Changes in the bacterial communities of Harmonia axyridis (Coleoptera: Coccinellidae) in response to long-term cold storage and progressive loss of egg viability in cold-stored beetles.

Bacteria have a profound influence on life history and reproduction of numerous insects, while the associations between hosts and bacteria are substantially influenced by environmental pressures. Cold storage is crucial for extending the shelf life of insects used as tools for biological control, but mostly causes detrimental effects. In this study, we observed a great decrease in egg hatch rate of cold-stored Harmonia axyridis during the later oviposition periods. Furthermore, most eggs produced by their F1 offspring exhibited complete loss of hatchability. We hypothesized that long-term exposure to cold may greatly alter the bacterial community within the reproductive tracts of H. axyridis, which may be an important factor contributing to the loss of egg viability. Through sequencing of the 16S rRNA gene, we discovered considerable changes in the bacterial structure within the reproductive tracts of female cold-stored beetles (LCS_F) compared to non-stored beetles (Control_F), with a notable increase in unclassified_f_Enterobacteriaceae in LCS_F. Furthermore, in accordance with the change of egg hatchability, we observed a slight variation in the microbial community of eggs produced by cold-stored beetles in early (Egg_E) and later (Egg_L) oviposition periods as well as in eggs produced by their F1 offspring (Egg_F1). Functional predictions of the microbial communities revealed a significant decrease in the relative abundance of substance dependence pathway in LCS_F. Moreover, this pathway exhibited relatively lower abundance levels in both Egg_L and Egg_F1 compared to Egg_E. These findings validate that long-term cold storage can greatly modify the bacterial composition within H. axyridis, thereby expanding our understanding of the intricate bacteria-insect host interactions.

Canola bee pollen is an effective artificial diet additive for improving larval development of predatory coccinellids: a lesson from Harmonia axyridis.

BACKGROUND: Pollen is a common plant-derived food source for predatory ladybird beetles under field conditions, yet the potential for pollen to improve the quality of artificial diets remains largely unexplored. In this study, we developed three pollen diets by incorporating varying proportions of canola bee pollen (7.5%, 15.0% and 22.5% with 2.5%, 5.0%, and 7.5% of water, respectively) into a conventional diet. The feeding efficiency of Harmonia axyridis, an omnivorous predator, was evaluated and compared on three pollen diets, a conventional nonpollen diet and pea aphids. RESULTS: The larvae fed a medium or high pollen diet exhibited significantly higher survival in the 4th instar, pupa and adult stages than those fed a nonpollen diet. These larvae also developed into significantly heavier adults, and their survival rates in adulthood were comparable to those fed pea aphids. Specifically, we revealed the underlying mechanisms through which a high pollen diet enhances pupal development. Consumption of high pollen diet versus nonpollen diet resulted not only in a significant decrease in pupal glycogen content, but also an increase in adult lipid content. Both diet treatments induced similar changes in carbohydrate and glycogen content compared to the aphid diet while exhibiting different alterations in pupal protein content and adult lipid content. Furthermore, the transcriptome analysis revealed that the nutrient metabolism, immune response, and cuticle development pathways were predominantly enriched among the differentially expressed genes (DEGs). CONCLUSION: Canola bee pollen offers diverse advantages in terms of rearing H. axyridis larvae with an artificial diet, which will advance the development of effective diets for predaceous coccinellids. © 2024 Society of Chemical Industry.

The Microscopic Morphology of Mouthparts and Their Sensilla in the Mycophagous Ladybeetle Illeis chinensis (Coleoptera: Coccinellidae).

The morphological diversity of insect mouthparts is closely related to changes in food sources and diets. Research into the structures of insect mouthparts may help to establish a fundamental basis for a better understanding of insect feeding mechanisms. In this study, we examined the fine morphology of the mouthparts of Illeis chinensis using scanning electron microscopy. We paid particular attention to the types, quantities, and distribution of sensilla on the mouthparts. Our results showed that the basic components of the mouthparts of I. chinensis are the same as those in other lady beetles, i.e., the labrum, mandible, maxillae, labium, and hypopharynx. We also found structural specialization indicating adaptation to fungal feeding. On the mouthparts, there are eight kinds of sensilla and two kinds of glandular structures, including sensilla chaetica, sensilla basiconica, sensilla styloconica, sensilla coeloconica, sensilla campaniformia, sensilla placodea, sensilla digitiformia, Böhm bristles, perforated plates, and cuticular pores. This is the first time that sensilla digitiformia has been reported in ladybirds. Finally, variations in mouthparts among ladybirds with differing diets, as well as the putative functions of each of the mouthparts and sensilla, were discussed. This research can provide a reference for understanding the functions of the mouthparts in ladybird feeding behavior and thereby contribute to the development of precise insect behavior regulation and management strategies.

Functional morphology of antennae and sensilla of Hippodamia variegata (Coleoptera: Coccinellidae).

The lady beetle Hippodamia variegata is an important biocontrol agent of many aphids. In this study, the fine morphology of antennae as well as the typology, morphology and distribution of antennal sensilla were comprehensively examined by scanning electron microscopy. The antennal morphology of female and male are similar and consist of the scape, pedicel, and nine flagellomeres. No significant difference was detected in the length of each segment between two sexes, while the male antennae are much stronger than females. In total, six types of sensilla can be defined on antenna, including Böhm bristle, sensilla chaetica (with three subtypes), sensilla basiconica (with three subtypes), sensilla trichodea, sensilla placodea and sensilla coeloconica. It is worth noting that sensilla chaetica III distributed only on the fixed position of male antennae. In addition, the functional morphology of antennae of H. variegata were compared with other lady beetles from multiple perspectives. Specially, the function of sensilla were also discussed according to their morphology, location and information from previous studies.

Investigating reproductive success of the ladybird beetle Harmonia axyridis from the perspective of micropyle variation.

Micropyles in insects are small openings that allow sperm entry into, and the number was usually decreased on unfertilized and (or) undeveloped eggs. However, reports showed that Harmonia axyridis, a reproductive success model, deposited similar number of micropyles on undeveloped and developing eggs. Thus, it was confusing whether micropyles in H. axyridis were unaffected. To solve this confusion, two experiments were conducted here. Firstly, virgin female and four different days delayed mating (DDM) experiments were conducted to reveal the effects of fertilization stimulus and delayed-fertilization. Secondly, intercrosses between a light-colored mutant (HAM, an adaptive deficiency) and wild type (HAW) were conducted to further reveal whether there were female and male interactions. We found that (1) eggs produced by virgin and DDM females had significantly less micropyles than control. Even so, more than 18 micropyles were observed on eggs following fertilization and, consequently, egg production as well as hatch rate was not negatively affected by mating delay; (2) number of micropyles was significantly varied among the four reciprocal crosses and virgin HAW female. Specifically, the heterozygous eggs (Cross-D) and wild-type homozygous eggs (Cross-B) respectively had the least and maximum micropyles, and eggs from virgin HAW female had significantly less micropyles compared to those from HAW female (Cross-B or Cross-C), but the number was significantly higher than those from HAM female (Cross-A or Cross-D). These results informed us that the number of micropyles in H. axyridis is plastic but maintaining a high-quantity that offers many benefits, which should contribute to its reproduction success.

Functional morphology of the mouthparts of lady beetle Coccinella transversoguttata (Coccinellidae, Coleoptera), with reference to their feeding mechanism.

The lady beetle Coccinella transversoguttata is an important biocontrol agent of aphids. As the main the feeding apparatus, mouthparts play essential roles in feeding process, and the morphological variation of mouthparts is correlated with variation in food source and feeding behavior. To better understand the feeding behavior of C. transversoguttata, we studied the functional morphology of mouthparts, with special attention to the fine morphology of each part of mouthpart and various kinds of sensilla. The mouthpart of C. transversoguttata is typical mandibulate type that composed of labrum, mandible, maxillae, labium, and hypopharynx. Detailed descriptions were given about the fine morphology of each part, and various types of sensilla were identified and classified. In total, two types of sensilla chaetica, four types of sensilla basiconica, two types of sensilla styloconica, two types of sensilla placodea, and one type of cuticular pore were identified according to their length, morphology and distribution. Specially, the putative function of each part of mouthpart as well as each kind of sensilla and their coordinative mechanisms in feeding process were discussed. These results would lay a solid foundation for understanding the feeding mechanism of lady beetles.

Morphological and biological characterization of a light-colored mutant in the multicolored Asian lady beetle, Harmonia axyridis.

Insect cuticle color formed with melanin pigments has numerous types of mutants which usually cause pleiotropic effects. Melanism has been widely studied, but mutants with light-colored phenotype as well as the consequent fitness changes have rarely been reported.Here, in the laboratory strain of Harmonia axyridis, we found a novel mutant gr and confirmed that the mutation was inherited in a simple Mendelian autosomal recessive manner. This mutant (HAM) continuously displayed a light-colored pigmentation versus dark blackish in the wild phenotype (HAW). L-DOPA and dopamine are melanin precursors, and less L-DOPA was present in the cuticle of larval and adult HAM mutants compared to HAW wild type, but more dopamine was detected in the larval cuticle of HAM (p ≤ 0.0235). For the orange background of elytra, the composition as well as total concentration of carotenoids was different between HAM and HAW, which resulted in significantly lower saturation value but significantly higher hue value in HAM than in HAW (p < 0.0001).Extensive fitness changes were detected in HAM. (a) HAM larvae had similar predation capacity and preimaginal development time as HAW, but the newly emerged adults were much smaller (p < 0.0001). (b) Both fecundity and egg hatch rate in cross ♀(HAM) × â™‚(HAM) were significantly lower than those in ♀(HAW) × â™‚(HAW) (p ≤ 0.0087), but were not different with those in ♀(HAW) × â™‚(HAM).

Gonadotropins facilitate potential differentiation of human bone marrow mesenchymal stem cells into Leydig cells in vitro.

Infertility due to low testosterone levels has increased in recent years. This has impacted the social well-being of the patients. This study was undertaken to investigate the potential of gonadotropins in facilitating differentiation of human bone marrow mesenchymal stem cells (BMSCs) into Leydig cells in vitro. BMSCs were isolated, cultured, and their biological characteristics were observed. BMSCs were induced with gonadotropins in vitro and their ability to differentiate into Leydig cells was studied. The level of expression of 3-beta hydroxysteroid dehydrogenase (3ß-HSD) and secretion of testosterone were determined using flow cytometry and enzyme-linked immunosorbent assay, respectively, and the results were compared between the experimental and control groups. The cultured BMSCs showed a typical morphology of the fibroblast-like colony. The growth curve of cells formed an S-shape. After inducing the cells for 8-13 days, the cells in the experimental group increased in size and showed typical characteristics of Leydig cells, and the growth occurred in spindle or stellate shapes. Cells from the experimental group highly expressed 3ß-HSD, and there was a gradual increase in the number of Leydig cells. The control group did not express 3ß-HSD. The level of testosterone in the experimental group was higher than the control group (p < 0.05). Additionally, the cells in the experimental group secreted higher levels of testosterone with increased culture time. The expression of Leydig cell-specific markers in the experimental group was significantly higher (p < 0.05). With these findings, BMSCs can be considered a new approach for the treatment of patients with low androgen levels.

Development and reproductive potential of diamondback moth (Lepidoptera: Plutellidae) on selected wild crucifer species.

The diamondback moth, Plutella xylostella (L.), is an oligophagous insect that primarily feeds on members of the family Cruciferae. The development, survival, and reproductive potential of P. xylostella were studied on eight wild cruciferous species: Rorippa indica (L.) Hiern, Cardamine hirsuta L., Descurainia sophia (L.) Webb ex Prantl, Capsella bursa-pastoris (L.) Medic, Cardamine leucantha (Tausch) O. E. Schulz, Orychophragmus violaceus (L.) O. E. Schulz, Thlaspi arvense L., and Cardamine macrophylla Willd. Developmental durations of immatures from egg to adult emergence differed significantly among the plant species, with the longest period recorded on C. macrophylla (20.8 d) and the shortest on R. indica (15.8 d). The female pupae of P. xylostella reared on C. leucantha and T. arvense were lighter (4.2 and 4.3 mg/pupa) than those reared on other hosts (5.2-6.5 mg/pupa), and the male pupae from T. arvense were the lightest (3.1 mg/pupa) among all colonies. Survival from egg to adult emergence ranged from 95.7% on R. indica to 48.8% on T. arvense. The longevity (10.1 d) of P. xylostella female and the oviposition period (7.7 d) were the longest when larvae fed R. indica than those that fed on other wild hosts. Female adults of P. xylostella from O. violaceus, C. macrophylla, and Ca. bursa-pastoris had higher fecundity (305-351 eggs/female) than from other wild host plants, whereas that from R. indica had the lowest fecundity (134 eggs/female). C. hirsuta was the best wild host plant for P. xylostella because of the highest intrinsic rates of increase (rm = 0.2402), whereas T. arvense was the least favorable hosts with the lowest intrinsic rates of increase (rm = 0.1577). The results from this study will be useful for interpretation of the performance and population dynamics of P. xylostella on wild hosts and cultivated cruciferous vegetables.