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Journal of Pest Science
Journal Prestige (SJR): 1.669
Citation Impact (citeScore): 4
Number of Followers: 2  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1612-4766 - ISSN (Online) 1612-4758
Published by Springer-Verlag Homepage  [2469 journals]
  • The zoophytophagous predator Pilophorus clavatus (Hemiptera: Miridae)
           induces plant defences in citrus

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      Abstract: Abstract The zoophytophagous mirid Pilophorus clavatus has been recently identified inhabiting citrus orchards in the Mediterranean region, where it feeds on several important citrus pests. In this work, we investigated whether the plant feeding by P. clavatus could induce defensive responses in citrus plants. Here, we show for the first time that the P. clavatus herbivory triggers the accumulation of the stress-related hormones salicylic acid (SA) and jasmonic acid (JA) in citrus plants. Moreover, the SA and JA pathways enhanced plant defence mechanisms as the expression of genes encoding enzymes from both biosynthetic and responsive pathways were upregulated in P. clavatus-punctured plants. We also investigated whether the induced defences could affect the plant host selection of Tetranychus urticae and the predatory mites Phytoseilus persimilis and Neouseiulus californicus. Neither T. urticae nor N. californicus preferred the odour source emitted by intact or P. clavatus-punctured plants in a Y-tube olfactometer assay. However, P. persimilis were significantly attracted to P. clavatus-induced plants. The performance of T. urticae was also compared when mites were released on control or previously P. clavatus-induced plants. Compared to the control, the infestation of T. urticae was significantly reduced up to 70% on those citrus plants previously activated by P. clavatus. Our results show for the first time that feeding of P. clavatus on citrus plants can have a dual beneficial effect due to its known predatory action and, at the same time, by inducing the plant’s immune system.
      PubDate: 2022-09-14
       
  • Investigating dispersal abilities of Aphrophoridae in European temperate
           regions to assess the threat of potential Xylella fastidiosa-based
           pathosystems

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      Abstract: Abstract Modeling the potential spread of Xylella fastidiosa can document contingency plans in northern Europe, so far uncolonized by the bacterium. Through mark–release–recapture (MRR) and flight-mill experiments, the flight capacity of two potential vectors for temperate Europe was studied: Philaenus spumarius, the reported southern European vector, and Aphrophora salicina, a xylem-specialist feeding on potential host plants of X. fastidiosa. Aphrophora salicina displayed significantly better flight performances than P. spumarius. In flight-mills, the average distance flown was, respectively, 623 m vs. 102 m and the maximal distance flown was 6.16 km vs. 1.54 km in 2.5 h. In MRRs, A. salicina travelled more than 30 m in a single flight, with a maximal interception distance of 80 m after two days, highlighting that dispersal is driven by connectivity and host plant quality. Philaenus spumarius mainly jumped, with 1 m movements in length and a maximal interception distance of 32 m in 27 days. Models estimated P. spumarius' daily mean dispersal at 1.5 m and A. salicina's at 3.5 m. Although only a small part of the population moves over very long distances, this pool of efficient insects could already be sufficient to effectively spread an epidemic. As Salicaceae have been reported as host plants of the bacterium, the association of Aphrophoridae and Salicaceae in riparian areas could create bacterium reservoirs in corridors allowing for transportation over medium to long distances.
      PubDate: 2022-09-13
       
  • Special issue on recent advances in zoophytophagous arthropods for
           agroecosystems sustainability

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      PubDate: 2022-09-12
       
  • Biological control using zoophytophagous bugs in Japan

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      Abstract: Abstract Zoophytophagous bugs feed on both arthropod pests and plants, and can survive or reproduce solely on particular plants. This characteristic ensures their survival when released as natural enemies when the density of target pests is low. When using zoophytophagous bugs, exotic species or strains should be avoided as biological control agents due to their ecological risks. This study reviews investigations of indigenous Orius species and indigenous strains of N. tenuis and their exploitations as biological control agents in Japan. Orius strigicollis, which can reproduce under short-day conditions, is recommended for augmentative biological control in greenhouses. Orius sauteri, the predominant and most abundant species in the field, is not recommended for releases in greenhouses because it enters diapause under short-day conditions. However, this species can be used for conservation biological control in the field, where the bug can be preserved through the use of selective pesticides or by conserving companion plants. Violet light illumination is a promising tool to manipulate the movement of this species in the field. Nesidiocoris tenuis occurs only in the southern region of Japan, and its density in the field is low. This bug can be used for augmentative biological control in greenhouses. It can reproduce on specific plants, including Sesamum indicum, Cleome hassleriana, Verbena × hybrida, and Scaevola aemula. These plants can be used as banker plants to improve the establishment and reproduction of N. tenuis in greenhouses. Indigenous Orius species and Nesidiocoris tenuis are promising biological control agents in Japan.
      PubDate: 2022-09-10
       
  • Disentangling arthropod and plant resources consumed by Orius spp. in
           peach and alfalfa crops by metagenomic analysis

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      Abstract: Abstract Agricultural intensification is affecting the biological control of insect pests, an important component for sustainable crop production. To understand the changing patterns of insect abundance within an agroecosystem, it is necessary to disentangle the trophic interactions between species, and metabarcoding is an excellent alternative to show them. In the Ebro Basin (NE Iberian Peninsula), agricultural landscapes are composed of a mosaic of crops scattered with natural and semi-natural habitats, where the presence of Orius spp., used as biocontrol agents, is well known. To shed light on their predatory role in this area, a previously developed metabarcoding multi-primer method has been used to study the arthropod and plant most frequently resources consumed by some field-collected Orius, sampled at different dates in a peach and an alfalfa adjacent crop. Their high-throughput sequencing (HTS) analysis showed the consumption of 15 arthropod and 12 plant taxa. Eight of them were consumed by O. laevigatus, six by O. majusculus and 23 by O. niger. The obtained results showed that HTS is a powerful tool in studies of trophic interactions in agroecosystems. Among the detected arthropods, other natural enemies were present, showing a certain degree of intraguild predation, which has been demonstrated by developing a new added strategy in the bioinformatic analysis. Detected plant consumption indicates that Orius forages on several plant species, showing their movement from them to the sampled crops. These plants could have a potential role in attracting or maintaining these predators in both crops in biological control strategies.
      PubDate: 2022-09-08
       
  • Combining mirid predators to reduce crop damages and sustain biocontrol in
           multi-prey systems

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      Abstract: Abstract With the invasion or local occurrence of Bemisia tabaci and Tuta absoluta in recent decades, they both have become two major insect pests of tomato crops in many countries. The biological control of these two pests through heteropteran predators, e.g., Nesidiocoris tenuis or Macrolophus pygmaeus, is a key pest management strategy. However, by contrast to M. pygmaeus, N. tenuis could usually cause plant damage and yield loss. The joint use of these two mirids for pest management has not been described yet, although it may be helpful in reducing the side effects of N. tenuis on crop (owing to competitive and/or agonistic interactions between the two species). In this study, we compared the abundance of predators and pests in treatments with N. tenuis and M. pygmaeus together versus N. tenuis alone and in the presence of B. tabaci only or B. tabaci and T. absoluta. We also measured necrotic rings and tomato flower production in these four treatments. We found that the joint use of both mirid predators together led to (1) a reduced overall mirid density and (2) a sustained biocontrol efficiency, when compared to the use of N. tenuis alone. In addition, plant feeding activities of mirids were significantly reduced when predators were used jointly (vs. N. tenuis alone). The applicability of zoophytophagous predators as biocontrol agents could be facilitated by simultaneously releasing two (or more) heteropteran predator species instead of a single one.
      PubDate: 2022-09-03
       
  • Prevalence and drivers of a tree-killing bark beetle, Ips typographus
           

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      Abstract: Abstract The unintentional transport of insects beyond their native ranges has greatly increased with globalization over the past century, leading to higher propagule pressure in non-native ranges of many species. Knowledge about the prevalence of a species in international invasion pathways is important for predicting invasions and taking appropriate biosecurity measures. We investigated the spatiotemporal patterns and drivers of interceptions—detections of at least one individual with imported goods that potentially serve as a proxy for arrival rates—for a tree-killing bark beetle, the European spruce bark beetle (Ips typographus L.; Coleoptera: Curculionidae: Scolytinae), in the USA from 1914 to 2008. Across the study period, there were 505 interceptions of I. typographus with shipments originating from > 25 countries at ports in 22 US states. Interceptions first occurred in 1938, peaked at 33 and 25 in 1984 and 1996, respectively, and declined after the mid-1990s. Interceptions of I. typographus did not have a statistically detectable relationship with outbreak levels in the native range, were inversely related to annual import volume (an artifact likely driven by changes in inspection policies), and were more frequent during the winter. Thus, while interceptions of I. typographus are challenging to predict, we found evidence that (i) biosecurity practices against this beetle could be increased during winter but not in response to outbreaks in source regions and (ii) the overall abundance of this beetle in invasion pathways has recently decreased, probably because strengthened phytosanitary protocols have reduced contamination levels and/or decreased the perceived need for inspections.
      PubDate: 2022-09-02
       
  • Is the control efficacy of two interacting predator species affected by
           the distribution and density of Tuta absoluta eggs on tomato plants'

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      Abstract: Abstract Macrolophus pygmaeus (Mp) and Nesidiocoris tenuis (Nt) are valuable biological control agents against Tuta absoluta. However, their predation rate on T. absoluta eggs over the entire plant has not been sufficiently studied. The aim of our study was to record the density and map the T. absoluta egg distribution per plant under different female densities. We also explored the predation rates of single (Mp/Nt), conspecific (2Mp/2Nt) or heterospecific pairs (MpNt) of predators on tomato plants on which T. absoluta eggs had been placed at the respective densities and sites as those selected by the T. absoluta females. The number of eggs laid per female was highest when the females were used singly. Females made active egg laying decisions preferring to oviposit on the 3rd and 4th leaves. Single M. pygmaeus showed a higher predatory efficacy than N. tenuis when 14 and 30 eggs were used per plant. Conspecifics of M. pygmaeus were more effective than N. tenuis at densities of 17 and 110 eggs. Interestingly, a pair was as effective as a single predator at 14, 17 and in many cases at the 30 and 110 egg/plant densities. The multiplicative model revealed that prey density has a strong impact on the effects of multiple predators on prey suppression. In all cases, 30% or more of the eggs were left unconsumed. These results suggest that the study of predation under field conditions and different pest pressure levels reveals useful information for the evaluation of predator efficacy in T. absoluta control.
      PubDate: 2022-08-28
       
  • CRISPR/Cas9-mediated F1534S substitution in the voltage-gated sodium
           channel reveals its necessity and sufficiency for deltamethrin resistance
           in Aedes albopictus

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      Abstract: Abstract Insecticide resistance in Aedes mosquitoes presents a major challenge to the control of arboviral diseases. However, resistance mechanisms for many of the insecticides remain unknown. A commonly used insecticide, deltamethrin, was used to select a resistance strain of the vector mosquito, Aedes albopictus, and we identified an F1534S substitution in the voltage-gated sodium channel (VGSC) gene product as the first event in generating resistance. Engineering an F1534S substitution using Cas9/gRNA technologies conferred deltamethrin resistance on a previously susceptible strain. Crosses that removed this mutation restored the susceptible phenotype. Predicted protein structural changes and differences in transcript accumulation levels were correlated with the resistance phenotype. Furthermore, F1534S mutations were detected in all resistant Ae. albopictus populations collected in the field. We conclude that the VGSC F1534S mutation is essential for resistance to deltamethrin in Ae. albopictus, and is a suitable molecular index for pyrethroid resistance detection and monitoring in this species.
      PubDate: 2022-08-22
       
  • Resistant cassava cultivars inhibit the papaya mealybug Paracoccus
           marginatus population based on their interaction: from physiological and
           biochemical perspectives

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      Abstract: Abstract Paracoccus marginatus papaya mealybugs cause considerable threats and challenges to cassava production and processing. The deployment of resistant cultivars offers effective, economical and eco-friendly management strategies for pest management. We measured P. marginatus mortality, development and reproduction to evaluate the resistance of fifteen cassava cultivars and conducted physiological and biochemical analyses when P. marginatus was fed on two resistant cultivars (Myanmar and C1115) and three susceptible cultivars (BRA900, Bread, SC205). Significantly lower digestive (amylase, sucrase, lipase), detoxification (glutathione-S-transferase and carboxylesterase) and antioxidant activity, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO), enzyme activities were observed in P. marginatus feeding on resistant cultivars compared to susceptible cultivars. For resistant cultivars, a significant reduction was found in nutritional components containing free amino acids, nitrogen, soluble sugars and the secondary metabolite malondialdehyde. Additionally, significantly higher enzymatic activity (SOD, CAT, POD and PPO) levels and secondary metabolite quantities (total phenol and tannins) were found in resistant cultivars induced by P. marginatus compared with susceptible ones. Additionally, RT-qPCR tests showed that the transcripts of ten genes involved in nutrition, secondary metabolites and antioxidant activities were consistent with physiology changes. Thus, the resistant cultivars suffered lower P. marginatus damage by elevating secondary metabolite contents and antioxidant activities, reducing plant nutrition levels and decreasing insect enzymatic activities. This study will be beneficial in developing indices for standard regulation to evaluate P. marginatus-resistant cassavas and effectively manage this pest.
      PubDate: 2022-08-22
       
  • Larvicidal, acetylcholinesterase inhibitory activities of four essential
           oils and their constituents against Aedes albopictus, and nanoemulsion
           preparation

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      Abstract: Abstract The potential for essential oils (EOs) to act as a natural alternative for controlling mosquito populations has aroused extensive interest in recent years. Four EOs (Thymus vulgaris (thyme), Foeniculum vulgare (fennel), Citrus medica (lime), and Camellia sinensis (green tea)) were selected in our previous larvicidal screening assays against Aedes albopictus. In this study, the active constituents of each EO were identified. Next, their acetylcholinesterase (AChE) inhibitory activity was evaluated, and the binding mode was studied by molecular docking. To improve EO stability and duration of activity, nanoemulsions were prepared and characterized. Thirteen constituents of the four EOs at the 100 ppm level led to 100% mortality of the larvae, the four most active constituents being α-hexyl cinnamaldehyde (LC50 = 24.0 ± 0.3 ppm), limonene (LC50 = 34.1 ± 0.7 ppm), α-terpinene (LC50 = 50.0 ± 0.5 ppm), and carvacrol (LC50 = 54.7 ± 0.6 ppm). These compounds, with the exception of α-hexyl cinnamaldehyde, also showed potent AChE inhibitory activity. Nanoemulsions with droplet size of 56.8–224.9 nm were prepared by emulsification at a 1:1 (v/v) ratio of EO and Tween 80. These EO nanoemulsions showed equally potent larvicidal activity as EOs themselves; moreover, they showed better stability and were active for longer time. These results suggest that natural EOs and their constituents have potential as larvicides for mosquito vector control and that nanoemulsification is an effective method for improving their physicochemical properties and efficacy.
      PubDate: 2022-08-19
       
  • Sublethal effects of plant essential oils toward the zoophytophagous mirid
           Nesidiocoris tenuis

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      Abstract: Abstract Zoophytophagous hemipteran predators provide relevant biological control services and their applications are consolidated in greenhouse pest management. The use of plant essential oils (EOs) for sustainable crop protection is being currently promoted. However, further knowledge of the potential side effects of EOs on predatory mirids (Hemiptera: Miridae) is required. Here, we evaluated the non-target impact of four EOs (anise, fennel, garlic and lavender) on the generalist predator Nesidiocoris tenuis (Reuter) in the laboratory. The baseline toxicity of EOs was firstly assessed on N. tenuis adults following topical contact exposure. Then, the predator reproduction and orientation behavior was tested following the exposure to three estimated EO lethal concentrations (LC1, LC10 and LC30). Garlic EO had the lowest estimated LCs (e.g., LC30 1.34 mg mL−1), being thus the most toxic compound among the tested EOs. The estimated LC30s for lavender, anise and fennel EOs were 2.75, 4.55 and 5.17 mg mL−1, respectively. The fertility and the orientation behavior of N. tenuis females was negatively affected by all the EOs at the highest tested concentration. Nevertheless, anise EO at LC1 and LC10 caused no sublethal effects on N. tenuis. Our findings suggest that careful attention should be given when EOs are used in combination with N. tenuis in pest management programs.
      PubDate: 2022-08-17
       
  • Molecular basis of mutual benefits between Cucurbit chlorotic yellows
           virus (CCYV) transmission and imidacloprid resistance in Bemisia tabaci

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      Abstract: Abstract Increased insecticide resistance among insect vectors and arboviruses results in significant economic losses to agricultural production and poses a continuous threat to food safety. To date, many studies have been conducted on how virus-infected host plants indirectly and plant virus directly change the physiological characteristics of insect vectors. However, the relationship between the insecticide resistance of the insect vector and the virulence of the viral pathogen has not received sufficient attention. Here, we investigated the effect of Cucurbit chlorotic yellows virus (CCYV), a plant virus transmitted by whitefly (Bemisia tabaci) in a semi-persistent manner, on the resistance of B. tabaci to the neonicotinoid imidacloprid. We found CCYV enhanced the resistance of B. tabaci to imidacloprid. The CYP6CM1 gene was significantly up-regulated in viruliferous susceptible B. tabaci compared with non-viruliferous B. tabaci after an acquisition access period of 10 d, including its upstream regulators. Silencing the CYP6CM1 gene by RNA interference reduced the ability of B. tabaci to acquire CCYV compared with the control. Additionally, imidacloprid-resistant B. tabaci outperformed sensitive adults in terms of virus transmission ability. These results suggest that CCYV enhances the ability of imidacloprid-sensitive B. tabaci to resist adverse external factors (insecticides). In turn, B. tabaci resistance affects virus transmission. Thus, to a certain extent, the plant virus and insect vector establish a mutually beneficial relationship that facilitates virus transmission.
      PubDate: 2022-08-17
       
  • Antiviral effect of the cotton plant-derived gossypol against tomato
           yellow leaf curl virus

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      Abstract: Abstract Current approaches to controlling plant viral diseases mainly focus on plant resistance, whereas suppression of viruses in vector species could provide an important alternative approach. Here we identified the therapeutic compound, gossypol, as capable of clearing Tomato yellow leaf curl virus (TYLCV) from its vector Bemisia tabaci (whitefly). Our initial field surveys showed that no whiteflies identified from cotton carried TYLCV, in contrast to a high incidence of this virus in whiteflies from other crops including tomato, cucumber and sweet potato. We found that when whiteflies were transferred from tomato or cucumber to cotton, there was a sharp reduction in the number of viruliferous whiteflies. When the whiteflies fed on cotton or ingested the metabolite, gossypol, derived from cotton, there was a sharp decrease in the incidence and abundance of TYLCV carried by the whiteflies. Gossypol degraded the coat protein and viral genome of TYLCV both in vitro and in vivo. Laboratory and field trials all showed that gossypol decreased TYLCV disease severity and had therapeutic efficacy on the disease. Our findings point to the possibility of identifying virus-therapeutic compounds by initially screening viruses in vectors derived from different crop plants.
      PubDate: 2022-08-09
       
  • Selecting aggressiveness to improve biological control agents efficiency

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      Abstract: Abstract In agroecosystems, omnivorous predators are recognized as potential biological control agents because of the numerous pest species they prey on. Nonetheless, it could be possible to enhance their efficiency through artificial selection on traits of economical or ecological relevance. Aggressiveness, which defines the readiness of an individual to display agonistic actions toward other individuals, is expected to be related to zoophagy, diet preferences and to a higher attack rate. The study aimed to assess the aggressiveness degree of the damsel bug, Nabis americoferus, and to estimate its heritability. We hypothesized that a high aggressiveness degree can be selected, and that males are more aggressive than females. Using artificial selection, we reared two separate populations, each composed of nine genetically isolated lines characterized by their different aggressiveness degree (aggressive, docile and non-selected). After three generations, we had efficiently selected aggressive behavior. The realized heritability was 0.16 and 0.27 for aggressiveness and docility in the first population. It was 0.25 and 0.23 for the second population. Males were more aggressive than females only for the second population. The potential of these individuals as biological control agents and the ecological consequences of aggressiveness are discussed.
      PubDate: 2022-08-08
       
  • Engytatus varians as agent for dispersal of Spodoptera exigua
           nucleopolyhedrovirus

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      Abstract: Abstract The interaction between the mirid predator Engytatus varians (Distant) and a Mexican isolate (SeSIN6) of Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) was examined under laboratory conditions. In a choice test, E. varians females and males demonstrated no preference for virus-infected Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) second instar compared with non-infected at two different post-inoculation times (48 and 72 h). Similarly, prey search time (5–6 h) did not differ significantly for each type of prey. Bioassays were performed to confirm the viability of occlusion bodies (OBs) from predator’s faces collected at 48, 96, and 144 h after exposure to virus-infected S. exigua larvae. The proportion of larval mortality was between 0.20 and 0.62 across all times and both E. varians sexes. Another experiment was performed to evaluate the dispersal of SeSIN6 OBs by physical contact with E. varians adults on tomato (Solanum lycopersicum Miller) leaflets treated with the pathogen. Engytatus varians adults were exposed to OB-treated tomato leaflets during 24 or 48 h using a clip cage. After each exposure time, these adults were removed and placed on clean uncontaminated leaflets for periods of 4–48 h. These leaflets were then exposed to groups of S. exigua second instars in clip cages. The proportion of virus-induced larval mortality of S. exigua (ranging from 0.45 to 1.0) was significantly affected by the duration of exposure of E. varians adults on OB-treated or untreated tomato leaflets. Our results reveal the potential of E. varians as an agent for the dispersal of SeMNPV OBs.
      PubDate: 2022-08-05
       
  • Push–pull plants in wheat intercropping system to manage Spodoptera
           frugiperda

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      Abstract: Abstract The fall armyworm, Spodoptera frugiperda, is one of the most notorious insect pests, and a major threat to maize (Zea mays) and other important crops, such as wheat (Triticum aestivum). Although the push–pull strategy based on intercropping has been reported to effectively prevent damage caused to maize, the potential of wheat-based intercropping systems for S. frugiperda management has rarely been assessed. In this study, the offspring performance, oviposition, and feeding preferences of S. frugiperda on four commonly planted crops—maize, pea (Pisum sativum), faba bean (Vicia faba), and alfalfa (Medicago sativa)—in wheat-based intercropping system were investigated to evaluate the roles of those host plants in the pest management. The results showed that S. frugiperda larvae performed poorly on pea and faba bean plants, as indicated by the longest duration for larval developmental, total pre-oviposition period, and mean generation time as well as the lowest pupal weight and larval survival rate. Lower offspring performance on pea and faba bean leaves coincided with lower efficiency of larval consumption. Preference tests revealed that female adults and larvae exhibited a stronger oviposition on, and feeding preference for maize than wheat, whereas no-preference was observed for faba bean plants. This study revealed the adaptability of S. frugiperda and its preference for wheat and its four common intercropped host plants and provided an insight into the management of S. frugiperda through the establishment of a push–pull strategy in wheat-based intercropping systems.
      PubDate: 2022-08-03
       
  • Potential of two omnivorous iolinid mites as predators of the tomato
           russet mite, Aculops lycopersici

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      Abstract: Abstract Two iolinid predatory mites were studied in the laboratory as potential biological control agents of the tomato russet mite, Aculops lycopersici (Acari: Eriophyidae). The development, reproduction and predation capacity of Pronematus ubiquitus and Homeopronematus anconai (Acari: Iolinidae) on A. lycopersici were investigated. Developmental time from egg to adult at 25 °C averaged 9.59, 9.31 and 9.52 days for P. ubiquitus on A. lycopersici, A. lycopersici and Typha angustifolia pollen, and pollen only, respectively. H. anconai required 11.18, 10.39 and 11.90 days to complete development on the respective diets. Survival of the immature stages exceeded 83% on all diets for both iolinids. In experimental arenas, both predators caused a substantial reduction of the immature population development of A. lycopersici. The number of tomato russet mite offspring was reduced by 78% and 57% by P. ubiquitus and H. anconai, respectively. The addition of pollen to the arena lowered this population reduction to 35% and 27% for the respective predators. However, supplementing a diet of tomato russet mites with pollen significantly increased the fecundity of both predatory mites from 14–15 to 24–25 eggs over a five-day period. The results suggest that both P. ubiquitus and H. anconai have good potential to suppress A. lycopersici populations and that T. angustifolia pollen can support population establishment of the predators. Overall, P. ubiquitus developed faster on the three diets tested and suppressed A. lycopersici stronger as compared to H. anconai, with or without pollen as a supplementary food source.
      PubDate: 2022-08-02
       
  • Development of multiple transgenic CRISPR/Cas9 methods for genome editing
           in the fall armyworm, Spodoptera frugiperda

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      Abstract: Abstract The use of CRISPR/Cas9 system in model insects has facilitated functional genomics studies. However, this system has not been applied to many pest insects. Here, we report on the establishment of multiple transgenic CRISPR/Cas9-based genome editing methods in a global agricultural pest, the fall armyworm (FAW), Spodoptera frugiperda. To identify fluorescent proteins suitable for screening for transgenic FAW, nine transgenic lines expressing genes coding for fluorescent proteins under the control of different promoters were produced and evaluated. The enhanced green fluorescent protein and a red fluorescent protein, tdTomato genes driven by the hr5ie1 promoter were found to be suitable for the identification of transgenic FAW. Multiple lines of transgenic FAW expressing Cas9 were generated and microinjection of sgRNAs into the embryos of these lines failed to induce target gene knockout. To overcome this problem, sgRNAs were expressed in FAW using U6-sgRNA and U6-tRNA-sgRNA systems, U6-tRNA-sgRNA system was found to be more efficient than U6-sgRNA system. Expression of Cas9 and sgRNAs in the same transgenic animal or in two separate strains followed by crossing them to bring Cas9 and sgRNA together resulted in an efficient knockout of target genes. The multiple transgenic CRISPR/Cas9-based genome editing methods developed provide invaluable tools for gene editing and functional genomics studies in this global pest and other lepidopteran pests.
      PubDate: 2022-07-30
       
  • Biological control in a changing climate: plant-mediated impact of
           elevated CO2 concentration on Lobesia botrana eggs and egg parasitism by
           Trichogramma cacoeciae

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      Abstract: Abstract Climate change can affect biological pest control by altering trophic interactions. Elevated carbon dioxide (CO2) concentrations can reduce host plant quality and, in turn, alter herbivore and natural enemy preference and performance. Using the Geisenheim VineyardFACE (free-air carbon dioxide enrichment) facility, we studied plant- and herbivore-mediated bottom-up effects of elevated CO2 concentration on the European grapevine moth, Lobesia botrana, and the parasitoid Trichogramma cacoeciae. Grapevine inflorescences of two cultivars cultivated at ambient or elevated CO2 (aCO2 and eCO2: 400 and 480 ppm) in the VineyardFACE were incorporated into L. botrana artificial diet. Eggs laid by the respective adults were parasitized by T. cacoeciae. Egg size and emergence rate of L. botrana as well as parasitism rate, parasitoid emergence rate and egg size preference of T. cacoeciae were evaluated. We observed an indirect grapevine cultivar-dependent bottom-up effect of CO2 on both herbivore and egg parasitoid. Compared to aCO2, eCO2 resulted in larger host eggs and higher parasitism rates regarding Riesling-feeding but not regarding Cabernet Sauvignon-feeding L. botrana larvae. Parasitoid emergence rate was higher when L. botrana had fed on Riesling compared to Cabernet Sauvignon-diet. Egg size preference depended on the host’s diet: T. cacoeciae preferred larger L. botrana eggs when the larvae had fed on grapevine-containing diet but not when they fed on standard artificial diet. Our results highlight the importance of the host’s diet for the parasitoid’s preference and performance. They furthermore suggest that the future efficiency of L. botrana-biocontrol by T. cacoeciae will not decrease under elevated CO2 concentrations.
      PubDate: 2022-07-27
       
 
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