Explore the vast range of titles available.

Pathogens are known to manipulate the reproduction and development of their hosts for their own benefit. Wolbachia is an endosymbiotic bacterium that infects a wide range of insect species. Wolbachia is known as an example of a parasite that manipulates the sex of its host's progeny. Infection of Ostrinia moths by Wolbachia causes the production of all-female progeny, however, the mechanism of how Wolbachia accomplishes this male-specific killing is unknown. Here we show for the first time that Wolbachia targets the host masculinizing gene of Ostrinia to accomplish male-killing. We found that Wolbachia-infected O. furnacalis embryos do not express the male-specific splice variant of doublesex, a gene which acts at the downstream end of the sex differentiation cascade, throughout embryonic development. Transcriptome analysis revealed that Wolbachia infection markedly reduces the mRNA level of Masc, a gene that encodes a protein required for both masculinization and dosage compensation in the silkworm Bombyx mori. Detailed bioinformatic analysis also elucidated that dosage compensation of Z-linked genes fails in Wolbachia-infected O. furnacalis embryos, a phenomenon that is extremely similar to that observed in Masc mRNA-depleted male embryos of B. mori. Finally, injection of in vitro transcribed Masc cRNA into Wolbachia-infected embryos rescued male progeny. Our results show that Wolbachia-induced male-killing is caused by a failure of dosage compensation via repression of the host masculinizing gene. Our study also shows a novel strategy by which a pathogen hijacks the host sex determination cascade.

Pest management on hemp is still in its infancy, and biological control options are limited. Helicoverpa zea (corn earworm) is one of the key pests of hemp cultivated outdoors, especially on cultivars grown for cannabinoids and grain. In a three-year study, we assessed the effect of diet on the performance of H . zea and its tachinid parasitoids. Parasitized (bearing fly eggs) and unparasitized (without eggs) H . zea larvae were fed on hemp flowers or an artificial diet. Five tachinid species parasitized H . zea larvae, but the most abundant species were Winthemia rufopicta (68.8%) and Lespesia aletiae (28.3%). Overall, 55.2% of H . zea larvae bearing tachinid eggs died, while the mortality of unparasitized larvae reached 24.7%. The success of tachinids increased by 2-fold when the host larvae were fed on an artificial diet. Our results demonstrated that high protein food (artificial diet), intensity of parasitism, and caterpillar size play a role in the fitness of both the herbivores ( H . zea ) and its tachinid parasitoids. These findings have important implications for understanding biological control mechanisms and open new insights into the impact of landscape variation on plant-herbivore-parasitoid interactions. This study contains supporting evidence that makes both Winthemia rufopicta and Lespesia aletiae excellent candidates for biological control programs against H . zea , a key pest of hemp in the United States.

Parasitic wasps produce several factors including venom, polydnaviruses (PDVs) and specialized wasp cells named teratocytes that benefit the survival of offspring by altering the physiology of hosts. However, the underlying molecular mechanisms for the alterations remain unclear. Here we find that the teratocytes of Cotesia vestalis , an endoparasitoid of the diamondback moth Plutella xylostella , and its associated bracovirus (CvBV) can produce miRNAs and deliver the products into the host via different ways. Certain miRNAs in the parasitized host are mainly produced by teratocytes, while the expression level of miRNAs encoded by CvBV can be 100-fold greater in parasitized hosts than non-parasitized ones. We further show that one teratocyte-produced miRNA (Cve-miR-281-3p) and one CvBV-produced miRNA (Cve-miR-novel22-5p-1) arrest host growth by modulating expression of the host ecdysone receptor ( EcR ). Altogether, our results show the first evidence of cross-species regulation by miRNAs in animal parasitism and their possible function in the alteration of host physiology during parasitism. The moth Plutella xylostella during its larval stage is the host of the endoparasitic wasp Cotesia vestalis . Here the authors show that the parasitoids deliver microRNAs to their hosts through their symbiotic virus and specialized cells leading to induced developmental delay.

Parasitoids modulate host development for the survival of their offspring, but the mechanisms underlying this phenomenon remain largely unknown. Here, we found that the endoparasitoid Cotesia vestalis disrupted the larval-larval ecdysis in its host Plutella xylostella by the 20-hydroxyecdysone (20E) synthesis pathway. After parasitization by C. vestalis , the 20E peak of host larvae disappeared before the onset of ecdysis and the expression of ecdysone synthesis genes was significantly downregulated. We further found that a Cotesia vestalis bracovirus (CvBV) gene CvBV_28 − 5 was transiently high-level expressed prior to the host’s 20E peak, enabling the precise suppression of this critical developmental signal. Consistently, the knockdown of CvBV_28 − 5 affected the expression of 20E response transcription factors in the cuticle and several ecdysis-related genes. Furthermore, we found that CvBV_28 − 5 bound directly to the Raf, a MAP3K member of the MAPK pathwaythat functions as a critical regulator of ecdysone synthesis genes in hosts. Collectively, our results provide the first evidence that parasitoids modulate host ecdysis by affecting MAPK-20E signaling during a defined developmental window and provide novel insights into the mechanism of parasitoid regulation of host development.

Some DNA viruses infect host animals usually by integrating their DNAs into the host genome. However, the mechanisms for integration remain largely unknown. Here, we find that Cotesia vestalis bracovirus (CvBV), a polydnavirus of the parasitic wasp C . vestalis (Haliday), integrates its DNA circles into host Plutella xylostella (L.) genome by two distinct strategies, conservatively and randomly, through high-throughput sequencing analysis. We confirmed that the conservatively integrating circles contain an essential “8+5” nucleotides motif which is required for integration. Then we find CvBV circles are integrated into the caterpillar’s genome in three temporal patterns, the early, mid and late stage-integration. We further identify that three CvBV-encoded integrases are responsible for some, but not all of the virus circle integrations, indeed they mainly participate in the processes of early stage-integration. Strikingly, we find two P . xylostella retroviral integrases (PxIN1 and PxIN2) are highly induced upon wasp parasitism, and PxIN1 is crucial for integration of some other early-integrated CvBV circles, such as CvBV_04, CvBV_12 and CvBV_24, while PxIN2 is important for integration of a late-integrated CvBV circle, CvBV_21. Our data uncover a novel mechanism in which CvBV integrates into the infected host genome, not only by utilizing its own integrases, but also by recruiting host enzymes. These findings will strongly deepen our understanding of how bracoviruses regulate and integrate into their hosts.

Trichogramma chilonis (Ishii) is an important egg parasitoid of Helicoverpa species in tomato growing areas of Pakistan. Different insecticides are used for the management of H. armigera , but these insecticides have significantly reduced the effectiveness of T. chilonis . Therefore, this research aims to understand the compatibility of the selected insecticides with biological control strategies involving T. chilonis for managing Helicoverpa armigera in tomato-growing areas. For this purpose, the effects of five insecticides namely Novaluron, Bifenthrin, Emamectin Benzoate, Chlorantraniliprole and Imidacloprid were assessed against T. chilonis under laboratory conditions. The assays involved direct applications of different insecticides on Sitotroga cerealella eggs and their subsequent effect of T. chilonis life history parameters. A total of 200 eggs were used in each treatment. The results revealed that all the tested insecticides had subsequent negative effects on T. chilonis performance. The results showed that the insecticides Imidacloprid and Chlorantraniliprole led to low mean fecundity, minimum number of male and female adults emergence and prolonged the total pre-oviposition period of T. chilonis as compared to Bifenthrin and Novaluron. The bootstrap results recorded the highest value of the net reproductive rate ( R 0 ), intrinsic rate of increase ( r ) and the finite rate of increase (λ) of T. chilonis in host eggs treated with Bifenthrin and Novaluron as compared to the other tested chemicals. The results regarding percent parasitism showed that maximum percent parasitism was noted in control, Bifenthrin and Novaluron, while the insecticides Imidacloprid and Chlorantraniliprole resulted in minimum % parasitism (63.5% and 71%) respectively. The study revealed that Bifenthrin and Novaluron are relatively more compatible with the T. chilonis in the different integrated pest management programs for H. armigera as compared to other tested chemicals.

The American grape berry moth (GBM), Paralobesia viteana (Clemens) (Lepidoptera: Tortricidae) is an economically important pest of grapes. The larvae of this insect burrow inside the fruit upon hatching, consuming, and contaminating grapes and clusters. Current GBM management relies on pesticide applications, which do not offer complete protection due to the cryptic behavior of the larvae and asynchrony in egg-laying, highlighting the need to develop new management strategies. In this study, we identified GBM larval parasitoids in commercial vineyards and quantified their parasitism rates. Parasitoid samplings were conducted biweekly in six conventionally managed ‘Concord’ vineyards in Erie County, Pennsylvania, during the 2023 and 2024 growing seasons. GBM-infested samples were monitored daily to track the emergence of both parasitoids and GBM, enabling the calculation of parasitism rates. We identified eight parasitoid species: Enytus obliteratus (Cresson) (Hymenoptera: Ichneumonidae), Campoplex tortricidis (Cushman) (Hymenoptera: Ichneumonidae), Scambus spp. Hartig (Hymenoptera: Ichneumonidae), Glypta cf . depressa Dasch, Glypta cf. ohioensis Dasch, and Glypta cf. ignota Dasch (Hymenoptera: Ichneumonidae); Bracon variabilis (Provancher) (Hymenoptera: Braconidae), and Goniozus fratellus Evans (Hymenoptera: Bethylidae) preying on GBM larvae. From these, B. variabilis , E. obliteratus , and G. fratellus were the most abundant. We also designed a graphic taxonomic key to facilitate the identification of these species. The parasitoid abundance differed over the growing season but was greatest in early August, reaching parasitism rates of up to 39% and 52.1% in 2023 and 2024, respectively. Our results demonstrate that GBM has several larval parasitoids that help reduce its populations in commercial vineyards. This research represents a first step toward our understanding of the GBM native natural enemies present in the Lake Erie Region and their potential use in pest management programs.

The influence of gut and gonad bacterial communities on insect physiology, behaviour, and ecology is increasingly recognised. Parasitism by parasitoid wasps alters many physiological processes in their hosts, including gut bacterial communities. However, it remains unclear whether these changes are restricted to the gut or also occur in other tissues and fluids, and the mechanisms underlying such changes are unknown. We hypothesise that host microbiome changes result from the injection of calyx fluid (that contain symbiotic viruses known as polydnaviruses) and venom during parasitoid oviposition and that these effects vary by host tissue. To test this, we microinjected Pieris brassicae caterpillars with calyx fluid and venom from Cotesia glomerata, using saline solution and natural parasitism by C. glomerata as controls. We analysed changes in the bacterial community composition in the gut, regurgitate, haemolymph, and labial salivary glands of the host insects. Multivariate analysis revealed distinct bacterial communities across tissues and fluids, with high diversity in the salivary glands and haemolymph. Parasitism and injection of calyx fluid and venom significantly altered bacterial communities in the salivary glands. Differential abundance analysis showed that parasitism affected bacterial relative abundance in the haemolymph, and that Wolbachia was only found in the haemolymph of parasitized caterpillars. Altogether, our findings reveal that parasitism influences the host haemolymph microbiome, and both parasitism and injection of calyx fluid and venom drive changes in the bacterial community composition within the host salivary glands. Given that the composition of salivary glands can influence plant response to herbivory, we discuss these results in the broader context of plant-parasitoid interactions.

The egg parasitoid Mesocomys trabalaeYao,Yang, and Zhao is used as a biocontrol agent against the emerging defoliator pest Caligula japonica Moore in East Asia. It has been proven that the eggs of Antheraea pernyi Guérin-Méneville can be used as a factitious host for the mass production of M. trabalae. We examined the parasitic behavior and morphological characteristics of the developmental stages of M. trabalae reared on A. pernyi eggs. The parasitic behavior of M. trabalae encompasses 10 steps, involving searching, antennation, locating the oviposition site, drilling, probing, detecting, oviposition, host feeding, grooming, and resting, with the oviposition step further divided into 3 stages. We determined that the parasitoid released an egg during the second stage of the oviposition step, while her body remained in a relatively static state. Among all the steps in parasitic behavior, probing occupied the longest time, accounting for 26.33% of the entire parasitism process. It was followed by oviposition (15.88%), drilling (15.10%), antennation (13.09%), detecting (10.79%), host feeding (10.02%), and the remaining steps, each occupying less than 5.00% of the total time in steps.The pre-emergence of adult M. trabalae comprised of 4 stages: egg (0–1 day), larva (2–6 days), prepupa (7–11 days), pupa (12–20 days), followed by the development into an adult, and it usually took 20–22 days to develop from an egg into an adult at 25°C.This study advances our understanding of the biology of Mesocomys parasitoids and their mass-rearing for use in augmentation programs.

A complete three-dimensional reconstruction of the internal damage (oviposition holes, entry and exit galleries, cavities caused by fungal infection) of three destructive pests of olive fruit was obtained using micro-computed tomography. In the case of the olive fruit fly ( Bactrocera oleae ), complete reconstruction of the galleries was achieved. The galleries were colour-coded according to the size of the internal lumens produced by larval instars. In the case of the olive moth ( Prays oleae ), we confirmed that the larvae only consume olive stones, leaving pulp tissue intact. This study revealed the evolutionary defensive adaptation developed by larvae, creating entrance/exit gallery in the form of a zigzag with alternating angles to avoid the action of possible parasitoids. In the case of olive fruit rot, caused by fungal infection transmitted by the midge ( Lasioptera berlesiana ), microtomography revealed the infection cavity, which was delimited by a protective layer of tissue produced by the plant to isolate the infection zone, which contained fungal hyphae and reproductive organs of the fungus. Two ovoid cavities were observed below a single external orifice in the concave necrotic depression. These results were interpreted as successive ovipositions of B. oleae , followed by the parasitoid L. berlesiana . High-resolution 3D rendered images are included as well as supplementary videos that could be useful tools for future research and teaching aids.