded from Afghanistan, China, Iran, and Tadzhikistan. Two new species of Urvaschia, Urvaschiaconvexa sp. nov. and U.recta sp. nov. are described from China and Nepal. A diagnosis of the genus, a key to all of the included species, habitus photographs, and male genitalia illustrations of selected species are presented.

Morphological diversity of the metathoracic spiracle in the Lygaeoidea (Hemiptera: Heteroptera).

Spiracles are the openings in the exoskeleton of insects through which air enters into the respiratory system that is formed by a series of tubes called tracheae. They are primarily located on the abdomen, but can also occur on the thorax, including the metathorax. An insect metathoracic spiracle is usually composed of an external opening and a more internal filter apparatus. We propose new terminology for these structures, and we explore the value in their use in taxonomic and phylogenetic studies within the true bug infraorder Pentatomomorpha, with emphasis on the superfamily Lygaeoidea (Insecta: Hemiptera: Heteroptera). These structures were studied using scanning electron microscopy. Two types of metathoracic spiracle external openings were recognized: a narrow opening (type N), which is slit-like; and a wide opening (type W), with internal fine structures located between the mesothoracic and metathoracic margins of the interpleural suture clearly visible. The filter apparatus in the Pentatomomorpha consists of modified mushroom bodies of the metathoracic scent gland evaporatorium, for which the term mycoid filter processes is proposed. Eight different types of mycoid filter processes, and an unmodified microsculpture type (a type with usual cuticular microsculpture) and filter setae can be found on the anterior or posterior margins of the metathoracic spiracle. We believe the wide opening (type W) to be the plesiomorphic character state in the Pentatomomorpha, with multiple, independent transformations leading to the narrow opening in Lygaeoidea. Considerable variability in the structure of the spiracle opening (in Lygaeoidea), and in the structure of the mycoid filter processes (in Pentatomomorpha) was detected. Overall, we found the morphology of these structures to be of limited value concerning the taxonomy or for determining phylogenetic relationships of the higher taxa (families) of Pentatomomorpha, but they may be useful as additional evidence for taxonomic and phylogenetic studies at the generic and perhaps the tribal levels.

Reciprocal-Activation Strategy for Allylic Sulfination with Unactivated Allylic Alcohols.

A reciprocal-activation strategy for allylic sulfination with unactivated allylic alcohols was developed. In this reaction, the hydrogen bond interaction between allylic alcohols and sulfinic acids allowed for reciprocal activation, which enabled a dehydrative cross-coupling process to occur under mild reaction conditions. This reaction worked in an environmentally friendly manner, yielding water as the only byproduct. A variety of allylic sulfones could be obtained in good to excellent yields with wide functional group tolerance. In gram scale reactions, allylic sulfones could be conveniently isolated in high yield by filtration.

Revision of the genus Sadoletus Distant, with description of new species from China and Australia (Hemiptera: Heteroptera: Heterogastridae).

The species of genus Sadoletus are revised based on re-examination of the type material. A total of eighteen species are recognized in this genus, including five new species: Sadoletus abathonotus sp. nov., Sadoletus alphus sp. nov., Sadoletus biprotuberans sp. nov., and Sadoletus planus sp. nov. from China, and Sadoletus variabilis sp. nov. as the first representative of the genus from Australia, described in the present contribution. The following new subjective synonymy is proposed: Sadoletus validus Distant, 1903 = Sadoletus subpellucidus Ban, 2018 syn. nov. Sadoletus valdezi as treated in Ban Ishikawa (2013) is proved to be a misidentification, now correctly described as Sadoletus planus sp. nov.. Three species, Sadoletus validus Distant, 1903, Sadoletus voluptarius Bergroth, 1918, Sadoletus melasmus Ban, 2018 are newly recorded from China. A key to all the known species of Sadoletus is provided. The lectotypes and paralectotypes are designated for S. validus Distant, 1903, S. pallescens Distant, 1909, S. valdezi Bergroth, 1918, S. voluptarius Bergroth, 1918, S. montanellus Bergroth, 1918 and S. montivagus Bergroth, 1918. Based on external and genitalia morphology, two "species groups" have been recognized amongst the species described in this genus until now. The main group, including 14 of the 18 known species, is confirmed as the typical Sadoletus (with type-species S. validus), for which a redefinition is provided. However the generic placement of the remaining four species is unclear at present, hence are tentatively retained under the present genus Sadoletus, pending further investigation involving other related heterogastrid genera, and using both morphological and molecular data.

A new genus and new species of Myodochini from Australia (Hemiptera: Heteroptera: Rhyparochromidae).

Pseudolaryngodus spectabilis gen. et sp. nov., from Little Desert National Park in Victoria, Australia, is described and illustrated. The monotypic new genus superficially resembles the udeocorine genus Laryngodus Herrich-Schaeffer in general facies, and is sympatric with one of the species of Laryngodus. Pseudolaryngodus has some characters that share its tribal placement within both Udeocorini and Myodochini of the family Rhyparochromidae. However, it lacks inner laterotergites on abdomen, making it a Myodochini rather than a Udeocorini. Details of the relationships between these two genera, along with their tribal placements, are discussed.

Meschia zoui sp. nov., first representative of the family Meschiidae from China (Hemiptera: Heteroptera: Lygaeoidea).

All the species of the family Meschiidae, known until now only from India and Australia, are reviewed. A new species, Meschia zoui sp. nov. from southern China, is described as the first representative of this family from China, also its cuticular structures are studied using the scanning electron microscope. A key to all species of Meschiidae is provided, along with a re-description of Meschia quadrimaculata Distant.

A Ba/Pd Catalytic System Enables Dehydrative Cross-Coupling and Excellent E-Selective Wittig Reactions.

A Ba/Pd cooperative catalysis system was developed to enable the dehydrative cross-coupling of allylic alcohols with P-ylides to occur directly and promote a subsequent Wittig reaction in one pot. A variety of multisubstituted 1,4-dienes were isolated in good to excellent yields with broad P-ylides (stabilized by both ester and ketone carbonyl groups) and aldehyde (aliphatic and aromatic) substrates with excellent E selectivity.

Allylic Phosphorus Ylides Directly Generated from Alcohols with Water as the Only Byproduct.

A novel strategy for the preparation of allylic phosphorus ylides directly from Morita-Baylis-Hillman (MBH) alcohols in an environmentally benign manner was developed. With the assistance of a calcium catalyst, the SN2' process between phosphines and allylic alcohols occurred smoothly, delivering allylic phosphorus salts and calcium-stabilized hydroxide ions. Then, in situ deprotonation gave the allylic phosphorus ylides with water as the only byproduct. Functionalized 1,3-diene moieties can be conveniently obtained by trapping the ylides through a Wittig olefination.

Barium-catalyzed C-OH/P-H dehydrative cross-coupling for C-P bond construction.

A barium-catalyzed C-OH/P-H dehydrative cross-coupling protocol for the construction of C-P bonds was developed. This reaction was performed in an environmentally benign manner with water as the only by-product. A variety of allylic phosphorus compounds can be isolated in good to excellent yields.

Direct Substitution of Secondary and Tertiary Alcohols To Generate Sulfones under Catalyst- and Additive-Free Conditions.

An environmentally benign protocol that affords propargylic sulfones containing highly congested carbon centers from easily accessible alcohols and sulfinic acids with water as the only byproduct is reported. The reaction proceeded via an in situ dehydrative cross-coupling process by taking advantage of the synergetic actions of multiple hydrogen bonds rather than relying on an external catalyst and/or additives to achieve high product distribution.

The identity of Equatobursa, with proposal of new genus and species level synonymies (Hemiptera: Heteroptera: Heterogastridae).

The identities of the genus Equatobursa Zou, 1985 and its single included species, E. nigra Zou, 1985 (Hemiptera: Heteroptera: Lygaeoidea: Heterogastridae) are clarified based on the re-examination of the type material of the species. The following new subjective synonymies are proposed: Sadoletus Distant, 1903 = Equatobursa Zou, 1985, syn. nov.; Sadoletus izzardi Hidaka, 1959 = Equatobursa nigra Zou, 1985, syn. nov.

The complete mitochondrial genome of the stalk-eyed bug Chauliops fallax Scott, and the monophyly of Malcidae (Hemiptera: Heteroptera).

Chauliops fallax Scott, 1874 (Hemiptera: Heteroptera: Malcidae: Chauliopinae) is one of the most destructive insect pests of soybean and rice fields in Asia. Here we sequenced the complete mitochondrial genome of this pest. This genome is 15,739 bp long, with an A+T content of 73.7%, containing 37 typical animal mitochondrial genes and a control region. All genes were arranged in the same order as most of other Heteroptera. A remarkable strand bias was found for all nine protein coding genes (PCGs) encoded by the majority strand were positive AT-skew and negative GC-skew, whereas the reverse were found in the remaining four PCGs encoded by the minority strand and two rRNA genes. The models of secondary structures for the two rRNA genes of sequenced true bugs and Lygaeoidea were predicted. 16S rRNA consisted of six domains (domain III is absent as in other known arthropod mitochondrial genomes) and 45 helices, while three domains and 27 helices for 12S rRNA. The control region consists of five subregions: a microsatellite-like region, a tandem repeats region and other three motifs. The unusual intergenic spacer between tRNA-H and ND4 only found in the species of Lygaeoidea, not in other heteropteran species, may be the synapomorphy of this superfamily. Phylogenetic analyses were carried out based on all the 13 PCGs showed that Chauliopinae was the sister group of Malcinae and the monophyly of Lygaeoidea.