Search Results (198)

There is a global demand for reducing the adoption of traditional chemical insecticides in agriculture. Among the most promising alternatives, botanical insecticides have been increasingly gaining attention due to their efficacy combined with a more environmentally safe impact. Among the different botanical insecticides commercially available, oxymatrine is an alkaloid found in the roots of Sophora flavescens which exhibits wide insecticide activity. However, their side-effects on non-target organisms have not been extensively evaluated. Therefore, this study aimed to investigate in laboratory conditions the insecticidal potential of a commercial botanical insecticide (Matrine^®) based on ethanolic extract of S. flavescens roots at 0.2; 0.6; 1.0; 1.4; 1.8; and 2.2 L of commercial product per hectare to control third-instar larvae of Rachiplusia nu and its selectivity in the egg parasitoid Trichogramma pretiosum. Overall, our results showed that the ethanolic extract of S. flavescens is an efficient tool to control R. nu from 0.6 to 2.2 L/ha, with similar R. nu mortality at 48 and 72 h after spraying (close to 100% mortality) associated with no impact to pupae and minimum impact to adults (slightly harmful) of the egg parasitoid. The botanical insecticide was classified as harmless to the pupae and slightly harmful to the adults of T. pretiosum according to the International Organization for Biological Control (IOBC) protocols. Thus, the use of the ethanolic extract of S. flavescens emerges as a relevant alternative to control R. nu, which needs to be confirmed in future field trials. Full article

Trichogramma wasps are highly effective biological control agents, offering an environmentally sustainable solution for pest management through their parasitism of insect eggs. This study evaluates the parasitism performance of six Trichogramma species—T. dendrolimi, T. chilonis, T. leucaniae, T. ostriniae, T. japonicum, and T. pretiosum—on five treatments of Eri silkworm (ES) eggs, a potential alternative to the large eggs of Antheraea pernyi for mass rearing. The ES egg treatments included the following: manually extracted, unfertilized, and washed eggs (MUW); naturally laid, unfertilized, and washed eggs (NUW); naturally laid, unfertilized, and unwashed eggs (NUUW); naturally laid, fertilized, and washed eggs (NFW); and naturally laid, fertilized, and unwashed eggs (NFUW). The results demonstrate that all Trichogramma species, except T. japonicum, successfully parasitized ES eggs across all treatments. Notably, washed eggs consistently supported higher parasitism and emergence rates compared to unwashed eggs, while unfertilized eggs outperformed fertilized eggs in these metrics. Among the treatments, unfertilized and washed eggs (MUW and NUW) exhibited the shortest pre-emergence time and the highest number of emerged adults, with no significant differences in female progeny ratios across most species. A striking exception was T. dendrolimi, which showed a significantly higher female offspring ratio in the MUW treatment. These findings highlight that MUW eggs of ES are a highly suitable alternative host for the mass production of Trichogramma wasps. This study provides critical insights for optimizing host egg treatments to enhance the efficiency of Trichogramma-based biological control programs. Full article

Stink bugs are widespread agricultural pests that damage crops and reduce yield. Their impact is influenced by host plant selection and interactions with natural enemies, particularly egg parasitoids. Understanding these relationships is crucial for improving biological control strategies. This paper investigates the seasonal host plant use and parasitism of Halyomorpha halys, Palomena prasina, and Pentatoma rufipes in South Tyrol, Italy. Over two years, we conducted field surveys at 27 sites, recording stink bug presence across 85 plant species and analyzing egg parasitism rates. Results show that stink bugs exhibit distinct host plant preferences, with H. halys utilizing the broadest range of host plants while P. prasina and P. rufipes showed stronger affinities for specific families such as Sapindaceae and Rosaceae. Parasitism rates varied across species and plant families: Trissolcus japonicus predominantly parasitized H. halys while T. cultratus and two Telenomus species targeted P. rufipes and P. prasina, respectively. Spatial–temporal features and host plant associations significantly influenced species distributions and parasitoid occurrence. These findings emphasize the role of plant–insect interactions in shaping pest and parasitoid dynamics. Integrating plant diversity into pest management strategies could enhance parasitoid effectiveness and reduce stink bug populations, contributing to more sustainable agricultural practices. Full article

Tomato is the most widely cultivated fruit–vegetable worldwide, and the tomato leafminer (Tuta absoluta) is the primary pest of this crop. In this context, biological control using parasitoids belonging to the genus Trichogramma is crucial. This study aimed to evaluate the biological characteristics of T. pretiosum strains collected from different locations and exposed to eggs from various T. absoluta populations/generations, using parameters such as parasitism capacity, viability (percentage of emergence), sex ratio, and female longevity. The presence of endosymbionts in the T. absoluta populations was also assessed. The experiment followed a randomized design, with treatments consisting of eggs from T. absoluta populations collected in different years (2019, 2020, 2021, 2022, and 2023) and different strains of T. pretiosum. We used 20 replicates, with one female per replicate in each treatment, organized in a 5 × 4 factorial scheme (five populations of T. absoluta × four strains of T. pretiosum). The S2 strain of T. pretiosum was found to be the most efficient in terms of biological characteristics for parasitism of T. absoluta eggs, especially in T. absoluta populations collected in recent years (2022 and 2023). These results suggest that S2 is the preferred strain for future studies aimed at using this parasitoid as a control agent to combat T. absoluta. The endosymbionts Arsenophonus and Serratia were identified in T. absoluta populations collected in 2019–2020 and 2020–2021, respectively. These findings highlight the presence of these microorganisms in pest populations in different years. Full article

Trichogramma dendrolimi, a key egg parasitoid for lepidopteran pest control, faces potential risks from neonicotinoid insecticides like acetamiprid used in integrated pest management (IPM). This study evaluated acetamiprid’s acute and sublethal toxicity to T. dendrolimi and assessed population-level risks via species sensitivity distribution (SSD). Acute toxicity assays using glass-vial residues revealed a 24 h LC₅₀ of 0.12 mg a.i. L⁻¹ for adults, three orders of magnitude below the maximum field rate (100 mg a.i. L⁻¹). Sublethal exposure (1/2–1/100 LC₅₀) significantly reduced parasitism and emergence rates (NOEC = 2.3 μg a.i. L⁻¹) but did not affect offspring survival. Acetamiprid also shortened offspring development at 11.5–57.5 μg a.i. L⁻¹. SSD analysis identified T. dendrolimi as the most sensitive parasitoid to acetamiprid (HC₅/HC₅₀) = 0.11/5.88 mg a.i. L⁻¹), with field rates (30–100 mg a.i. L⁻¹) indicating a potentially affected fraction (PAF) of 76.8–97.9%. These findings underscore the need to integrate sublethal effects into pesticide regulations to conserve parasitoid-mediated ecosystem services. Full article

Trichogramma wasps, egg parasitoids widely used to control lepidopteran pests, have long eluded in-depth molecular mechanistic studies due to their minute size and genetic tool scarcity. While previous RNAi efforts were restricted to T. dendrolimi, we developed the first cross-species RNAi system for both T. dendrolimi and the previously intractable T. ostriniae. Temporal expression profiling identified white and laccase 2 as stage-specific RNAi targets, peaking during prepupal/pupal stages, which were tested across species and developmental stages using microinjection and soaking dsRNA delivery methods. Survival analysis prioritized soaking for T. dendrolimi prepupae/pupae, while microinjection was essential for T. ostriniae to bypass prepupal mortality during soaking. Concentration-dependent RNAi targeting the white gene achieved 85.61% transcript reduction in T. dendrolimi via soaking and 89.36% in T. ostriniae via microinjection at 2000 ng/μL, correlating with 64.06% and 32.09% white-eyed pupae, causing a significant reduction in eye pigments. For the laccase 2 gene, soaking at 2000 ng/μL induced 88.35% transcript reduction in T. dendrolimi and 73.31% in T. ostriniae, leading to incomplete cuticle tanning and sclerotization. This study resolves the long-standing challenge of genetic manipulation in Trichogramma wasps, providing a universally applicable framework to decipher parasitoid–host interactions at the molecular scale, which is useful for sustainable pest management strategies. Full article

Agriculture plays an essential role in meeting global food demand, and so effective pest control is crucial. Aphids (Hemiptera: Aphididae) are a significant problem for many crops worldwide, and cause crop losses. They are considered one of the most important groups of pests in the world. Aphid parasitoids are very important as biological agents, both for their effectiveness and their host range selectivity. This study provides a review of these groups of parasitoids and their possible role and use in aphid biological control. Two groups of primary parasitoids, Aphelinidae and Braconidae: Aphidiinae, are the main groups that can be used in the biological control of aphids. There is also a diversity of hyperparasitoids whose hosts are these primary parasitoids and therefore are likely to be detrimental to the biological control programs: Megaspilidae in the superfamily Ceraphronoidea, the following Chalcidoidea families: Encyrtidae, Eulophidae, Moranilidae, Pteromalidae, and Signiphoridae, and Cynipoidea: Figitidae: Charipinae. Records of Mymaridae emerging from aphids, while assumed to be obligate egg-parasitoids, are discussed. Dichotomous keys are provided to identify the superfamilies, families and most important genera associated with aphids. Full article

Due to the biofactories’ concern for the quality of the parasitoid Cotesia flavipes (Hymenoptera: Braconidae), a common practice is to introduce a population collected from the field into the laboratory mass rearing, even without prior information about the introduced population’s quality or potential positive outcomes. Thus, the objective of this study was to determine whether populations of the C. flavipes parasitoid collected from the field exhibit better biological characteristics and flight activity, with the aim of incorporating them into laboratory mass rearing to enhance the quality of the parasitoids. To achieve this, a population of C. flavipes collected from the field (Pradópolis, SP, Brazil) was studied for twenty generations and compared with a population maintained in the laboratory for 42 years. The egg-to-pupa period in the field population was shorter across generations, particularly in the twentieth generation (11.0 days). Although the field population exhibited a lower number of adults that emerged per host in the fifth and tenth generations, by the twentieth generation, it showed higher offspring production per parasitized host (56.5 parasitoids/host). The results of the flight activity test revealed that both the laboratory-maintained population and the field-collected population exhibited higher percentages of insects classified as walkers compared to flyers (25.7% to 32.3% flying). The field-collected population stabilized in the laboratory by the tenth generation. Moreover, the results of the biological characteristics, longevity, and flight activity of the parasitoids indicate similar quality between the two populations studied after stabilization of the field-collected population. Full article

This study reports the first complete mitochondrial genomes of three egg parasitoid wasps parasitizing Nilaparvata lugens—Pseudoligosita nephotetticum, Anagrus frequens, and Anagrus nilaparvatae. Genome sizes ranged from 15,429 to 15,889 bp, with all three mitogenomes displaying strong A + T bias, standard gene content, and characteristic strand asymmetries. While A. frequens and A. nilaparvatae exhibited conserved gene orders, extensive gene rearrangements, including multiple inversions in both protein-coding genes (PCGs) and tRNAs, were observed in P. nephotetticum. Codon usage analyses revealed a preference for codons ending in A or U. The non-synonymous (Ka) to synonymous (Ks) substitution ratio analysis identified signs of positive selection in multiple PCGs, particularly in atp8, nad6, and nad3, suggesting possible adaptive evolution related to host-searching behavior. Secondary structure analyses showed the loss of trnL1 in all Anagrus species, while trnS1 and trnR lacked the DHU arm, indicating possible derived traits in Mymaridae. Phylogenetic analysis was the first time to describe the relationship of the genus Anagrus within Mymaridae from the perspective of 13 protein genes. Furthermore, the grouping of (Pseudoligosita + Megaphragma) + Trichogramma was supporting the distinct evolutionary lineage of Pseudoligosita. This work provides new molecular resources and phylogenetic insight for Chalcidoidea, with implications for parasitoid evolution and biological control strategies. Full article

Aprostocetus nitens Prinsloo & Kelly (Hymenoptera: Eulophidae) was identified as one of four hymenopteran ectoparasitoids utilizing three erythrina gall wasps, Quadrastichus bardus, Q. erythrinae, and Q. gallicola) (Hymenoptera: Eulophidae) in the native eastern Africa. In Hawaiʻi, the eurytomid wasp, Eurytoma erythrinae Gates & Delvare (Hymenoptera: Eurytomidae), was introduced and approved for statewide release in 2008 to control the erythrina gall wasp (EGW) Q. erythrinae Kim. EGW has devastated the wiliwili trees, Erythrina sandwicensis Degener (Fabaceae), an ecologically and culturally important native Hawaiian tree species. However, the parasitoid’s impact on the galled inflorescences and shoots was not adequate to ensure adequate seed set and maturation for successful tree recruitment. Aprostocetus nitens was thus evaluated as a prospective natural enemy to enhance the biological control of EGW to further protect the wiliwili trees in Hawaiʻi. Both choice and no-choice host specificity tests were conducted on seven non-target gall formers in the Hawaii Department of Agriculture, Insect Containment Facility, and showed that the parasitoid was extremely specific to EGW. The potential for competition between this parasitoid and the established E. erythrinae was also investigated, showing that the release of a second parasitoid will potentially complement the success of the eurytomid wasp for control of EGW. Unlike what was found in the native region, the Hawaiian laboratory colony is thelytokous, producing only female offspring. The life cycle took 20.1 ± 0.28 days under the laboratory conditions. Non-ovipositing female survived for 102.5 ± 2.9 days when fed honey and laid eggs for 25.1 ± 2.3 days with average fecundity of 156.7 ± 22.3 offspring/female. This value is 3.9-fold higher than offspring produced by E. erythrinae. Aprostocetus nitens, host specificity, competition with E. erythrinae, and its tri-trophic association with 15 Erythrina host plants and 5 gall wasp assemblages in the native African regions were defined. Implications to reduce frequent galls on the native Erythrina plants and likely domination over E. erythrinae, are discussed. Full article

This study investigated the lethal and transgenerational effects of botanical and synthetic insecticides on the egg parasitoid Trichogramma atopovirilia, an important natural enemy of Spodoptera frugiperda in Brazil and beyond. The treatments were assessed for their impact on parasitism, emergence, sex ratio, and flight capacity of adults exposed to contaminated eggs. The botanical insecticide ESAM (ethanolic seed extract of Annona mucosa) significantly reduced the parasitism in the F₀ generation by 99.76%, categorizing it as toxic. Anosom^® [acetogenins (annonin as a major component)] and Azamax^® [limonoids (azadirachtin + 3-tigloilazadirachtol)] also caused substantial reductions (99.13% and 92.36%, respectively) in the parasitism rate. EFAMON (ethanolic leaf extract of Annona montana) reduced the parasitism by 62%, while the synthetic insecticide Premio^® (chlorantraniliprole) resulted in a 28.21% reduction. In the F₁ generation, emergence rates for EFAMON, Azamax^®, and Premio^® exceeded 70%, showing no significant differences from the negative control (82%), while Anosom^® resulted in a lower emergence rate of 61.39%. No significant effects were observed on sex ratio or parasitism in the F₁ and F₂ generations. Most adults reached high flight capacity (above 80%). These results indicate that while ESAM was toxic, the other treatments showed no transgenerational effects. Our findings contribute to understanding insecticide selectivity and highlight the importance of such studies for the sustainable management of S. frugiperda within integrated pest management programs. Full article

This study explores the molecular mechanisms underlying diapause in the parasitoid wasp Telenomus remus (Nixon) (Hymenoptera: Platygastridae), a critical egg parasitoid for the biological control of the invasive pest Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). While effective in pest management, T. remus faces limitations in large-scale applications due to its short lifespan and low viability under storage conditions. Diapause, a state of developmental arrest, was successfully induced in T. remus using photoperiod manipulation (0L:24D), allowing for extended survival and improved storage potential. Transcriptome sequencing identified 2642 differentially expressed genes, with 617 involved in 284 enriched pathways, including calcium signaling and phototransduction. The study found that the expression levels of CBP1 and CBP2, genes encoding calcium-binding proteins, were significantly downregulated during diapause. As key regulators in calcium ion-mediated signal transduction pathways, the downregulation of CBP1 and CBP2 may lead to the suppression of intracellular calcium signaling, thereby affecting light signal transduction and energy metabolism regulation. This suggests that during diapause, insects may reduce calcium signaling activity to suppress physiological functions, maintain a low metabolic state, and decrease sensitivity to environmental stimuli. Additionally, ARR genes still exhibited differential expression, further supporting their potential role in phototransduction and diapause regulation. Full article

Biological control by releasing a large number of parasitoids has been an effective strategy for coping with stored-product pest insects. Habrobracon hebetor (Say) (Hymenoptera: Braconidae) has strong control capabilities over Lepidoptera pests. Exploring the optimum storage temperature, life stage, and cold storage period of H. hebetor is of great importance for the utilization of parasitoids. In this context, the survival, parasitism, and fecundity of H. hebetor were evaluated after 10, 20, 30, 40, 50, and 60 d of exposure at −5, 0, 5, 10, and 15 °C for H. hebetor eggs, larvae, pupae, and adults, and the survival, parasitism, and fecundity of H. hebetor individuals that had been maintained at normal rearing condition were taken as a control. The cold exposure duration dramatically affected the development and survival of eggs, larvae, and pupae of H. hebetor, regardless of the temperatures tested. Habrobracon hebetor eggs, larvae, and pupae failed to develop into the next life stage at −5, 0, and 5 °C. Habrobracon hebetor eggs, larvae, pupae, and adults failed to survive after 10 d exposure at −5 and 0 °C. The parasitism rate, fecundity and oviposition duration of H. hebetor adults that originated from eggs, larvae, pupae, and adults after different cold storage durations markedly decreased with increasing cold storage duration. The highest parasitism rate of adults was 34.12% after exposure at 5 °C for 10 d, which was not significantly different from the control (31.86%). The maximum level of egg production of H. hebetor adults developed from initial larvae exposed at 15 °C for 10 d and 20 d were 344.67 and 340.67 eggs/female, respectively, which were not significantly different from the control (392.00 eggs/female). When H. hebetor larvae were stored at 15 °C for 10 and 60 d, the oviposition duration of newly emerged adults reached the maximum and minimum levels recorded, with 17.00 and 0.83 d, respectively. These results provide empirical support for the large-scale production and storage of H. hebetor. Full article

Related species of parasitoid Hymenoptera often coexist on a certain host, but many details of interactions between these organisms remain unclear. The present review summarizes the main existing concepts and facts and suggests principal patterns and mechanisms that allow for the coexistence of several members of a particular parasitoid genus at the expense of the same host. Although the successful introduction of exotic parasitic wasps into the existing ecosystems often leads to the competitive displacement of related parasitoids, mere spatial and/or temporal niche partitioning between these insects is also possible. Nevertheless, many cases of coexistence of related wasp species on the same host defy simple explanations since they apparently result from complex interactions between the host and its parasitoids. The main characteristics of the oviposition process, i.e., egg volume, fecundity, and duration of the egg-laying period, are likely to correlate with other basic features of life-history strategies in parasitoid Hymenoptera. Specialist parasitic wasps often aggregate over the host patches, whereas generalists can be randomly distributed, thus reducing the degree of interspecific competition among parasitoids. However, some of the coexisting parasitic wasps, usually the weakest competitors, must also have access to enemy-free space to survive. Full article

Volatile plant compounds are essential for host plant selection by herbivores and particularly important for the behaviour of parasitoids seeking larvae in which to lay eggs. Headspace extracts were collected from intact plants of four Brassica oleracea genotypes, as well as from plants damaged by larvae of Mamestra brassicae or Pieris rapae. In total, 52 volatiles present in the headspaces of four genotypes were selected for multivariate analyses. The most abundant groups of volatiles were terpenes and esters, represented by 20 and 14 compounds, respectively. The qualitative and quantitative differences in odour profiles between the four genotypes were sufficient to differentiate between groups using multivariate analysis techniques. The most distinct volatile blends originated from curly kale, followed by cabbage, cauliflower and broccoli. Multivariate analysis revealed that genotypes affected the composition of the volatile blends to a large extent compared to the herbivore damage by the different species tested. In curly kale, broccoli and cauliflower, the differences in odour bouquets were more expressed between plants with and without active feeding, independent of the herbivore identity, while in cabbage, larger differences were observed between odour profiles with different herbivore feedings, independent of whether the herbivore was present or removed. Full article