On Some Rare and Little-Known True Bugs (Heteroptera) in Siberia and the Russian Far East

The models for forewarning about the infestation of green leafhopper Nephotettix virescens Dist (Cicadellidae, Hemiptera), plant hopper Cofana spectra Dist (Delphacidae, Hemiptera), C. yasumatsui Young (Kolla mimica, Hemiptera), rice gundhi bug Leptocoriza acuta Thunberg (Alydidae, Hemiptera) and yellow stem borer Scirpophaga incertulas Walker (Pyralidae, Lepidoptera) in rice growing season (July to November) was studied through light trap collection over fifteen years (1985-1999). Maximum population of N. virescens Dist (Cicadellidae, Hemiptera), C. yasumatsui Young (Kolla mimica, Hemiptera) and L. acuta Thunberg (Alydidae, Hemiptera) were recorded in the third week of October all the years. C. spectra Dist (Delphacidae, Hemiptera) had maximum population in the second and third weeks of October during the aforesaid period. Maximum population of S. incertulas Walker (Pyralidae, Lepidoptera) was recorded in the month of September in all the years. After making a transformation on the response variable that is, population of insects, the cubic polynomial model was fitted with week as explanatory variable and it described the dynamics of the populations of all considered insects during the weeks. The values of multiple correlations for N. virescens Dist (Cicadellidae, Hemiptera), C. spectra Dist (Delphacidae, Hemiptera), C. yasumatsui Young (Kolla mimica, Hemiptera), L. acuta Thunberg (Alydidae, Hemiptera) and S. incertulas Walker (Pyralidae, Lepidoptera) were in the order of 0.964, 0.947, 0.971, 0.881 and 0.949, respectively. We also include meteorological factors in the model and it provides the dynamics of the populations of all the above mentioned insects for forecasting. Key words: Meteorological factors, transformation, regression analysis, rice insect pests.

Simple SummaryThere is a wide variety of insects in the suborder Heteroptera (true bugs), with various feeding habits and living habitats. Microbes that live inside insect guts play critical roles in aspects of host nutrition, physiology, and behavior. However, most studies have focused on herbivorous stink bugs of the infraorder Pentatomomorpha and the gut microbiota associated with the megadiverse heteropteran lineages, and the implications of ecological and diet variance have been less studied. Here, we investigated the gut microbial biodiversity of 30 species of true bugs representative of different ecological niches and diets. Proteobacteria and Firmicutes dominated all samples. True bugs that live in aquatic environments had a variety of bacterial taxa that were not present in their terrestrial counterparts. Carnivorous true bugs had distinct gut microbiomes compared to herbivorous species. In particular, assassin bugs of the family Reduviidae had a characteristic gut microbiota consisting mainly of Enterococcus and different species of Proteobacteria, implying a specific association between the gut bacteria and the host. These findings reveal that the environmental habitats and diets synergistically contributed to the diversity of the gut bacterial community of true bugs.Insects are generally associated with gut bacterial communities that benefit the hosts with respect to diet digestion, limiting resource supplementation, pathogen defense, and ecological niche expansion. Heteroptera (true bugs) represent one of the largest and most diverse insect lineages and comprise species consuming different diets and inhabiting various ecological niches, even including underwater. However, the bacterial symbiotic associations have been characterized for those basically restricted to herbivorous stink bugs of the infraorder Pentatomomorpha. The gut microbiota associated with the megadiverse heteropteran lineages and the implications of ecological and diet variance remain largely unknown. Here, we conducted a bacterial 16S rRNA amplicon sequencing of the gut microbiota across 30 species of true bugs representative of different ecological niches and diets. It was revealed that Proteobacteria and Firmicute were the predominant bacterial phyla. Environmental habitats and diets synergistically contributed to the diversity of the gut bacterial community of true bugs. True bugs living in aquatic environments harbored multiple bacterial taxa that were not present in their terrestrial counterparts. Carnivorous true bugs possessed distinct gut microbiota compared to phytophagous species. Particularly, assassin bugs of the family Reduviidae possessed a characterized gut microbiota predominantly composed of one Enterococcus with different Proteobacteria, implying a specific association between the gut bacteria and host. Overall, our findings highlight the importance of the comprehensive surveillance of gut microbiota association with true bugs for understanding the molecular mechanisms underpinning insect–bacteria symbiosis.

Beneficial bugs

Land abandonment is a multifaceted, nonlinear, worldwide phenomenon that is influenced by a variety of factors and opinions. The goal of this study was to understand the significance of land abandonment for true bugs and syrphids in three grassland management regimes that includes abandoned, intensive, and extensive alpine organic grasslands. In 2021 and 2022, we sampled true bugs and syrphids by applying observation plot and sweep netting sampling methods. Extensive grasslands had significantly higher true bug and syrphid abundance compared to abandoned grasslands. However, no difference of species richness was found in studied grassland regimes. Large numbers of unique species (25.5% true bugs and 21.5% syrphids) only occurred in the abandoned grasslands but not in intensive and extensive grasslands. Similarly, true bug assemblages in abandoned grasslands differed significantly from assemblages in intensive and extensive grasslands. We found that extensive grassland can manage to increase true bugs and syrphid abundance. Likewise, undisturbed abandoned grassland is not a threat to insect diversity, and supports the survival of more unique true bug and syrphid species. A mosaic landscape consisting of abandoned grassland along with grassland having different, mainly extensive, management intensity could be an ideal arrangement for alpine biodiversity conservation.

The impact of cattle grazing on cursorial spiders (Aranei) and true bugs (Heteroptera) in steppe gullies of northeastern Ukraine

ABSTRACTTrue bugs (Hemiptera, suborder Heteroptera) constitute the largest suborder of nonholometabolous insects and occupy a wide range of habitats various from terrestrial to semiaquatic to aquatic niches. The transition and occupation of these diverse habitats impose various challenges to true bugs, including access to oxygen for the aquatic species and plant defense for the terrestrial phytophagans. Although numerous studies have demonstrated that microorganisms can provide multiple benefits to terrestrial host insects, a systematic study with comprehensive higher taxa sampling that represents aquatic and semiaquatic habitats is still lacking. To explore the role of symbiotic microorganisms in true bug adaptations, 204 samples belonging to all seven infraorders of Heteroptera were investigated, representing approximately 85% of its superfamilies and almost all known habitats. The symbiotic microbial communities of these insects were analyzed based on the full-length amplicons of the bacterial 16S rRNA gene and fungal ITS region. Bacterial communities varied among hosts inhabiting terrestrial, semiaquatic, and aquatic habitats, while fungal communities were more related to the geographical distribution of the hosts. Interestingly, co-occurrence networks showed that species inhabiting similar habitats shared symbiotic microorganism association types. Moreover, functional prediction analyses showed that the symbiotic bacterial community of aquatic species displayed richer amino acid and lipid metabolism pathways, while plant-feeding true bugs benefited more from the symbiont-provided xenobiotics biodegradation pathway. These results deepened the recognition that symbiotic microorganisms were likely to help heteropterans occupy diverse ecological habitats and provided a reference framework for further studies on how microorganisms affect host insects living in various habitats.IMPORTANCE Symbiotic bacteria and fungi generally colonize insects and provide various benefits for hosts. Although numerous studies have investigated symbionts in terrestrial plant-feeding insects, explorations of symbiotic bacterial and fungal communities in aquatic and semiaquatic insects are rare. In this study, the symbiotic microorganisms of 204 aquatic, semiaquatic, and terrestrial true bugs were explored. This comprehensive taxon sampling covers ~85% of the superfamilies of true bugs and most insect habitats. Analyses of the diversity of symbionts demonstrated that the symbiotic microbial diversities of true bugs were mainly affected by host habitats. Co-occurrence networks showed that true bugs inhabiting similar habitats shared symbiotic microbial association types. These correlations between symbionts and hosts together with the functions of bacterial communities indicated that symbiotic microbial communities may help true bugs adapt to (semi)aquatic habitats.

The real impact of true bug damage on cocoa pods has never been assessed precisely. We conducted a 2-yr study on 1,080 cocoa trees on 36 farms in Cameroon to assess the contribution of true bugs to fruit mortality and production loss. The cocoa fruiting cycle, fruit mortality, and damage caused by true bugs as well as other pests and diseases were monitored on a weekly basis. True bug damage also was described on 2,500 ripe pods per year. Pod weight, bean number, and bean weight were measured and compared for different degrees and types of damage on the ripe pods. Our results showed that true bugs were the main external cause of young fruit abortion. They reduced the abundance of young fruit by up to 10%. In contrast, although one-third of the ripe pods sampled had true bug lesions, only 4% were moderately to heavily damaged. The mean weight of ripe pods was reduced by 12% when there was medium to heavy damage. While the mean weight of wet beans was reduced significantly (by 3-10%), the number of beans per pod was not changed by damage. Despite the reduction in mean weight, the overall weight of beans for the pods sampled was reduced by <2%. Therefore, our study confirmed the common assumption that the economic impact of true bug damage on mature pods is negligible on cocoa farms in Cameroon. However, true bugs have a significant impact on young fruit mortality.

Since the introduction of genetically modified cotton (GM or Bt cotton) to Mexico in 1996, less insecticide is used, and cotton yields have increased significantly. Considering the controversy over potential environmental impact of Bt cotton, and particularly the lack of information on its effects on diversity of entomofauna, the objective of this study was to determine insect diversity in non-Bt and Bt cottons in the Comarca Lagunera, Mexico. Insects collected in both types of cotton were in the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, and Thysanoptera. Insects in the order Hemiptera were most abundant, followed by Diptera and Thysanoptera. Insects belonged to 40 families, with most abundant being Aleyrodidae, Anthocoridae, Thripidae, Noctuidae, Chrysopidae, Agromyzidae, Syrphidae, Coccinellidae, Aphididae, and Lygaeidae. In total, 35 species of insects were identified, of which 18 and 17 were entomophagous and phytophagous, respectively. The most abundant species were sweetpotato whitefly, Bemisia tabaci (Gennadius); minute pirate bug, Orius tristicolor (White); onion thrips, Thrips tabaci Lindeman; western flower thrips, Frankliniella occidentalis (Pergande); beet armyworm, Spodoptera exigua (Hubner); pirate bug, Orius laevigatus (Fieber); serpentine leafminer, Liriomyza trifolii (Burgess); Allograpta obliqua; convergent lady beetle, Hippodamia convergens Guerin-Meneville; and green lacewing, Chrysoperla carnea (Stephens). The total numbers of entomophagous and phytophagous insects were similar in both types of cotton. Only bollworm, Helicoverpa zea (Boddie), and beet armyworm were more abundant in non-Bt than in Bt cotton. The 33 other species were similar in abundance in both types of cotton. Based on Margalef, Simpson and Shannon-Wiener indices, insect diversity did not different between Bt and non-Bt cottons. Minute pirate bug, O. laevigatus, and to some extent insidious flower bug, Orius insidiosus (Say), might be species to use for risk assessment and management of Bt cotton in the region, because of their abundance and presence during most of the cotton-growing season and in adjacent crops.

BackgroundThe true bugs (Heteroptera) occupy nearly all of the known ecological niches of insects. Among them, as a group containing more than 30,000 species, the phytophagous true bugs are making increasing impacts on agricultural and forestry ecosystems. Previous studies proved that symbiotic bacteria play important roles in these insects in fitting various habitats. However, it is still obscure about the evolutionary and ecological patterns of the microorganisms of phytophagous true bugs as a whole with comprehensive taxon sampling.ResultsHere, in order to explore the symbiotic patterns between plant-feeding true bugs and their symbiotic microorganisms, 209 species belonging to 32 families of 9 superfamilies had been sampled, which covered all the major phytophagous families of true bugs. The symbiotic microbial communities were surveyed by full-length 16S rRNA gene and ITS amplicons respectively for bacteria and fungi using the PacBio platform. We revealed that hosts mainly affect the dominant bacteria of symbiotic microbial communities, while habitats generally influence the subordinate ones. Thereafter, we carried out the ancestral state reconstruction of the dominant bacteria and found that dramatic replacements of dominant bacteria occurred in the early Cretaceous and formed newly stable symbiotic relationships accompanying the radiation of insect families. In contrast, the symbiotic fungi were revealed to be horizontally transmitted, which makes fungal communities distinctive in different habitats but not significantly related to hosts.ConclusionsHost and habitat determine microbial communities of plant-feeding true bugs in different roles. The symbiotic bacterial communities are both shaped by host and habitat but in different ways. Nevertheless, the symbiotic fungal communities are mainly influenced by habitat but not host. These findings shed light on a general framework for future microbiome research of phytophagous insects.DpRsUfddvNEYPX-MDhm9d6Video

Runtime Verification (RV) can help find software bugs by monitoring formally specified properties during testing. A key problem when using RV during testing is how to reduce the manual inspection effort for checking whether property violations are true bugs. To date, there was no automated approach for determining the likelihood that property violations were true bugs to reduce tedious and time-consuming manual inspection.We present RVPRIO, the first automated approach for prioritizing RV violations in order of likelihood of being true bugs. RVPRIO uses machine learning classifiers to prioritize violations. For training, we used a labeled dataset of 1,170 violations from 110 projects. On that dataset, (1) RVPRIO reached 90% of the effectiveness of a theoretically optimal prioritizer that ranks all true bugs at the top of the ranked list, and (2) 88.1% of true bugs were in the top 25% of RVPRIO-ranked violations; 32.7% of true bugs were in the top 10%. RVPRIO was also effective when we applied it to new unlabeled violations, from which we found previously unknown bugs—29 bugs in 7 projects and two bugs in two properties. Our dataset is publicly available online.

SummaryRuntime verification (RV) helps to find software bugs by monitoring formally specified properties during testing. A key problem in using RV during testing is how to reduce the manual inspection effort for checking whether property violations are true bugs. To date, there was no automated approach for determining the likelihood that property violations were true bugs to reduce tedious and time‐consuming manual inspection. We present RVprio, the first automated approach for prioritizing RV violations in order of likelihood of being true bugs. RVprio uses machine learning classifiers to prioritize violations. For training, we used a labelled dataset of 1170 violations from 110 projects. On that dataset, (1) RVprio reached 90% of the effectiveness of a theoretically optimal prioritizer that ranks all true bugs at the top of the ranked list, and (2) 88.1% of true bugs were in the top 25% of RVprio‐ranked violations; 32.7% of true bugs were in the top 10%. RVprio was also effective when we applied it to new unlabelled violations, from which we found previously unknown bugs—54 bugs in 8 open‐source projects. Our dataset is publicly available online.

How steady is the nested pattern in saline grassland true bug communities? Effects of sampling effort and data completeness on nestedness

Effect of site history on forest plant and insect communities was studied by comparing afforestations on former agricultural land with reafforestations on ancient woodland sites. Vascular plants, mosses, true bugs, lacewings and saproxylic beetles were surveyed at 18 young broadleaved forest sites dominated by oak (Quercus robur), established between 1986 and 1994 in three different growth regions in Bavaria, Germany. Two strata, near ground level and the canopy, were sampled. Compared to woodland reafforestations greater species density and abundance of plants and true bugs were observed in field layer of afforestation sites. Proportion of forest species among plants and true bugs was however significantly lower in afforestations than on ancient woodland sites. In the canopy, zoo-phytophagous true bugs were significantly better represented in afforestations and zoophagous true bugs in reafforestations. Saproxylic beetles, especially inhabitants of old dead wood, were species-poor in afforestations. Results indicate that site history affects both producer and consumer communities in multiple ways, even 20 years after afforestation of former agricultural land. However, afforestations adjacent to existing forest stands can be regarded as valuable to nature conservation in effectively extending forest habitats. Investment in such afforestation therefore represents more than just an agricultural subsidy.

Estimating the biodiversity of hay meadows in north-eastern Switzerland on the basis of vegetation structure

IntroductionIndustrialization has ushered in massive changes in agriculture. Particularly in low mountain ranges, large-scale afforestation with Norway spruce on traditionally managed, semi-natural grasslands has caused a severe decline in biodiversity. Tree removal, hay transfer and resumption of grazing or mowing are typical measures to re-create species-rich grasslands. The aim of this study was to use vascular plants and three insect taxa (leafhoppers, true bugs, and grasshoppers) as bioindicators to evaluate the success of montane grassland restoration on former spruce forests in Central Europe. In addition, we intended to identify the drivers of species richness within the studied grasslands in order to derive suitable recommendations for habitat management.MethodsWe analyzed two different treatments: (i) grazed restoration sites where trees had been cut and species-rich green hay had been applied (N = 9) and (ii) target sites with a long continuity of low-intensity grazing (N = 9).Results and DiscussionOur study revealed that all studied taxa responded rapidly to the restoration measures. After a development period of 3 to 5 years, we found no differences in species richness and diversity of leafhoppers, true bugs and grasshoppers (all, target and threatened species). In addition, non-metric multidimensional scaling showed a large overlap in species composition between restoration and target grasslands. Among target and threatened species, vascular plants displayed the same pattern as insects and reached similar values when comparing the two treatments. However, total species richness and diversity of vascular plants were still higher on the target sites and species composition overlapped only partially. Grazing intensity was the predictor with the highest explanatory power in multivariable (Generalized) Linear Mixed-effects Models, being negatively related to species richness of leafhoppers and true bugs. We conclude that the measures implemented were effective in re-establishing target communities of different taxa. The transfer of seed-containing hay enabled or accelerated the development of the vegetation. Insects, on the other hand, were able to recolonize the restored grasslands on their own, given that these sites were embedded in a network of species-rich grasslands. With regard to insects (e.g., leafhoppers and true bugs), it should be ensured that grazing is applied at low intensity.