Parasitoid Wasp Research Articles

Immature stages and natural history of Eruga unilabiana (Hymenoptera: Ichneumonidae), an ectoparasitoid of two linyphiid spiders

AbstractWasps from the Polysphincta genus group (Hymenoptera: Ichneumonidae: Pimplinae) are currently the only parasitoid wasps that are ectoparasitoids of spiders. The species of the group exhibit several morphological and behavioral adaptations, which allow exploiting their host spiders. Here, we describe the external morphology, behavior and natural history of the immature stages of a Darwin wasp Eruga unilabiana Pádua & Sobczak, 2018, a parasitoid of sheet‐weaving spiders, Sphecozone sp. and Eurymorion sp. (Linyphiidae). The egg of E. unilabiana is a white mass that is deposited in the anterior region of the spider's abdomen. First stage larvae partially emerge from the egg's chorion. Second stage larvae have a body divided into 13 segments and induce spiders to build a modified web. The third stage larvae have eight pairs of retractable dorsal tubercles with tiny little hooks that help the larvae hang and move on the web threads after the spider dies. These results indicate that the immature stages of E. unilabiana present the same basic morphological and behavioral characteristics already known for the species of the group. However, the last stage larva's strategy of moving first to hang on the web threads before killing the spider is the first record in the group and more studies are needed to assess whether this behavior is adaptive for the wasp.

A naturally occurring mitochondrial genome variant confers broad protection from infection in Drosophila

The role of mitochondria in immunity is increasingly recognized, but it is unclear how variation in mitochondrial DNA (mtDNA) contributes to variable infection outcomes. To quantify the effect of mtDNA variation on humoral and cell-mediated innate immune responses, we utilized a panel of fruit fly Drosophila melanogaster cytoplasmic hybrids (cybrids), where unique mtDNAs (mitotypes) were introgressed into a controlled isogenic nuclear background. We observed substantial heterogeneity in infection outcomes within the cybrid panel upon bacterial, viral and parasitoid infections, driven by the mitotype. One of the mitotypes, mtKSA2 protected against bacterial, parasitoid, and to a lesser extent, viral infections. Enhanced survival was not a result of improved bacterial clearance, suggesting mtKSA2 confers increased disease tolerance. Transcriptome sequencing showed that the mtKSA2 mitotype had an upregulation of genes related to mitochondrial respiration and phagocytosis in uninfected flies. Upon infection, mtKSA2 flies exhibited infection type and duration specific transcriptomic changes. Furthermore, uninfected mtKSA2 larvae showed immune activation of hemocytes (immune cells), increased hemocyte numbers and ROS production, and enhanced encapsulation response against parasitoid wasp eggs and larvae. Our results show that mtDNA variation acts as an immunomodulatory factor in both humoral and cell-mediated innate immunity and that specific mitotypes can provide broad protection against infections.

Inhibition of the Notch signal transducer CSL by Pkc53E-mediated phosphorylation to fend off parasitic immune challenge in Drosophila.

Notch signalling activity regulates hematopoiesis in Drosophila and vertebrates alike. Parasitoid wasp infestation of Drosophila larvae, however, requires a timely downregulation of Notch activity to allow the formation of encapsulation-active blood cells. Here, we show that the Drosophila CSL transcription factor Suppressor of Hairless [Su(H)] is phosphorylated at Serine 269 in response to parasitoid wasp infestation. As this phosphorylation interferes with the DNA binding of Su(H), it reversibly precludes its activity. Accordingly, phospho-deficient Su(H)S269A mutants are immune-compromised. A screen for kinases involved in Su(H) phosphorylation identified Pkc53E, required for normal hematopoiesis as well as for parasitoid immune response. Genetic and molecular interactions support the specificity of the Su(H)-Pkc53E relationship. Moreover, phorbol ester treatment inhibits Su(H) activity in vivo and in human cell culture. We conclude that Pkc53E targets Su(H) during parasitic wasp infestation, thereby remodelling the blood cell population required for wasp egg encapsulation.

Regulation of melanization in aphids by parasitoid wasp venom proteins enhances mummification.

Interactions between parasitic insects and their hosts demonstrate the complexity of evolutionary processes. Specifically, the parasitoid wasp Aphidius ervi manipulates its host, the pea aphid Acyrthosiphon pisum, through strategic venom injection to enhance mummification. This study explores how this venom affects the aphid's immune system, particularly targeting the activity of the phenoloxidase (PO) enzyme. Following the injection of venom from A. ervi, significant changes were observed in the expression of immune-related genes in A. pisum, especially notable expression changes of ApPPOs and a reduction of PO activity. Multi-omics sequencing identified 74 potential venom proteins in the venom gland of A. ervi, including serine protease homolog 1 (AeSPH1) and serine protease inhibitor (AeSPN1), hypothesized to regulate PO activity. The injection of recombinant protein AeSPH1 and AeSPN1 into the A. pisum hemocoel selectively reduced the expression of ApPPO1, without affecting ApPPO2, and effectively suppressed melanization. Moreover, RNAi targeting AeSPH1 significantly reduced the mummification rate in A. pisum population parasitized by A. ervi. Our findings clarify the complex biochemical mechanisms underlying host-wasp interactions and highlight potential avenues for developing targeted biological control strategies. © 2024 Society of Chemical Industry.

Potential benefits of male diploidy and female triploidy for parasitoid wasps used as biological control agents: A case study in Nasonia

Potential benefits of male diploidy and female triploidy for parasitoid wasps used as biological control agents: A case study in Nasonia

New species of braconid parasitoid wasps from the subfamilies Doryctinae and Brachistinae from late Eocene Baltic amber

Three new fossil species of braconid wasps are described and illustrated from late Eocene Baltic amber: Palaeorhoptrocentrus tenuicornis sp. nov. (Doryctinae), Taphaeus obscurus sp. nov. (Brachistinae: Diospilini), and Eubazus electrus sp. nov. (Brachistinae: Brachistini). Keys to the known species of Palaeorhoptrocentrus Belokobylskij, 2023 and to species of Eubazus Nees, 1812 described from Baltic amber are provided. An illustrated redescription of Blacus (Electroblacus) facialis Brues, 1933 (Brachistinae: Blacini) is also provided, along with digital photographs for the first time of the female of B. (Electroblacus) facialis, whose type material was lost during the World War II. We also provide morphological notes and digital photographs of a male belonging to an undescribed species of Meteorus (Euphorinae).

Sodalis praecaptivus subsp. spalangiae subsp. nov., a nascent bacterial endosymbiont isolated from the parasitoid wasp, Spalangia cameroni.

An endosymbiotic bacterium of the genus Sodalis, designated as strain HZT, was cultured from the parasitoid wasp Spalangia cameroni, which develops on the pupae of various host flies. The bacterium was detected in S. cameroni developed on houseflies, Musca domestica, in a poultry facility in Hazon, northern Israel. After culturing, this bacterium displayed no surface motility on Luria-Bertani agar and was rod-shaped and irregular in size, ~10-30 nm in diameter and 5-20 µm in length. Phylogenetic analyses revealed that strain HZT is closely related to Sodalis praecaptivus strain HST, a free-living species of the genus Sodalis that includes many insect endosymbionts. Although these bacteria maintain >98% sequence identity in shared genes, genomic characterization revealed that strain HZT has undergone substantial reductive evolution, such that it lacks many gene functions that are maintained in S. praecaptivus strain HST. Based on the results of phylogenetic, genomic and chemotaxonomic analyses, we propose that this endosymbiont should be classified in a new subspecies as S. praecaptivus subsp. spalangiae subsp. nov. The type strain for this new subspecies is HZT (=ATCC TSD-398T=NCIMB 15482T). The subspecies Sodalis praecaptivus subsp. praecaptivus strain HST is created automatically with the type strain ATCC BAA-2554T (=DSMZ 27494T).

Host Plants for the Lanternfly Saiva formosana Kato, 1929 (Hemiptera, Fulgoridae) Endemic to Taiwan, and Parasitism of Its Eggs by Wasps

Since Saiva formosana Kato, 1929 was first reported as a new species in Taiwan; there have been few published reports on its ecology, and fundamental knowledge of this species is still lacking. The objectives of this study are to (1) determine the preferred plants of adults, egg-laying, and nymphs, (2) analyze the change in host plants with time and development, and (3) explore the relationship between the survival of eggs and parasitism by their wasps. We detected the adults of this species between May and September 2023, and again in April 2024, mainly on Elaeocarpus decipiens F. B. Forbes & Hemsl. During our investigation, we frequently observed parasitic wasps ovipositing on the egg masses. We established that most egg masses produced only Saiva nymphs or Anastatus adults. This lanternfly might better survive parasitic pressure by laying lower numbers of eggs per mass across a broader range of plant species. The first batch of hatching nymphs was found on Magnolia compresssa Maxim. on 20 June 2023; however, most nymphs in the second and third instars were detected on Ficus fistulosa Reinw. ex Blume, between August and October 2023. After the autumn, the occurrences of nymphs increased on Heptapleurum heptaphyllum (L.) Y. F. Deng which probably served as a shelter for overwintering.

Preliminary observations on the physiology and behavior of Sytretomorpha szaboi Papp

Sytretomorpha szaboi Papp (Hymenoptera: Braconidae) is a parasitic wasp that specializes in parasitizing the Apis cerana and is widely distributed in the Eastern Ocean region, particularly in southern China and northern India. The parasitization rate of this parasitic wasp can reach as high as 20%, which poses a significant threat to the health of bee colonies. This study reports the results of observations of S. szaboi in Chongqing, China. Current research on the physiology and behavior of S. szaboi is limited; thus, this report provides a valuable contribution to the existing body of knowledge on this type of parasitic wasp. Consequently, during the summers of 2023 and 2024, we observed the physiological and behavioral characteristics of S. szaboi and their hosts in the field at the Bee Breeding Center of Chongqing, along with additional incubated observations conducted in the laboratory.

Afrotropical Centistidea Rohwer, 1914 (Hymenoptera, Braconidae) with description of four new species.

The braconid parasitoid wasp genus Centistidea Rohwer, 1914 is revised for the Afrotropical region, with four new species described; Centistideaareolaris Liu & Polaszek, sp. nov., C.linearis Liu & Polaszek, sp. nov., C.longipedes Liu & Polaszek, sp. nov., and C.turneri Liu & Polaszek, sp. nov. are described based on specimens from the Natural History Museum, United Kingdom, and the Royal Museum for Central Africa, Belgium. An illustrated key to species in the Afrotropical region is provided.

Hymenopterous parasitoids of the fig leaf roller moth, Phycodes radiata (Ochsenheimer, 1808) (Lepidoptera: Brachodidae) in Iran

ABSTRACT The fig leaf roller (FLR), Phycodes radiata (Ochsenheimer, 1808) (Lepidoptera: Brachodidae), is an Oriental defoliator pest of Ficus spp. In the Oriental region, only two parasitic wasps, belonging to the Chalcididae and Eulophidae (Hymenoptera) families have been identified as natural enemies of FLR. Therefore, attempts are being made to discover parasitoids for biological control in Iran. In the laboratory condition (25 ± 1°C, 50%RH), two parasitoid species were successfully reared from FLR pupae. A chalcid species, Psilochalcis ceratoniae Delvare, 2011 (Hymenoptera: Chalcididae) was obtained for the first time on FLR, previously known to parasitise the carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae). Additionally, an ichneumonid species, Goryphus nursei (Cameron, 1907) (Hymenoptera: Ichneumonidae), was also recorded parasitising FLR for the first time. These newly discovered associations bring the total count of parasitoids of FLR to four species from three different families.

Host adaptability of Microplitis manilae (Hymenoptera: Braconidae) in Noctuidae.

Biological control is an effective and sustainable method of integrated pest management. Microplitis manilae (Hymenoptera: Braconidae) is a common internal parasitoid wasp of the order Lepidoptera. To determine a suitable host species for the reproduction of parasitoids, it is essential to assess host suitability and parasitic potential of the parasitized pests. Herein, we investigated host selection and exploitation of M. manilae. We evaluated the parasitic efficacy of M. manilae in 4 pest species in the Spodoptera and Mythimna genera of the Noctuidae family. The results indicated that the parasitism rate of M. manilae on 3 species in the Spodoptera genus is higher than on Mythimna separata in the Mythimna genus, with M. manilae exhibiting a higher parasitism rate and shorter development duration on Spodoptera litura compared to other species. The parasitism rate for 1st instars hosts was 86.67 ± 0.04%, while the development duration was 14.1 ± 0.03 days. However, when parasitizing the 3rd instar of Spodoptera frugiperda, parasitoids showed a higher sex ratio, of 0.71 ± 0.05. Additionally, M. manilae had parasitic effect on M. separata, providing a new choice for its parasitism. The results identify the optimal host, which could enhance and reproduction rate and survival rate of M. manilae, thus facilitating their large-scale propagation. Understanding the parasitic effects of M. manilae on pests can further its field application, also plays a major role in promoting the development of biological control technologies and sustainable agricultural production.

Three new species of parasitoid wasps of the genus Mnioes Townes, 1946 (Ichneumonidae: Banchinae) in a humid forest in Peru

Mnioes is a predominantly Neotropical genus of Banchinae (Ichneumonidae), currently including 26 species. Three new species of Mnioes are described, found in a humid montane forest in southern Peru, M. chunka sp. nov, M. chusaq sp. nov. and M. isqun sp. nov, and the male of M. huk Alvarado 2020 is also described. DNA barcoding for all the species treated here is included and provides information to match females with males, especially for M. chunka sp. nov., M. chusaq sp. nov., and M. soqta Alvarado 2020 where females are similar to each other and occur in sympatry. Additionally, an updated key to the Peruvian species is provided.

Anomalous latitudinal gradients in parasitoid wasp diversity-Hotspots in regions with larger temperature range.

Knowledge of global patterns of genetic diversity is essential for biodiversity conservation as this parameter describes the ability of a species to respond to environmental changes. Ichneumonoids parasitoid wasps are among the few taxa showing an anomalous latitudinal diversity gradient. Using the largest georeferenced molecular dataset for this group, we used a macrogenetics approach to examine latitudinal patterns and predictors of intraspecific genetic diversity. We calculated the mean nucleotide diversity of mitochondrial DNA barcode sequences at three geographic levels: grid cells, latitudinal bands and climatic zones. Nucleotide diversity values were consistently higher at northern temperate latitudes, peaking at 50°. We found a positive but weak relationship between intraspecific diversity and the latitude, between intra- and interspecific diversity, and a positive effect of the temperature range. Examining the spatial relationship between different levels of biodiversity and its drivers is particularly relevant considering climate change and its impact on species distribution. Yet, in insects, it has been challenging to integrate ecological, evolutionary and geographical components when analysing the processes leading to species richness gradients.

Identification and Occurrence of the Dominant Parasitic Wasp Therophilus festivus of Larval Grapholita molesta

The oriental fruit moth, Grapholita molesta, is one of the most destructive orchard pests worldwide. Due to its behavior of boring into twigs and fruits, controlling the pest at the larval stage using insecticides is challenging. We studied the enemy species at the larval stage of G. molesta from seven fruit-growing areas by sampling peach shoots and fruits bored by its larvae. The occurrence and biological characteristics of the dominant enemy were verified using field investigation and laboratory experiments. The results showed that the dominant enemy species of larval G. molesta was identified as Therophilus festivus. The larval, cocoon, and pupal stages of T. festivus could not survive at 35 °C. The developmental durations of these three stages at 20 °C were significantly longer than those at 25 °C and 28 °C. Consecutive years of investigation in Xinxiang, China, indicated that T. festivus can parasitize G. molesta larvae collected at each generation. The parasitism rates in June (45.16%), July (63.50%), and August (48.37%) were significantly higher than those in April (15.27%). Most field research in China has focused on the release of parasitoids to control G. molesta eggs. Our study establishes a foundation for the control of G. molesta larvae using T. festivus.

Characterizing virulence differences in a parasitoid wasp through comparative transcriptomic and proteomic

BackgroundTwo strains of the endoparasitoid Cotesia typhae (Hymenoptera: Braconidae) present a differential parasitism success on the host, Sesamia nonagrioides (Lepidoptera: Noctuidae). One is virulent on both permissive and resistant host populations, and the other only on the permissive host. This interaction provides a very interesting frame for studying virulence factors. Here, we used a combination of comparative transcriptomic and proteomic analyses to unravel the molecular basis underlying virulence differences between the strains.ResultsFirst, we report that virulence genes are mostly expressed during the pupal stage 24 h before adult emergence of the parasitoid. Especially, 55 proviral genes are up-regulated at this stage, while their expression is only expected in the host. Parasitoid gene expression in the host increases from 24 to 96 h post-parasitism, revealing the expression of 54 proviral genes at early parasitism stage and the active participation of teratocytes to the parasitism success at the late stage. Secondly, comparison between strains reveals differences in venom composition, with 12 proteins showing differential abundance. Proviral expression in the host displays a strong temporal variability, along with differential patterns between strains. Notably, a subset of proviral genes including protein-tyrosine phosphatases is specifically over-expressed in the resistant host parasitized by the less virulent strain, 24 h after parasitism. This result particularly hints at host modulation of proviral expression. Combining proteomic and transcriptomic data at various stages, we identified 8 candidate genes to support the difference in reproductive success of the two strains, one proviral and 7 venom genes, one of them being also produced within the host by the teratocytes.ConclusionsThis study sheds light on the temporal expression of virulence factors of Cotesia typhae, both in the host and in the parasitoid. It also identifies potential molecular candidates driving differences in parasitism success between two strains. Together, those findings provide a path for further exploration of virulence mechanisms in parasitoid wasps, and offer insights into host-parasitoid coevolution.

Identification and validation of reference genes for RT-qPCR analysis in Sclerodermus guani (Hymenoptera: Bethylidae).

Gene expression studies in organisms are often conducted using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), and the accuracy of RT-qPCR results relies on the stability of reference genes. We examined ten candidate reference genes in Sclerodermus guani, a parasitoid wasp that is a natural enemy of long-horned beetle pests in forestry, including ACT, EF1α, Hsc70, Hsp70, SRSF7, α-tubulin, RPL7A, 18S, 28S, and SOD1, regarding variable biotic and abiotic factors such as body part, life stage, hormone, diet, and temperature. Data were analysed using four dedicated algorithms (ΔCt, BestKeeper, NormFinder, and geNorm) and one comparative tool (RefFinder). Our results showed that the most stable reference genes were RPL7A and EF1α regarding the body part, SRSF7 and Hsc70 regarding the diet, RPL7A and α-tubulin regarding the hormone, SRSF7 and RPL7A regarding the life stage, and SRSF7 and α-tubulin regarding temperature. To ascertain the applicability of specific reference genes, the expression level of the target gene (ACPase) was estimated regarding the body part using the most stable reference genes, RPL7A and EF1α, and the least stable one, SOD1. The highest expression level of ACPase was observed in the abdomen, and the validity of RPL7A and EF1α was confirmed. This study provides, for the first time, an extensive list of reliable reference genes for molecular biology studies in S. guani.

Evaluating the effects of short-term low temperature on the growth and development of Trichopria drosophilae based on the age–stage two-sex life table

BackgroundThe effects of low temperatures on parasitic wasps are crucial for maintaining farmland biodiversity and enhancing biological control, especially given the implications of global warming and frequent extreme cold events.MethodsWe studied the effects of different low temperatures (−8 ± 1 °C, −4 ± 1 °C, 0 ± 1 °C, 4 ± 1 °C, and 8 ± 1 °C) on the mating frequency and duration of male adults of Trichopria drosophilae and the number of pupae beaten by female adults, and constructed the age–stage two-sex life table of T. drosophilae.ResultsThis study found that male T. drosophilae adults exposed to low temperatures for 12 h significantly altered their mating behavior, peaking between 15:00 and 17:00. As the temperature dropped during the exposure, both the mating frequency of T. drosophilae and the duration of pupal beating were affected. The survival rate of female adults dropped from 39.55% at 8 °C to just 21.17% at −8 °C. Low-temperature treatment shortened the development period and lifespan for T. drosophilae adults. They developed 4.71 days faster and had a total lifespan that was 10.66 days shorter than those in the control group after being exposed to −8 °C. Furthermore, the average number of eggs laid by females at −8 °C was 4.46 less than that at 8 °C and 6.16 less than that in the control group, which laid an average of 21.55 eggs. The net reproductive rate (R0) of T. drosophilae decreased with lower temperatures, reaching a low of 23.64 at −8 °C. Conversely, the intrinsic growth rate (rm) actually increased as temperatures dropped, with the lowest value being 0.21 at −8 °C.ConclusionsThe findings indicate that short-term exposure to low temperatures hampers the growth and population increase of T. drosophilae, thereby reducing their effectiveness as biological control agents.Graphical

The Cocoon of the Developing Emerald Jewel Wasp (Ampulex compressa) Resists Cannibalistic Predation of the Zombified Host

Introduction: To reproduce, the parasitoid emerald jewel wasp (Ampulex compressa) envenomates an American cockroach (Periplaneta americana) and barricades it in a hole with an egg on the host’s leg. The larval wasp feeds externally before entering the host and consuming internal organs before forming a cocoon inside the host carcass. Methods: The vulnerability of jewel wasp larvae to predation by juvenile cockroaches was investigated, and data were recorded with time-lapse videography. Results: Cockroaches were found to be predators of parasitized hosts. When parasitized cockroaches were exposed to hungry cockroaches on days 0–8 of development, the developing larva was killed. Eggs were dislodged or consumed, larvae on the leg were eaten, and larvae inside the host were eaten along with the host. On day 9, 80% of the wasp larvae were killed and eaten along with the host. Conversely, on day 10, 90% of the larvae survived. On developmental day 11 or later, the wasp larva always survived, although the host carcass was consumed. Survival depended entirely on whether the cocoon had been completed. Conclusion: The results highlight the vulnerability of larvae to predation and suggest the cocoon defends from insect mandibles. This may explain the unusual feeding behavior of the jewel wasp larvae, which eat the host with remarkable speed, tapping into the host respiratory system in the process, and consuming vital organs early, in contrast to many other parasitoids. Results are discussed in relation to larval wasp behavior, evolution, and development, and potential predators are considered.

Infection with pathogenic fungi is a major threat to the mass production of the parasitoid wasp Habrobracon hebetor: 20 generations under surveillance

Pathogen infection is one of the most important challenges threatening the success of mass rearing of natural enemies either in insectaries or in augmentative biological control programs. In this investigation, we studied the biological and population growth parameters of a naturally infected colony of the parasitoid wasp Habrobracon hebetor (Say) (Hymenoptera: Braconidae) over 20 generations (G1inf − G20inf) of rearing on Ephestia kuehniella (Zeller) (Pyralidae: Lepidoptera) under laboratory conditions. Based on morphological characteristics and ITS sequences, two types of fungal colonies were isolated from the diseased females and identified as Thermothielavioides terrestris and Aspergillus flavus. The results showed that although no significant differences were found in the female longevity and fecundity of H. hebetor on E. kuehniella up to G15inf, the duration of the immature period was extended as the number of generations increased. In addition, the intrinsic rate of increase (r) and finite rate of increase (λ) had no significant differences up to G8inf. The net reproductive rate (R0) of G15inf had no significant differences with G2inf, G8inf, and G10inf. On the other hand, in G15inf, R0 was significantly higher than G4inf, G6inf, and G20inf. The findings underscore the negative impact of fungal infection on population growth parameters compared with uninfected population. This study showed that naturally fungal infection of the parasitoid affected the population growth and life table parameters through mass rearing, compared and discussed with the healthy parasitoid.