Chrysoperla Sinica Research Articles

Sublethal concentration of λ-cyhalothrin inhibits insulin-like peptides and leads to reproductive toxicity in Chrysoperla sinica.

Insulin-like peptides (ILPs) act as crucial reproductive neuropeptides in insects, regulating insect reproduction through the insulin signaling pathway (ISP). Our previous studies have found that the sublethal concentrations (LC1 and LC10) of lambda-cyhalothrin (λCy) could induce severe reproductive toxicity in the lacewing, Chrysoperla sinica (Tjeder), but the toxicological mechanism remains unclear. This study discovered that λCy could inhibit CsILP transcription, leading to a decrease in insulin content and downregulation of C. sinica insulin receptor (CsInR) and C. sinica forkhead box O (CsFOXO) expression in ISP. Interference with CsILP expression resulted in downregulation of C. sinica vitellogenin (CsVg) and decreasing fecundity, while exogenous injection of bovine insulin promoted upregulation of CsVg expression and facilitated reproduction in female adults of C. sinica. Meanwhile, interference with FOXO of ILP downstream transcription factor could lead to downregulation of CsVg, hindering ovarian development and resulting in a decrease in egg production. However, exogenous injection of bovine insulin could remedy the effects caused by FOXO interference. In addition, ILP mediates juvenile hormone and 20-hydroxyecdysone biosynthesis by acting on their synthetic regulatory enzymes and influences the signal transduction of the 2 reproductive endocrine hormones, thereby regulating the reproductive endocrine environment in C. sinica. In conclusion, λCy inhibits CsILP expression, leading to disorder of ISP, leading to the reduced fecundity of C. sinica.

Volatile chemical cues emitted by an agricultural companion plant (Cnidium monnieri) attract predatory lacewings (Chrysoperla sinica)

Plant volatiles play an important role in the recruitment of arthropod natural enemies and are widely used in foraging by many species. Therefore, identification of plants that release useful volatile organic compounds (VOCs) for influencing natural enemies and for the control of pests can be helpful in conservation biological control. Cnidium monnieri (L.) can convene many predatory enemies (lady beetles, hoverflies, lacewings) as a functional plant. The Chrysoperla sinica (Tjeder) is a dominant generalist predator, and can control the population of various pests in agricultural fields. However, how C. monnier recruits C. sinica and the chemical association between them is unknown. In this study, we tested the attractiveness of odor released by flowers and leaves of C. monnieri to C. sinica in Y-tube olfactometer. Next, we conducted solid phase microextraction (SPME), gas chromatography-mass spectrometry (GC–MS), and electrophysiological studies (EAG) to analyze the compounds and identified the volatile components which have effects on C. sinica. We also used a Y-tube olfactometer to verify the effectiveness of the volatile components on C. sinica under laboratory conditions. In olfactometer trials, C. sinica adults preferred flowers compared with leaves and fresh air. In GC–MS and electroantennography trials, seventy-six volatiles extracted from C. monnieri, twelve antenna-active components in three different concentrations (0.1 μg/mL, 1 μg/mL, 10 μg/mL) were detected for electroantennography. In the last behavioral identification assays, four synthetic compounds (10 μg/mL) had significant attractiveness of adult C. sinica antenna (i.e., γ-terpinene, trans-β-Ocimene, nerolidol, (Z)-3-Hexen-1-ol). These studies suggest that there is a chemical association between natural enemies C. sinica and the functional plant C. monnieri. This study provides a basis that can facilitate the production and application of attracting natural enemy and development and application of enhancing attractants.

Combination of functional plants conserves predators, repels pests, and enhances biological control of Aphis spiraecola in apple orchards

Functional plants possess the ability to attract natural enemies or repel pests, and they play an important role in ecological regulation. While most studies have focused on the impacts of individual plants or plant combinations with similar functions on pests, there is a scarcity of research on the effects of combining plants with different functions, particularly in the case of orchard pests. In this study, we combined plants (Cnidium monnieri (L.) or Brassica napus L.) that attract predators with plants (Ocimum basilicum L. or Mentha haplocalyx Briq.) that repel pests to determine if these combinations can enhance biocontrol of Aphis spiraecola Patch on apple trees. All four combinations reduced the A. spiraecola population on apple trees. B. napus & M. haplocalyx achieved the highest reduction rate (88.58%), followed by C. monnieri & O. basilicum (88.06%), B. napus & O. basilicum (86.11%), and C. monnieri & M. haplocalyx (79.41%). Cage exclusion tests on 29 June and 4 July 2023 showed that biocontrol services index of all combinations was significantly higher than that of the control. Rubidium marking test showed that 61.90%–71.43% of Chrysoperla sinica (Tjeder) individuals in trees had transferred from functional plants. Behavioral responses and field trapping indicated that compounds such as cis-citral, nepetalactone, caryophyllene, beta-pinene, and eugenol, which are present in repellent plants, had significant repellency against A. spiraecola. The use of functional plant combinations in apple orchards can enhance biocontrol of A. spiraecola by promoting predators and by repelling aphid. This supports the potential of functional plant combinations in agroforestry ecosystems for pest biocontrol.

Comigration and interactions between two species of rice planthopper (Laodelphax striatellus and Sogatella furcifera) and natural enemies in eastern Asia.

Natural enemies are important in pest control. However, control by natural enemies is hindered by the migration of rice planthoppers. Therefore, comigration and interactions between Laodelphax striatellus (Fallén) and Sogatella furcifera (Horváth) and five predator species, Chrysoperla sinica Tjeder, Harmonia axyridis (Pallas), Episyrphus balteatus, Syrphus corollae (Fab.) and Chrysopa pallens (Rambur) in eastern Asia were investigated. From 2012 to 2021, the migration patterns of two rice planthoppers and five natural enemy species were monitored by suction trapping on Beihuang Island, Shandong Province, China. Both planthoppers and the five natural enemies regularly comigrated from late April to late October each year. There were significant interannual and seasonal differences in the numbers of two rice planthoppers migrating across this island. Simulated seasonal migration trajectories indicated different source areas for the two rice planthoppers, which mainly originated in northeast, north and east China. The biomass of planthoppers was significantly positively correlated with that of the ladybug H. axyridis in all migration periods, and significant differences in the ratio of rice planthoppers to natural enemies among months. A time-lag effect between seasons was obtained when natural enemies and pests comigrated. Migration was coordinated between rice planthoppers and natural enemies in East Asia. When natural enemies and rice planthoppers comigrated, time lags between seasons were observed. The unique insights into the migration patterns will help to increase understanding of the occurrence of rice planthoppers in eastern Asia and provide an important theoretical basis for regional monitoring and management of rice planthoppers. © 2023 Society of Chemical Industry.

Energy Utilization and Flight Muscle Development in Chrysoperla sinica (Neuroptera: Chrysopidae) Female Adults: Relationship With Age and Flight Behavior.

We investigated the accumulation of energy substances, dynamics of flight muscle development, changes in energy substances accumulation, and flight muscle structure after flight activities in female adults of the green lacewing Chrysoperla sinica (Tjeder), a common natural enemy of various insect pests in China. Virgin individuals were chosen at 24, 72, and 120 h after eclosion for energy substance determination and flight muscle observation in this study. Individuals with strong flight ability at 72 h after eclosion were selected for tethered flight assays, followed by detection of energy substances, and flight muscle observation. The results showed that virgin female adults had the highest fat content 72 h after eclosion. Sarcomere length and myofibril diameter changed significantly with age, with the lowest at 24 h after eclosion. With an increase in flight distance, the fat and glycogen contents, sarcomere length, and volume fraction of the transverse tubular system (T-system) decreased and myofibril diameters increased. The volume fraction of the mitochondria did not significantly change, but the structure of the mitochondrial membrane was destroyed, inclusions were reduced, and cavities appeared. The reserves of energy substances, especially lipids, are closely related to the flight ability of C. sinica. The observational results of both flight muscle structure and morphology of mitochondria build a strong relationship with flight behavior. This research should help reveal the regulatory mechanism of flight activity of C. sinica.

Sublethal effects of an indoxacarb enantiomer insecticide on Plutella xylostella caterpillar and Chrysoperla sinica predator

Plutella xylostella (L.) is a migratory species and an important insect pest of cruciferous crops worldwide, and Chrysoperla sinica (Tjeder) is a predaceous insect of agricultural and forest pests in the field. Indoxacarb has two enantiomers: (+)-S-indoxacarb and (−)-R-indoxacarb. This study was conducted to clarify the selective toxicity and sublethal effects of both enantiomers on P. xylostella and C. sinica. The (+)-S-indoxacarb isomer had greater acute toxicity to P. xylostella and C. sinica, while (−)-R-indoxacarb had less toxicity to P. xylostella and low toxicity to C. sinica. Lethal concentration 25 % (LC25) of (+)-S-indoxacarb had significant effects on the development, population, and fecundity of P. xylostella and C. sinica. The LC25 concentration of (−)-R-indoxacarb had a significant effect on the oviposition of P. xylostella. The field recommended concentration of (−)-R-indoxacarb significantly affected the pupal stage, adult survival rate, oviposition, and larval survival rate of C. sinica. Both enantiomers could significantly affect the search efficiency, successful attack rate, prey handling time, and maximum predation of C. sinica larvae, and the effects of (+)-S-indoxacarb alone were greater than those of (−)-R-indoxacarb. This study provided evidence of the different selective toxicity, sublethal effects of indoxacarb enantiomers on P. xylostella and C. sinica, which of the results could provide a basis for more rational use of indoxacarb in ecosystems.

Intercropping flowering plants facilitate conservation, movement and biocontrol performance of predators in insecticide-free apple orchard

Habitat management is an important approach suppressing pest via conservation biological control in agricultural systems. Intercropping flowering plants is a well- practiced habitat management measure, supporting predators with shelter, nectar, alternative prey and pollen. However, few studies systematically revealed predator’s conservation performance, transfer process and biocontrol ability by intercropping flowering plants in apple orchards. Here, an experimental model of intercropping flowering plants in apple orchard was planned for two consecutive years to response above questions. Four flowering plants conserve a different number and proportions of six main predator species (three ladybeetles (Propylaea japonica, Harmonia axyridis and Hippodamia variegata), one lacewing (Chrysoperla sinica), one hoverfly (Episyrphus balteatus) and one spider (Misumenops tricuspidatus)). By rubidium (Rb) marking technique, transfer rate of predators C. sinica from flowering plant Cnidium monnieri to apple trees were 79.5 % and 84.1 % in 2020 and 2021, respectively. Transfer rate of predators H. axyridis from flowering plant C. monnieri to apple trees were 74.2 % and 80.1 % in 2020 and 2021, respectively. By predator exclusion trials, the Biocontrol Services Index (BSI) was calculated in sampling date, in which the number of aphids on the caged and uncaged branch has significant difference in the four flowering plants and untreated control plots in 2020 and 2021, respectively. Thus, our results suggest that, intercropping flowering plants in insecticide-free apple orchard contributed to increase the number of predators and biological control of aphid Aphis spiraecola. These findings support that intercropping flowering plants as a promising management option could be implemented in apple orchards.

Density and seasonal dynamics of Bemisia tabaci and its predators in different agricultural landscapes in South China.

Bemisia tabaci is the main pest of agriculture in many regions of the world. The resistance of whitefly to pesticides has increased as a consequence of the continuous irrational use of wide-spectrum pesticides. Thus, pesticides are no longer always effective as a long-term control method. The agricultural landscape can affect the occurrence of an insect population. The objective of this study was to clarify the occurrence of whitefly and its predators in tomato fields in different agricultural landscapes. Different landscapes are classified into urban, flower, water, and mountain landscapes by the principal component analysis method. In 2018–2019, whitefly had the longest main activity period and the lowest density in the flower landscape. The water landscape helped to maintain the highest densities of whitefly during the main activity period. Nine species of predators were sampled, and Nesidiocoris tenuis, Chrysoperla sinica, Menochilus sexmaculata, and Harmonia axyridis were the dominant species throughout the sampling season in both years. During the main activity period, N. tenuis had the highest density in all sampled landscapes. The density of the dominant predators was the highest in the flower landscape, and each natural predator had the largest temporal niche width in the 2-year sampling period. Bemisia tabaci, N. tenuis, and M. sexmaculata were highly synchronized temporally. The flower landscape showed satisfactory results in suppressing whitefly. Increasing the proportion of flowering plants and increasing the diversity of plant crops in the agricultural landscape can effectively reduce the densities of whitefly during an outbreak.

Analysis of the bacterial communities of four predatory natural enemies collected from a Northern China Bt cotton field

• 16 s RNA sequencing was used to study microbial diversity of four natural enemies. • Harmonia axyridis and Propylaea japonica have the highest microbial diversity. • There are three similar dominant phyla in H. axyridis and P. japonica . • They have 11 common dominant symbiotic bacteria. Predatory natural enemies are major insect species in cotton field ecosystems. Microbes that live inside these insects play essential roles in vital host activities, however, the microbiota of these insects have not been well characterized. In this study, we used Illumina 16S rRNA amplicon sequencing to investigate microbial diversity of the natural enemies Chrysoperla sinica, Harmonia axyridis , Propylaea japonica and Orius similis from a cotton field in northern China. The microbial diversity of C. sinica was low and its dominant bacterial community were Rickettsia (87.78%) and Wolbachia (6.29%). The microbial community of O. similis was more diverse than that of C. sinica . The microbial diversity of H. axyridis and P. japonica was higher, and they had similar dominant phyla, which included Firmicutes, Proteobacteria and Bacteroidetes. Their common dominant bacterial community were Romboutsia , Escherichia-Shigella , Bacteroides , Terrisporobacter , Enterobacter , Lactobacillus , Fusobacterium , Actinobacillus , Sphaerochaeta , Bacteroidales_S24-7_group and Cyanobacteria. This study also forms the basis for further study on the microbiota of natural enemies from different habitats.

Sublethal effects of tolfenpyrad on the development, reproduction, and predatory ability of Chrysoperla sinica

The lacewing, Chrysoperla sinica, is a predaceous insect that is important in crop pest management. Chemical pesticides have adversely impacted predaceous insect species. Here we studied the effect of tolfenpyrad on C. sinica. The acute toxicity of tolfenpyrad to the second-instar larvae was determined and indicated that tolfenpyrad is a medium-risk insecticide. Sublethal concentrations (LC10, LC20, and LC30) of tolfenpyrad had effects on the development, reproduction, and predatory ability of C. sinica. When the second-instar larvae of C. sinica were exposed to sublethal concentrations of tolfenpyrad, the activities of protective enzymes, such as superoxide dismutase, peroxidase, and catalase, and detoxification enzymes, including carboxylesterase, glutathione-S-transferase, and P450 monooxygenases, were increased with exposure time. The second-instar larvae of C. sinica exposed to sublethal concentrations of tolfenpyrad exhibited an oxidative stress response that increased the levels of malondialdehyde and reactive oxygen species (ROS). Within 48–120 h after treatment, the contents of mitochondrial respiratory chain complex I and adenosine triphosphate in the second-instar larvae were decreased. This resulted in an imbalance between the production and clearance of ROS and caused cellular damage.

Biological control of Aphis spiraecola in apples using an insectary plant that attracts and sustains predators

Habitat management, such as adding insectary plants to agroecosystems, is a useful technique for biological control. It can improve pest control through natural enemy augmentation and conservation. We evaluated use of the insectary plant Cnidium monnieri (L.) Cuss. to increase the diversity and population density of natural enemies, promote the movement of natural enemies, and improve suppression of the spirea aphid (Aphis spiraecola Patch). An apple orchard experiment included C. monnieri as the treatment and the absence of C. monnieri as the control. The results suggested that C. monnieri can foster predatory natural enemies, such as Propylaea japonica, Harmonia axyridis, Hippodamia variegata, Chrysoperla sinica, and Episyrphus balteata. Density of the predators on the apple trees in the treatment was significantly higher than in the control. Density of spirea aphids on the apple trees in the treatment was significantly lower than in the control. Rubidium (Rb) was used as a tracking marker transferred along the food chain of C. monnieri (4.08 μg/ml) – celery aphid (Semiaphis heraclei) (0.46 μg/ml) – lady beetle (0.51 μg/ml) in a laboratory experiment. The highest Rb content in a lady beetle (0.62 μg/ml) was found 3 days after marking. Combined with field sampling and Rb marking, the results showed that 24.2% and 42.7% of H. axyridis on the apple trees moved from the insectary plant C. monnieri in 2018 and 2019, and that 53.2% and 48.4% of C. sinica on the apple trees transferred from C. monnieri in 2018 and 2019. The insectary plant C. monnieri attracts and fosters predatory natural enemies, which then move to the apple trees and suppress spirea aphids. These findings illustrate an effective method for enhancing biological control of aphids in apple orchards.

Analysis of Differentially Expressed Genes of Chrysoperla sinica Related to Flight Capacity by Transcriptome.

The lacewing Chrysoperla sinica (Tjeder) is a common natural enemy of many insect pests in China and is frequently employed for biological control programs. Adults make migratory flights after emergence, which reduces their effectiveness as biological control agents. Previously, we proved that 2-d-old unmated females exhibited significantly stronger flight ability than 3-d-old ones. Meanwhile, 3-d-old unmated adults flew significantly longer distances than mated ones. In this study, Illumina RNA sequencing was performed to characterize differentially expressed genes (DEGs) between virgin and mated adults of different ages in a single female strain of C. sinica. In total, 713,563,726 clean reads were obtained and de novo assembled into 109,165 unigenes with an average length of 847 bp (N50 of 1,754 bp), among which 4,382 (4.01%) unigenes matched known proteins. Based on these annotations, many putative transcripts were related to C. sinica’s flight capacity and muscle structure, energy supply, growth, development, environmental adaptability, and metabolism of nutritional components and bioactive components. In addition, the differential expression of transcripts between different ages and mating status were analyzed, and DEGs participating in flight capacity and muscles were detected, including glutathione hydrolase, NAD-specific glutamate dehydrogenase, aminopeptidase, and acidic amino acid decarboxylase. The DEGs with functions associated with flight capacity and muscles exhibited higher transcript levels for younger (2 d--old) virgins. This comprehensive C. sinica transcriptomic data provide a foundation for a better understanding of the molecular mechanisms underlying the flight capacity to meet the physiological demands of flight muscles in C. sinica.

Transgenic Cry1Ac/CpTI cotton assessment finds no detrimental effects on the insect predator Chrysoperla sinica

The widespread commercialization of genetically modified (GM) cotton makes it important to assess the potential impact of this recombinant crop on non-target organisms. As important natural enemies of cotton field predators, green lacewing Chrysoperla sinica larvae are exposed to Bt insecticidal proteins expressed by GM cotton by feeding on herbivorous pests, and adults are directly exposed to Bt proteins by cotton pollen consumption. However, potential impacts of transgenic Bt cotton on C. sinica remain unclear. In this study, we evaluated the effects of two transgenic cotton varieties, CCRI41 and CCRI45, which express Cry1Ac (Bt toxin) and CpTI (Cowpea Trypsin Inhibitor), on C. sinica larvae and adults. After being fed with cotton aphids Aphis gossypii reared on transgenic cotton, the survival rate, developmental duration, pupation rate, and emergence rate of larvae were not adversely affected. After being fed two types of transgenic cotton pollen, the 7-day weight of adults and the preoviposition period and the cumulative oviposition of females were not significantly different from control specimen. Taken together, these results indicate that the potential risks of the two tested GM cotton varieties for the predator C. sinica are negligible. CapsuleOur study indicated that GM cotton varieties CCRI41 and CCRI45 have no adverse effects on insect predator C. sinica.

Field control efficacy of 12 insecticides and five species of natural enemies to Thysanogyna limbata

Thysanogyna limbata is a pest on the landscape plant Firmiana platanifolia. In this study, we evaluated the control efficacy of twelve insecticides and five common natural enemies to T. limbata. The results showed that the control efficacy of thiamethoxam and imidacloprid to T. limbata was much better than other insecticides. For the three application methods evaluated (spraying, injection, and root-irrigation), the spraying method should be avoided and the injection performed better. If conditions permitted, root-irrigation method could be used as a supplementary method. Among the five natural enemies, Chrysoperla sinica and Lemnia saucia had the best control effect on T. limbata, which could replace insecticide in the long-term control effect. Therefore, C. sinica and L. saucia could be used as safe and environment-friendly pattern to prevent T. limbata in the medium- and long-term in the garden, whereas injection of thiamethoxam and imidacloprid could be used as a short-term and rapid treatment.

Known Target and Nontarget Effects of the Novel Neonicotinoid Cycloxaprid to Arthropods: A Systematic Review.

Neonicotinoids are the most widely used insecticide class worldwide, and unfortunately, the widely used neonicotinoid imidacloprid is problematic for pollinators and other nontarget organisms. These nontarget impacts and the development of resistance prompt the ongoing development and testing of new neonicotinoids. The novel neonicotinoid cycloxaprid was described in 2011 and registered in China in 2015. Studies investigating its use and effect on target and nontarget species are recent and ongoing, and empirical evidence has not yet been collectively considered. Therefore, a systematic review was performed to identify and summarize data associated with target and nontarget, lethal and sublethal impacts of cycloxaprid for its use as a new insecticide. We performed keyword literature searches in Web of Science, PubMed, Academic Search Complete, and Google Scholar and explored citations used in identified articles. The search strategy yielded 66 citations; 25 citations fulfilled eligibility criteria and were included in the review. Under experimental conditions, cycloxaprid reduced populations of plant-feeding insect pests, suppressed populations of sucking and biting insect pests, and affected reproduction, development time, longevity, growth, gene regulation and expression, and phloem-feeding behavior of various life stages of certain insects. Studies focus on pest control efficacy and comparison with imidacloprid. Five nontarget organisms have been evaluated: Apis mellifera, Chrysoperla sinica, Harmonia axyridis, Daphnia magna, and Eisenia fetida. Variation in study design, to date, precludes a metaanalysis. However, these results provide valuable insight into possible effects to target and nontarget arthropods. Because cycloxaprid is a new insecticide, additional research is needed to clarify the mechanism of action of cycloxaprid and its metabolites, and to determine if it harms natural enemies or other nontarget organisms, if resistance develops, and if it exhibits cross-resistance with other insecticides. Although research on target arthropods will inform some effects on nontarget organisms, studies focusing explicitly on impacts to nontarget organisms are needed. Integr Environ Assess Manag 2020;16:831-840. © 2020 SETAC.

Acute lethal and sublethal effects of four insecticides on the lacewing (Chrysoperla sinica Tjeder)

The lacewing, Chrysoperla sinica, is an important predatory insect, which plays an important role in the integrated pest management of agroforestry pests. However, the extensive use of insecticides negatively affects C. sinica. The acute toxicity, risk level, and, sublethal effects on growth and production, predation ability, protective enzyme activity and genotoxicity of four insecticides: indoxacarb, emamectin benzoate, imidacloprid and lambda-cyhalothrin to C. sinica were studied. The results showed that all four insecticides had lethal toxicity to larvae of C. sinica. Among them, emamectin benzoate had the highest toxicity with LC50 value of 7.41 mg/L. The insecticides also had different effects on the growth and reproduction of C. sinica, of which lambda-cyhalothrin had the greatest impacts. Even at a very low LC1 concentration (3.37 mg/L), it had strong impacts on the growth, reproduction and predatory ability of C. sinica. The four insecticides also caused a decrease in the predatory ability of the lacewing, of which lambda-cyhalothrin had the greatest effect. During the larval stage, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were significantly decreased by the four insecticides. At the pupal and adult stages, the effects of the four insecticides on the activities of protective enzymes were different, and the activities of SOD, CAT and POD decreased or increased. Indoxacarb and lambda-cyhalothrin exposure induced DNA damage in the haemocytes of C. sinica and produced obvious genotoxicity. These results provide important scientific basis for the rational use of these insecticides and the protection and utilization of lacewing.

Drip chemigation of flonicamid effectively controls cotton aphid (Aphis gossypii) and is benign to lady beetle (Coccinella septempunctata) and lacewing larva (Chrysoperla sinica)

Cotton can suffer from injury and yield loss caused by the cotton aphid (Aphis gossypii Glover). Current control of this pest relies heavily on insecticides, which is associated with hazardous effects on non-target organisms, environmental pollution, and pest resistance. The present study examined the efficacy of drip chemigation of flonicamid, a systemic insecticide, to control the cotton aphid and evaluated its effect on two natural enemies of aphids, seven spotted lady beetle adults (Coccinella septempunctata L.) and green lacewing larvae (Chrysoperla sinica T.) in a cotton field in Xinjiang, China in 2016 and 2017. The results showed that flonicamid applied via drip chemigation (700 g a.i. ha−1) effectively controlled cotton aphid for 40 days compared to 20 days when applied through foliar spray (75 g a.i. ha−1). Drip chemigation of flonicamid was safer to the two natural enemies compared to foliar spray. Additionally, the cost of drip application of flonicamid was lower than foliar spray as cotton plants were commonly irrigated via drip system in Xinjiang. Our results show that drip chemigation is much simpler, cheaper, and safer for application of flonicamid and more effective in aphid control compared to a conventional foliar spray, although the rate of flonicamid applied through drip irrigation was substantially higher than the foliar application.

The Developmental Stage Symbionts of the Pea Aphid-Feeding Chrysoperla sinica (Tjeder).

Chrysoperla sinica (Tjeder) is widely recognized as an important holometabolous natural enemy of various insect pests in different cropping systems and as a non-target surrogate in environmental risk assessment of Bt rice (i.e., genetically modified rice to express a toxin gene from Bacillus thuringiensis). Like other complex organisms, abundant microbes live inside C. sinica; however, to date, microbiome composition and diversity of the whole life cycle in C. sinica has not yet been well characterized. In the current study, we analyze the composition and biodiversity of microbiota across the whole life cycle of C. sinica by using high-throughput Illumina sequencing of the 16S ribosomal RNA gene. Collectively, Proteobacteria and Firmicutes dominated the microenvironment at all stages, but their relative abundances fluctuated by host developmental stage. Interestingly, eggs, neonates, and adults shared similar microbes, including an abundance of Rickettsia and Wolbachia. After larva feeding, Staphylococcus, Enterobacteriaceae, and Serratia were enriched in larvae and pupa, suggesting that food may serve as a major factor contributing to altered microbial community divergence at different developmental stages. Our findings demonstrated that C. sinica harbor a variety of bacteria, and that dynamic changes in community composition and relative abundances of members of its microbiome occur during different life cycle stages. Evaluating the role of these bacterial symbionts in this natural enemy may assist in developing environmental risk assessments and novel biological control strategies.

No detrimental effect of Bt maize pollen containing Cry1Ab/2Aj or Cry1Ac on adult green lacewings Chrysoperla sinica Tjeder

Adult Chrysoperla sinica Tjeder is a common pollen feeder in maize fields. They are thus directly exposed to insecticidal proteins by consumption of genetically engineered maize pollen containing Bacillus thuringiensis (Bt) proteins. Here we assessed the potential effects of Cry1Ab/2Aj- or Cry1Ac-containing Bt maize pollen on the fitness of adult C. sinica via a dietary-exposure assay under laboratory conditions. Survival, pre-oviposition, fecundity and adult dry weight did not differ between adult C. sinica consuming Bt or the corresponding non-Bt maize pollen. The stability of the Cry protein in the food sources and uptake of the Cry protein by adult C. sinica during the feeding experiment were confirmed by ELISA. These results demonstrate that adult C. sinica are not affected by the consumption of Cry1Ab/2Aj- or Cry1Ac-containing maize pollen, suggesting that production of Bt maize expressing cry1Ab/2Aj or cry1Ac genes will pose a negligible risk to adult C. sinica.

Distinct binding affinities of odorant-binding proteins from the natural predator Chrysoperla sinica suggest different strategies to hunt prey

Chrysoperla sinica is an important natural predator of many notorious agricultural pests. Understanding its olfactory mechanism can help enhance the effectiveness of C. sinica in biological control. In the present study, we investigated the tissue expression patterns of 12 odorant-binding protein (OBP) genes from C. sinica (CsinOBPs). The results of quantitative real-time polymerase chain reaction (qPCR) showed that CsinOBP1, CsinOBP2, CsinOBP3, CsinOBP4, CsinOBP6, CsinOBP7, CsinOBP9, CsinOBP10, and CsinOBP12 were predominantly expressed in the antennae of both sexes, indicating their roles in olfaction. Additionally, the qPCR analysis revealed that the 12 CsinOBP genes had distinct expression patterns, while the motif-pattern investigation suggested that the OBPs had different ligands. The ligand-binding assay showed that CsinOBP1 and CsinOBP10 had broader binding spectra than did the other OBPs. Thus, CsinOBP1 was able to bind not only plant volatiles (such as farnesol, cis-3-hexenyl hexanoate, geranylacetone, β-ionone, 2-tridecanone, and trans-nerolidol) but also the aphid alarm pheromone (E)-β-farnesene. On the other hand, CsinOBP2 and CsinOBP6 exhibited relatively narrow binding spectra, only binding ethyl benzoate. The study also identified several compounds that can potentially be used to develop slow-release agents attracting C. sinica and to improve search strategies for insect pest control.