Effects of aphid-induced semiochemicals from cover plants on Harmonia axyridis (Coleoptera: Coccinellidae).

BACKGROUND: Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is an important natural enemy of aphids. Plant species and plant health conditions can affect the behavior of H. axyridis. To determine plant effects on this lady beetle, we examined beetle responses to four cover crops: coriander (Coriadrum sativum L., Apiales: Apiaceae), marigold (Tagetes erecta L., Asterales: Asteraceae), sweet alyssum (Lobularia maritima L., Brassicales: Brassicaceae), and alfalfa (Medicago sativa L., Fabales: Fabaceae). Our goal was to better understand this predator's ovipositional behavior in response to different plants and its olfactory response to the aphid-induced volatiles from these plants. RESULTS: We found that this lady beetle did not have any significant oviposition preference among the four plant species, but H. axyridis preferred to lay eggs on the lower surface of leaves, regardless of the plant species. H. axyridis females had a significant preference for aphid-infested marigolds, but were not attracted by any of the other three cover plants or marigolds without aphid damage. Compared to the uninfested marigold plants, the emission of 12 compounds significantly increased on the aphid-infested marigolds, and two of them were attractive to H. axyridis under suitable concentrations. CONCLUSION: H. axyridis did not show any significant oviposition preference among the four cover crops. Aphid-infested marigolds can attract H. axyridis. Indole and terpinen-4-ol mediated lady beetle attraction. These synomones have potential for manipulating populations of H. axyridis as a component of conservation biological control. © 2022 Society of Chemical Industry.

Influence of Plant Physical and Anatomical Characteristics on the Ovipositional Preference of Orius sauteri (Hemiptera: Anthocoridae).

Natural enemies play an important role in managing insect pests. Orius sauteri (Poppius) (Hemiptera: Anthocoridae), a predator of many soft-body insects, is an important biological control agent in Asia. Understanding this predator's egg-laying preferences and a habitat needs is important for its success in pest control. We investigated the plant acceptability and ovipositional preference of O. sauteri for coriander (Coriadrum sativum L., Apiales: Apiaceae), marigold (Tagetes erecta L., Asterales: Asteraceae), sweet alyssum (Lobularia maritima L., Brassicales: Brassicaceae), and alfalfa (Medicago sativa L., Fabales: Fabaceae), and focused on the effects of plant physical and anatomical characteristics on the ovipositional preference of O. sauteri. The results showed that O. sauteri can lay eggs on uninfested plants in the vegetative stage and their eggs hatched normally. Orius sauteri females prefer plants with high stomatal density, a large stomatal area, and fewer trichomes as oviposition hosts, and the depth of egg placement was determined by leaf thickness. Our studies suggested that O. sauteri females can select oviposition hosts and specific oviposition sites by assessing the structural qualities of plant surface. Coriander and marigold are potentially suitable host plants for O.sauteri. The results aid the selection of cover crops to enhance natural enemies in the fields.

Impact assessment of Bt maize expressing the Cry1Ab and Cry2Ab protein simultaneously on non-target arthropods.

Transgenic maize expressing the Cry1Ab and Cry2Ab protein simultaneously from Bacillus thuringiensis (Bt-maize) has been grown for farm-scale study to investigate its potential impact to non-target arthropod (NTA). The trials were conducted between Bt maize 2A-7 and its parental line (B73-329) in Beijing, China, over 3 years. Richness (C), Shannon index (H), Pielou index (J), Simpson index (D), and Bray-Curtis index were used to evaluate the population dynamics and biodiversity of the dominant arthropods from per 50 plants in crop field. The mainly abundant groups were Aphidoidea, Araneae, Coccinellidae, Anthocoridae, and Thripidae which represented about 90% of the total number of NTA. Although the abundance of NTA varied from year to year, there is no significant difference between Bt maize and non-Bt maize field. Fluctuations were found at individual sample dates, but the trend of these descriptors remained consistent. Further analysis showed the biodiversity indexes of the dominant arthropods C, H, J, D, and Bray-Curtis dissimilarity between Bt maize producing Cry1Ab and Cry2Ab toxin simultaneously and its parental line had no significant difference except for some sampling dates. These results suggested that Bt maize is compatible with the NTAs and provides further evidence of the ecological impact of genetically modified maize.

The male-produced aggregation pheromone of the bean flower thrips Megalurothrips usitatus in China: identification and attraction of conspecifics in the laboratory and field.

BACKGROUND: Thrips, Megalurothrips usitatus, usually display aggregation behavior, which is probably mediated by a male-produced aggregation pheromone. Aggregation pheromones are species-specific, and can be used to develop commercial lures for monitoring and mass-trapping of pests. The active components of the aggregation pheromone for four thrips species have been identified. However, the components of M. usitatus-produced aggregation pheromone are still not clear. RESULT: Y-tube olfactometer assays showed that both male and virgin female M. usitatus were significantly attracted to male but not female volatiles. This was additionally supported by electroantennogram (EAG) assays. Coupled gas chromatography-electroantennogram detection (GC-EAD) showed that one component of male-specific odors elicited a significant electrophysiological response. This compound was characterized as (2E,6E)-farnesyl acetate, which is structurally different from the active components of the aggregation pheromones of other reported thrips species. Electroantennal responses of M. usitatus increased with increasing doses of synthetic (2E,6E)-farnesyl acetate. Additionally, this compound significantly attracted adults in laboratory behavioral bioassays. Under field conditions, sticky traps with synthetic (2E,6E)-farnesyl acetate caught 1.5-7-fold more M. usitatus than controls, and this effect of the compound at a dose of 60 µg lasted at least 6 days. CONCLUSION: (2E,6E)-Farnesyl acetate was identified as the male-produced aggregation pheromone of M. usitatus. It could attract this thrips species under laboratory and field conditions, suggesting considerable potential as a commercial application to control M. usitatus populations. © 2020 Society of Chemical Industry.

Different predation capacities and mechanisms of Harmonia axyridis (Coleoptera: Coccinellidae) on two morphotypes of pear psylla Cacopsylla chinensis (Hemiptera: Psyllidae).

Pear psylla, Cacopsylla chinensis (Yang & Li) are present as two seasonal morphotypes in pear orchards where they, suck phloem sap, defoliate pear trees, and cause fruit russet. Despite the importance of natural enemies in psyllid control, the interactions between predators and the two seasonal morphotypes of psyllids remain poorly documented. Here we determined the predation efficiencies of the Asian lady beetle, Harmonia axyridis (Pallas) on the two psyllid morphotypes. Predation of H. axyridis on both morphotypes conformed to a Type II functional response: the proportion of consumed psyllids decreased with increasing prey densities. Predation efficiency of H. axyridis against the winterforms increased with temperature when measured from 8 to 25°C. Predation rate on the summerforms was significantly higher than that of the winterforms. This was linked to smaller body size, higher soluble protein level, thinner cuticle, and lower chitin content of summerform psyllids compared to winterform psyllids. Predation capacities of H. axyridis on both morphotypes indicated its potential as a biocontrol agent in psyllids management. Predation efficiency was higher on summerforms, likely due to the difference in body size, exoskeleton fragility, and nutritional value between the two morphotypes. Due to the Type II functional response of H. axyridis to both morphotypes of pear psylla, application of H. axyridis in pear orchards under suitable temperatures could be taken into consideration for suppression of C. chinensis, although further experiments conducted in field conditions are needed to validate our findings.

The impact of Bt maize expressing the Cry1Ac protein on non-target arthropods.

From 2014 to 2016, individuals of the principal non-target arthropod (NTA) species in a field of Bt maize expressing the Cry1Ac protein (Bt38) were compared to those in a control field of the corresponding non-transformed near isoline (Z58). For all 3 years, the population dynamics and biodiversity of NTAs were analyzed to determine if any differences might be attributable to the genetically modified (GM) maize being evaluated. The main NTAs in these fields were Aphidoidea, Pentatomidae,Araneae, and Coccinellidae. Temporal variation in NTA diversity across sample dates within a year showed no significant differences between the Bt maize and the non-Bt maize field in the total number of individuals of the dominant arthropod species per 25 plants, the Shannon index (H), Pielou index (J), Simpson index (D), and Bray-Curtis index. The cultivation of Bt corn failed to show any detrimental evidence on individuals, H, J, D, and Bray-Curtis index of NTAs, and these parameters were identical in Bt and non-Bt corn plots. These results provide further evidence of the lack of ecological impact of GM maize.

De novo transcriptome sequencing and comprehensive analysis of the heat stress response genes in the basidiomycetes fungus Ganoderma lucidum.

Ganoderma lucidum is a valuable basidiomycete with numerous pharmacological compounds, which is widely consumed throughout China. We previously found that the polysaccharide content of Ganoderma lucidum fruiting bodies could be significantly improved by 45.63% with treatment of 42 °C heat stress (HS) for 2 h. To further investigate genes involved in HS response and explore the mechanisms of HS regulating the carbohydrate metabolism in Ganoderma lucidum, high-throughput RNA-Seq was conducted to analyse the difference between control and heat-treated mycelia at transcriptome level. We sequenced six cDNA libraries with three from control group (mycelia cultivated at 28 °C) and three from heat-treated group (mycelia subjected to 42 °C for 2 h). A total of 99,899 transcripts were generated using Trinity method and 59,136 unigenes were annotated by seven public databases. Among them, 2790 genes were identified to be differential expressed genes (DEGs) under HS condition, which included 1991 up-regulated and 799 down-regulated. 176 DEGs were then manually classified into five main responsive-related categories according to their putative functions and possible metabolic pathways. These groups include stress resistance-related factors; protein assembly, transportation and degradation; signal transduction; carbohydrate metabolism and energy provision-related process; other related functions, suggesting that a series of metabolic pathways in Ganoderma lucidum are activated by HS and the response mechanism involves a complex molecular network which needs further study. Remarkably, 48 DEGs were found to regulate carbohydrate metabolism, both in carbohydrate hydrolysis for energy provision and polysaccharide synthesis. In summary, this comprehensive transcriptome analysis will provide enlarged resource for further investigation into the molecular mechanisms of basidiomycete under HS condition.

Effect of heat stress on production and in-vitro antioxidant activity of polysaccharides in Ganoderma lucidum.

Ganoderma lucidum is a traditional Chinese medicine, and its polysaccharides possess diverse and significant pharmacological activities. This study aimed to investigate the polysaccharide production, molecular characteristics and in-vitro antioxidant activity of G. lucidum fruiting body after the mushroom was harvested and treated with heat stress (HS). HS enhanced the production of polysaccharides after harvest and treatment of 42 °C HS for 2 h, and that resulted in the highest polysaccharide yield of 10.50%, which was 45.63% higher than that of the control, while 37, 45 °C HS had no significant effect on the production. In terms of molecular characteristics, 42 °C HS significantly changed monosaccharide ratio of polysaccharides, but no apparent molecular weight and functional group changes were found in polysaccharides after HS treatment. The results of in-vitro antioxidant activity assay revealed that 42 °C HS significantly improved the antioxidant activities of polysaccharides at the concentration of 2 mg/mL. In conclusion, this study provides a promising strategy to improve the production of G. lucidum fruiting body polysaccharides.

[Immunogenicity of interleukin 12 and DNA vaccine prime-BCG boost against Mycobacterium tuberculosis].

OBJECTIVE: To investigate the immunogenicity of vaccine strategies about human interleukin 12 associated with combined DNA (Ag85A and ESAT-6) prime-BCG boost. METHODS: BALB/c mice were divided into PBS negative control and 4 immunity groups: BCG group, DNA/BCG group, DNA + IL-12/BCG group and DNA/BCG + IL-12 group. All mice received three immunizations at 2-week interval. Specific IgG antibody in serum of mice was determined with indirect ELISA in 4, 6, 8 weeks respectively after final vaccination. The splenic lymphocytes of mice were separated and stimulated with PPD to measure their proliferation by flow cytometry, and to evaluate the production of interferon-gamma (IFN-gamma) in cell suspensions of spleen cells by ELISA. The levels of CD4+ and CD8+ T-cell on surface of spleens lymphocyte were determined by flow cytometry. RESULTS: PPD could stimulate specific IgG responses in 4 immunity groups, and the average valences of 4 groups are 1:80, 1:120,1:160,1:160; the splenic lymphocyte proliferation reactions and IFN-gamma production were detectable in 4 immunity groups, and the most significant response occurred in 12 weeks. DNA + IL-12/BCG group and DNA/ BCG+IL-12 group induced higher production than BCG group and DNA/BCG group (P < 0.05), and the effects between DNA + IL-12/BCG group and DNA/BCG + IL-12 group had little difference. The numbers of CD4+ and CD8+ T-cell in 4 immunity groups were much higher than PBS group (P < 0.05), and DNA+IL-12/BCG group and DNA/BCG+IL-12 group were detected much more CD4+ and CD8+ T-cell than BCG group and DNA/BCG group (P < 0.05). The level of T-cell between DNA + IL-12/BCG group and DNA/BCG + IL-12 group had little difference. CONCLUSION: Interleukin 12 associated with the strategy of priming with the combined DNA vaccines and boosting with attenuated M. bovis vaccine (BCG) could induce much stronger specific cellular immunity compared with simple DNA/BCG or attenuated M. bovis vaccine alone.