Olfactory responses of Trissolcus mitsukurii to plants attacked by target and non-target stink bugs suggest low risk for biological control.

In crop systems, successful management of invasive insect herbivores can be achieved through the introduction of exotic biocontrol agents, parasitoids or predators, having a coevolutionary history with the pest. To avert threats to local biodiversity, recent legislations require a risk assessment for the organism to be released. Evaluation of its ability to exploit, for host location, odours associated with target and non-target species is crucial for a better definition of its ecological host range. Using Y-tube olfactometer bioassays in a quarantine laboratory, we investigated the ability of the Asian egg parasitoid Trissolcus mitsukurii (Hymenoptera: Scelionidae) to exploit odours associated with the global invader Halyomorpha halys (Hemiptera: Pentatomidae) and with non-target stink bugs native to Southern Europe. We demonstrated that T. mitsukurii is attracted by plants exposed to feeding and egg deposition of the coevolved H. halys and the native Nezara viridula, while it is not attracted by physogastric (gravid) females or eggs alone. Remarkably, T. mitsukurii is repelled by plants bearing eggs of the beneficial Arma custos. Our results contribute to a more thorough and nuanced assessment of the potential non-target risks in the case of mass-release of parasitoids as part of a biological control programme for invasive stink bugs.

Pre-oviposition behavior of Aedes aegypti in the field: first report of eggs laying on water surface in an artificial breeding site in the city of Rio de Janeiro

This study presents the first report of Aedes aegypti laying eggs on the water surface of an artificial breeding site in the field. This report occurred in the city of Rio de Janeiro inside a white bucket containing 11 liters of rainwater. Conspecific larvae had previously been found in this bucket. From the 219 eggs obtained, 135 (61.6%) were laid on the water and 84 (38.3%) on the border of the bucket. Larvae (4th instar) and adults obtained from the eggs were identified as A. aegypti. This behavior may influence the population dynamics of A. aegypti and expands the knowledge about the species adaptation. This report confirms the species' ability to lay eggs on the water surface of artificial breeding sites in the field and suggests the hypothesis that pheromones in the water may influence the females to lay eggs on water.

Performance of Trichogramma japonicum under field conditions as a function of the factitious host species used for mass rearing.

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.

Cold storage-mediated rearing of Trichogramma evanescens Westwood on eggs of Plodia interpunctella (Hübner) and Galleria mellonella L.

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.

Regulating the expression of gene drives is key to increasing their invasive potential and the mitigation of resistance.

Homing-based gene drives use a germline source of nuclease to copy themselves at specific target sites in a genome and bias their inheritance. Such gene drives can be designed to spread and deliberately suppress populations of malaria mosquitoes by impairing female fertility. However, strong unintended fitness costs of the drive and a propensity to generate resistant mutations can limit a gene drive's potential to spread. Alternative germline regulatory sequences in the drive element confer improved fecundity of carrier individuals and reduced propensity for target site resistance. This is explained by reduced rates of end-joining repair of DNA breaks from parentally deposited nuclease in the embryo, which can produce heritable mutations that reduce gene drive penetrance. We tracked the generation and selection of resistant mutations over the course of a gene drive invasion of a population. Improved gene drives show faster invasion dynamics, increased suppressive effect and later onset of target site resistance. Our results show that regulation of nuclease expression is as important as the choice of target site when developing a robust homing-based gene drive for population suppression.

Effect of dry heating on egg white powder influencing water mobility and intermolecular interactions of its gels.

BACKGROUND: Dry heat processing remains the most promising and simple approach for achieving better gelling properties of spray-dried egg white powder (EWP). Water mobility and intermolecular interactions in gels derived from EWP were investigated after subjecting EWP to various dry heating times (0-21 days). RESULTS: The gel hardness and water-holding capacity significantly increased with an increase in dry heating time (P < 0.05), and both parameters were positively correlated with gel transparency. In contrast to the coarser structure of untreated EWP gel, the gel of EWP corresponding to 15 days of dry heating time had a fine-stranded and orderly network structure with smaller pores. An increase in the binding force between the gel and water was observed with an increase in dry heating time due to the formation of more 'protein-water' hydrogen bonds. Increasing the dry heating time resulted in an increase in the contribution of disulfide bonds, which in turn made a significant contribution to the rigidity of the EWP gels. By contrast, a decrease in the contribution of ionic bonds and hydrophobic interactions upon increasing the dry heating time promoted the formation of orderly networks. CONCLUSIONS: Overall, gel corresponding to EWP dry heating for 15 days had better gel properties, the highest transparency and water-holding capacity, as well as a fine-stranded and orderly network structure. These results provide more information on improvement of the gel properties of EWP through dry heat treatment. © 2020 Society of Chemical Industry.

Maintenance of Life Cycle Stages of Fasciola hepatica in the Laboratory.

Fasciola hepatica has a heteroxenous complex life cycle that alternates between an invertebrate intermediate and a mammalian definitive host. The life cycle has five well-defined phases within their hosts and the environment: (1) eggs released from the vertebrate host to the environment and its subsequent development; (2) emergence of miracidia and their search and penetration into an intermediate snail host; (3) development and multiplication of larval stages within the snail; (4) emergence of cercariae and the encystment in metacercariae; and (5) ingestion of infective metacercariae by the definitive host and development to its adult form. Here we describe some protocols to obtain and maintain different developmental stages of F. hepatica in the laboratory for different applications (molecular/cellular biology studies, vaccination trials, etc.).

Testing Albendazole Resistance in Fasciola hepatica.

The egg development test is a useful in vitro tool to detect albendazole (ABZ) resistance in Fasciola hepatica. ABZ is the only flukicidal compound with ovicidal activity. The described test is based on the ABZ capacity to affect parasite egg development and hatching in susceptible parasites, while this effect is lost in ABZ-resistant liver fluke isolates. Among many advantages, it is noted that the diagnostic test can be performed on eggs isolated from fecal samples (sheep and cattle), avoiding the sacrifice of animals necessary in controlled efficacy trials. The egg development test described here is a simple, inexpensive, and accessible method, previously employed for diagnosis of ABZ resistance in F. hepatica.

Suitability of Chinese oak silkworm eggs for the multigenerational rearing of the parasitoid Trichogramma leucaniae.

Trichogramma leucaniae is believed to be an efficient biological control agent for controlling the soybean pod borer [SPB; Leguminivora glycinivorella]. The large eggs of Chinese oak silkworm, Antheraea pernyi, are one of the best alternative host for mass production of Trichogramma. However, they are considered poor host for the growth and development of T. leucaniae. Here, we determine the feasibility of successive rearings of T. leucaniae on the large eggs for eight generations and evaluated their capacity of parasitizing SPB eggs of different ages. In the first four generations, the suitability of T. leucaniae reared on large eggs exhibited a significant increasing tendency and then decreased with the successive generations thereafter. The percentage of parasitized eggs and number of emerged adults per egg were increased from 40.0% and 10.8 adults/egg in F1 generation to 86.7% and 36.4 adults/egg in F4 generation respectively. In addition, T. leucaniae reared on A. pernyi for four generations significantly parasitized more SPB eggs regardless of egg age compared with those reared on Corcyra cephalonica eggs. These results provided useful information on the feasibility of mass production of T. leucaniae by reared for successive generations on A. pernyi large eggs.

Determination of Eight Coccidiostats in Eggs by Liquid-Liquid Extraction-Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

A method for the simultaneous determination of robenidine, halofuginone, lasalocid, monensin, nigericin, salinomycin, narasin, and maduramicin residues in eggs by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The sample preparation method used a combination of liquid-liquid extraction (LLE) and solid-phase extraction (SPE) technology to extract and purify these target compounds from eggs. The target compounds were separated by gradient elution using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC). Tandem mass spectrometry was used to quantitatively and qualitatively analyze the target compounds via electrospray ionization (ESI+) and multiple reaction monitoring mode. The HPLC-MS/MS and UPLC-MS/MS methods were validated according to the requirements defined by the European Union and the Food and Drug Administration. The limits of detection and limits of quantification of the eight coccidiostats in eggs were 0.23-0.52 µg/kg and 0.82-1.73 µg/kg for HPLC-MS/MS, and 0.16-0.42 µg/kg and 0.81-1.25 µg/kg for UPLC-MS/MS, respectively. The eggs were spiked with four concentrations of the eight coccidiostats, and the HPLC-MS/MS and UPLC-MS/MS average recoveries were all higher than 71.69% and 72.26%, respectively. Compared with the HPLC-MS/MS method, utilizing UPLC-MS/MS had the advantages of low reagent consumption, a short detection time, and high recovery and precision. Finally, the HPLC-MS/MS and UPLC-MS/MS methods were successfully applied to detect eight coccidiostats in 40 eggs.

Efficacy of silver nanoparticles against the adults and eggs of monogenean parasites of fish.

Monogeneans are a diverse group of parasites that are commonly found on fish. Some monogenean species are highly pathogenic to cultured fish. The present study aimed to determine the in vitro anthelmintic effect of silver nanoparticles (AgNPs) against adults and eggs of monogeneans in freshwater using Cichlidogyrus spp. as a model organism. We tested two types of AgNPs with different synthesis methodologies and size diameters: ARGOVIT (35 nm) and UTSA (1-3 nm) nanoparticles. Damage to the parasite tegument was observed by scanning electron microscopy. UTSA AgNPs were more effective than ARGOVIT; in both cases, there was a concentration-dependent effect. A concentration of 36 µg/L UTSA AgNPs for 1 h was 100% effective against eggs and adult parasites, causing swelling, loss of corrugations, and disruption of the parasite's tegument. This is an interesting result considering that monogenean eggs are typically tolerant to antiparasite drugs and chemical agents. To the best of our knowledge, no previous reports have assessed the effect of AgNPs on any metazoan parasites of fish. Therefore, the present work provides a basis for future research on the control of fish parasite diseases.

Chicken eggs as a surveillance tool for malaria and leishmaniasis vector presence.

INTRODUCTION: Malaria and leishmaniases are transmitted by vectors during blood-feeding. Vector-infected animals develop antibodies against the vector's saliva. This study evaluated IgY antibody detection in the chicken eggs exposed to bites from Migonemyia migonei, Lutzomyia longipalpis and Anopheles aquasalis. METHODS: We used ELISA to quantify the antibody levels in the sera and exposed chicken eggs. RESULTS: High IgY levels were observed following immunization; furthermore, higher reactivity was observed in the eggs and species-specific immune response was observed post final immunization. CONCLUSIONS: Chicken eggs can be used as sentinels to surveil vector saliva antibodies.

Chicken eggs as a surveillance tool for malaria and leishmaniasis vector presence

Abstract INTRODUCTION: Malaria and leishmaniases are transmitted by vectors during blood-feeding. Vector-infected animals develop antibodies against the vector's saliva. This study evaluated IgY antibody detection in the chicken eggs exposed to bites from Migonemyia migonei, Lutzomyia longipalpis and Anopheles aquasalis. METHODS: We used ELISA to quantify the antibody levels in the sera and exposed chicken eggs. RESULTS: High IgY levels were observed following immunization; furthermore, higher reactivity was observed in the eggs and species-specific immune response was observed post final immunization. CONCLUSIONS: Chicken eggs can be used as sentinels to surveil vector saliva antibodies.

Toxoplasma gondii infection and food consumption: A systematic review and meta-analysis of case-controlled studies.

BACKGROUND: Toxoplasmosis is a zoonotic disease causing severe symptoms in pregnant women and immunocompromised individuals. On average, worldwide, around 30% of people are seropositive. The oral transmission route is of great significance and food, particularly meat, is an important transmission vehicle for T. gondii. However, the role of different food matrices is debated. OBJECTIVES: The aim of this review was to assess the risk of humans developing acute T. gondii infection via the foodborne route. STUDY ELIGIBILITY CRITERIA: Case-control studies including acute cases of T. gondii infection were included after literature searches, without time limits, in several databases. All studies estimating the risk of acquiring T. gondii infection after consumption of specific food categories were included. RESULTS: Three risk factors proved to be significantly associated with acute T. gondii infection in humans: consumption of raw/undercooked meat, Odds Ratio (OR) 3.44 (1.29-9.16), consumption of raw/undercooked beef, OR 2.22 (1.57-3.12), and consumption of raw/undercooked sheep meat, OR 3.85 (1.85-8.00). Consumption of raw/undercooked pork, raw eggs, and unpasteurized milk proved to be non-significant risk factors. LIMITATIONS: Limitations in the present review and meta-analysis are due to the low number of case-control studies available for analysis and the lack of a search strategy targeting gray literature. CONCLUSION: Consumption of raw/undercooked beef and sheep meat are important risk factors for T. gondii infection. Their consumption should be avoided in order to prevent toxoplasmosis, particularly by those in at-risk categories, including pregnant women. The review protocol is registered in PROSPERO database (CRD42016043295).

Evaluation of the immunogenicity of Schistosoma mansoni egg surface.

INTRODUCTION: Immunogenicity of Schistosoma mansoni egg surface was examined to determine whether intact eggshells have lower antigenicity than ruptured eggs. METHODS: Swiss Webster mice were inoculated with intact or ultrasonicated S. mansoni eggs isolated from infected human feces. Mice were separated into four groups of six animals each and immunizations were performed approximately every 20 days during a 60-day period. Groups 1-4 were administered with saline solution, sonicated eggs with Freund's adjuvant, sonicated eggs without Freund's adjuvant, and intact eggs, respectively. IgG humoral immune response was assessed by ELISA using Soluble Egg Antigen produced from eggs isolated from the livers of infected mice. RESULTS: Sonicated eggs co-administered with adjuvant induced the highest humoral response at 58 days, which was 11.9-fold (95% CI 6.2-17.5) greater than the response induced by saline solution. Sonicated eggs without adjuvant induced a 4.3-fold stronger response (95% CI 2.4-6.2) than normal saline. Intact eggs induced humoral response that was nominally twice stronger (95% CI 0.8-3.2) than that induced by normal saline but the effect did not reach statistical significance. CONCLUSIONS: Soluble antigens are not abundant on the surface of S. mansoni eggs and/or are not secreted in sufficient quantities to induce a significant immune response to intact eggs. Assuming that isolation procedures had not damaged the eggs used for inoculation, our observations suggest that intact eggs either do not induce a significant immune response or, if they do, the mechanism involves insoluble antigens from the egg surface.

Evaluation of the immunogenicity of Schistosoma mansoni egg surface

Abstract INTRODUCTION Immunogenicity of Schistosoma mansoni egg surface was examined to determine whether intact eggshells have lower antigenicity than ruptured eggs. METHODS: Swiss Webster mice were inoculated with intact or ultrasonicated S. mansoni eggs isolated from infected human feces. Mice were separated into four groups of six animals each and immunizations were performed approximately every 20 days during a 60-day period. Groups 1-4 were administered with saline solution, sonicated eggs with Freund's adjuvant, sonicated eggs without Freund's adjuvant, and intact eggs, respectively. IgG humoral immune response was assessed by ELISA using Soluble Egg Antigen produced from eggs isolated from the livers of infected mice. RESULTS Sonicated eggs co-administered with adjuvant induced the highest humoral response at 58 days, which was 11.9-fold (95% CI 6.2-17.5) greater than the response induced by saline solution. Sonicated eggs without adjuvant induced a 4.3-fold stronger response (95% CI 2.4-6.2) than normal saline. Intact eggs induced humoral response that was nominally twice stronger (95% CI 0.8-3.2) than that induced by normal saline but the effect did not reach statistical significance. CONCLUSIONS Soluble antigens are not abundant on the surface of S. mansoni eggs and/or are not secreted in sufficient quantities to induce a significant immune response to intact eggs. Assuming that isolation procedures had not damaged the eggs used for inoculation, our observations suggest that intact eggs either do not induce a significant immune response or, if they do, the mechanism involves insoluble antigens from the egg surface.

Poultry red mite (Dermanyssus gallinae) infestation: a broad impact parasitological disease that still remains a significant challenge for the egg-laying industry in Europe.

The poultry red mite, Dermanyssus gallinae, has been described for decades as a threat to the egg production industry, posing serious animal health and welfare concerns, adversely affecting productivity, and impacting public health. Research activities dedicated to controlling this parasite have increased significantly. Their veterinary and human medical impact, more particularly their role as a disease vector, is better understood. Nevertheless, red mite infestation remains a serious concern, particularly in Europe, where the prevalence of red mites is expected to increase, as a result of recent hen husbandry legislation changes, increased acaricide resistance, climate warming, and the lack of a sustainable approach to control infestations. The main objective of the current work was to review the factors contributing to this growing threat and to discuss their recent development in Europe. We conclude that effective and sustainable treatment approach to control poultry red mite infestation is urgently required, included integrated pest management.

Correlation between the proportion of stained eggs and the number of mites (Dermanyssus gallinae) monitored using a 'non-parallel board trap'.

The poultry red mite (Dermanyssus gallinae) is a serious problem for the poultry industry worldwide. However, the relationship between the mite population and the damage that they cause is still unclear. In this study, the mite population in poultry houses was examined using an established trap method, and the risk of blood-stained eggs caused by the mites was assessed. Traps were placed once a week outside the egg channels and/or on the floor in two poultry farms in Fukuoka Prefecture, Japan, from April 2012 to July 2014. The numbers of blood-stained eggs and total eggs were counted at weekly intervals. The results showed that the number of mites increased from April to May, and reached a peak around the beginning of June when the average temperature and humidity were >24°C and 70-90%, respectively. In the segmented model, the correlation between the proportion of blood-stained eggs and the number of mites or temperature was positive over a threshold. In conclusion, our established trap method is useful for monitoring mites and can be used to predict when poultry farms should be treated to prevent appearance of blood-stained eggs.

A new species of Carcinonemertes, Carcinonemertes conanobrieni sp. nov. (Nemertea: Carcinonemertidae), an egg predator of the Caribbean spiny lobster, Panulirus argus.

A new species of nemertean worm belonging to the genus Carcinonemertes is described from egg masses of the Caribbean spiny lobster Panulirus argus from the Florida Keys, Florida, USA. This is the first species of Carcinonemertes reported to infect P. argus or any other lobster species in the greater Caribbean and western Atlantic Ocean. Carcinonemertes conanobrieni sp. nov. varies in body color from a translucent white to a pale orange, with males ranging in total body length from 2.35 to 12.71 mm and females ranging from 0.292 to 16.73 mm. Among the traits that separate this new species from previously described species in the genus Carcinonemertes are a relatively wide stylet basis, minimal sexual size dimorphism, and a unique mucus sheath decorated with external hooks. Also, juvenile worms were found to encyst themselves next to lobster embryos and female worms lay both long strings of eggs wound throughout the lobster's setae as well as spherical cases that are attached to lobster embryos. The stylet length and stylet basis remain unchanged throughout ontogeny for both male and female worms. Maximum likelihood and Bayesian inference phylogenetic analyses separated this newly described species from all other species of Carcinonemertes with available COI sequences. Carcinonemertes spp. are voracious egg predators and have been tied to the collapse of various crustacean fisheries. The formal description of this new species represents the first step to understand putative impacts of this worm on the population health of one of the most lucrative yet already depressed crustacean fisheries.

Quantitative PCR and Digital PCR for Detection of Ascaris lumbricoides Eggs in Reclaimed Water.

The reuse of reclaimed water from wastewater depuration is a widespread and necessary practice in many areas around the world and must be accompanied by adequate and continuous quality control. Ascaris lumbricoides is one of the soil-transmitted helminths (STH) with risk for humans due to its high infectivity and an important determinant of transmission is the inadequacy of water supplies and sanitation. The World Health Organization (WHO) recommends a limit equal to or lower than one parasitic helminth egg per liter, to reuse reclaimed water for unrestricted irrigation. We present two new protocols of DNA extraction from large volumes of reclaimed water. Quantitative PCR (qPCR) and digital PCR (dPCR) were able to detect low amounts of A. lumbricoides eggs. By using the first extraction protocol, which processes 500 mL of reclaimed water, qPCR can detect DNA concentrations as low as one A. lumbricoides egg equivalent, while dPCR can detect DNA concentrations as low as five A. lumbricoides egg equivalents. By using the second protocol, which processes 10 L of reclaimed water, qPCR was able to detect DNA concentrations equivalent to 20 A. lumbricoides eggs. This fact indicated the importance of developing new methodologies to detect helminth eggs with higher sensitivity and precision avoiding possible human infection risks.