Long-term suitability of an alternative host for rearing the sugarcane stalk borer parasitoid Tetrastichus howardi.

The continuous utilisation of an alternative host may influence parasitoid performance across successive generations due to conditioning in natal hosts. Tetrastichus howardi (Olliff) has successfully been reared using Tenebrio molitor L. pupae as a feasible alternative host. However, the extended rearing of T. howardi on this alternative host may impact the biological features of the parasitoids. Parasitoids were reared using T. molitor pupae for 30 consecutive generations. Quality criteria were assessed during the generations F5, F15, and F30, offering pupae of the target pest, Diatraea saccharalis (Fabr.), and compared with the F0 generation (parasitoids reared in D. saccharalis pupae). Criteria included assessments of parasitism performance, host selection, and wing form variation in the parasitoid wasps. Additionally, we examined the fecundity of T. howardi females that emerged from both hosts, considering their age, egg loading before and after one oviposition, as well as parasitism of sugarcane stalk borer pupae. Rearing T. howardi using pupae of T. molitor did not affect its biological traits or preference for the target pest for 30 generations. After parasitism, the parasitoid left the host pupa inside the stalk, and one oviposition was enough to kill D. saccharalis pupae and obtain viable parasitoid progeny. Female sexual maturation and egg loading occurred 72 and 96 h after parasitoid emergence. Egg-loading recovery after parasitism did not happen within 24 h. T. howardi can be reared for up to 30 generations using alternative hosts without compromising its parasitism performance or egg loading.

Timing of sub-lethal insecticide exposure determines parasite establishment success in an insect-helminth model.

Environmental toxicants are pervasive in nature, but sub-lethal effects on non-target organisms and their parasites are often overlooked. Particularly, studies on terrestrial hosts and their parasites exposed to agricultural toxicants are lacking. Here, we studied the effect of sequence and timing of sub-lethal exposures of the pyrethroid insecticide alpha-cypermethrin on parasite establishment using the tapeworm Hymenolepis diminuta and its intermediate insect host Tenebrio molitor as a model system. We exposed T. molitor to alpha-cypermethrin (LD20) before and after experimental H. diminuta infection and measured the establishment success of larval tapeworms. Also, we conducted in vitro studies quantifying the direct effect of the insecticide on parasite viability. Our results showed that there was no direct lethal effect of alpha-cypermethrin on H. diminuta cysticercoids at relevant concentrations (LD10 to LD90 of the intermediate host). However, we observed a significantly increased establishment of H. diminuta in beetles exposed to alpha-cypermethrin (LD20) after parasite infection. In contrast, parasite establishment was significantly lower in beetles exposed to the insecticide before parasite infection. Thus, our results indicate that environmental toxicants potentially impact host-parasite interactions in terrestrial systems, but that the outcome is context-dependent by enhancing or reducing parasite establishment depending on timing and sequence of exposure.

Tolerance of the mealworm beetle, Tenebrio molitor, to an entomopathogenic nematode, Steinernema feltiae, at two infection foci, the intestine and the hemocoel.

An entomopathogenic nematode, Steinernema feltiae K1, exhibits pathogenicity in various insect hosts, however, its virulence among the target insect species varies. Specifically, a coleopteran insect, Tenebrio molitor, is less susceptible to S. feltiae than are lepidopteran insects. We analyzed the low virulence of S. feltiae against T. molitor sequentially, in entering the gut lumen and penetrating the hemocoel, and in hemocoelic immune defenses by comparing the responses to those of a lepidopteran insect, Spodoptera exigua. Infective juveniles (IJs) of S. feltiae exhibited higher virulence and produced more progeny IJs in S. exigua than in T. molitor. The difference in IJ behavior was observed in the IJ invasion rate (IJs in gut lumen/IJs treated) after treatment, in which a lower rate was observed in T. molitor (20.4%) than in S. exigua (55.5%). Also, a lower hemocoelic penetration rate of IJs (IJs in hemocoel/IJs in gut) was observed in T. molitor (54%) than in S. exigua (74%) 24 h after feeding treatment. To investigate the immune defense in the hemocoel, insect hemolymph samples were incubated with IJs. The encapsulation behavior and phenoloxidase activity was higher in T. molitor hemolymph than in S. exigua hemolymph, which resulted in a significantly higher nematicidal activity in S. exigua. The humoral immune responses against S. feltiae were also different between the two species. The expression of two antimicrobial peptides, cecropin and attacin 1, was much higher in T. molitor. Furthermore, eicosanoid biosynthetic activity against S. feltiae was different in the two host species; sPLA2 activity was highly inducible in T. molitor but not in S. exigua. These results suggest that variability of the immune defense in the target insects, as well as in the invasion and penetration rates of IJs to the hemocoel, plays a crucial role in determining the insecticidal virulence of S. feltiae.

Hydrocarbons catalysed by TmCYP4G122 and TmCYP4G123 in Tenebrio molitor modulate the olfactory response of the parasitoid Scleroderma guani.

Hydrocarbons (HCs) present on the epicuticle of terrestrial insects are not only used to reduce water loss but are also used as chemical signals. The cytochrome p450 CYP4G gene is essential for HC biosynthesis in some insects. However, its function in Tenebrio molitor is unknown. Moreover, it is not yet known whether CYP4G of a host can modulate the searching behaviours of its parasitoid. Here, we explore the function of the TmCYP4G122 and CYP4G123 genes in T. molitor. The TmCYP4G122 and CYP4G123 transcripts could be detected in all developmental stages. Their expression was higher in the fat body and abdominal cuticle than in the gut. Their transcript levels in mature larvae under desiccation stress [relative humidity (RH) < 5%] was significantly higher than that in the control (RH = 70%). Injection of dsCYP4G122 and dsCYP4G123 caused a reduction in HC biosynthesis and was associated with increased susceptibility to desiccation. Individuals of the parasitoid Scleroderma guani that emerged from mealworm pupae showed host preference for normal pupae whereas S. guani that emerged from pupae lacking CYP4G122 or/and CYP4G123 lost this searching preference. The current results confirm that CYP4G122 and CYP4G123 regulate the biosynthesis of HCs and modulate the olfactory response of its parasitoid S. guani.

Parasitism and venom of ectoparasitoid Scleroderma guani impairs host cellular immunity.

Venom is a prominently maternal virulent factor utilized by parasitoids to overcome hosts immune defense. With respect to roles of this toxic mixture involved in manipulating hosts immunity, great interest has been mostly restricted to Ichneumonoidea parasitoids associated with polydnavirus (PDV), of which venom is usually considered as a helper component to enhance the role of PDV, and limited Chalcidoidea species. In contrast, little information is available in other parasitoids, especially ectoparasitic species not carrying PDV. The ectoparasitoid Scleroderma guani injects venom into its host, Tenebrio molitor, implying its venom was involved in suppression of hosts immune response for successful parasitism. Thus, we investigated the effects of parasitism and venom of this parasitoid on counteracting the cellular immunity of its host by examining changes of hemocyte counts, and hemocyte spreading and encapsulation ability. Total hemocyte counts were elevated in parasitized and venom-injected pupae. The spreading behavior of both granulocytes and plasmatocytes was impaired by parasitization and venom. High concentration of venom led to more severely increased hemocyte counts and suppression of hemocyte spreading. The ability of hemocyte encapsulation was inhibited by venom in vitro. In addition to immediate effects observed, venom showed persistent interference in hosts cellular immunity. These results indicate that venom alone from S. guani plays a pivotal role in blocking hosts cellular immune response, serving as a regulator that guarantees the successful development of its progenies. The findings provide a foundation for further investigation of the underlying mechanisms in immune inhibitory action of S. guani venom.

Transient anoxia during Metarhizium robertsii growth increases conidial virulence to Tenebrio molitor.

Little is known about the phenotypic effects of hypoxia and transient anoxia on the virulence of an entomopathogenic fungus. Conidia of Metarhizium robertsii were produced on: (1) potato dextrose agar medium (PDA) under normoxia; (2) PDA medium under continuous hypoxia; (3) PDA medium under transient anoxia; and (4) minimal medium with lactose (MML) under normoxia. Conidia produced under transient anoxia and produced on MML were the most virulent to Tenebrio molitor. Conidia produced under normoxia and hypoxia were the least virulent. Conidial production and germination speed of conidia produced under normoxia, hypoxia, and transient anoxia were similar; however, MML produced less conidia, but germinated faster than any other treatments.

Activity changes of antioxidant and detoxifying enzymes in Tenebrio molitor (Coleoptera: Tenebrionidae) larvae infected by the entomopathogenic nematode Heterorhabditis beicherriana (Rhabditida: Heterorhabditidae).

Entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis are lethal parasites of many insect species. To investigate defensive mechanisms towards EPNs in relation to antioxidative and detoxifying enzymes, we chose Tenebrio molitor (Coleoptera: Tenebrionidae) as experimental insect. We studied the activity changes of superoxide dismutases (SODs), peroxidases (PODs), and catalases (CATs), as well as tyrosinase (TYR), acetylcholinesterase (AChE), carboxylesterase (CarE), and glutathione S-transferase (GSTs) for 40 h in T. molitor larvae infected with Heterorhabditis beicherriana infective juveniles (IJs) at 5 rates (0, 20, 40, 80, and 160 IJs/larva). We found that when T. molitor larvae infected with H. beicherriana at higher rates (80 and 160 IJs/larva), SOD activity quickly increased to more than 70 % higher than that control levels. The activities of POD and CAT increased after 24 h. TYR activity increased slowly at lower rates of infection for 16 h, followed by a slight decrease, and then increasing from 32 to 40 h. The other detoxifying enzymes (GST, CarE, and AChE) were enhanced at lower infection rates, but were inhibited at higher rates. Our results suggested that host antioxidative response and detoxification reactions played a central role in the defensive reaction to EPNs, and that this stress which was reflected by the higher level enzymes activity contributed to the death of hosts. Further study should explore the exact function of these enzymes using different species of EPNs and investigate the links between enzyme activity and host susceptibility to EPNs.

Parasitization by Scleroderma guani influences expression of superoxide dismutase genes in Tenebrio molitor.

Superoxide dismutase (SOD) is an antioxidant enzyme involved in detoxifying reactive oxygen species. In this study, we identified genes encoding the extracellular and intracellular copper-zinc SODs (ecCuZnSOD and icCuZnSOD) and a manganese SOD (MnSOD) in the yellow mealworm beetle, Tenebrio molitor. The cDNAs for ecCuZnSOD, icCuZnSOD, and MnSOD, respectively, encode 24.55, 15.81, and 23.14 kDa polypeptides, which possess structural features typical of other insect SODs. They showed 20-94% identity to other known SOD sequences from Bombyx mori, Musca domestica, Nasonia vitripennis, Pediculus humanus corporis, and Tribolium castaneum. Expression of these genes was analyzed in selected tissues and developmental stages, and following exposure to Escherichia coli and parasitization by Scleroderma guani. We recorded expression of all three SODs in cuticle, fat body, and hemocytes and in the major developmental stages. Relatively higher expressions were detected in late-instar larvae and pupae, compared to other developmental stages. Transcriptional levels were upregulated following bacterial infection. Analysis of pupae parasitized by S. guani revealed that expression of T. molitor SOD genes was significantly induced following parasitization. We infer that these genes act in immune response and in host-parasitoid interactions.

Activity of eight strains of entomopathogenic nematodes (Rhabditida: Steinernematidae, Heterorhabditidae) against five stored product pests.

Stored product pests are responsible for losses that can amount 10% during cereal storage in the world. Aiming to find an alternative method to the chemicals used for the stored-product pests, eight strains of entomopathogenic nematodes (EPNs) were tested against five species of stored product pests. The bioassays were conducted in microtubes containing paper, inoculated with EPNs and insect diet. All the insect species were susceptible to the EPNs strains. Anagasta kuehniella and Tenebrio molitor larvae and Acanthoscelides obtectus adults were highly sensitive to the higher doses with most species and/or strains of EPNs. Adults of Sitophilus oryzae and Sitophilus zeamais were relatively less sensitive to all EPNs. Therefore, EPNs show as potential control agents for stored products pests in prophylactic applications in warehouses.

A nuptially transmitted ichthyosporean symbiont of Tenebrio molitor (Coleoptera: Tenebrionidae).

The yellow mealworm, Tenebrio molitor, harbors a symbiont that has spores with a thick, laminated wall and infects the fat body and ventral nerve chord of adult and larval beetles. In adult males, there is heavy infection of the epithelial cells of the testes and between testes lobes with occasional penetration of the lobes. Spores are enveloped in the spermatophores when they are formed at the time of mating and transferred to the female's bursa copulatrix. Infection has not been found in the ovaries. The sequence of the nuclear small subunit rDNA indicates that the symbiont is a member of the Ichthyosporea, a class of protists near the animal-fungi divergence.

Intraspecific variability of Steinernema feltiae strains from Cemoro Lawang, eastern Java, Indonesia.

Four strains of Steinernema feltiae from Eastern Java, Indonesia were characterized based on morphometric, morphological and molecular data. In addition, their virulence against last instar Tenebrio molitor and heat tolerance was tested. Infective juvenile have a mean body length ranging from 749 to 792 microm. The maximum sequence difference among the four strains was 7 bp (8.8%) in the ITS and 2 bp (0.3%) in D2D3 regions of the rDNA. All the strains are not reproductively isolated and can reproduce with European strain S. feltiae Owiplant. The lowest LC50 was observed for strain SCM (373) and the highest for S. feltiae strain Owiplant (458) IJs/40 T. molitor. All four strains showed relatively better mean heat tolerance when compared with S. feltiae Owiplant, both in adapted and non-adapted heat tolerance experiments.

Selectivity of deltamethrin doses on Palmistichus elaeisis (Hymenoptera: Eulophidae) parasitizing Tenebrio molitor (Coleoptera: Tenebrionidae).

Insecticides are the main method of controlling lepidopteran pests of eucalyptus plantations and those selective to natural enemies, such as the endoparasitoid Palmistichus elaeisis Delvare et LaSalle (Hymenoptera: Eulophidae), are preferable. The objective of this study was to evaluate the selectivity and effects on biological parameters of the insecticide deltamethrin, registered for the control of defoliator caterpillars of eucalyptus, to the parasitoid P. elaeisis aiming the rational use of this insecticide and its compatibility with parasitoids. The experiment was in a completely randomized design. The treatments were the doses of 0.64, 1.40, 3.10, 6.83, 15.03, 33.05, 72.7 and 160 mg a.i./L of deltamethrin and the control (distilled water) with 10 replications, each with a pupae of the alternative host Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae) exposed by the immersion method. The parasitism, biological cycle, emergence, longevity, head width and metatibia length of the natural enemy were evaluated. Deltamethrin reduced parasitism and the emergence rates of P. elaeisis. The duration of the biological cycle of this parasitoid, emerged from T. molitor pupae exposed to 15.03 mg a.i./L of deltamethrin, was higher. The morphometric parameters of P. elaeisis exposed to the doses of 0.64 and 1.40 mg a.i./L of the insecticide were lower. However, the morphometric parameter values were higher with the doses above 3.10 mg a.i./L than in the control. The parasitism and emergence of P. elaeisis were also reduced by the deltamethrin doses lower than the commercially recommended one and therefore, this insecticide is not selective for this natural enemy.

Optimized pupal age of Tenebrio molitor L. (Coleoptera: Tenebrionidae) enhanced mass rearing efficiency of Chouioia cunea Yang (Hymenoptera: Eulophidae).

Chouioia cunea Yang (Hymenoptera: Eulophidae) has been widely used for biological control of the fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), in China. The yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), an important resource insect species distributed worldwide, is considered to be a potential alternative host for mass rearing of C. cunea to the Chinese oak silkworm, Antheraea pernyi (Guerin-Meneville) (Lepidoptera: Saturniidae), which is currently used. In this study, we investigated the effects of host age on C. cunea mass rearing by measuring parasitism, development and adult fertility of C. cunea on T. molitor pupae of different ages. The results showed no significant differences in the percentage of parasitized hosts and developmental time of C. cunea in pupae of different ages. However, the number of C. cunea adults (137.2-154.7 adults per host) that emerged from 0, 1, and 2-day-old pupae was significantly higher than that from 4-day-old pupae. The lowest percentages of unemerged adults were found in 2-day-old (1.2%) and 3-day-old (1.4%) pupae, which were significantly lower than that of 4-day-old pupae (10.3%). The emergence of adult females from 0 to 2-day-old pupae (120.2-142.3 per pupa) was significantly higher than that from 4-day-old hosts (64.6). Adult females emerging from 2-day-old pupae carried significantly more eggs (258.2 eggs/female) than those from 0 and 1-day-old pupae (178.4-178.9 eggs/female). Our findings indicated that 2-day-old pupae of T. molitor were most suitable to rear C. cunea. Overall, this research provided valuable information to optimize pupae for the mass rearing of C. cunea on host T. molitor.

A parasitological evaluation of edible insects and their role in the transmission of parasitic diseases to humans and animals.

From 1 January 2018 came into force Regulation (EU) 2015/2238 of the European Parliament and of the Council of 25 November 2015, introducing the concept of "novel foods", including insects and their parts. One of the most commonly used species of insects are: mealworms (Tenebrio molitor), house crickets (Acheta domesticus), cockroaches (Blattodea) and migratory locusts (Locusta migrans). In this context, the unfathomable issue is the role of edible insects in transmitting parasitic diseases that can cause significant losses in their breeding and may pose a threat to humans and animals. The aim of this study was to identify and evaluate the developmental forms of parasites colonizing edible insects in household farms and pet stores in Central Europe and to determine the potential risk of parasitic infections for humans and animals. The experimental material comprised samples of live insects (imagines) from 300 household farms and pet stores, including 75 mealworm farms, 75 house cricket farms, 75 Madagascar hissing cockroach farms and 75 migrating locust farms. Parasites were detected in 244 (81.33%) out of 300 (100%) examined insect farms. In 206 (68.67%) of the cases, the identified parasites were pathogenic for insects only; in 106 (35.33%) cases, parasites were potentially parasitic for animals; and in 91 (30.33%) cases, parasites were potentially pathogenic for humans. Edible insects are an underestimated reservoir of human and animal parasites. Our research indicates the important role of these insects in the epidemiology of parasites pathogenic to vertebrates. Conducted parasitological examination suggests that edible insects may be the most important parasite vector for domestic insectivorous animals. According to our studies the future research should focus on the need for constant monitoring of studied insect farms for pathogens, thus increasing food and feed safety.

GpMyoF, a WD40 repeat-containing myosin associated with the myonemes of Gregarina polymorpha.

This study presents the first characterization of a WD40 repeat-containing myosin identified in the apicomplexan parasite Gregarina polymorpha. This 222.7 kDa myosin, GpMyoF, contains a canonical myosin motor domain, a neck domain with 6 IQ motifs, a tail domain containing short regions of predicted coiled-coil structure, and, most notably, multiple WD40 repeats at the C-terminus. In other proteins such repeats assemble into a beta-propeller structure implicated in mediating protein-protein interactions. Confocal microscopy suggests that GpMyoF is localized to the annular myonemes that gird the parasite cortex. Extraction studies indicate that this myosin shows an unusually tight association with the cytoskeletal fraction and can be solubilized only by treatment with high pH (11.5) or the anionic detergent sarkosyl. This novel myosin and its homologs, which have been identified in several related genera, appear to be unique to the Apicomplexa and represent the only myosins known to contain the WD40 domain. The function of this myosin in G. polymorpha or any of the other apicomplexan parasites remains uncertain.

Postembryonic RNAi in Heterorhabditis bacteriophora: a nematode insect parasite and host for insect pathogenic symbionts.

BACKGROUND: Heterorhabditis bacteriophora is applied throughout the world for the biological control of insects and is an animal model to study interspecies interactions, e.g. mutualism, parasitism and vector-borne disease. H. bacteriophora nematodes are mutually associated with the insect pathogen, Photorhabdus luminescens. The developmentally arrested infective juvenile (IJ) stage nematode (vector) specifically transmits Photorhabdus luminescens bacteria (pathogen) in its gut mucosa to the haemocoel of insects (host). The nematode vector and pathogen alone are not known to cause insect disease. RNA interference is an excellent reverse genetic tool to study gene function in C. elegans, and it would be useful in H. bacteriophora to exploit the H. bacteriophora genome project, currently in progress. RESULTS: Soaking L1 stage H. bacteriophora with seven dsRNAs of genes whose C. elegans orthologs had severe RNAi phenotypes resulted in highly penetrant and obvious developmental and reproductive abnormalities. The efficacy of postembryonic double strand RNA interference (RNAi) was evident by abnormal gonad morphology and sterility of adult H. bacteriophora and C. elegans presumable due to defects in germ cell proliferation and gonad development. The penetrance of RNAi phenotypes in H. bacteriophora was high for five genes (87-100%; Hba-cct-2, Hba-daf-21, Hba-icd-1; Hba-nol-5, and Hba-W01G7.3) and moderate for two genes (usually 30-50%; Hba-rack-1 and Hba-arf-1). RNAi of three additional C. elegans orthologs for which RNAi phenotypes were not previously detected in C. elegans, also did not result in any apparent phenotypes in H. bacteriophora. Specific and severe reduction in transcript levels in RNAi treated L1s was determined by quantitative real-time RT-PCR. These results suggest that postembryonic RNAi by soaking is potent and specific. CONCLUSION: Although RNAi is conserved in animals and plants, RNAi using long dsRNA is not. These results demonstrate that RNAi can be used effectively in H. bacteriophora and can be applied for analyses of nematode genes involved in symbiosis and parasitism. It is likely that RNAi will be an important tool for functional genomics utilizing the high quality draft H. bacteriophora genome sequence.

Individual and population effects of eugregarine, Gregarina niphandrodes (Eugregarinida: Gregarinidae), on Tenebrio molitor (Coleoptera: Tenebrionidae).

Gregarines are single-celled parasites in the phylum Apicomplexa that infect invertebrates. They are highly abundant on three levels: among a large diversity of invertebrates, in the proportion of population of organisms they infect, and within individually infected organisms. Because of their remarkable prevalence, we hypothesize that they play an important role in support of their hosts. However, studies done to date on the impact of gregarines on their host are conflicting. Therefore, we studied the impact of gregarines on their host using a model Gregarina niphandrodes infection in Tenebrio molitor. The impact of infection was measured by comparing beetles with no or low infection to those with artificially induced high infection. The numbers of individuals in each of the three easily visible developmental stages of the T. molitor (larva, pupa, and adult) were censused weekly. From these observations, fertilities and probabilities of survival with transition between stages were estimated. These estimated vital rates were used to construct a stage-classified projection matrix model. We also measured the longevity of individual beetles with low and high infection that were grown in isolation. The results indicate that there is no significant difference in the population dynamics of beetles with low and high infection. However, the longevity was significantly different between beetles with low infection than the deliberately highly infected group.

Gregarina niphandrodes (Eugregarinorida: Septatorina): oocyst surface architecture.

The surface architecture of oocysts produced by Gregarina niphandrodes (Eugregarinorida) from Tenebrio molitor adults (Coleoptera: Tenebrionidae) as revealed by scanning electron microscopy is reported. Gametocysts were allowed to dehisce on 15-mm, round cover glasses; the cover glasses with their oocysts chains were then mounted on stubs without further processing, and sputter-coated with 20-nm gold palladium. Scanning electron microscopy was performed at 10-15 kV with a Hitachi 3000N SEM. Oocysts retained their characteristic shapes as reported in the original species description but showed longitudinal ridges of relatively uniform height, width, and spacing, in separate fields on either side of a central equatorial bulge in the oocysts. There was no ultrastructural evidence of an enclosing external sheath holding the oocysts in a chain. Oocyst ends were flared slightly, and the chain itself was twisted, with adjacent oocysts offset slightly from one another. This article now provides an additional set of structural characters potentially useful in gregarine systematics.

Ultrastructure of the Gregarina niphandrodes nucleus through stages from unassociated trophozoites to gamonts in syzygy and the syzygy junction.

In Gregarina niphandrodes, an apicomplexan parasite, the sexual stage of its life cycle begins with the association of 2 gamonts. Here, we describe the ultrastructure of the syzygy junction and the nucleus during the transition from unassociated trophozoites to paired gamonts to gamonts in syzygy. Throughout this process, the folds within the syzygy junction undergo changes that correspond to changes of the epicytic folds. The nucleus goes through dramatic changes from multiple spheres of condensed chromatin in unassociated trophozoites, to mostly uncondensed chromatin in paired gamonts, to a large single sphere of condensed chromatin encasing many smaller spheres in gamonts in syzygy. These differing nuclear ultrastructures reflect the dramatic cellular and transcriptional changes associated with life cycle transitions and are indicative of the numerous cell divisions that follow.

Efficacy of condensed tannins against larval Hymenolepis diminuta (Cestoda) in vitro and in the intermediate host Tenebrio molitor (Coleoptera) in vivo.

Natural anti-parasitic compounds in plants such as condensed tannins (CT) have anthelmintic properties against a range of gastrointestinal nematodes, but for other helminths such effects are unexplored. The aim of this study was to assess the effects of CT from three different plant extracts in a model system employing the rat tapeworm, Hymenolepis diminuta, in its intermediate host, Tenebrio molitor. An in vitro study examined infectivity of H. diminuta cysticercoids (excystation success) isolated from infected beetles exposed to different concentrations of CT extracts from pine bark (PB) (Pinus sps), hazelnut pericarp (HN) (Corylus avellana) or white clover flowers (WC) (Trifolium repens), in comparison with the anthelmintic drug praziquantel (positive control). In the in vitro study, praziquantel and CT from all three plant extracts had dose-dependent inhibitory effects on cysticercoid excystation. The HN extract was most effective at inhibiting excystation, followed by PB and WC. An in vivo study was carried out on infected beetles (measured as cysticercoid establishment) fed different doses of PB, HN and praziquantel. There was a highly significant inhibitory effect of HN on cysticercoid development (p=0.0002). Overall, CT showed a promising anti-cestodal effect against the metacestode stage of H. diminuta.