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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., Competing Interests: The authors declare no conflict of interest., (Copyright: © 2024 Falcon-Brindis, Villanueva. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Different factitious hosts were used to mass rear Trichogramma japonicum Ashmead in different parts of the globe because thorough details were lacking in both the laboratory and the field. The objective of this study was to compare, parasitoid, T. japonicum reared in different factitious hosts. Three commonly used factitious host eggs, Corcyra cephalonica (Stainton), Ephestia kuehniella Zeller and Sitotroga cerealella Olivier were tested under laboratory conditions and then in the field over a yellow stem borer, Scirpophaga incertulus (Walker) of rice. The highest parasitism by T. japonicum was observed on E. kuehniella eggs. The parasitoid's highest emergence (88.99%) was observed on S. cerealella eggs at 24 h exposure, whereas at 48 h it was on E. kuehniella eggs (94.66%). Trichogramma japonicum females that emerged from E. kuehniella eggs were significantly long-lived. The days of oviposition by hosts and the host species were significant individually, but not their interaction. Higher proportions of flying T. japonicum were observed when reared on E. kuehniella and C. cephalonica eggs. Field results showed that T. japonicum mass-reared on E. kuehniella showed higher parasitism of its natural host, S. incertulus eggs. Hence, by considering these biological characteristics and field results, E. kuehniella could be leveraged for the mass rearing of quality parasitoids of T. japonicum in India, the Asian continent and beyond., Competing Interests: The authors have declared that no competing interests exist.

Entomopathogenic nematodes (EPNs) have been successfully applied as biological control agents against above ground and soil stages of insect pests. However, for commercial application, it is crucial to mass culture these nematodes using in vitro liquid culture technology, as it is not attainable when using susceptible insects as hosts. Lobesia vanillana (Lepidoptera: Tortricidae) is regarded a sporadic pest of wine grapes in South Africa. The in vivo- and in vitro-cultured South African EPNs, Steinernema yirgalemense and Steinernema jeffreyense (Rhabditida: Steinernematidae), were evaluated against larvae and pupae of L. vanillana in laboratory bioassays. For larvae, high mortality was observed for all treatments: In vitro-cultured S. yirgalemense (98%) performed better than S. jeffreyense (73%), while within in vivo cultures, there was no difference between nematode species (both 83%). No significant difference was detected between in vivo- and in vitro cultures of the same nematode species. The LD50 of the in vitro-cultured S. yirgalemense, was 7.33 nematodes per larva. Mortality by infection was established by dissecting L. vanillana cadavers and confirming the presence of nematodes, which was > 90% for all treatments. Within in vitro cultures, both S. yirgalemense and S. jeffreyense were able to produce a new cohort of infective juveniles from L. vanillana larvae. Pupae, however, were found to be considerably less susceptible to EPN infection. This is the first study on the use of EPNs to control L. vanillana. The relative success of in vitro-cultured EPN species in laboratory assays, without any loss in pathogenicity, is encouraging for further research and development of this technology., Competing Interests: The authors have declared that no competing interests exist.

The egg parasitoid Trichogramma evanescens Westwood is considered as an efficient biological control agent for managing several lepidopteran pests and it is widely distributed throughout the world. Mass rearing protocols of parasitoids that are currently in use in biocontrol programs require a meticulous quality control plan, in order to optimize their efficacy, but also their progeny production capacity. In this paper, the effect of different factors on the quality control in mass rearing of T. evenescens, using Plodia interpunctella (Hübner) and Galleria mellonella L. as host species, were investigated. The impact of egg agewas significant in the rates of parasitism, for both host species tested. Significantly highest percent of parasitoid emergence was noticed in two day-old eggs for both host species, while one day-old eggs day exhibited the maximum emergence when both species were used togetherin the same trials. Age-dependent storage egg preservation at either 4 or 9°C significantly influenced the parasitism percentages on both species. The highest parasitism percentage was recorded in two day-old G. mellonella eggs that are kept for 15 days at 9°C while the lower in one day-old P. interpunctella eggs for 60 d storage. Moreover, the highest parasitoid mortality was recorded in T. evanescens reared either on P. interpunctella or G. mellonella at 20°C. Rearing of the parasitoid on a mixture of eggs of both host species resulted in higher parasitism, but not always in higher rates of parasitoid emergence. The results of the present work provide useful information that can be further utilized in rearing protocols of T. evanescens., Competing Interests: The authors have declared that no competing interests exist.

A new species of bethylid parasitoid wasp, Goniozus omanensis Polaszek sp. n., is described based on morphology and DNA sequence data. The species is currently known only from the lesser date moth Batrachedra amydraula, a pest of economic importance, but can be reared on two factitious host species. G. omanensis is compared with G. swirskiana, known from the same host in Israel. We summarise current knowledge of G. omanensis life-history, and its potential as an agent of biological pest control., Competing Interests: The authors have declared that no competing interests exist.

Nematode parasites rely on successful host infection to perpetuate their species. Infection by individual nematode parasites can be risky, however; any one individual could be killed by the host's immune response. Here we use a model system to show that environmental cues and parasite past experience can be used by entomopathogenic nematodes to reduce individual risk of infection. Past parasite experience can more than double the infective virulence (number of host invaders) of a given cohort of entomopathogenic nematode parasites. This plasticity in individual parasite risk-taking and associated infection can be used to manage infection of parasitic nematodes: enhancing biological control with entomopathogenic nematodes and developing behavioral and chemical strategies to reduce infection by vertebrate and plant parasitic nematodes., Competing Interests: The authors have declared that no competing interests exist.

Under predicted global climate change, species will be gradually exposed to warmer temperatures, and to a more variable climate including more intense and more frequent heatwaves. Increased climatic variability is expected to have different effects on species and ecosystems than gradual warming. A key challenge to predict the impact of climate change is to understand how temperature changes will affect species interactions. Herbivorous insects and their natural enemies belong to some of the largest groups of terrestrial animals, and thus they have a great impact on the functioning of ecosystems and on the services these ecosystems provide. Here we studied the life history traits of the plant-feeding insect Plutella xylostella and its specialist endoparasitoid Diadegma semiclausum, when exposed to a daily heat pulse of 5 or 10°C temperature increase during their entire immature phase. Growth and developmental responses differed with the amplitude of the heat pulse and they were different between host and parasitoid, indicating different thermal sensitivity of the two trophic levels. With a +5°C heat pulse, the adult parasitoids were larger which may result in a higher fitness, whereas a +10°C heat pulse retarded parasitoid development. These results show that the parasitoid is more sensitive than its host to brief intervals of temperature change, and this results in either positive or negative effects on life history traits, depending on the amplitude of the heat pulse. These findings suggest that more extreme fluctuations may disrupt host-parasitoid synchrony, whereas moderate fluctuations may improve parasitoid fitness.

In this study we assessed the relationship between the laboratory and field performance of different isofemale lines of Trichogramma pretiosum Riley. In comparative assays, we used three rare mitochondrial haplotypes as genetic markers of the isofemale lines, and by introgressing these mitochondrial haplotypes into each of 15 genetically different nuclear lines, also tested the assumption that mitochondria are neutral markers. In a laboratory trial, 45 isofemale lines (15 nuclear genotypes x three mitochondrial haplotypes) were ranked in three categories (best, intermediate and worst) according to the mean offspring production and the proportion of female offspring. Subsequently, lines from each of the three categories were selected for field releases to quantify field parasitism on Ephestia kuehniella. Temporally separate releases were done in a transgenic Bt cornfield, with four plots, each with 50 points of recapture. The points of recapture consisted of trap cards with eggs of E. kuehniella collected daily. The trap cards were maintained in the laboratory at 25°C until the adult wasps emerged, and the maternal identity of the wasps was determined using qPCR and high-resolution melt curve analysis to determine the mitochondrial haplotype. The results showed that these measures of laboratory performance (fecundity and offspring sex ratio) were good predictors of field success in T. pretiosum. We also report strong evidence discrediting the assumption that mitochondria are neutral, in view of the correlation between performance and mitochondrial haplotype.

Entomopathogenic nematodes have been classified into cruisers (active searchers) and ambushers (sit and wait foragers). However, little is known about their dispersal and foraging behavior at population level in soil. We studied lateral dispersal of the ambush foraging Steinernema carpocapsae (ALL strain) and cruise foraging Heterorhabditis bacteriophora (GPS11 strain) from infected host cadavers in microcosms (0.05 m2) containing Wooster silt-loam soil (Oxyaquic fragiudalf) and vegetation in the presence or absence of non-mobile and mobile hosts. Results showed that the presence of a non-mobile host (Galleria mellonella larva in a wire mesh cage) enhanced H. bacteriophora dispersal for up to 24 hr compared with no-host treatment, but had no impact on S. carpocapsae dispersal. In contrast, presence of a mobile host (G. mellonella larvae) increased dispersal of S. carpocapsae compared with no host treatment, but had no effect on H. bacteriophora dispersal. Also H. bacteriophora was better at infecting non-mobile than mobile hosts released into the microcosms and S. carpocapsae was better at infecting mobile than non-mobile hosts, thus affirming the established cruiser-ambusher theory. However, results also revealed that a large proportion of infective juveniles (IJs) of both species stayed near (≤ 3.8 cm) the source cadaver (88-96% S. carpocapsae; 67-79% H. bacteriophora), and the proportion of IJs reaching the farthest distance (11.4 cm) was significantly higher for S. carpocapsae (1.4%) than H. bacteriophora (0.4%) in the presence of mobile hosts. S. carpocapsae also had higher average population displacement than H. bacteriophora in the presence of both the non-mobile (5.07 vs. 3.6 cm/day) and mobile (8.06 vs. 5.3 cm/day) hosts. We conclude that the two species differ in their dispersal and foraging behavior at the population level and this behavior is affected by both the presence and absence of hosts and by their mobility.

The light brown apple moth, Epiphyas postvittana is a key pest of wine grapes in Australia. Two parasitoids, Dolichogenidea tasmanica and Therophilus unimaculatus, attack the larval stage of this pest. D. tasmanica is dominant in vineyards, whereas T. unimaculatus is mainly active in native vegetation. We sought to understand why they differ in their use of habitats. Plants are a major component of habitats of parasitoids, and herbivore-infested plants influence parasitoid foraging efficiency by their architecture and emission of volatile chemicals. We investigated how different plant species infested by E. postvittana could affect the foraging success of the two parasitoid species in both laboratory and field experiments. Four common host-plant species were selected for this study. In paired-choice experiments to determine the innate foraging preferences for plants, both parasitoid species showed differences in innate search preferences among plant species. The plant preference of D. tasmanica was altered by oviposition experience with hosts that were feeding on other plant species. In a behavioral assay, the two parasitoid species allocated their times engaged in various types of behavior differently when foraging on different plant species. For both parasitoids, parasitism on Hardenbergia violacea was the highest of the four plant species. Significantly more larvae dropped from Myoporum insulare when attacked than from the other three host-plant species, which indicates that parasitism is also affected by interactions between plants and host insects. In vineyards, parasitism by D. tasmanica was significantly lower on M. insulare than on the other three host-plant species, but the parasitism rates were similar among the other three plant species. Our results indicate that plants play a role in the habitat preferences of these two parasitoid species by influencing their foraging behavior, and are likely to contribute to their distributions among habitats.

The increased use of molecular tools for species identification in recent decades revealed that each of many apparently generalist parasitoids are actually a complex of morphologically similar congeners, most of which have a rather narrow host range. Ooencyrtus pityocampae (OP), an important egg parasitoid of the pine processionary moth (PPM), is considered a generalist parasitoid. OP emerges from PPM eggs after winter hibernation, mainly in spring and early summer, long before the eggs of the next PPM generation occurs. The occurrence of OP in eggs of the variegated caper bug (CB) Stenozygum coloratum in spring and summer suggests that OP populations alternate seasonally between PPM and CB. However, the identity of OP population on CB eggs seemed uncertain; unlike OP-PPM populations, the former displayed apparently high male/female ratios and lack of attraction to the PPM sex pheromone. We studied the molecular identities of the two populations since the morphological identification of the genus Ooencyrtus, and OP in particular, is difficult. Sequencing of COI and ITS2 DNA fragments and AFLP analysis of individuals from both hosts revealed no apparent differences between the OP-PPM and the OP-CB populations for both the Israeli and the Turkish OPs, which therefore supported the possibility of host alternation. Sequencing data extended our knowledge of the genetic structure of OP populations in the Mediterranean area, and revealed clear separation between East and West Mediterranean populations. The overall level of genetic diversity was rather small, with the Israeli population much less diverse than all others; possible explanations for this finding are discussed. The findings support the possibility of utilizing the CB and other hosts for enhancing biological control of the PPM.

Entomopathogenic nematodes (EPNs) are small worms whose ecological behaviour consists to invade, kill insects and feed on their cadavers thanks to a species-specific symbiotic bacterium belonging to any of the genera Xenorhabdus or Photorhabdus hosted in the gastro-intestinal tract of EPNs. The symbiont provides a number of biological functions that are essential for its EPN host including the production of entomotoxins, of enzymes able to degrade the insect constitutive macromolecules and of antimicrobial compounds able to prevent the growth of competitors in the insect cadaver. The question addressed in this study was to investigate whether a mammalian pathogen taxonomically related to Xenorhabdus was able to substitute for or "hijack" the symbiotic relationship associating Xenorhabdus and Steinernema EPNs. To deal with this question, a laboratory experimental model was developed consisting in Galleria mellonella insect larvae, Steinernema EPNs with or without their natural Xenorhabdus symbiont and Yersinia pseudotuberculosis brought artificially either in the gut of EPNs or in the haemocoel of the insect larva prior to infection. The developed model demonstrated the capacity of EPNs to act as an efficient reservoir ensuring exponential multiplication, maintenance and dissemination of Y. pseudotuberculosis.

To combat parasitism hosts often rely on their immune system, which is the last line of defense. However, the immune system may not always be effective, and other non-immunological defenses might be favored to reduce the cost of parasite infection. Here we report that larvae of the moth Lobesia botrana can rapidly accelerate their development and reach maturity earlier in response to cues perceived at a distance from parasitoids. Such a phenotypically plastic life history shift, induced by the perception of deadly enemies in the environment, is likely to be an adaptive defensive strategy to prevent parasitoid attack, and has important implications in host-parasite dynamics.

Tachinid flies are natural enemies of many lepidopteran and coleopteran pests of forests, crops, and fruit trees. In order to address the lack of genetic data in this economically important group, we sequenced the complete mitochondrial genome of the Palaearctic tachinid fly Elodia flavipalpis Aldrich, 1933. Usually found in Northern China and Japan, this species is one of the primary natural enemies of the leaf-roller moths (Tortricidae), which are major pests of various fruit trees. The 14,932-bp mitochondrial genome was typical of Diptera, with 13 protein-coding genes, 22 tRNA genes, and 2 rRNA genes. However, its control region is only 105 bp in length, which is the shortest found so far in flies. In order to estimate dipteran evolutionary relationships, we conducted a phylogenetic analysis of 58 mitochondrial genomes from 23 families. Maximum-likelihood and Bayesian methods supported the monophyly of both Tachinidae and superfamily Oestroidea. Within the subsection Calyptratae, Muscidae was inferred as the sister group to Oestroidea. Within Oestroidea, Calliphoridae and Sarcophagidae formed a sister clade to Oestridae and Tachinidae. Using a Bayesian relaxed clock calibrated with fossil data, we estimated that Tachinidae originated in the middle Eocene.

Heat shock proteins (Hsps) play important roles in the environmental adaptation of various organisms. To explore the functions of Hsps in relation to heat stress and development in Cotesia vestalis, a solitary larval endoparasitoid of Plutella xylostella, four heat shock protein genes, CvHsp40, CvHsc70, CvHsp70 and CvHsp90, were cloned and sequenced from C. vestalis by real-time quantitative PCR and RACE. The cDNA sequence of CvHsp40, CvHsc70, CvHsp70 and CvHsp90 were 1473 bp, 2316 bp, 2279 bp and 2663 bp long, which encode proteins with calculated molecular weights (MW) of 39.1 kDa, 71.2 kDa, 70.1 kDa and 83.3 kDa, respectively. Furthermore, the analysis of genomic DNA confirmed that no introns existed in CvHsp40, CvHsp70 and CvHsp90 while two introns were present in CvHsc70. The amino acid sequence analysis of CvHsps indicated that CvHsp40 is a Type II Hsp40 homolog, CvHsp70 and CvHsc70 are the eukaryotic cytoplasmic Hsp70s, and CvHsp90 is the β-isoform of Hsp90. The divergent transcriptional patterns of CvHsp40, CvHsp70 and CvHsp90 in the different developmental stages suggested that CvHsp transcripts were under different mechanisms of regulation during the development of parasitoid larvae. The dramatic increase of transcripts of CvHsp70 at the third-instar larva coincided with its developmental change in this stage, that is, from inside host to outside host. CvHsp40, CvHsc70 and CvHsp70 showed a trend of sex-specific differences of transcript abundance in the adult stage. All CvHsp transcripts in different developmental stages were significantly induced by heat stress, and the lowest transcript abundances appeared around the temperature 27°C, which probably suggest that this is the most favorable temperature for the development of C. vestalis. Our results suggest that the expression of heat shock proteins reflects to some extent the developmental changes and environmental requirements of insects.

Organisms are attacked by different natural enemies present in their habitat. While enemies such as parasitoids and predators will kill their hosts/preys when they successfully attack them, enemies such as micropredators will not entirely consume their prey. However, they can still have important consequences on the performance and ecology of the prey, such as reduced growth, increased emigration, disease transmission. In this paper, we investigated the impact of a terrestrial micropredator, the yellow fever mosquito Aedes aegypti, on its unusual invertebrate host, the Egyptian cotton leaf worm, Spodoptera littoralis. Larvae developing in presence of mosquitoes showed a slower development and reached a smaller pupal weight when compared to a control without mosquitoes, apparently because of a reduced feeding time for larvae. In addition, larvae tended to leave the plant in presence of mosquitoes.These results suggest that mosquitoes act as micropredators and affects lepidopteran larvae behaviour and development. Ecological impacts such as higher risks of food depletion and longer exposure to natural enemies are likely to be costly consequences. The importance of this phenomenon in nature - the possible function as last resort when vertebrates are unavailable - and the evolutionary aspects are discussed.

Background: Ophiocordyceps sinensis (syn. Cordyceps sinensis), which is a parasite of caterpillars and is endemic to alpine regions on the Tibetan Plateau, is one of the most valuable medicinal fungi in the world. "Natural O. sinensis specimens" harbor various other fungi. Several of these other fungi that have been isolated from natural O. sinensis specimens have similar chemical components and/or pharmaceutical effects as O. sinensis. Nevertheless, the mycobiota of natural O. sinensis specimens has not been investigated in detail., Methodology/principal Findings: Based on the technique of PCR-single-strand conformation polymorphism (PCR-SSCP), the mycobiota of three different sections (stromata, sclerotia, and mycelial cortices) from natural O. sinensis specimens were investigated using both culture-dependent and -independent methods. For the culture-dependent method, 572 fungal strains were isolated, and 92 putative operational taxonomic units (OTUs) were identified from 226 sequenced strains with the threshold of 97%. For the culture-independent method, 490 fungal clones were identified from about 3000 clones of ITS fragments from the whole-community DNA; based on PCR-SSCP analyses, 266 of these clones were selected to be sequenced, and 118 putative OTUs were detected. The overwhelming majority of isolates/clones and OTUs were detected from mycelial cortices; only a few were detected from stromata and sclerotia. The most common OTUs detected with both methods belonged to Ascomycota; however, only 13 OTUs were detected simultaneously by both methods. Potential novel lineages were detected by each of the two methods., Conclusions/significance: A great number of fungal species present in the mycobiota of naturally-occurring O. sinensis specimens were detected, and many of them may represent undescribed lineages. That only a few of the same OTUs were detected by both methods indicated that different methods should be used. This study increased our understanding about the fungal community structure of this valuable medicinal herb.

Self-medication is a specific therapeutic behavioral change in response to disease or parasitism. The empirical literature on self-medication has so far focused entirely on identifying cases of self-medication in which particular behaviors are linked to therapeutic outcomes. In this study, we frame self-medication in the broader realm of adaptive plasticity, which provides several testable predictions for verifying self-medication and advancing its conceptual significance. First, self-medication behavior should improve the fitness of animals infected by parasites or pathogens. Second, self-medication behavior in the absence of infection should decrease fitness. Third, infection should induce self-medication behavior. The few rigorous studies of self-medication in non-human animals have not used this theoretical framework and thus have not tested fitness costs of self-medication in the absence of disease or parasitism. Here we use manipulative experiments to test these predictions with the foraging behavior of woolly bear caterpillars (Grammia incorrupta; Lepidoptera: Arctiidae) in response to their lethal endoparasites (tachinid flies). Our experiments show that the ingestion of plant toxins called pyrrolizidine alkaloids improves the survival of parasitized caterpillars by conferring resistance against tachinid flies. Consistent with theoretical prediction, excessive ingestion of these toxins reduces the survival of unparasitized caterpillars. Parasitized caterpillars are more likely than unparasitized caterpillars to specifically ingest large amounts of pyrrolizidine alkaloids. This case challenges the conventional view that self-medication behavior is restricted to animals with advanced cognitive abilities, such as primates, and empowers the science of self-medication by placing it in the domain of adaptive plasticity theory.

The ecological safety of transgenic insecticidal plants expressing crystal proteins (Cry toxins) from the bacterium Bacillus thuringiensis (Bt) continues to be debated. Much of the debate has focused on nontarget organisms, especially predators and parasitoids that help control populations of pest insects in many crops. Although many studies have been conducted on predators, few reports have examined parasitoids but some of them have reported negative impacts. None of the previous reports were able to clearly characterize the cause of the negative impact. In order to provide a critical assessment, we used a novel paradigm consisting of a strain of the insect pest, Plutella xylostella (herbivore), resistant to Cry1C and allowed it to feed on Bt plants and then become parasitized by Diadegma insulare, an important endoparasitoid of P. xylostella. Our results indicated that the parasitoid was exposed to a biologically active form of the Cy1C protein while in the host but was not harmed by such exposure. Parallel studies conducted with several commonly used insecticides indicated they significantly reduced parasitism rates on strains of P. xylostella resistant to these insecticides. These results provide the first clear evidence of the lack of hazard to a parasitoid by a Bt plant, compared to traditional insecticides, and describe a test to rigorously evaluate the risks Bt plants pose to predators and parasitoids.