A Mosquito Parasite Is Locally Adapted to Its Host but Not Temperature.

AbstractClimate change will alter interactions between parasites and their hosts. Warming may affect patterns of local adaptation, shifting the environment to favor the parasite or host and thus changing the prevalence of disease. We assessed local adaptation to hosts and temperature in the facultative ciliate parasite Lambornella clarki, which infects the western tree hole mosquito Aedes sierrensis. We conducted laboratory infection experiments with mosquito larvae and parasites collected from across a climate gradient, pairing sympatric or allopatric populations across three temperatures that were either matched or mismatched to the source environment. Lambornella clarki parasites were locally adapted to their hosts, with 2.6 times higher infection rates on sympatric populations compared with allopatric populations, but they were not locally adapted to temperature. Infection peaked at the intermediate temperature of 12.5°C, notably lower than the optimum temperature for free-living L. clarki growth, suggesting that the host's immune response can play a significant role in mediating the outcome of infection. Our results highlight the importance of host selective pressure on parasites, despite the impact of temperature on infection success.

Plancitoxin-1 mediates extracellular trap evasion by the parasitic helminth Trichinella spiralis.

BACKGROUND: Trichinella spiralis (T. spiralis) is a parasitic helminth that causes a globally prevalent neglected zoonotic disease, and worms at different developmental stages (muscle larvae, adult worms, newborn larvae) induce immune attack at different infection sites, causing serious harm to host health. Several innate immune cells release extracellular traps (ETs) to entrap and kill most pathogens that invade the body. In response, some unicellular pathogens have evolved a strategy to escape capture by ETs through the secretion of nucleases, but few related studies have investigated multicellular helminths. RESULTS: In the present study, we observed that ETs from neutrophils capture adult worms of T. spiralis, while ETs from macrophages trap muscle larvae and newborn larvae, and ETs had a killing effect on parasites in vitro. To defend against this immune attack, T. spiralis secretes plancitoxin-1, a DNase II-like protein, to degrade ETs and escape capture, which is essential for the survival of T. spiralis in the host. CONCLUSIONS: In summary, these findings demonstrate that T. spiralis escapes ET-mediated capture by secreting deoxyribonuclease as a potential conserved immune evasion mechanism, and plancitoxin-1 could be used as a potential vaccine candidate.

Coordinated molecular and ecological adaptations underlie a highly successful parasitoid.

The success of an organism depends on the molecular and ecological adaptations that promote its beneficial fitness. Parasitoids are valuable biocontrol agents for successfully managing agricultural pests, and they have evolved diversified strategies to adapt to both the physiological condition of hosts and the competition of other parasitoids. Here, we deconstructed the parasitic strategies in a highly successful parasitoid, Trichopria drosophilae, which parasitizes a broad range of Drosophila hosts, including the globally invasive species D. suzukii. We found that T. drosophilae had developed specialized venom proteins that arrest host development to obtain more nutrients via secreting tissue inhibitors of metalloproteinases (TIMPs), as well as a unique type of cell-teratocytes-that digest host tissues for feeding by releasing trypsin proteins. In addition to the molecular adaptations that optimize nutritional uptake, this pupal parasitoid has evolved ecologically adaptive strategies including the conditional tolerance of intraspecific competition to enhance parasitic success in older hosts and the obligate avoidance of interspecific competition with larval parasitoids. Our study not only demystifies how parasitoids weaponize themselves to colonize formidable hosts but also provided empirical evidence of the intricate coordination between the molecular and ecological adaptations that drive evolutionary success.

Shaping the Microbial Landscape: Parasitoid-Driven Modifications of Bactrocera dorsalis Microbiota.

Koinobiont endoparasitoids regulate the physiology of their hosts through altering host immuno-metabolic responses, processes which function in tandem to shape the composition of the microbiota of these hosts. Here, we employed 16S rRNA and ITS amplicon sequencing to investigate whether parasitization by the parasitoid wasps, Diachasmimorpha longicaudata (Ashmaed) (Hymenoptera: Braconidae) and Psyttalia cosyrae (Wilkinson) (Hymenoptera: Braconidae), induces gut dysbiosis and differentially alter the gut microbial (bacteria and fungi) communities of an important horticultural pest, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). We further investigated the composition of bacterial communities of adult D. longicaudata and P. cosyrae to ascertain whether the adult parasitoids and parasitized host larvae share microbial taxa through transmission. We demonstrated that parasitism by D. longicaudata induced significant gut perturbations, resulting in the colonization and increased relative abundance of pathogenic gut bacteria. Some pathogenic bacteria like Stenotrophomonas and Morganella were detected in both the guts of D. longicaudata-parasitized B. dorsalis larvae and adult D. longicaudata wasps, suggesting a horizontal transfer of microbes from the parasitoid to the host. The bacterial community of P. cosyrae adult wasps was dominated by Arsenophonus nasoniae, whereas that of D. longicaudata adults was dominated by Paucibater spp. and Pseudomonas spp. Parasitization by either parasitoid wasp was associated with an overall reduction in fungal diversity and evenness. These findings indicate that unlike P. cosyrae which is avirulent to B. dorsalis, parasitization by D. longicaudata induces shifts in the gut bacteriome of B. dorsalis larvae to a pathobiont-dominated community. This mechanism possibly enhances its virulence against the pest, further supporting its candidacy as an effective biocontrol agent of this frugivorous tephritid fruit fly pest.

Cellular dynamics of host - parasitoid interactions: Insights from the encapsulation process in a partially resistant host.

Cotesia typhae is an eastern African endoparasitoid braconid wasp that targets the larval stage of the lepidopteran stem borer, Sesamia nonagrioides, a maize crop pest in Europe. The French host population is partially resistant to the Makindu strain of the wasp, allowing its development in only 40% of the cases. Resistant larvae can encapsulate the parasitoid and survive the infection. This interaction provides a very interesting frame for investigating the impact of parasitism on host cellular resistance. We characterized the parasitoid ovolarval development in a permissive host and studied the encapsulation process in a resistant host by dissection and histological sectioning compared to that of inert chromatography beads. We measured the total hemocyte count in parasitized and bead-injected larvae over time to monitor the magnitude of the immune reaction. Our results show that parasitism of resistant hosts delayed encapsulation but did not affect immune abilities towards inert beads. Moreover, while bead injection increased total hemocyte count, it remained constant in resistant and permissive larvae. We conclude that while Cotesia spp virulence factors are known to impair the host immune system, our results suggest that passive evasion could also occur.

Honey bee (Apis mellifera) nurse bee visitation of worker and drone larvae increases Varroa destructor mite cell invasion.

The life cycle of Varroa destructor, the ectoparasitic mite of honey bees (Apis mellifera), includes a dispersal phase, in which mites attach to adult bees for transport and feeding, and a reproductive phase, in which mites invade worker and drone brood cells just prior to pupation to reproduce while their bee hosts complete development. In this study, we wanted to determine whether increased nurse bee visitations of adjacent drone and worker brood cells would increase the likelihood of Varroa mites invading those cells. We also explored whether temporarily restricting the nurses' access to sections of worker brood for 2 or 4 h would subsequently cause higher nurse visitations, and thus, higher Varroa cell invasions. Temporarily precluding larvae from being fed by nurses subsequently led to higher Varroa infestation of those sections in some colonies, but this pattern was not consistent across colonies. Therefore, removing highly infested sections of capped worker brood could be further explored as a potential mechanical/cultural method for mite control. Our results provide more information on how nurse visitations affect the patterns of larval cell invasion by Varroa. Given that the mite's successful reproduction depends on the nurses' ability to visit and feed developing brood, more studies are needed to understand the patterns of Varroa mite invasion of drone and worker cells to better combat this pervasive honey bee parasite.

Predicting and reducing potential parasite infection between migratory livestock and resident Asiatic ibex of Pin valley, India.

Disease cross-transmission between wild and domestic ungulates can negatively impact livelihoods and wildlife conservation. In Pin valley, migratory sheep and goats share pastures seasonally with the resident Asiatic ibex (Capra sibirica), leading to potential disease cross-transmission. Focussing on gastro-intestinal nematodes (GINs) as determinants of health in ungulates, we hypothesized that infection on pastures would increase over summer from contamination by migrating livestock. Consequently, interventions in livestock that are well-timed should reduce infection pressure for ibex. Using a parasite life-cycle model, that predicts infective larval availability, we investigated GIN transmission dynamics and evaluated potential interventions. Migratory livestock were predicted to contribute most infective larvae onto shared pastures due to higher density and parasite levels, driving infections in both livestock and ibex. The model predicted a c.30-day antiparasitic intervention towards the end of the livestock's time in Pin would be most effective at reducing GINs in both hosts. Albeit with the caveats of not being able to provide evidence of interspecific parasite transmission due to the inability to identify parasite species, this case demonstrates the usefulness of our predictive model for investigating parasite transmission in landscapes where domestic and wild ungulates share pastures. Additionally, it suggests management options for further investigation.

Glucose and trehalose metabolism through the cyclic pentose phosphate pathway shapes pathogen resistance and host protection in Drosophila.

Activation of immune cells requires the remodeling of cell metabolism in order to support immune function. We study these metabolic changes through the infection of Drosophila larvae by parasitoid wasp. The parasitoid egg is neutralized by differentiating lamellocytes, which encapsulate the egg. A melanization cascade is initiated, producing toxic molecules to destroy the egg while the capsule also protects the host from the toxic reaction. We combined transcriptomics and metabolomics, including 13C-labeled glucose and trehalose tracing, as well as genetic manipulation of sugar metabolism to study changes in metabolism, specifically in Drosophila hemocytes. We found that hemocytes increase the expression of several carbohydrate transporters and accordingly uptake more sugar during infection. These carbohydrates are metabolized by increased glycolysis, associated with lactate production, and cyclic pentose phosphate pathway (PPP), in which glucose-6-phosphate is re-oxidized to maximize NADPH yield. Oxidative PPP is required for lamellocyte differentiation and resistance, as is systemic trehalose metabolism. In addition, fully differentiated lamellocytes use a cytoplasmic form of trehalase to cleave trehalose to glucose and fuel cyclic PPP. Intracellular trehalose metabolism is not required for lamellocyte differentiation, but its down-regulation elevates levels of reactive oxygen species, associated with increased resistance and reduced fitness. Our results suggest that sugar metabolism, and specifically cyclic PPP, within immune cells is important not only to fight infection but also to protect the host from its own immune response and for ensuring fitness of the survivor.

Performance and preference of larval parasitoid, Microplitis pallidipes (Hymenoptera: Braconidae), on 2 Spodoptera pest species.

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Spodoptera litura (Fabricius) are the main pests on corn (Poaceae: Gramineae). The performance of the larval wasp, Microplitis pallidipes Szépligeti (Hymenoptera: Braconidae), was reported on S. frugiperda and S. litura. In this study, we evaluated host selectivity, constructed an age-stage, 2-sex life table, and assessed the pest control potential of M. pallidipes against these 2 pests under laboratory conditions. In a 2-choice host preference experiment, M. pallidipes exhibited a stronger preference for S. frugiperda over S. litura and a distinct preference for second instars. We also investigated the parasitism of females that were either unfed or fed with 10% honey-water solution under different host densities and found that the highest parasitism rate was observed when M. pallidipes were fed with honey-water solution on the first day after mating and a presented female wasp:host ratio of 1:90. In a nonselective assay, M. pallidipes successfully completed a full generation on both hosts. However, the parasitoids exhibited higher fitness and population growth potential when reared on S. frugiperda, with a net reproductive rate (R0) of 24.24, an intrinsic rate of increase (r) of 0.20 per day, a finite rate of increase (λ) of 1.23 per day, and a mean generation time (T) of 15.69 days. This study elucidates the performance of M. pallidipes on 2 Spodoptera host species and offers insights into its biological control potential on lepidopteran pests.

Recognition of nonself is necessary to activate Drosophila's immune response against an insect parasite.

BACKGROUND: Innate immune responses can be activated by pathogen-associated molecular patterns (PAMPs), danger signals released by damaged tissues, or the absence of self-molecules that inhibit immunity. As PAMPs are typically conserved across broad groups of pathogens but absent from the host, it is unclear whether they allow hosts to recognize parasites that are phylogenetically similar to themselves, such as parasitoid wasps infecting insects. RESULTS: Parasitoids must penetrate the cuticle of Drosophila larvae to inject their eggs. In line with previous results, we found that the danger signal of wounding triggers the differentiation of specialized immune cells called lamellocytes. However, using oil droplets to mimic infection by a parasitoid wasp egg, we found that this does not activate the melanization response. This aspect of the immune response also requires exposure to parasite molecules. The unidentified factor enhances the transcriptional response in hemocytes and induces a specific response in the fat body. CONCLUSIONS: We conclude that a combination of danger signals and the recognition of nonself molecules is required to activate Drosophila's immune response against parasitic insects.

To live free or being a parasite: The optimal foraging behavior may favor the evolution of entomopathogenic nematodes.

Facultative parasites can alternate between a free-living and a parasitic existence to complete their life cycle. Yet, it remains uncertain which lifestyle they prefer. The optimal foraging theory suggests that food preferences align with fitness benefits. To test this hypothesis, we investigated the facultative parasite nematode Rhabditis regina, assessing its host preference and the associated benefits. Two experiments were conducted using wild nematode populations collected from Phyllophaga polyphylla, their natural host. In the first experiment, we used a behavioral arena to assess host preference between the natural host and two experimental hosts: Spodoptera frugiperda which is an alternative host and dead Tenebrio molitor, which simulates a saprophytic environment. In the second experiment, we subjected wild nematodes to "experimental evolution" lasting 50 generations in S. frugiperda and 53 generations in T. molitor carcass. We then compared life history traits (the size, survival, number of larvae, and glycogen and triglycerides as energy reserves) of dauer larvae with those nematodes from P. polyphylla (control group). We found a significant preference for P. polyphylla, which correlated with higher values in the nematode's life history traits. In contrast, the preference for S. frugiperda and the saprophytic environment was lower, resulting in less efficient life history traits. These findings align with the optimal foraging theory, as the nematode's parasitic preferences are in line with maximizing fitness. This also indicates that R. regina exhibits specificity to P. polyphylla and is better adapted to a parasitic lifestyle than a free-living one, suggesting an evolutionary pathway towards parasitism.

A parasitoid regulates 20E synthesis and antibacterial activity of the host for development by inducing host nitric oxide production.

Parasitoids are important components of the natural enemy guild in the biological control of insect pests. They depend on host resources to complete the development of a specific stage or whole life cycle and thus have evolved towards optimal host exploitation strategies. In the present study, we report a specific survival strategy of a fly parasitoid Exorista sorbillans (Diptera: Tachinidae), which is a potential biological control agent for agricultural pests and a pest in sericulture. We found that the expression levels of nitric oxide synthase (NOS) and nitric oxide (NO) production in host Bombyx mori (Lepidoptera: Bombycidae) were increased after E. sorbillans infection. Reducing NOS expression and NO production with an NOS inhibitor (NG-nitro-L-arginine methyl ester hydrochloride) in infected B. mori significantly impeded the growth of E. sorbillans larvae. Moreover, the biosynthesis of 20-hydroxyecdysone (20E) in infected hosts was elevated with increasing NO production, and inhibiting NOS expression lowered 20E biosynthesis. More importantly, induced NO synthesis was required to eliminate intracellular bacterial pathogens that presumably competed for shared host resources. Inhibiting NOS expression down-regulated the transcription of antimicrobial peptide genes and increased the number of bacteria in parasitized hosts. Collectively, this study revealed a new perspective on the role of NO in host-parasitoid interactions and a novel mechanism for parasitoid regulation of host physiology to support its development.

Trichinella spiralis cathepsin L damages the tight junctions of intestinal epithelial cells and mediates larval invasion.

BACKGROUND: Cathepsin L, a lysosomal enzyme, participates in diverse physiological processes. Recombinant Trichinella spiralis cathepsin L domains (rTsCatL2) exhibited natural cysteine protease activity and hydrolyzed host immunoglobulin and extracellular matrix proteins in vitro, but its functions in larval invasion are unknown. The aim of this study was to explore its functions in T. spiralis invasion of the host's intestinal epithelial cells. METHODOLOGY/PRINCIPAL FINDINGS: RNAi significantly suppressed the expression of TsCatL mRNA and protein with TsCatL specific siRNA-302. T. spiralis larval invasion of Caco-2 cells was reduced by 39.87% and 38.36%, respectively, when anti-TsCatL2 serum and siRNA-302 were used. Mice challenged with siRNA-302-treated muscle larvae (ML) exhibited a substantial reduction in intestinal infective larvae, adult worm, and ML burden compared to the PBS group, with reductions of 44.37%, 47.57%, and 57.06%, respectively. The development and fecundity of the females from the mice infected with siRNA-302-treated ML was significantly inhibited. After incubation of rTsCatL2 with Caco-2 cells, immunofluorescence test showed that the rTsCatL2 gradually entered into the cells, altered the localization of cellular tight junction proteins (claudin 1, occludin and zo-1), adhesion junction protein (e-cadherin) and extracellular matrix protein (laminin), and intercellular junctions were lost. Western blot showed a 58.65% reduction in claudin 1 expression in Caco-2 cells treated with rTsCatL2. Co-IP showed that rTsCatL2 interacted with laminin and collagen I but not with claudin 1, e-cadherin, occludin and fibronectin in Caco-2 cells. Moreover, rTsCatL2 disrupted the intestinal epithelial barrier by inducing cellular autophagy. CONCLUSIONS: rTsCatL2 disrupts the intestinal epithelial barrier and facilitates T. spiralis larval invasion.

Comparative investigation of different chemicals on the germination of two aquatic microsporidia.

Microsporidia are eukaryotic obligatory intracellular parasites that infect a wide range of vertebrates and invertebrate hosts. Spores infect target cells of the host by transferring their sporoplasm through a distinctive polar tube. This study investigated how selected chemicals influence the germination of two newly discovered microsporidia species from central-western Iran. Spores of Parathelohania iranica were extracted from infected larvae of Anopheles superpictus s.l. and purified by the Percoll discontinuous density gradient method. Because of the small number of spores per copepod, extraction and purification were not performed for spores of the microsporidium infecting Paracyclops chiltoni. Both spores were exposed to KCl, NaCl, KI, NaI, and H2O2 and the effects of concentration (0.5, 1.5, and 2.5 M), pH (7.0, 9.0, and 11.0), temperature (4 °C and 25 °C), and duration of exposure (10 and 30 min) on spore germination were investigated and compared. This study indicated that the type of the ionic nature of the surrounding environment of spores plays an important role in the release of polar tubes of both microsporidia. Additionally, anions played a more significant role than cations. This effect was directly related to concentration, temperature, and time. However, no specific pattern was recognized at different alkaline pH levels. Hydrogen peroxide was not effective in releasing the polar tubes of the spores of these microsporidia. This study demonstrated the comparative role of some chemicals and the associated factors in the release of the polar tube of two aquatic microsporidia. Future research should examine the practical value of these findings in the mass production of candidate microsporidia for the biological control of pest invertebrate hosts.

Dynamics of the natural enemy community of Hyphantria cunea (Lepidoptera: Erebidae) in Dandong, China.

This study aims to explore the composition of natural enemy species in the fall webworm, Hyphantria cunea (Drury) population and the dynamics of its natural enemy community in Dandong, Liaoning Province, China, where it was first reported. We collected the natural enemy of eggs, larvae, and pupae of H. cunea on host trees at 12 survey sites from June 2019 to October 2020. The results showed that the community consists of 34 species: 20 predatory species, including 15 spiders and 5 insects, and 14 parasitic species, including 10 parasitic wasps and 4 parasitic flies. The top 3 dominant species based on the importance value index for both parasitic and predatory species were Pediobius pupariae > Chouioia cunea > Cotesia gregalis in the natural enemy community of H. cunea. Analysis of all 3 principal components by principal component analysis showed that Clubionidae sp. 1, Parena cavipennis, or other predators were the main factors affecting the natural enemy community. Analysis of the community structure parameters of the H. cunea natural enemy community in different developmental stages across generations revealed the following: (i) Compared with the degree of complexity of the egg and pupal stages, the larval stage was the highest. (ii) The complexity was determined by means of comprehensive evaluation: first-generation larvae in 2020 > first-generation larvae in 2019 > second-generation larvae in 2020 > second-generation larvae in 2019. These results clarify the dynamics of natural enemy species, coevolution with the host in the invaded habitat of H. cunea and development of biological control technologies.

Evaluation in vitro of the virulence of two entomopathogenic heterorhabditid nematodes in the control of Stomoxys calcitrans (Diptera: Muscidae) larvae in byproducts of the sugar and alcohol industry.

Stomoxys calcitrans causes losses to livestock, mainly to cattle. This study aimed to determine the pathogenic potential of Heterorhabditis bacteriophora HP88 and H. baujardi LPP7 against S. calcitrans larvae after being exposed to byproducts of the sugar and alcohol industry. The efficacy of EPNs on stable fly larvae was evaluated in bioassays with vinasse at three temperatures (16, 25 and 35 °C) and concentrations (0, 50 and 100%), as well as in relation to larva age (4, 6 and 8 days) in filter cake and EPNs concentration (100, 300 and 500 IJs/larva) in sugarcane bagasse. H. bacteriophora showed higher efficacy than H. baujardi at all temperatures. Vinasse did not have a negative effect on the virulence of H. bacteriophora. The age of fly larvae did not affect the mortality rates caused by the EPNs. In bagasse, H. bacteriophora presented higher mortality rates than the control group. It is concluded that EPNs can be a potential component in integrated strategies of stable fly control and outbreak prevention in areas of sugar and alcohol production.

Effects of minimum Strigea robusta (Digenea: Strigeidae) cercariae doses and localization of cysts on the anomaly P manifestation in Pelophylax lessonae (Anura: Ranidae) tadpoles.

The anomaly P is a mass morphological anomaly found in some populations of anuran amphibians (water frogs of the genus Pelophylax and toads of the genera Bufo and Bufotes) caused by the parasitic flatworm Strigea robusta. Minimum dose of cercariae for the appearance of the anomaly P remains unknown. However, it is important information for understanding of host population dynamics after invasion and the effects of the parasite on the second intermediate hosts. Herein, the invasion properties of S. robusta in Pelophylax lessonae tadpoles (Anura: Ranidae) and minimum dose for appearance of mild and severe forms of the anomaly P syndrome were described after direct experiments with certain numbers of cercariae exposure. Experimental groups of tadpoles have been exposed to eight doses of cercariae (2, 4, 6, 8, 10, 12, 14 and 16). A total of 63.8% tadpoles survived to the end of this experiment. It was revealed that a mild form of the anomaly P (polydactyly) can appear after infection by two cercariae, while the severe form traits appear after infection by four cercariae. The mean number of detected encysted metacercariae was reached to 53.5%. Differences in infection rates can be explained by the presence of an individual immune response in tadpoles or by the presence of different genetic lineages of the parasite infecting the same snail, which have different infectious potential. Low doses of infection leading to the induction of anomalies characterize S. robusta as a highly pathogenic species for amphibian species that are susceptible to infection and show an abnormal phenotype.

Ocorrência de Cochliomyia hominivorax em bovinos no Maranhão, Brasil / Occurrence of Cochliomyia hominivorax in cattle in Maranhão, Brazil

A bovinocultura possui grande importância na economia brasileira, entretanto, enfermidades afetam a produção, ocasionando perdas econômicas, como a miíase. O agente causador da miíase é Cochliomyia hominivorax, mosca-da-bicheira. Os agentes são aptos às regiões tropicais e subtropicais no Brasil, e exibem resistência parasitária aos fármacos. O objetivo deste trabalho foi verificar a ocorrência de C. hominivorax em bovinos no estado do Maranhão, Brasil. Foram escolhidas 19 propriedades de bovinos leiteiros e de corte, distribuídas em 11 municípios maranhenses. Foi indagado, por questionário, o manejo, os medicamentos utilizados e o custo de prevenção relacionado à mazela. Os bovinos foram examinados por inspeção, recolhendo-se parcialmente as larvas encontradas na superfície corporal. O número de larvas por bovino, local das lesões, a origem e complicações foram observadas e anotadas. Em seguida, os espécimes coletados foram acondicionados em frascos individuais, por hospedeiro amostrado, contendo álcool a 70°Gay-Lussac (GL). No laboratório as larvas das moscas foram examinadas em estereomicroscópio e identificadas pela sua morfologia. Verificou-se que mais de 60% (12/19) das propriedades possuíam bovinos parasitados. Dentre os 4.509 animais observados, 0,57% (26/4509) estavam parasitados com as larvas de C. hominivorax. Encontraram-se infestações no umbigo (50%), bem como na tábua do pescoço (42%), vulva (4%) e chifre (4%). Conclui-se que houve uma baixa prevalência de miíase causada por C. hominivorax em bovinos no estado do Maranhão, porém a prevenção e cuidados sanitários sempre devem ser adotados pelos pecuaristas.

Cattle breeding has great importance in the Brazilian economy, however, diseases affect production, causing economic losses, such as myiasis. The causative agent of myiasis is Cochliomyia hominivorax, the screwworm fly. The agents are suitable for tropical and subtropical regions in Brazil, and exhibit parasitic drug resistance. The objective of this work was to verify the occurrence of C. hominivorax in cattle in the state of Maranhão, Brazil. In the first stage, 19 dairy and beef cattle properties were chosen, distributed in 11 municipalities in Maranhão. Questionnaires asked about the management, the drugs used and the cost of prevention related to the disease. The cattle were examined by inspection, partially collecting the larvae found on the body surface. The number of larvae per bovine, location of lesions, origin and complications were observed and noted. Then, the collected specimens were placed in individual flasks, per sampled host, containing alcohol at 70°Gay-Lussac (GL). In the second stage, the fly larvae were identified in the laboratory, examined under a stereomicroscope and identified by their morphology and analysis of perithematics plaques and respiratory spiracles. It was found more that 60% (12/19) of the properties had parasitized cattle. Among the 4.509 animals observed, 0.57% (26/4509) were parasitized with the larvae of C. hominivorax. Infestations were found in the navel (50%), as well as in the neck plate (42%), vulva (4%) and horn (4%). It is concluded that there was a low prevalence of myiasis caused by C. hominivorax in cattle in the state of Maranhão, but prevention and health care should always be adopted by livestock farmers.

Effect of Pepper Variety on the Susceptibility of Pepper Weevil Parasitoids.

Anthonomus eugenii Cano (Coleoptera: Curculionidae) is a key pest of cultivated peppers (Capsicum species) in tropical and subtropical America. Here we evaluated the effect of five pepper varieties on the susceptibility of A. eugenii to the parasitoids Bracon sp. (Hymenoptera: Braconidae), Eupelmus cushmani (Crawford) (Hymenoptera: Eupelmidae), and Jaliscoa hunteri Crawford (Hymenoptera: Pteromalidae). Potential parasitism was estimated by comparative analysis of parasitoid ovipositor size and the depth to which host larvae develop inside the fruit. Highest potential parasitism rates were achieved by Bracon sp. and E. cushmani on árbol and habanero peppers (84-99%) while the lowest rates were achieved by J. hunteri on serrano, bell, and jalapeño (7-18%). To validate potential parasitism rates, the actual parasitism rate by Bracon sp. and J. hunteri on three varieties of peppers was assessed. Actual parasitism rates of A. eugenii larvae in árbol were similar for Bracon sp. and J. hunteri (33%), while on bell and jalapeño Bracon sp. achieved 24% and 13% parasitism and J. hunteri achieved 14% and 8%, respectively. In most cases, actual parasitism was lower than estimated potential parasitism, although the latter had a notable predictive power (predicted R2 = 0.84). Results showed that the host was more vulnerable on small-fruited varieties because larvae were closer to the pericarp and could be reached by parasitoid ovipositors; likewise, in varieties with little placenta and seed, some larvae fed in the pericarp, where they were more vulnerable.

Nematódeos de interesse médico veterinário em represa urbana no município de Catalão, no sudeste do estado de Goiás, Brasil / Nematodes of veterinary medical interest in an urban reservoir in the municipality of Catalão, southeastern Goiás State, Brazil

Objetivo: realizar análises parasitológicas em amostras de solo provenientes da represa da Bica situada no município de Catalão-GO. Métodos: a área do entorno da represa foi dividida em cinco parcelas, sendo realizadas coletas em dois pontos de cada parcela, superior e inferior. Foram realizadas quatro coletas em dias alternados, totalizando 40 amostras de, aproximadamente, 50g da camada superficial do solo, com profundidade máxima de cinco centímetros. As amostras foram processadas no Setor de Diagnóstico Parasitológico do Laboratório de Biologia Molecular da Universidade Federal de Catalão (UFCAT). Para as análises parasitológicas, foram utilizados cinco métodos encontrados na literatura, Rugai, Willis, Sedimentação espontânea, Ritchie e Ritchie modificado. Resultados: pelo método de Rugai, foi possível detectar larvas rabditoides do gênero Ancylostoma e Strongyloides. Utilizando o método de Ritchie modificado, foram encontrados ovos de Ascaris lumbricoidese Ancylostoma sp. Conclusão: a presença de formas evolutivas no solo da represa indica contaminação por dejetos animais e humanos, favorecendo o estabelecimento de ciclos biológicos das espécies encontradas e de outras diferentes zoonoses. Os dados obtidos demonstram a importância de sensibilizar a população de medidas de promoção da saúde, além de ações preventivas e programas de educação em saúde.

Objective: to conduct parasitological analyses in soil samples from the Bica reservoir located in the municipality of Catalão-GO. Methods: the area around the dam was divided into five plots, and samples were collected from two points in each plot, upper and lower. Four samples were collected on alternate days, totaling 40 samples of approximately 50g of topsoil, with a maximum depth of five centimeters. The samples were processed in the Parasitological Diagnostic Sector of the Molecular Biology Laboratory of the Federal University of Catalão (UFCAT). For the parasitological analyses, we used five methods found in the literature, Rugai, Willis, spontaneous sedimentation, Ritchie, and modified Ritchie. Results: by the Rugai method, it was possible to detect rhabditoid larvae of the genus Ancylostoma and Strongyloides. Using the modified Ritchie method, eggs of Ascaris lumbricoidesand Ancylostoma sp were found. Conclusion: the presence of evolutive forms in the soil of the reservoir indicates contamination by animal and human waste, favoring the establishment of biological cycles of the species found and of other different zoonoses. The data obtained demonstrated the importance of raising the population's awareness of health promotion measures besides preventive actions and health education programs.