Control Of Lepidopteran Pests Research Articles

Differential susceptibility of Spodoptera frugiperda (Lepidoptera: Noctuidae) to single versus pyramided Bt traits in Brazilian soybean: what doesn't kill you makes you stronger?

Lepidopteran pest control in agriculture has become heavily dependent on cultivars that express Bacillus thuringiensis (Bt) toxins as 'plant-incorporated protectants'. However, populations of Spodoptera frugiperda (Smith) in Brazil appear resistant to the Bt traits currently available in commercial soybean cultivars. This study evaluated S. frugiperda life history when feeding on three different Bt soybean cultivars. Cultivars expressing Cry1Ac + Cry1F and Cry1A.105 + Cry2Ab2 + Cry1Ac Bt toxins caused 100% larval mortality in S. frugiperda. Both non-Bt and Cry1Ac-expressing soybean induced transgenerational effects that increased the survival of subsequent generations. A Cry1Ac soybean diet reduced the generation time (T) of S. frugiperda relative to non-Bt soybean, resulting in shorter generation time and more rapid population growth. The implications of these results revealed how diet can alter aspects of insect life history and biology, and have important implications for sustainable management of S. frugiperda on soybean. © 2024 Society of Chemical Industry.

Baculoviruses in Integrated Pest Management of Fall Armyworm, (Spodoptera frugiperda) (Lepidoptera: Noctuidae): Structure, Classification and Application

Baculoviruses are crucial biological agents in integrated pest management (IPM), particularly for controlling lepidopteran pests in agriculture. These are highly specific, eco-friendly viruses characterized by rod-shaped nucleocapsids containing a protein-encased genome. The Baculoviridae family comprises four genera: Alphabaculovirus, Betabaculovirus, Gammabaculovirus, and Deltabaculovirus, each targeting specific insect orders. Nucleo polyhedron virus (NPVs) and granuloviruses (GVs) are extensively used in pest management due to their high virulence and specificity, ensuring safety for non-target organisms. Ascoviruses are dsDNA viruses that infect Spodoptera frugiperda larvae, transmitted primarily by parasitoids. Despite high virulence, their use in pest control is limited due to ineffective oral transmission. Combining ascoviruses with other pathogens, such as Bacillus thuringiensis kurstaki (Btk), may enhance their pest control potential. The infection process begins when insect larvae ingest viral occlusion bodies, leading to systemic infection and host death. Despite their narrow host range and slower action compared to chemical insecticides, baculoviruses are invaluable in sustainable agriculture. Their application has expanded beyond pest control to include gene therapy and vaccine production. This review examines the structure, classification, infection process, and current status of baculoviruses in controlling the fall armyworm, Spodoptera frugiperda, a significant agricultural pest. By exploring their potential as a cornerstone in biological pest management, we highlight the importance of baculoviruses in developing sustainable and environmentally friendly pest control strategies. The integration of baculoviruses into IPM programs offers a promising approach to reduce chemical pesticide use, preserve biodiversity, and enhance crop protection, ultimately contributing to more sustainable agricultural practices and food security.

CRISPR/Cas9-mediated disruption of orf76 as an antiviral therapy against BmNPV in the transgenic silkworm

Viral diseases pose a significant threat to livestock husbandry and plant cultivation. CRISPR/Cas9-mediated targeted editing of viral genes offers a promising approach to antiviral therapy. The silkworm, Bombyx mori, is an economically important insect susceptible to infection by B. mori nucleopolyhedrovirus (BmNPV), and viral outbreaks cause severe economic losses to the sericulture industry. Here, we identified BmNPV orf76 as a viral late gene that is highly similar to Autographa californica multiple nucleopolyhedrovirus Ac93. The deletion of orf76 abolished BmNPV proliferation and hindered the production of infectious budded viruses. We generated a transgenic line, Cas9(+)/sgorf76(+), that did not affect the growth or development of the silkworm and demonstrated that the transgenic line Cas9(+)/sgorf76(+) efficiently cleaved orf76 at the sgorf76 site, resulting in large deletions at 120 h post-infection, with no observed off-target effects. Survival analyses revealed that the transgenic line Cas9(+)/sgorf76(+) exhibited significantly higher survival rates than the control lines Cas9(−)/sgorf76(−), regardless of the BmNPV inoculation dose. Additionally, the number of BmNPV DNA copies and the expression levels of viral genes were markedly inhibited in the transgenic line Cas9(+)/sgorf76(+) compared with the control line Cas9(−)/sgorf76(−). The results provide a promising target for Cas9-mediated antiviral therapy against BmNPV, and the findings provide new insights for baculovirus gene function studies and lepidopteran pest control.

Resistance of Lepidopteran Pests to Bacillus thuringiensis Toxins: Evidence of Field and Laboratory Evolved Resistance and Cross-Resistance, Mode of Resistance Inheritance, Fitness Costs, Mechanisms Involved and Management Options.

Bacillus thuringiensis (Bt) toxins are potential alternatives to synthetic insecticides for the control of lepidopteran pests. However, the evolution of resistance in some insect pest populations is a threat and can reduce the effectiveness of Bt toxins. In this review, we summarize the results of 161 studies from 20 countries reporting field and laboratory-evolved resistance, cross-resistance, and inheritance, mechanisms, and fitness costs of resistance to different Bt toxins. The studies refer mainly to insects from the United States of America (70), followed by China (31), Brazil (19), India (12), Malaysia (9), Spain (3), and Australia (3). The majority of the studies revealed that most of the pest populations showed susceptibility and a lack of cross-resistance to Bt toxins. Factors that delay resistance include recessive inheritance of resistance, the low initial frequency of resistant alleles, increased fitness costs, abundant refuges of non-Bt, and pyramided Bt crops. The results of field and laboratory resistance, cross-resistance, and inheritance, mechanisms, and fitness cost of resistance are advantageous for predicting the threat of future resistance and making effective strategies to sustain the effectiveness of Bt crops.

CRISPR/Cas9-mediated Nap knockout affects female reproduction and egg shape in Bombyx mori.

Insect reproductive capacity can affect effective pest control and infertility studies and has become an important focus in recent molecular genetic research. Nucleosome assembly protein (Nap) is highly conserved across multiple species and is involved in forming the sperm nucleus in many species. We used clustered regularly interspaced palindromic repeats/Cas9 technology to knockout BmNap in Bombyx mori and observed that the mutations caused female infertility, whereas male fertility was not affected. BmNap mutants grew and mated normally; however, female mutants laid smaller eggs that could not be fertilised and did not hatch. In addition, female sterility produced by the mutation could be inherited stably via male mutants; therefore, Nap could be used as a potential target for lepidopteran pest control through population regulation. In the current study, we elucidated a new function of BmNap, increased the understanding of the oogenesis regulation network in Lepidoptera and promoted the development of insect sterility technologies.

Effect of X-ray irradiation on the biological parameters of Xestia c-nigrum.

The sterile insect technique (SIT) is widely used to control Lepidopteran pests by inducing inherited sterility. The noctuid moth Xestia c-nigrum is a polyphagous pest whose subterranean larvae severely injure cereals and some vegetables. The goals of this study were to assess the impact of X-ray irradiation on the development and survival of X. c-nigrum and use the data to select suitable sterilizing doses for potential future use in pest management. Batches of male pupae were exposed to 0 (control), 10, 30, 50, 100, 200, 300, or 400Gy of X-rays, approximately 24h before adult emergence. Exposure of late-stage pupae to 10-200Gy of radiation had no significant effect on adult emergence, but all doses (10-400Gy) reduced adult longevity, the number of spermatophores in mated females, and the number of eggs laid per female in the irradiated parental generation compared with the controls. Exposure to 10 and 30Gy had no significant effects in the F1 generation on 1) the rate of egg hatch, 2) the duration of larval or pupal development, or 3) adult longevity. However, exposure to 50Gy reduced the rate of egg hatch in the F1 generation, and when male pupae were exposed to 100Gy only 1% of the F1 eggs hatched. Also at 100Gy, the developmental durations of larvae and pupae were significantly prolonged, and longevity of adult moths was reduced. There were no significant differences between the control group and any treatments in 1) the sex ratio of the F1 adults, 2) the duration of F1 pre-oviposition or oviposition periods, or 3) the number of eggs laid per F1 female. Our findings indicate that a dose of 100Gy can effectively slow pest development and reduce larval survival in the F1 generation. In addition, F1 adults from lines treated with 100Gy were able to mate and lay eggs, but all F2 eggs failed to hatch. Our results suggest that use of X-ray irradiation has potential to control this polyphagous pest at the regional level.

Engineering of Bacillus thuringiensis Cry2Ab toxin for improved insecticidal activity

Bacillus thuringiensis Cry2Ab toxin was a widely used bioinsecticide to control lepidopteran pests all over the world. In the present study, engineering of Bacillus thuringiensis Cry2Ab toxin was performed for improved insecticidal activity using site-specific saturation mutation. Variants L183I were screened with lower LC50 (0.129 µg/cm2) against P. xylostella when compared to wild-type Cry2Ab (0.267 µg/cm2). To investigate the molecular mechanism behind the enhanced activity of variant L183I, the activation, oligomerization and pore-formation activities of L183I were evaluated, using wild-type Cry2Ab as a control. The results demonstrated that the proteolytic activation of L183I was the same as that of wild-type Cry2Ab. However, variant L183I displayed higher oligomerization and pore-formation activities, which was consistence with its increased insecticidal activity. The current study demonstrated that the insecticidal activity of Cry2Ab toxin could be assessed using oligomerization and pore-formation activities, and the screened variant L183I with improved activity might contribute to Cry2Ab toxin’s future application.

A Rapid and Sensitive Gold Nanoparticle-Based Lateral Flow Immunoassay for Chlorantraniliprole in Agricultural and Environmental Samples.

Chlorantraniliprole (CAP) is a new type of diamide insecticide that is mainly used to control lepidopteran pests. However, it has been proven to be hazardous to nontarget organisms, and the effects of its residues need to be monitored. In this study, five hybridoma cell lines were developed that produced anti-CAP monoclonal antibodies (mAbs), of which the mAb originating from the cell line 5C5B9 showed the highest sensitivity and was used to develop a gold nanoparticle-based lateral flow immunoassay (AuNP-LFIA) for CAP. The visible limit of detection of the AuNP-LFIA was 1.25 ng/mL, and the detection results were obtained in less than 10 min. The AuNP-LFIA showed no cross-reactivity for CAP analogs, except for tetraniliprole (50%) and cyclaniliprole (5%). In the detection of spiked and blind samples, the accuracy and reliability of the AuNP-LFIA were confirmed by a comparison with spiked concentrations and verified by ultra-performance liquid chromatography-tandem mass spectrometry. Thus, this study provides the core reagents for establishing CAP immunoassays and a AuNP-LFIA for the detection of residual CAP.

Cas9-Mediated Gene Editing Using Receptor-Mediated Ovary Transduction of Cargo (ReMOT) Control in Bombyx mori.

Lepidoptera is one of the most speciose insect orders, causing enormous damage to agricultural and forest crops. Although genome editing has been achieved in a few Lepidoptera for insect controls, most techniques are still limited. Here, by injecting female pupae of the Lepidoptera model species, Bombyx mori, gene editing was established using the Receptor-Mediated Ovary Transduction of Cargo (ReMOT) control technique. We identified a B. mori oocytes-targeting peptide ligand (BmOTP, a 29 aa of vitellogenin N-terminal of silkworms) with a highly conserved sequence in lepidopteran insects that could efficiently deliver mCherry into oocytes. When BmOTP was fused to CRISPR-associated protein 9 (Cas9) and the BmOTP-Cas9 ribonucleoprotein complex was injected into female pupae, heritable editing of the offspring was achieved in the silkworms. Compared with embryo microinjection, individual injection is more convenient and eliminates the challenge of injecting extremely small embryos. Our results will significantly facilitate the genetic manipulation of other lepidopteran insects, which is essential for advancing lepidopteran pest control.

Physical Factors Affecting the Scale-Up of Vegetative Insecticidal Protein (Vip3A) Production by Bacillus thuringiensis Bt294

Vip3A (vegetative insecticidal protein) is a representative member of the Vip3 family, which is widely used for lepidopteran pest control. This Vip3A protein, a non-growth-associated protein, is an effective bioinsecticide against insect pests, but there is relatively little information about its production processes at large scales. Hence, the effects of environmental factors on Vip3A production by Bacillus thuringiensis Bt294 (antifoam agents, shaking speeds, agitation and aeration rates), as well as controlling physical conditions such as the lowest point of dissolved oxygen and controlling of culture pH, were observed in shaking flasks and bioreactors. The results showed that antifoam agents, flask types and shaking speeds had significant effects on Vip3A and biomass production. Cultivation without pH control and DO control in 5 L bioreactors at lower agitation and aeration rates, which was not favorable for biomass production, resulted in a high Vip3A protein production of 5645.67 mg/L. The scale-up studies of the Vip3A protein production in a pilot-scale 750 L bioreactor gave 3750.0 mg/L. Therefore, this study demonstrated the significant effects of agitation, aeration rates and culture pH on Vip3A production by B. thuringiensis Bt294. Balancing of physical conditions was necessary for obtaining the highest yield of Vip3A by slowing down the production rate of biomass. Moreover, this Vip3A protein has high potential as a bioinsecticide for lepidopteran pest control in organic crops. This information will be important for significantly increasing the Vip3A protein concentration by the bacterium and will be useful for field application at a lower cost.

Use of Selected Chemical and Biological Insecticides to Control Lepidopteran Pests of Maize Fields in Central Côte d'Ivoire

Control of lepidopteran larvae, the main pests in maize fields, has become necessary since the appearance and spread of Spodoptera frugiperda. The study was carried out at the Institut National Polytechnique Houphouët-Boigny in Yamoussoukro (Central Côte d’Ivoire). The study aimed to determine the effectiveness of three chemical - Viper 46 EC (Acetamiprid 16 g/l and Indoxacarb 30 g/l), K-Optimal 35 EC (Lambdacyhalothrin 15 g/l and Acetamiprid 20 g/l) and Ampligo 150 ZC (Chlorantanlipol 100 g/l and Lambdacyhalothrin 50 g/l) - and one biological insecticide Bio-Elit (Azadirachtin, Salanin, Nimbin and Melandriol) on lepidopteran larvae in maize fields using a randomized complete block design with five treatments and three repetitions. Data on insect identification, plant infestation, damage, and yield were collected. Insects’ identification was based on morphology using identification keys. Plant damage was assessed by visually estimating the plant health status (unattacked and attacked plants). Grain dry weight was used to estimate field yield. The encountered maize field insects belonged to 10 orders: Heteroptera, Hymenoptera, Homoptera, Coleoptera, Diptera, Dictyoptera, Odonata, Orthoptera, Dermaptera, and Lepidoptera. Five lepidopteran pest larvae have been recorded. Three of them were classified as minor pests (Eldana saccharina, Ostrinia nubilalis, and Helicoverpa zea), one as important (Sesamia calamistis), and one as a major pest (Spodoptera frugiperda). On untreated plots, more than 76% of plants were moderately to heavily attacked. However, on treated plots, plants showed isolated to moderate attacks. Insecticide sprayings controlled pest populations, reduced damage, and increased yield. The yields obtained on untreated plots (2.26±0.21 t/ha) were lower than those on treated plots (3.29±0.11 to 3.60±0.09 t/ha). The yield increase rate ranged from 45.74 to 59.63%. The best control was recorded with Ampligo (59.63%) and Bio-Elit (50.83%) compared to Viper (49.41%) and K-Optimal (45.74%). Therefore, the alternating use of synthetic or biological insecticides, which are not very toxic for humans and the environment but are effective on insect pests, increases the effectiveness of the control and provides a positive response to the problem of pest resistance while protecting the environment.

Is ‘pupae busting’ or destroying overwintering pupae of Helicoverpa spp. (Lepidoptera: Noctuidae) still relevant today in Australian Bt cotton?

AbstractTransgenic Bt cotton was developed to control lepidopteran pests like the cotton bollworm, Helicoverpa armigera. However, there was concern that H. armigera would develop resistance to Bt cotton as this species had developed resistance to many insecticides and Bt toxins. To counter resistance, the cotton industry developed a resistance management plan (RMP) that included techniques to block resistant genes surviving from one season to the next (seasonal quarantining). One such technique is pupae busting, where cotton fields are cultivated after harvest, destroying potentially resistant pupating Helicoverpa spp. While pupae busting was important when there was only one insecticidal gene in Bt cotton, is it still relevant now Bt cotton has three insecticidal Bt genes? To address this question, we reviewed the development of pupae busting as a tool and its role in the current RMP. This included examining the ecology and behavioural characteristics of Helicoverpa spp. that impact on pupae busting efficacy (e.g., diapause, pupal mortality and pupae depth); the effect of soil type and different tillage techniques on pupae busting efficacy; and pupae busting within the context of Australia's current cotton farming system. We also looked at alternative forms of seasonal quarantining, such as using bisexual attract‐and‐kill techniques against adults. We confirmed that soil for pupae busting needs to be checked for moisture, which ideally should be less than the soil plastic limit. Comparisons between reports indicated that under good conditions, ‘go‐devils’ and chisel ploughs were excellent pupae busters. While a bisexual attract‐and‐kill strategy of late season moths has a place within the industry, pupae busting is still the best method in seasonal quarantining and has a good fit within the modern cotton industry, particularly given differences in the biology and ecology of H. armigera and H. punctigera, and the presence of dominant resistance to Bt toxins by H. armigera in China.

Extracting Venom from the Parasitoid Wasp Trichogramma dendrolimi using an Artificial Host.

Parasitoid wasps are a diverse group of hymenopteran insects that serve as invaluable resources for pest biocontrol. To ensure successful parasitism, parasitoid wasps inject venom into their hosts to suppress their hosts' immunity, modulate hosts' development, metabolism, and even behavior. With over 600,000 estimated species, the diversity of parasitoid wasps surpasses that of other venomous animals, such as snakes, cone snails, and spiders. Parasitoid wasp venom is an underexplored source of bioactive molecules with potential applications in pest control and medicine. However, collecting parasitoid venom is challenging due to the inability to use direct or electrical stimulation and the difficulty in dissection because of their small size. Trichogramma is a genus of tiny (~0.5 mm) egg parasitoid wasps that are widely used for the biological control of lepidopteran pests in both agriculture and forests. Here, we report a method for extracting venom from T. dendrolimi using artificial hosts. These artificial hosts are created with polyethylene film and amino acid solutions and then inoculated with Trichogramma wasps for parasitism. The venom was subsequently collected and concentrated. This method enables the extraction of large amounts of Trichogramma venom while avoiding contamination from other tissues caused by dissection, a common issue in venom reservoir dissection protocols. This innovative approach facilitates the study of Trichogramma venom, paving the way for new research and potential applications.

Dichotomous sperm in Lepidopteran insects: a biorational target for pest management.

Lepidoptera are unusual in possessing two distinct kinds of sperm, regular nucleated (eupyrene) sperm and anucleate (apyrene) sperm ('parasperm'). Sperm of both types are transferred to the female and are required for male fertility. Apyrene sperm play 'helper' roles, assisting eupyrene sperm to gain access to unfertilized eggs and influencing the reproductive behavior of mated female moths. Sperm development and behavior are promising targets for environmentally safer, target-specific biorational control strategies in lepidopteran pest insects. Sperm dimorphism provides a wide window in which to manipulate sperm functionality and dynamics, thereby impairing the reproductive fitness of pest species. Opportunities to interfere with spermatozoa are available not only while sperm are still in the male (before copulation), but also in the female (after copulation, when sperm are still in the male-provided spermatophore, or during storage in the female's spermatheca). Biomolecular technologies like RNAi, miRNAs and CRISPR-Cas9 are promising strategies to achieve lepidopteran pest control by targeting genes directly or indirectly involved in dichotomous sperm production, function, or persistence.

Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance.

Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020-2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa.

The gut microbiome of Helicoverpa armigera enhances immune response to baculovirus infection via suppression of Duox-mediated reactive oxygen species.

Baculoviruses such as Helicoverpa armigera nucleopolyhedrovirus (HearNPV) infect their lepidopteran hosts via the larval midgut where they interact with host immune responses and gut microbiota. Here we demonstrate that gut microbiota proliferating in response to HearNPV infection promote larval immune responses which impede the infection process. The microbial load of the larval midgut increased following HearNPV infection, due primarily to increases in Enterococcus spp., whereas most other bacterial genera declined, with Firmicutes replacing Proteobacteria as the dominant phylum. Injection of abdominal prolegs of infected larvae with H2 O2 promoted viral infection, diminished microbial abundance, and accelerated larval death, mimicking the effects of HearNPV infection, which up-regulated dual oxidase (Duox) expression, increasing H2 O2 levels in the midgut. Knockdown of Duox with RNAi reduced H2 O2 production in the guts of infected larvae, increased bacterial loads, decreased viral replication, and improved larval survival. Germ-free larvae were more susceptible to HearNPV than control larvae, exhibiting greater expression of Duox, higher levels of H2 O2 , and lower survival. Replenishment of gut bacteria in germ-free larvae restored the base-line immunity to HearNPV observed in normal larvae. Enterococcus spp., Levilactobacillus brevis, and Lactobacillus sp. bacteria were isolated and implicated in immunity restoration via replenishment in germ-free larvae. These findings illuminate how gut microbiota play important roles in larval defense against oral baculovirus infection, and suggest novel avenues of investigation to enhance the efficacy of baculoviruses and improve control of lepidopteran pests. © 2023 Society of Chemical Industry.

Variation among populations of Trichogramma euproctidis (Hymenoptera: Trichogrammatidae) revealed by life table parameters: perspectives for biological control.

The successful mass-rearing of potential biological control agents is a prerequisite for sustainable pest control. In this study, the performance of 3 Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae) populations collected from different locations in Khuzestan (Southwest Iran) were evaluated to optimize the egg parasitoid mass-rearing for augmentative biological control of lepidopteran pests. We aimed to investigate the effects of both population origin and host quality on biological traits of ovipositing females (number of parasitized eggs) and of their progeny (development time, survival rate, sex ratio, longevity, and fecundity). The effect of host quality was assessed by allowing the parasitoid to oviposit into 1, 2, 3, or 4-day-old Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. The 3 T. euproctidis populations developed successfully regardless the age of the host eggs. However, we found significant variation among populations and a strong influence of host quality on the traits investigated. Progeny performance in all populations decreased with increasing host age. The best-performing population (collected in Mollasani) showed the highest parasitization rate, highest survival rate, and progeny sex ratio with the greatest percentage of females. A life table corroborated these findings with superior estimates of the net reproductive rate (R0), intrinsic rate of increase (r), and reduced generation time (T) for the Mollasani population on 1-day-old host eggs. We conclude that ample variation exists among T. euproctidis populations and that rearing the Mollasani population on young rather than old eggs of E. kuehniella would be recommended to implement the biological control programs to target lepidopteran pests in Southwestern Iran.

A New Cypovirus-1 Strain as a Promising Agent for Lepidopteran Pest Control.

Now more than ever researchers provide more and more evidence that it is necessary to develop an ecologically friendly approach to pest control. This is reflected in a sharp increase in the value of the biological insecticide market in recent decades. In our study, we found a virus strain belonging to the genus Cypovirus (Reoviridae); the strain was isolated from Dendrolimus sibiricus, possessing attractive features as a candidate for mass production of biological agents for lepidopteran-pest control. We describe the morphological, molecular, and ecological features of the new Cypovirus strain. This strain was found to be highly virulent to D. sibiricus (the half-lethal dose is 25 occlusion bodies per second-instar larva) and to have a relatively wide host range (infecting representatives of five families of Lepidoptera: Erebidae, Sphingidae, Pieridae, Noctuidae, and Lasiocampidae). The virus strain showed a strong interaction with a nontoxic adjuvant (optical brightener), which decreased the lethal dose for both main and alternative hosts, decreased lethal time, and may expand the host range. Moreover, we demonstrated that the insecticidal features were preserved after passaging through the most economically suitable host. By providing strong arguments for the possible use of this strain in pest control, we call on virologists, pest control specialists, and molecular biologists to give more attention to the Cypovirus genus, which may lead to new insights in the field of pest control research and may provide significant advantages to compare with baculoviruses and Bacillus thuringiensis products which are nowadays main source of bioinsecticides. IMPORTANCE In this article, we describe a newly discovered cypovirus strain that displays features ideally suited for the development of a modern biological insecticide: high potency, relatively broad host range, true regulating effect, flexible production (possibility to choose host species for production), interaction with enhancing adjuvants, and ecologically friendly. Based on an alignment of CPV genomes, we suggest that the enhanced host range of this new strain is the sequence of evolutionary events that occurred after coinfections involving different CPV species within the same host. These findings suggest that we need to positively reconsider CPVs as prospective agents as biocontrol products.

Comprehensive Overview of Diamide Derivatives Acting as Ryanodine Receptor Activators.

The world's hunger is continuously rising due to conflicts, climate change, pandemics (such as the recent COVID-19), and crop pests and diseases. It is widely accepted that zero hunger is impossible without using agrochemicals to control crop pests and diseases. Diamide insecticides are one of the widely used green insecticides developed in recent years and play important roles in controlling lepidopteran pests. Currently, eight diamine insecticides have been commercialized, which target the insect ryanodine receptors. This review summarizes the development and optimization processes of diamide derivatives acting as ryanodine receptor activators. The review also discusses pest resistance to diamide derivatives and possible solutions to overcome the limitations posed by the resistance. Thus, with reference to structural biology, this study provides an impetus for designing and developing diamide insecticides with improved insecticidal activities.

Performance of two dominant trichogrammatid species of fall armyworm from China and Africa under contrasted temperature and humidity regimes

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), has become an international pest with its ability to spread rapidly. The FAW has successfully invaded Africa, Asia, and Australia, and recently China. It has become a serious threat to food security as a major pest of cereals and other crops. Trichogrammatid parasitoids are the dominant biological control agents that have been applied to control lepidopteran pests of crops, vegetables and forests worldwide. The aim of this study was to evaluate parasitism, development, and emergence of two trichogrammatid species, Trichogramma dendrolimi and Trichogrammatoidea lutea, from China and Africa on FAW at four temperatures (21, 25, 29, 33 °C) and three relative humidity (RH) (30, 60, 90 %) conditions. The temperature and humidity significantly affected the performance of the two trichogrammatid species on their host, including parasitic ability and development. The parasitism of T. dendrolimi was significantly higher than that of T. lutea (except for the treatment of 33 °C × RH 60 %) under various temperature and humidity conditions, however, T. lutea could not parasitize host eggs at 33 °C × RH 90 %. The higher parasitism was observed at 25 °C and 29 °C, while the lower at 21 °C and 33 °C for both two trichogrammatid species. The developmental time of T. dendrolimi and T. lutea significantly decreased with the increase of temperature under all three humidity treatments. The developmental time of T. dendrolimi under different temperature and humidity conditions (except for the treatment of 33 °C × RH 30 %), was significantly shorter than that of T. lutea. Temperature and humidity significantly influenced the sexual ratio of T. dendrolimi, the highest female ratio (94.6 %) was recorded at 33 °C × RH 60 %, while the lowest (79.5 %) was recorded at 25 °C × RH 60 %, but had no effect on T. lutea. The emergence rate of T. dendrolimi and T. lutea under different temperature and humidity conditions was only significantly different at 25 °C. Generally, T. dendrolimi had a better temperature and humidity adaptation than that of T. lutea, thus, T. dendrolimi appears to be a potential candidate for the control FAW under varying environmental conditions.