This report is a review of pertinent scientific literature on the chemical communication of the Miridae (Order Hemiptera; Suborder Heteroptera), with a focus on the sympatric species Eccritotarsus catarinensis Carvhalho and Eccritotarsus eichhorniae Henry. Both species have been deployed as biological control agents of water hyacinth, Pontederia (Eichhornia) crassipes (Martius) Solms-Laubach, in over 30 sites in South Africa. Our aim in this review was to gather and assimilate information on the chemical communication and chemical ecology of mirids, with an ultimate goal of enhancing the effectiveness of biological control agents of water hyacinth, particularly E. catarinensis and E. eichhorniae. Many hemipterans have highly developed metathoracic scent glands (MTGs), Brindley's glands, and secretory setae that store and emit chemicals that may act as allomones, kairomones, or pheromones. The preponderance of the available literature dealt with sex pheromones. Hexyl butyrate, (E)-4-oxo-2-hexenal, and (E)-2-hexenyl butyrate are reported to be sex pheromones in many mirids: for example, Adelphocoris fasciaticollis Reuter, Apolygus spinolae Meyer-Dür, Liocoris tripustulatus F., Lygocoris pabulinus L., several Lygus spp. (Lygus hesperus Knight, Lygus lineolaris Beauvois, Lygus elisus van Duzee, Lygus pratensis L., and Lygus rugulipennis Poppius), and Stenotus rubrovittatus Matsumura. Hexyl butyrate is the most prevalent sex pheromone in Miridae, while (E)-4-oxo-2-hexenal is the most prevalent sex pheromone in Heteroptera. Both pheromones co-occur in some species and exhibit many functionalities. The constancy of sex pheromones linked to behavioral patterns in Miridae suggest a punctuated equilibrium pattern of evolution (dating back to the Triassic), similar to morphological characters of many insects.

Systena frontalis (F.) is a major insect pest of nursery production systems in the Midwest, Northeast, and Southeast regions of the United States. Adults feed on plant leaves, which reduces salability of nursery-grown plants. There are limited options available to protect plants from S. frontalis adult feeding damage, and foliar insecticide applications are labor intensive. Systemic insecticides applied to the growing medium may protect plants from S. frontalis adult feeding. Consequently, in 2021 and 2022, we conducted two laboratory and two greenhouse experiments to determine if the systemic insecticides thiamethoxam, dinotefuran, cyantraniliprole, acephate, imidacloprid, and cyfluthrin + imidalcoprid protect plants from feeding by field-collected populations of S. frontalis adults. In the laboratory experiments, growing medium containing Itea plants was treated with the aforementioned systemic insecticides. Seven and 25 d after the treatments were applied, leaves were collected and placed into Petri dishes with a single S. frontalis adult. In the greenhouse experiments, Itea plants were placed into observation cages. Eight S. frontalis adults were released into each cage with an Itea plant. In the laboratory experiments, treatments associated with thiamethoxam and dinotefuran resulted in 100% mortality of S. frontalis adults after 72 h. In the greenhouse experiments, thiamethoxam, dinotefuran, and acephate protected plants from S. frontalis adult feeding 7 d after applying the systemic insecticide treatments. Therefore, systemic insecticides can mitigate feeding damage caused by S. frontalis adults on nursery-grown plants.

Bed bugs (Hemiptera: Cimicidae) are common, hematophagous ectoparasites of humans and other animals and are experiencing an international resurgence. Cimicids have been suspected in the transmission of many disease agents, including Bartonella species; however, disease transmission of any kind has not yet been confirmed in natural disease cycles. Bartonella spp. are transmitted by a variety of arthropods, including fleas, lice, and sand flies, but the potential role of bed bugs in transmission remains unknown. In this study, we used an artificial membrane to feed rabbit blood, either infected or uninfected with Bartonella henselae Regnery et al. (Alphaproteobacteria: Bartonellaceae) to two groups of adult Cimex lectularius L. After 2 wks, the presence of B. henselae in the gut and salivary glands of bugs was assessed via PCR and transmission electron microscopy (TEM), respectively. Although 4 of 10 bed bug guts showed evidence of B. henselae, we were unable to visually detect B. henselae in any of the salivary gland TEM images.

Juvenile hormone (JH) is a major endocrine hormone that mediates development, metamorphosis, and reproduction in insects. It binds directly to its methoprene-tolerant receptor and recruits a heterodimer partner to form the JH–receptor complex that then activates a JH-inducible gene known as the Krüppel homolog 1 (Kr-h1). There is evidence that this gene is a downstream factor mediating both physiological and biochemical processes; however, the functional mechanism of Kr-h1 is largely unknown. Using the economically important rice (Oryza sativa L.) pest Chilo suppressalis (Walker) (Lepidoptera: Crambidae) as a model, we used a combination of RNA interference (RNAi), high-throughput RNA sequencing, and real-time quantitative polymerase chain reaction (RT-qPCR) to identify candidate transcription factor (TF) genes that are regulated by Kr-h1. RNAi knockdown of Krh1 identified the Zinc finger proteins, ZBTB, THAP, PAX, MYB, HSF, Homeobox, HMG, CSD, basic helix-loop-helix, STAT, RHD, and MBD families as regulated by Kr-h1. RT-qPCR confirmed the transcription levels of these putative TFs and indicated that knockdown of Kr-h1 can induce or suppress the expression of these proteins in C. suppressalis. These results provide the basic information required for in-depth research on the TFs regulated by Kr-h1 in C. suppressalis and other insects.

Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is an ectoparasitoid of the pine sawyer beetle, Monochamus alternatus Hope (Coleoptera: Cerambycidae). A sensitive and precise olfactory system is required for the accurate location of the coleopteran host by D. helophoroides neonates. Herein, we characterized the relative expression patterns of six representative olfactory-related genes at different stages of M. alternatus parasitism and in different body regions of D. helophoroides neonates. The genes encoding chemosensory protein 2 (DhelCSP2), odorant receptor 2 (DhelOR2), and ionotropic receptor 2 (DhelIR2) were significantly upregulated before parasitization was initiated, whereas the genes encoding odorant binding protein 8 (DhelOBP8), gustatory receptor 5 (DhelGR5), and sensory neuron membrane protein 1 (DhelSNMP1) were significantly upregulated 4–5 d after initiation of parasitism. In D. helophoroides neonates, four genes (DhelOBP8, DhelCSP2, DhelOR2, and DhelIR2) were significantly upregulated in the head compared with the thoracoabdominal region, and one gene (DhelGR5) was significantly upregulated in the thoracoabdominal area compared with the head. Double-stranded RNAs (dsRNAs) targeting the six olfactory-related genes were synthesized and delivered to D. helophoroides neonates via immersion. After dsRNA treatment, the transcript levels of four olfactory-related genes (DhelOBP8, DhelCSP2, DhelOR2, and DhelSNMP1) were significantly reduced compared with that of the controls. These results provide a basis for further functional explorations of D. helophoroides olfactory genes, which may lead to the development of improved biological pest control methods using D. helophoroides larvae.

A stable and specific heat shock protein 27.2 (HSP27.2) antibody was prepared and analyzed for protein level research in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). The full-length hsp27.2 was amplified from H. armigera larvae and constructed into the prokaryotic expression vector. The purified His-tag fused protein was used to immunize rabbits for the antibody preparation. Western blot analysis indicated that this antibody specifically recognized the HSP27.2 encoded by H. armigera and detected the HSP27.2 encoded by other noctuid larvae. Further analysis of HSP27.2 expression in H. armigera under infection by different pathogenic microorganisms and in different tissues showed that the expression of HSP27.2 is continually stable. The HSP27.2 antibody is efficient and capable as a reference antibody for functional studies involving genes and proteins in H. armigera and other lepidopteran insects.

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is one of the most destructive pests of stored products. Although there have been studies on the potential use of essential oils from plants in the Artemisia genus as insecticides, no comprehensive bioactivity data are available on the efficacy of Artemisia vulgaris L. (Asterales: Asteraceae) essential oil and its chemical constituents on stored-product pests. Therefore, in this study, the bioactivity of A. vulgaris essential oil and its chemical constituents, eugenol and terpinen-4-ol, against T. castaneum were determined by contact, fumigant, and repellent bioassays. Analysis of contact and fumigant bioassays showed that A. vulgaris essential oil, eugenol, and terpinen-4-ol have contact and fumigant toxicities against T. castaneum, of which terpinen-4-ol has a strong killing effect on larvae and adults, suggesting that terpinen-4-ol may be the main active component of A. vulgaris essential oil in contact and fumigant effects. Additionally, A. vulgaris essential oil and eugenol have higher repellent activity against T. castaneum larvae and adults, whereas the repellent activity of terpinen-4-ol is low, indicating that the main component of A. vulgaris essential oil in repellence may be eugenol. These results further provide relevant theoretical basis for the development of plant essential oil pesticides.