The recent outbreaks of thrips in subtropical and tropical regions of the world caused serious economic losses. This has increased interest in releasing predatory insects to manage thrips in cowpea and other important crops. Therefore, we assessed the potential of the green lacewing, Chrysopa formosa Rambur (Neuroptera: Chrysopidae), a generalist predator, for controlling Megalurothrips usitatus Bagnall (Thysanoptera: Thripidae) and Frankliniella intonsa Trybom (Thysanoptera: Thripidae), the 2 major pests of cowpea in South China. Chrysopa formosa larvae displayed a type III functional response to M. usitatus. The theoretical maximum predation of a C. formosa third instar larvae on M. usitatus second instar nymphs and adults was 1054 and 570, respectively. The C. formosa second instar larvae consumed more than 71% of a mixed population of M. usitatus and F. intonsa in a cowpea field by 14 days after release. The predation of C. formosa on M. usitatus increased as the temperature increased from 15 °C to 35 °C, whereas the predator developed slower above 25 °C. There was no significant difference in the hatch of C. formosa eggs kept at 25 °C and 30 °C, and the survival of first to third instar C. formosa larvae maintained at 25 °C was more than 80%. Thus, C. formosa can effectively suppress M. usitatus and F. intonsa in cowpea.

Trichogramma wasps are widely utilized as critical biological control agents in agricultural systems. Its efficacy relies on detecting host-derived chemical cues, yet the key molecular determinants underlying this process remain elusive. Here, we demonstrate that the odorant-binding protein TostOBP12 is indispensable for the host-seeking behavior of T. ostriniae. Interspecific behavioral assays revealed that only T. ostriniae exhibited significantly enhanced parasitism driven by the host sex pheromone. TostOBP12 was identified as the most highly expressed OBP in female heads. Molecular docking and competitive binding assays confirmed its high and broad affinity for both sex pheromones ((Z)-12:14AC and (E)-12:14AC) and egg surface compounds. Crucially, RNAi-mediated silencing of TostOBP12 completely abolished the wasp's behavioral response to sex pheromones without affecting its development, confirming its essential in vivo function. Our findings reveal a key molecular sensor in a tritrophic interaction and provide a promising target for enhancing biocontrol efficacy.

Trichogramma wasps serve as crucial biological control agents against the Asian corn borer (Ostrinia furnacalis). To find hosts within their short life span, the wasps must adjust their host-seeking behaviors via chemical cues such as host sex pheromones. To elucidate the molecular mechanism of host location, we systematically investigated how Trichogramma wasps detect the host's sex pheromone. Behavioral assays in a four-arm olfactometer revealed a pronounced preference of Trichogramma ostriniae for the sex pheromones of O. furnacalis, with significant responsiveness to its key components, (Z)-12-tetradecenyl acetate ((Z)-12:14AC) and (E)-12-tetradecenyl acetate ((E)-12:14AC). Subsequent transcriptomic analysis of female heads exposed to these pheromones identified eight upregulated olfactory receptor (OR) genes. Functional validation via RNAi demonstrated that silencing TostOR9a or TostOR92a significantly reduced the wasps' behavioral response to the sex pheromones, confirming their necessity in host-seeking behavior. Molecular docking simulations indicated strong binding activity, with TostOR9a exhibiting the lowest binding energy for (Z)-12:14AC (-8.68 kcal/mol) and TostOR92a for (E)-12:14AC (-9.50 kcal/mol). Finally, heterologous expression and electroantennogram (EAG) validation in Drosophila melanogaster confirmed that TostOR9a and TostOR92a are sufficient to confer olfactory sensitivity to (Z)-12:14AC and (E)-12:14AC, respectively. This study describes how Trichogramma wasps detect host sex pheromones at the molecular level and can thus provide a theoretical basis for the development of new biological control tools for olfaction.

Metarhizium acridum is a highly specialized entomopathogenic fungus widely used as a biocontrol agent against locusts. Despite its ecological and agricultural importance, the genomic basis of its host specificity and pathogenicity remains poorly understood. We present the first telomere-to-telomere (T2T) genome assembly of M. acridum, using PacBio HiFi sequencing and Hi-C scaffolding data, for seven chromosomes (45.1 Mb, N50 = 5.9 Mb) with 96.7

A male-biased sex ratio (MBS) is a widespread phenomenon in nature, which contributes to inbreeding avoidance, more efficient resource allocation, and the regulation of population dynamics. The factors driving MBS primarily involve genetic and chromosomal mechanisms, environmental conditions, and the influence of endosymbiotic microorganisms. However, the underlying molecular mechanism remains largely elusive. This study aims to investigate the role of Heterochromatin protein 1 (HP1) in driving an extreme MBS in the parasitic wasp Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae). An extremely male-biased T. dendrolimi line was identified from field collections, with a male offspring proportion of 80–100

This study investigates the endophytic biocontrol potential of Beauveria bassiana strain B094 against Spodoptera exigua in sweet corn through laboratory, greenhouse and field assessments. Laboratory virulence screening identified B094 as pathogenic to S. exigua, inducing 99.8% mortality and exceeding 75% infection in 1st- and 3rd-instar larvae at 1 × 108 spores/mL. The LC50 for 3rd-instar larvae was 4.8 × 105 spores/mL. B094 established endophytic colonization in sweet corn varieties Zhetian 19 and Zaotiannuo 211 via seed inoculation. Colonization peaked at 7 d after emergence (DAE), with leaves exhibiting markedly higher frequency and density (91.1%, 1367 ± 95 CFU/g) than stems (40%, 353 ± 12 CFU/g) and roots (37.8%, 93 ± 9 CFU/g), then progressively declined to 24.3% in leaves and below 17.3% in stems and roots by 28 DAE. Feeding bioassay demonstrated that leaves from colonized plants at 14-21 DAE significantly increased larval mortality and disrupted development. Greenhouse and field trials confirmed efficacy, with inoculated plants exhibiting less foliar damage than controls and similar colonization patterns and biocontrol effects across varieties. Rhizosphere microbiome analysis revealed community shifts after B094 colonization. Bacterial genera often associated with plant growth promotion or biocontrol (e.g., Bacillus, Gemmatimonas), increased by 22.5% and 81.6%, whereas fungal genera commonly reported as plant pathogens (e.g., Gibberella and Fusarium), decreased by 87.7% and 78.1%, respectively. Our findings establish B. bassiana B094 as a dual-action biocontrol agent against S. exigua, combining direct pathogenicity with endophytic effects, supporting seed-treatment as an environmentally friendly strategy for sustainable pest management in sweet corn systems.

The widespread use of neonicotinoid insecticides has led to increasing resistance in non-target organisms, including the egg parasitoid Trichogramma dendrolimi, a crucial biological control agent. Film-residue bioassays on 17 geographic strains revealed striking inter-strain variability in susceptibility to imidacloprid, with mortality at a discriminating dose of 0.1 mg/L ranging from 25.7% to 87%. The most tolerant (FS) and least tolerant (HA) strains were subsequently selected for evaluation of biological parameters and comparative transcriptomics. Tolerant strains (FS) showed adaptive trade-offs: extended longevity (5.47 ± 0.57 d) and emergence (93.6 ± 1.9%), but reduced fecundity (54.6 ± 4.9 eggs) compared to HA. Transcriptome analysis revealed 2115 differentially expressed genes, with GO enrichment highlighting metabolic and detoxification pathways. KEGG analysis the most enriched pathways were “Protein digestion and absorption” and “Neuroactive ligand-receptor interaction”. RT-qPCR confirmed overexpression of CYP4C1, CYP6K1, and GstS1 in FS, indicating their potential roles in metabolic resistance if present. This study presents preliminary evidence of potential fitness trade-offs and molecular mechanisms that could underly imidacloprid resistance in T. dendrolimi, which may lead to important insights for resistance monitoring and more sustainable integrated pest management strategies.

The 14 species of Terrilimosina Roháček now known from China are reviewed and keyed, including three new species (T. bicruris sp. nov., T. dentata sp. nov., and T. digitata sp. nov.), three newly recorded species (T. deemingi Marshall, 1987, T. longipexa Marshall, 1987, and T. unio Marshall, 1987), and one subspecies (T. maoershanensis Su, 2011) is elevated to species rank. Chinese distribution records are updated, and figures and illustrations are provided for the 14 species of Terrilimosina recorded from China.

BACKGROUND:The egg parasitoids, Trichogramma ostriniae (Hymenoptera: Trichogrammatidae), is an important biological control agent against the Asia corn borer, Ostrinia furnacalis, a destructive maize pest. These short-lived wasps (adult longevity of several to tens of days) have to locate their host within a limited time by exploiting reliable cues related to their hosts, for example, host egg volatiles. This study identified specific compounds in O. furnacalis egg volatiles that attract female Trichogramma ostriniae and tested the effects of these compounds and synthetic sex pheromones analogue of O. furnacalis, (Z)-12:14AC and (E)-12:14AC with a ratio of 47:53 (ZE) on parasitism of Trichogramma ostriniae on O. furnacalis eggs in a maize-plant cage. RESULTS:The egg volatiles from O. furnacalis and Helicoverpa armigera were the most attractive to Trichogramma ostriniae among the egg volatiles of five host tested species. Among the 13 specific compounds identified in O. furnacalis egg volatiles using gas chromatography-mass spectrometry (GC-MS) analysis, Trichogramma ostriniae females preferred six compounds (oleic acid, stearic acid, dioctyl phthalate, tetracosane, palmitic acid, and 4-hydroxyphenylethanol), and were repelled by three (heptadecanoic acid, phenylacetaldehyde, and elaidic acid). Trichogramma ostriniae females showed a significant preference for 'OSDTP4' (a mixture of the six preferred compounds) at 1, 0.1, and 0.01 μg/μL, but not at 10 and 0.001 μg/μL. The females preferred ZE, at 1 and 10 μg/μL, but not at 0.001, 0.01, and 0.1 μg/μL. In the cage and field experiments, Trichogramma ostriniae displayed higher parasitism rate on O. furnacalis eggs treated with OSDTP4, ZE, or their mixture than the control. The mixture of OSDTP4 and ZE was more effective in promoting parasitism than either alone. CONCLUSION:The present results identified six specific compounds from volatiles of O. furnacalis eggs attract to Trichogramma ostriniae females. By enhancing the attraction of Trichogramma ostriniae to O. furnacalis eggs, we can potentially improve capability of parasitoid wasps to find the target pest and increase the efficacy of Trichogramma ostriniae against O. furnacalis in biological control programs. © 2025 Society of Chemical Industry.

The egg parasitoid, Trichogramma dendrolimi, plays an important role as a biological control agent for the control of various lepidopteran pests. The reproductive capacity of T. dendrolimi is essential for both mass-rearing and effective pest control. In this study, a T. dendrolimi line with a high fecundity trait (Td-H) and another with a low fecundity trait (Td-L) were selected from 13 isofemale lines collected across different regions of China. The fecundity trait of Td-H and Td-L females was validated through assessments of oocyte number in the ovary, fecundity, body size, and adult longevity. To investigate the expression patterns of fecundity-related genes in T. dendrolimi, transcriptomes of Td-H and Td-L females were sequenced and compared. A total of 441 differentially expressed genes (DEGs), including 181 up-regulated genes and 260 down-regulated genes, were identified. Moreover, 11 genes were specifically expressed in Td-H females, while 16 genes were exclusive to Td-L females. These DEGs were mainly enriched in categories such as “metabolic process” (102 DEGs), “organelle”(53 DEGs), “catalytic activity” (90 DEGs), and “binding” (174 DEGs) in GO analysis, as well as various metabolic pathways (58 DEGs) and the “Neuroactive ligand-receptor interaction” pathway (22 DEGs) in KEGG analysis. The accuracy of seven up-regulated DEGs and seven down-regulated DEGs in the transcriptome was confirmed using RT-qPCR. These findings will be helpful for investigating the regulatory mechanisms associated with the fecundity traits of T. dendrolimi and provide a reference for improving biological control agents against pests.

Trichogramma dendrolimi is an essential egg parasitic wasp with a broad host range and has been widely used for controlling agricultural and forestry pests. Despite the availability of fragmented genomes of Trichogramma, a high-quality, chromosome-level genome reference is not yet available for this diverse genus. In this study, we assembled a high-quality chromosome-level genome of T. dendrolimi using PacBio CLR long sequencing and further scaffolded it with Hi-C technologies. The genome size was 216.24 Mb, featuring a N50 of 39.07 Mb, and 98.79% of scaffolds were anchored to five chromosomes. In addition, we annotated 12,902 protein-coding genes and 60.74 Mb repeat sequences for this genome assembly. In conclusion, our chromosome-level genome assembly provided important genomic resources that benefit the utilization of Trichogramma parasitoids in pest control.

The egg parasitoids, Trichogramma spp. are important biological control agents targeting various lepidopteran pests in agriculture. However, laboratory rearing often reduces genetic diversity, and potentially decreased fitness of Trichogramma wasps. Besides, infection of parthenogenesis-inducing Wolbachia allow Trichogramma females to produce nearly 100 % females, but may decrease fitness of infected females. This study investigated whether outbreeding the Wolbachia-infected thelytokous line (Td-W) with the high-fecundity bisexual line (Td-H) could improve its fitness. Furthermore, a bisexual Wolbachia-free line (Td), sharing the same genetic background as Td-W, and a line with less favorable traits (Td-L) were involved in cross-breeding experiments. The results showed that Td-W females could mate and be fertilized by bisexual males. Short Tandem Repeat (STR) analysis revealed no significant difference in the proportion of heterozygous offspring between mated Td-W and uninfected bisexual females. Outbreeding significantly increased the fecundity and body size of infected and uninfected offspring. Heterozygous offspring exhibited heterosis in fecundity and body size, regardless of Wolbachia infection, and displayed heterosis in emergence rates in Td-H♂×Td♀, Td♂×Td-L♀, and Td-L♂×Td♀ crosses. However, the emergence rate of Wolbachia-infected heterozygous offspring was lower than that of their Td-H or Td-L parents. Additionally, the adult longevity of heterozygous offspring did not differ significantly from that of their parents, irrespective of Wolbachia infection. Our findings suggest that outbreeding enhances fecundity and body size of Wolbachia-infected T. dendrolimi, regardless of the particular bisexual isofemale line used. This study proposes a strategy to improve the quality of Wolbachia-infected Trichogramma by outbreeding different isofemale lines before field release in biological control programs.

Seed priming with beneficial endophytic fungi is an emerging sustainable strategy for enhancing plant resistance against insect pests. This study examined the effects of Beauvaria bassiana Bb20091317 and Metarhizium rileyi MrCDTLJ1 fungal colonization on maize growth, defence signalling, benzoxazinoid levels and gene expression. The colonization did not adversely affect plant growth but reduced larval weights of Spodoptera frugiperda. Maize leaves treated with M. rileyi exhibited higher levels of jasmonic acid, jasmonoyl-Isoleucine, salicylic acid, and indole acetic acid compared to control. B. bassiana and M. rileyi accelerated phytohormone increase upon S. frugiperda herbivory. Gene expression analysis revealed modulation of benzoxazinoid biosynthesis genes. We further elucidated the immune regulatory role of the transcription factor zmWRKY36 using virus-induced gene silencing (VIGS) in maize. zmWRKY36 positively regulates maize immunity against S. frugiperda, likely by interacting with defense-related proteins. Transient overexpression of zmWRKY36 in tobacco-induced cell death, while silencing in maize reduced chitin-triggered reactive oxygen species burst, confirming its immune function. Overall, B. bassiana and M. rileyi successfully colonized maize, impacting larval growth, defense signalling, and zmWRKY36-mediated resistance. This sheds light on maize-endophyte-insect interactions for sustainable plant protection.

Background Wolbachia-infected thelytokous Trichogramma wasps have been considered as potential effective biocontrol agents against lepidopteran pests in agriculture and forests. However, intra-specific competition may arise when Wolbachia-infected thelytokous Trichogramma coexist with their uninfected bisexual counterparts in fields or during mass-rearing procedures. This competition could potentially impact the efficacy of Trichogramma females in biological control programs. Results This study examined the parasitic capacities of bisexual (TdB) and Wolbachia-infected thelytokous (TdT) strains of Trichogramma dendrolimi as influenced by host density (ranging from 5 to 70 host eggs) and wasp density (two, four, and six females per arena). The experiments involved inter-strain competition between TdB and TdT strains (Inter-Td) as well as intra-strain competition within the TdT (Intra-TdT) or TdB (Intra-TdB) strains. Results revealed that females in the Inter-Td group exhibited a higher attack rate compared to those in the Intra-TdT and Intra-TdB groups, irrespective of wasp density. Specifically, when six females were present, the Inter-Td group showed significantly shorter host handling times than the Intra-TdT group. Within intra-strain cohorts, TdT females displayed a lower attack rate than TdB females when four or six females were present, and longer host handling times when six females were present. Mutual interference between individuals was not affected by competition types. Females of the Inter-Td group exhibited a higher probability of superparasitism than those of the Intra-TdB group or Inter-Td group. When both strains coexisted, the proportion of TdT offspring with six females was higher than that with two females or four females. Male ratios of bisexual offspring in Inter-Td groups were higher than those in Intra-TdB groups. The male ratio of bisexual offspring in the Inter-Td group increased with wasp density. Conclusions Our study highlights the negative impact of Wolbachia on parasitic capacity of Trichogramma females, increasing the likelihood of superparasitism. The coexistence of both strains enhances total parasitic efficacy, albeit resulting in a higher proportion of male offspring compared to scenarios with only uninfected females. The results will provide the reference for the usage of Wolbachia-infected thelytokous strain of T. dendrolimi in augmentative biological control programs.

Abstract Background Metarhizium rileyi is an important entomopathogenic fungus which has a wide range of host pests. In this work, the virulence of M. rileyi EFNL-08 against 3rd instar larvae of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), was quantified. Additionally, the infection process and aspects of the host immunological response were described in the laboratory. Results Bioassay results proved that M. rileyi was highly virulent to 3rd instar S. frugiperda larvae with 98.33% mortality at 1 × 108 conidia/ml. Scanning electron microscopy was used to monitor morphological aspects of the infection process. When hyphal bodies (Hbs) of M. rileyi were injected into the hemocoel of host, they were not recognized by the host’s immune system as invaders. There were nonsignificant differences in the hemocytes and phenoloxidase activity between the infected and control larvae at the initial 30 h, indicating that fungus successfully avoids the attack from the immune system. However, it inhibited the enzyme activity at the latest stage when Hbs reached a high density. After infection with M. rileyi, the activity of glutathione-S-transferase (GST) of S. frugiperda larvae presented a significant upward trend, while the activity of acetylcholinesterase (AchE) initially increased, followed by a decrease, and eventually stabilized. However, the activity of both detoxification enzymes in the control group showed slight fluctuations in the initial stage, and then stabilized at a low level. Conclusion Obtained results provided new insights into the virulence and potential physiological responses of M. rileyi. This provides ideas for further development of novel and efficient entomopathogenic fungi (EPF) for pest control.

Larvae of Melolonthinae (white grubs) are usually considered as serious pests for some of them attacking plant roots and causing great losses of agriculture and forestry. However, not all the white grubs are pest species. In this study, the adult Apogonia cupreoviridis were observed to feed on gramineous grasses and fallen ginkgo leaves, while their larvae were frequently collected in the lawn. The larvae were reared in the laboratory and observed using scanning electron microscopy. The larvae have the plegmatia expanded in the middle; distal antennomere with an apical process bearing one bifurcated sensilla and nine sensilla basiconica on the apex; the palidia are V-shaped and each palidium bearing five to nine pali. The V-shaped palidia are found in the known larvae of Diplotaxini, as to genera Apogonia and Liogenys.

The spotted alfalfa aphid (Therioaphis trifolii) is a kind of destructive pest of cultivated alfalfa (Medicago sativa) that results in significant financial losses for the livestock sector. To understand how T. trifolii navigates the biochemical defenses of its host, we investigated the effects of susceptible and resistant aphid strains on two alfalfa cultivars. T. trifolii was reared for over 50 generations on two cultivars—WL343, which is susceptible to T. trifolii, and Zhongmu No. 1, which is resistant—resulting in the development of a resistant aphid strain (R-aphid) and a susceptible aphid strain (S-aphid). The results showed that the survival rate of R-aphids was significantly higher than that of S-aphids (p = 0.039) on the resistant cultivar Zhongmu No. 1, while there was no significant difference in survival rates between the two aphid strains on WL343 (p = 0.139). This suggests that S- and R-aphids differ in their ability to modulate plant defense mechanisms, influencing their survival rates. The application of saliva from R-aphids reared on Zhongmu No. 1 (R-saliva) reduced the repellency and toxicity of treated plants, improving aphid survival. Furthermore, R-aphid infestation and R-saliva application activated the salicylic acid (SA) signaling pathway while suppressing the jasmonic acid (JA) pathway, enhancing the host plant’s suitability for aphid colonization. We propose that R-aphids may use their saliva to activate the SA pathway, which in turn inhibits JA synthesis, weakening the plant’s defenses. These findings provide valuable insights into how T. trifolii interacts with host plant defense systems.

The ten species of Opalimosina Roháček now known from China are reviewed and keyed including two new species, O. aculeata sp. nov. and O. setifera sp. nov., and two newly recorded species O. calcarifera (Roháček, 1975) and O. spathulata Hayashi, 2010.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is one of the most important insect pests affecting corn crops worldwide. Although planting transgenic corn expressing Bacillus thuringiensis (Bt) toxins has been approved as being effective against FAW, its populations’ resistance to Bt crops has emerged in different locations around the world. Therefore, it is important to understand the interaction between different Bt proteins, thereby delaying the development of resistance. In this study, we performed diet-overlay bioassays to evaluate the toxicity of Cry1Ab, Cry1Ac, Cry1B, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, Vip3Aa11, Vip3Aa19, and Vip3Aa20, as well as the interaction between Cry1Ab-, Cry1F-, Cry2Ab-, and Vip3Aa-class proteins against FAW. According to our results, the LC50 values of Bt proteins varied from 12.62 ng/cm2 to >9000 ng/cm2 (protein/diet), among which the Vip3Aa class had the best insecticidal effect. The combination of Cry1Ab and Vip3Aa11 exhibited additive effects at a 5:1 ratio. Cry1F and Vip3Aa11 combinations exhibited additive effects at 1:1, 1:2, and 5:1 ratios. The combination of Cry1F and Vip3Aa19 showed an antagonistic effect when the ratio was 1:1 and an additive effect when the ratio was 1:2, 2:1, 1:5, and 5:1. Additionally, the combinations of Cry1F and Vip3Aa20 showed antagonistic effects at 1:2 and 5:1 ratios and additive effects at 1:1 and 2:1 ratios. In addition to the above combinations, which had additive or antagonistic effects, other combinations exhibited synergistic effects, with variations in synergistic factors (SFs). These results can be applied to the establishment of new pyramided transgenic crops with suitable candidates, providing a basis for FAW control and resistance management strategies.