Trypanosomatids are obligate parasites of animals, predominantly insects and vertebrates, and flowering plants. Monoxenous species, representing the vast majority of trypanosomatid diversity, develop in a single host, whereas dixenous species cycle between two hosts, of which primarily insect serves as a vector. To explore in-depth the diversity of insect trypanosomatids including their co-infections, sequence profiling of their 18S rRNA gene was used for true bugs (Hemiptera; 18% infection rate) and flies (Diptera; 10%) in Cuba. Out of 48 species (molecular operational taxonomic units) belonging to the genera Vickermania (16 spp.), Blastocrithidia (7), Obscuromonas (4), Phytomonas (5), Leptomonas/Crithidia (5), Herpetomonas (5), Wallacemonas (2), Kentomonas (1), Angomonas (1) and two unnamed genera (1 + 1), 38 species have been encountered for the first time. The detected Wallacemonas and Angomonas species constitute the most basal lineages of their respective genera, while Vickermania emerged as the most diverse group. The finding of Leptomonas seymouri, which is known to rarely infect humans, confirms that Dysdercus bugs are its natural hosts. A clear association of Phytomonas with the heteropteran family Pentatomidae hints at its narrow host association with the insect rather than plant hosts. With a focus on multiple infections of a single fly host, using deep Nanopore sequencing of 18S rRNA, we have identified co-infections with up to 8 trypanosomatid species. The fly midgut was usually occupied by several Vickermania species, while Herpetomonas and/or Kentomonas species prevailed in the hindgut. Metabarcoding was instrumental for analysing extensive co-infections and also allowed the identification of trypanosomatid lineages and genera.

Juvenile hormone (JH) plays a pivotal role in almost every aspect of insect development and reproduction. The chemical structure of the JH in heteropteran species has long remained elusive until methyl (2R,3S,10R)-2,3;10,11-bisepoxyfarnesoate, commonly named as juvenile hormone III skipped bisepoxide (JHSB3), was isolated from Plautia stali (Hemiptera: Heteroptera: Pentatomidae). Recently, several groups reported the presence of JHSB3 in other heteropteran species. However, most of the studies paid no attention to the determination of the relative and absolute structure of the JH. In this study, we investigated the JH of the cabbage bug Eurydema rugosa (Hemiptera: Heteroptera: Pentatomidae), known as a pest for wild and cultivated crucifers. JHSB3 was detected in the hexane extract from the corpus allatum (CA) product using a chiral ultraperformance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) which can inform the absolute stereochemistry of the JH. Its stereoisomers were not detected. Topical application of the synthetic JHSB3 to the last instar nymphs inhibited their metamorphosis and induced nymphal-type colouration of the dorsal abdomen in a dose-dependent manner. Additionally, the topical application of JHSB3 effectively terminated summer and winter diapauses in females. These results indicate that the JH of E. rugosa is JHSB3. Although individuals in summer and winter diapauses are physiologically distinct in E. rugosa, the results suggest that the physiological differences between these diapauses are based, not on the responsiveness to JH, but on the processes governing activation of the CA or on its upstream cascades.

The introduction of alien species is one of the main problems in conservation. Many successful invaders cause severe economic and ecological damage. Such is the case of Leptoglossus occidentalis, a phytophagous true bug native to North America, which has become a pest in Europe, Asia, Africa and South America. Within the genus, another species whose distributional range is expanding toward the east of North America is Leptoglossus clypealis. As climate determines the successful establishment of insects, the identification of climatically suitable areas for invasive species based on ecological niche models (ENMs) offers an excellent opportunity for preventing invasions. In this study, ENMs were built for both species and their native climatic niches were compared. Their niche breath was also measured. The climatic niches of both species are identical and the niche breadth of L. clypealis is broader than that of L. occidentalis. In view of the great ecological resemblance between these two species, we believe that L. clypealis could became a major pest thus it should be carefully monitored. The results of the present worldwide ENMs showed numerous regions with suitable conditions for the establishment of both species. The future ENMs exhibited a retraction in the suitable areas in North America, Europe and Asia.

Elasmucha ferrugata (Fabricius, 1787) (Heteroptera: Acanthosomatidae) provides maternal care of eggs and larvae. Adults of both sexes have functional anterior dorsal abdominal scent glands (DAGs). Study of all internal and external cuticular structures of DAGs revealed that no DAGs are fully functional in the 1st larval instar, and very probably they are only slightly functional in the 2nd instar. Median and posterior DAGs are undoubtedly not functional in adults. There exists sexual dimorphism in the number of multicellular glandular units in anterior glands in adults. The occurrence of cuticular ductules of these units proves these to be functional glands. This is best considered in combination with the findings of a well-developed evaporatorium. Developed cuticular intima of the gland reservoir and/or the nearly closed ostiole or ostiolar scar bears no information about the functionality of the gland.

The study was conducted in tropical lowland forest in the Dumoga Bone National Park, Sulawesi, Indonesia. It sought (a) to establish the typical densities of sap-sucking Hemip tera, (b) to quantify the intensity of Hemiptera feeding on leaves, and (c) to investigate, using multivariate techniques, the relationships between Hemiptera density and/or feeding damage and a range of leaf or plant characteristics. Only 3% of shrubs examined had colonial Hemiptera feeding on growing shoots. Feeding punctures on leaves were common but the insects which produced them such as the Cicadellidae and various Heteroptera were scarce. Coccoidea and Aleyrodoidea were the dominant and ubiquitous Hemipterans, feeding primarily on the surface of the leaves. Psylloidea were relatively rare and Aphidoidea were not recorded. For the complete data set, which included all leaves examined, there were few significant correlations, either singly or in combination, between the various measures of insect abundance and the state of the 17 leaf characteristics recorded. However, when the data for young leaves were extracted there was evidence to suggest that the number of feeding punctures cm−2 of leaf and the number of coccids cm−2 of upper leaf surface increased rapidly to a maximum as the young leaf aged and certain characters changed accordingly. Other more stable leaf characteristics such as hairiness, spininess, glossiness, etc. explained only a small additional amount of the total variance in Hemiptera abundance.

The global increase of the human parasite, the common bed bug Cimex lectularius, calls for specific pest control target sites. The bed bug is also a model species for sexual conflict theory which suggests that seminal fluids may be highly diverse. The species has a highly unusual sperm biology and seminal proteins may have unique functions. One-dimensional PAGE gels showed 40–50% band sharing between C. lectularius and another cimicid species, Afrocimex constrictus. However, adult, sexually rested C. lectularius males were found to store 5–7 μg of seminal protein and with only 60 μg of protein we obtained informative 2-D PAGE gels. These showed 79% shared protein spots between 2 laboratory populations, and more than half of the shared protein spots were detected in the mated female. Further analysis using liquid chromatography electrospray ionization tandem mass spectrometry revealed that 26·5% of the proteins had matches among arthropods in databases and 14·5% matched Drosophila proteins. These included ubiquitous proteins but also those more closely associated with reproduction such as moj 29, ubiquitin, the stress-related elongation factor EF-1alpha, a protein disulfide isomerase and an antioxidant, Peroxiredoxin 6.

Herbivorous insects are influenced by both ‘bottom-up’ forces mediated through host plants and ‘top-down’ forces from natural enemies. Few studies have tried to evaluate the relative importance of the two forces in determining the abundance of insects. The leaf beetle Phratora vulgatissima Linnaeus sometimes occurs at high densities and severely damages the willow Salix cinerea in forest habitats. For willows growing in open agricultural landscapes (farmland S. cinerea), the leaf beetle generally occurs at low densities and plants receive little damage. The purpose of the present study was to evaluate the relative importance of host plant quality and natural enemies behind the observed difference in P. vulgatissima abundance. Female egg-laying and larval performance (growth and survival) were studied on caged willow branches in the field to investigate if plant quality differs between S. cinerea trees growing in forest and farmland habitats. The survival of eggs exposed to natural enemies was examined to see if predation could explain the low abundance of leaf beetles on farmland willows. The results indicated no difference in plant quality; female egg laying and larval performance did not differ between the forest and the farmland. However, heteropteran predators (true bugs) were more abundant, and the survival of eggs was lower, on plants in the farmland habitat than in the forest habitat. The data suggest that the low abundance of P. vulgatissima on farmland willows could not be explained by a poor quality of plants, but more likely by high predation from heteropterans.

Podisus nigrispinus (Dallas) is a common predator in agricultural and natural systems in Neotropical America. Its feeding strategy involves extra-oral digestion and to better understand this process its salivary glands were extracted and subjected to morphological and preliminary enzyme characterization. The salivary glands of P. nigrispinus are formed by a pair of main and accessory gland complexes. The main salivary glands are further divided into an anterior and a posterior lobe. The compartmentalization of the salivary gland complex is likely to be important for the production, activation and release of the digestive enzymes used in the extra-oral digestion of prey items. Proteases and lipase, important digestive enzymes involved in zoophagy, were detected in the salivary glands of P. nigrispinus. The prevailing trypsin-like protease activity was characterized by using the serine-protease substrate N-α-benzoyl-L-Arg-p-nitroanilidine (L-BApNA) and the trypsin inhibitors tosyl-L-lysine chloromethyl ketone (TLCK) and benzamidine. The KM value obtained for trypsin-like activity was 1.57 mm and the different peaks of optimum pH and temperature activity suggest the presence of multiple forms of this enzyme in P. nigrispinus. Detection of amylase activity in the salivary glands of this predator suggests its ability to digest starch and obtain nutrients from plants, which may have adaptative value under prey scarcity.

The sensory receptors on the antennal flagellar segments and on the rostral tip of four adult hemipteran insects were identified and compared using scanning electron microscopy in order to better understand the role of sensillae in the process of host plant selection and the structural adaptations of feeding organs for phytophagy. The species studied are Riptortus pedestris Fabricius (Alydidae), Elasmolomus sordidus (Fabricius) (Lygaeidae), Cyclopelta siccifolia Westwood (Pentatomidae) and Chrysocoris purpurea (Westwood) (Pentatomidae). Differences in the distribution and arrangement of sensory receptors in the hemipteran families were noted, especially in the shape of the antennal apices, which are of taxonomical significance. A large array of trichoid basiconic and coeloconic sensillae is distributed on the antennal surface. Distal antennal segments have more sensillae and more types of sensillae than the proximal segments, indicating their prominent role in host plant surface exploration. There is only a slight variation in the shape of the stylets owing to the similarity in feeding habits. The mandibular tips are straight and sharp and do not contain any hooks or barbs as in carnivorous species.

A study was conducted to determine the morphology, histology and ultrastructure of the salivary apparatus of Lethocerus indicus. The apparatus was found to consist of a principal and accessory salivary gland. The former is bilobed, having a small superior lobe and a larger inferior lobe, made up of many lobules/acini. Each lobule is made up of a simple glandular layer of syncytial epithelium encompassing the lumen, which is filled with secretory granules that are elaborated from the epithelium predominantly by the apocrine mode of secretion. The accessory salivary gland is vesicular cum tubular. The vesicular part is made up of a thin layer of flat, polygonal cells, having no signs of secretory activity, while the tubular part consists of a single layer of columnar epithelial cells that show signs of secretory activity. Both the principal and accessory glands discharge their secretions through a common salivary duct which opens at the base of the hypopharynx. The ultrastructure of the lobules of the principal salivary gland reveals a thick amorphous, basement membrane (800–1000Å) which supports the glandular epithelium. The basal and apical plasma membranes of the epithelium show basal infoldings and microvilli respectively. The nucleus is highly branched and remains surrounded by a double layered nuclear envelope. The ergastoplasmic membranes show abundance of ribosomes. Many mitochondria are also visible in the cytoplasm. It is concluded that the salivary gland of L. indicus is an organ of high synthetic activity.

Eight surface-living insect species, two gyrinid beetles and six heteropteran bugs, were studied in 27 pools in a Tenerifestream. Gyrinus urinator was on average the most abundant species whereas Velia lindbergi was the most widely distributed one. Gyrinid abundance (numbers per pool), but not density (numbers per square metre), was positively associated with pool size and depth. In contrast, the densities of the bugs Velia lindbergi and Hydrometra stagnorum decreased with pool size. Both the number of species and individuals increased with pool area. Widely distributed species were represented with higher average densities than species with a more restricted distribution. Contrary to theory, there was a positive relationship between mean adult body size and density within the guild.