Search Results (9)

Two new species, Aprostocetus eucalyptus Zheng & Yefremova sp. nov. (Hymenoptera: Eulophidae) and Megastigmus bipolaris Zheng & Yefremova sp. nov. (Hymenoptera: Megastigmidae), were discovered on populations of the invasive gall wasp Ophelimus bipolaris (Hymenoptera: Eulophidae) infesting Eucalyptus in Guangxi, China. An integrative taxonomic approach combining morphological characterization and 28S rRNA-based phylogenetic analysis was used for species identification and classification. Detailed morphological descriptions, illustrations, and an identification key for both sexes are provided. Field parasitism data confirm their potential as native natural enemies, supporting their utility for the biological control of this economically important pest. Full article

In the complex dynamics of plant–insect interactions, the specialized galling of reproductive structures presents unique evolutionary adaptations. This study investigates the parasitic relationship between Arastichus gallicola (Hymenoptera, Eulophidae), an ovary-galling wasp, and the inflorescences of Thaumatophyllum bipinnatifidum (Araceae). We employed field experiments and histological analyses to investigate the mechanisms driving this interaction. We reveal that ovule fertilization is not required for gall formation; however, pollination substantially enhances gall retention by reducing inflorescence abscission. Inflorescences exposed solely to galling presented a 64% abscission rate, whereas those with both galling and pollination experienced 33% abscission, underscoring pollination’s role in mitigating inflorescence loss. Detailed observations of A. gallicola oviposition and larval development reveal the intricate gall formation process characterized by progressive tissue hypertrophy surrounding the larva. Galling and seed development were mutually exclusive, with only 9% of fruits containing both. This mutual exclusivity suggests a competitive interaction for developmental resources within the ovary. Our findings underscore the specialized larval biology of galling chalcid wasps, illustrating how interactions between gall formation and host reproductive strategies shape the evolution of gall induction in floral tissues. Our study advances the understanding of ovary-galling adaptations and the selective pressures shaping antagonistic and mutualistic interactions in plant reproductive structures. Full article

Two species of Psilochalcis wasps (P. minuta and P. quadratis) were recently described from Utah’s eastern Great Basin. The extent of their known distributions is extremely limited, based on few data points. We developed species distribution models (SDMs) using Maxent modeling software for each Psilochalcis species to identify areas of probable suitable habitat for targeted collecting to improve our knowledge of their distributions. We used six occurrence data points for P. minuta and eight occurrence data points for P. quadratis, along with ten environmental variables as inputs into the Maxent modeling software. Model-predicted areas with a potential suitable habitat value greater than 0.69 were mapped using ArcGIS Pro to help select locations for model accuracy assessment. Employing Malaise traps, eighteen sites were sampled to evaluate each SDM’s ability to predict the occurrence of Psilochalcis species. Psilochalcis minuta occurred at eight of nine juniper-dominated sample sites that were predicted as having high suitability by the model for this species. Likewise, P. quadratis occurred at two of four cheatgrass-dominated sample sites predicted by the model. Psilochalcis minuta occurred at three of nine sampled sites that were not predicted by the model, and P. quadratis occurred at seven of fourteen non-predicted sites. The Maxent SDM results yielded an AUC value of 0.70 and p-value of 0.02 for P. minuta and 0.68 and 0.02. for P. quadratis. These results were reflected in our model accuracy assessment. Of the selected environmental variables, aspect, historic fire disturbance, and elevation yielded the greatest percent contributions to both species’ models. Sympatric distributions were observed for P. minuta and P. quadratis. Elevation, vegetation type, NDVI, and soil type are the most important environmental variables in differentiating areas of optimal suitable habitat for the two species. Full article

Although Chalcidoidea is one of the megadiverse superfamilies in Hymenoptera, numerous species are still being discovered and described. However, the difficulties in delimiting intra- and interspecific variation hinder this process. In this study, DNA barcoding methods using the COI gene were employed to investigate the morphological variation within Dzhanokmenia Kostjukov, 1977. The nuclear locus, 28S D2, was used to infer a phylogeny to gain an understanding of the relationship of Dzhanokmenia with other potentially close genera. Through a preliminary DNA barcode library established here, including eight species, we calibrated the intraspecific variation in certain diagnostic characters for the new species described here, D. brevifunis Ganbaatar & Cao sp. nov. Maximum likelihood results show that Dzhanokmenia is clustered with the genera associated with Tetrastichus, such as Chaenotetrastichus Graham, 1987, Baryscapus Förster, 1856, Tetrastichus Haliday, 1844, and Oomyzus Rondani, 1870 involved in this study. Our results indicate that the species diversity of Dzhanokmenia is understudied and tentatively confirm that Dzhanokmenia has a potential close relationship with Baryscapus. Along with the DNA barcode library, the referenced phylogeny datasets improve the understanding of the systematic position of Dzhanokmenia within the subfamily Tetrastichinae and the definition of this genus in terms of morphology, thereby facilitating species delimitation, discovery, and description within Dzhanokmenia. Full article

The chalcid wasp Tetrastichus septentrionalis Yang (Hymenoptera: Eulophidae) is one of the dominant pupal parasitoids of Hyphantria cunea (Drury) (Lepidoptera: Erebidae). In this study, the photoperiod’s effect on diapause induction in T. septentrionalis using the alternative host Tenebrio molitor was measured, revealing that T. septentrionalis is of the long-day type. The critical photoperiods for diapause induction in T. septentrionalis were estimated to be between photoperiods of 13:11 and 14:10 (L:D) h at 18 °C, and between photoperiods of 12:12 and 13:11 (L:D) h at 21 °C and 24 °C. We also found that T. septentrionalis diapausing larvae were grey-brown, while normally developed (non-diapausing) individuals were light yellow. The diapause-sensitive insect state was the larval stage, and the short light exposure treatment had a significant cumulative effect on diapause induction. The least squares method was used to calculate a lower developmental threshold of 13.34 ± 0.50 °C and an effective cumulative temperature of 184.46 ± 11.46 d·°C for post-diapause development. The average supercooling point of diapausing mature larvae was significantly lower than that of non-diapausing ones. Our research on T. septentrionalis provides a reference for the biological control of H. cunea and other leaf-eating pests. Full article

The seed predator Argyresthia conjugella Zeller has rowan as its preferred host plant. In years of poor fruiting in rowan, it oviposits on apples. To improve the knowledge of this apple pest, rowanberries were collected from localities all over Norway from 1971 to 1985, and seed predators and their parasitoids were allowed to emerge for up to five years. Two species of seed predators, A. conjugella and Megastimus brevicaudis Ratzeburg, and seven species of parasitic Hymenoptera were common. The distribution of these species is shown on EIS (European Invertebrate Survey) maps of Norway. The biology of the parasitoids is summarized based on the published literature and their behavior during emergence. The tendency for delayed emergence, which is an indication of prolonged diapause, was more pronounced in M. brevicaudis than in A. conjugella, the former appearing in all five years. Five of the parasitoids also delayed their emergence, and three of them to a high degree, up to five years. Prolonged diapause must be taken into account in studies of rowanberry insect guilds. Full article

Body size is the most essential feature that significantly correlates with insects’ longevity, fecundity, metabolic rate, and sex ratio. Numerous biogeographical rules have been proposed to illustrate the correlation between the body sizes of different taxa and corresponding geographical or environmental factors. Whether the minute and multifarious chalcids exhibit a similar geographical pattern is still little known. In this research, we analyzed morphological data from 2953 specimens worldwide, including the two most abundant and diverse taxa (Pteromalidae and Eulophidae), which are both composed of field-collected and BOLD system specimens. We examined forewing length as a surrogate of body size and analyzed the average size separately for males and females using two methods (species and assemblage-based method). To verify Bergmann’s rule, we included temperature, precipitation, wind speed and solar radiation as explanatory variables in a generalized linear model to analyze the causes of the size variation. We found that there was an increasing trend in the body size of Pteromalidae and Eulophidae with altitude. The optimal Akaike information criterion (AIC) models showed that larger sizes are significantly negatively correlated with temperature and positively correlated with precipitation, and the possible reasons for this variation are discussed and analyzed. Full article

The ocellated skink (Chalcides ocellatus) is a widespread lizard, naturally distributed between the Maghreb and coastal Pakistan, with few insular populations in the Mediterranean coastal area. Some populations of this species have also been recorded in peninsular Italy, Campania and Southern Tuscany due to accidental introductions via touristic and commercial routes. In this work, we conducted genetic analyses on mitochondrial DNA COXI, cytb and 16S mtDNA genes on a sample of Italian insular and peninsular populations. Differently from what previously suggested, the nucleus in Portici (Southern Italy) may have originated from Sardinia. The intense trade and touristic traffic between Sardinia and Southern Tuscany may have been responsible for the introduction of this lizard also to Central Italy. Full article

The effects of herbivorous insects on a plant population are not always well tolerated. This is especially true if the herbivorous actions are directed toward rare plant species. Salvia ceratophylloides Ard. is a rare endemism of southern Italy. Observations of the plants in situ revealed that many of them were under severe stress and did not produce seeds. Therefore, to find out which factors affect the reproductive activity as a whole, an observational study was carried out. We found bottom-up and top-down effects on plant health and reproduction associated with herbivorous action. Squamapion elongatum (Coleoptera, Curculionoidea, Apionidae), in all monitored sites, infested plants non-uniformly but was able to threaten the health condition, flowering, and seed production of sage by digging tunnels into the sage branches (bottom-up action), and then secondarily by seed feeder Systole salvia Zerova (Hymenoptera, Eurytomidae) predating sage seeds (top-down action). Mainly, chalcid parasitoid wasps such as Trichomalus spp. (Hymenoptera, Pteromalidae), as well as Eupelmus vesicularis and E. muellneri (Hymenoptera, Eupelmidae), limited the herbivorous S. elongatum population and the seed herbivore S. salviae emerged with its parasitoid Ormyrus diffinis (Hymenoptera, Ormyridae). Overall, this study showed how ecological interactions among herbivores, their host, and their natural enemies act on this sage species in all sites investigated. Among the herbivores, mainly S. elongatum affected this rare sage species, which should be taken into consideration, especially in the formulation of biological control solutions and for improving operating practice aimed at reproducing the species. This study provides the molecular characterization of the herbivorous species involved, in order to support future projects to evaluate the intra- and interspecific genetic variability of insects, their evolutionary relationships, and phylogeny studies. Full article