Active and Covert Infections of Cricket Iridovirus and Acheta domesticus Densovirus in Reared Gryllodes sigillatus Crickets

Interest in developing food, feed, and other useful products from farmed insects has gained remarkable momentum in the past decade. Crickets are an especially popular group of farmed insects due to their nutritional quality, ease of rearing, and utility. However, production of crickets as an emerging commodity has been severely impacted by entomopathogenic infections, about which we know little. Here, we identified and characterized an unknown entomopathogen causing mass mortality in a lab-reared population of Gryllodes sigillatus crickets, a species used as an alternative to the popular Acheta domesticus due to its claimed tolerance to prevalent entomopathogenic viruses. Microdissection of sick and healthy crickets coupled with metagenomics-based identification and real-time qPCR viral quantification indicated high levels of cricket iridovirus (CrIV) in a symptomatic population, and evidence of covert CrIV infections in a healthy population. Our study also identified covert infections of Acheta domesticus densovirus (AdDNV) in both populations of G. sigillatus. These results add to the foundational research needed to better understand the pathology of mass-reared insects and ultimately develop the prevention, mitigation, and intervention strategies needed for economical production of insects as a commodity.

PROTEÍNAS DE INSETOS: FONTE DE PEPTÍDEOS BIOATIVOS

Introdução: A entomofagia, isto é, a prática de comer insetos, vem crescendo ao longo dos últimos anos devido ao baixo impacto ambiental, elevado valor nutricional e potenciais benefícios à saúde. A composição nutricional destes animais varia de acordo com a espécie, estágio de desenvolvimento, origem, alimentação, entre outros fatores. Estes alimentos apresentam elevado teor proteico (atingido valores de até 61%) de alta qualidade nutricional com um adequado perfil de aminoácidos essenciais. Em paralelo, a hidrólise enzimática de proteínas vem sendo aplicada visando a geração de peptídeos com relevantes propriedades biológicas, como exemplo, atividade antioxidante, antidiabética, anti-hipertensiva, antimicrobiana e outras. Objetivo: Neste contexto, essa revisão apresenta o potencial de insetos comestíveis, como substrato proteico para a produção de peptídeos bioativos. Materiais e Métodos: O processo metodológico adotado foi a pesquisa bibliográfica em bases acadêmicas virtuais (Scoups, Scielo e Google acadêmico) utilizando as palavras chaves: “insetos comestíveis”, “peptídeos bioativos”, “hidrólise enzimática de insetos comestíveis” para obtenção de artigos científicos publicados nos últimos 5 anos. As proteínas de insetos comestíveis são fontes de peptídeos bioativos. Resultados: Geralmente, esses pequenos fragmentos são formados por menos de 20 resíduos de aminoácidos com massa molecular <6 kDa. Pesquisadores sugerem que os peptídeos com massa molecular menor que 1kDa são melhores para incorporação em alimentos, devido à melhor absorção na forma intacta pelo sistema circulatório. Dentre os principais insetos com potencial de geração de peptídeos bioativos, destacam-se os peptídeos obtidos do Grilo (Amphiacusta annulipes) e do tenébrio gigante (Zophobasmorio) com capacidade antioxidante, os peptídeos do gafanhoto-do-deserto (Schistocerca gregária) e da larva-da-farinha (Tenebrio molitor) com bioatividade anti-hipertensiva e os peptídeos do grilo-doméstico tropical (Gryllodes sigillatus) desempenhando atividade antioxidante, antidiabética e anti-hipertensiva. Conclusão: Desta forma, a hidrólise enzimática das proteínas de insetos possibilita a obtenção de peptídeos bioativos, podendo estes serem utilizados em formulações alimentícias ou em nutracêuticos. Neste sentido, outros estudos vem sendo conduzidos para o desenvolvimento de técnicas de incorporação desses peptídeos em diferentes matrizes alimentícias.

Desde Cundinamarca. Harina de grillo: gastronomía y sostenibilidad para Colombia y el mundo

La incorporación de harina de grillo, como ingrediente en la cocina, trae diversos beneficios nutricionales y ambientales. Este ingrediente innovador se valora especialmente por su notorio contenido de proteínas y aminoácidos esenciales; además, su producción tiene un impacto ambiental mínimo, por lo que se considera una fuente proteica sostenible. Los desafíos ambientales que se viven en la actualidad y las proyecciones de crecimiento de la población plantean diversas problemáticas y, a su vez, impulsan la creación de estrategias innovadoras y disruptivas orientadas a mitigar las consecuencias negativas de un sistema de producción de alimentos no sostenible. Por tales razones, en este libro se plantea la utilización de la harina de grillo en la cocina de Cundinamarca, un departamento de Colombia, ubicado en el centro del país, en la región andina, que se caracteriza por su biodiversidad y condiciones ambientales que favorecen la actividad agrícola. En efecto, en las regiones con climas cálidos de este departamento se encuentra la especie de grillo Gryllodes sigillatus (Walker) con base en la cual en la actualidad se está produciendo harina para uso alimentario, un ingrediente versátil que puede ser incluido en diversas preparaciones gastronómicas. El presente libro cuenta con un amplio recetario en el que el lector descubrirá cómo la harina de grillo puede aportar al desarrollo de una alimentación saludable y sostenible.

Molecular approach for insect detection in feed and food: the case of Gryllodes sigillatus

The production of insects on an industrial scale has attracted the attention of the research and agricultural industry as novel protein sources. To detect the presence of Gryllodes sigillatus (GS) in feed and food, a real-time PCR method based on the mitochondrial cytochrome b (CYB) gene is proposed by this study. Forty DNA samples of animal and plant origin were used to confirm the specificity of the qPCR system. The detection method’s performance was evaluated on different processed GS matrices including native GS (UnGS) and different commercial products: crunchy roasted samples (RoGS), insect meal mixtures (ACGS) and energetic snacks containing GS (GSS). Data on sequencing were aligned with the reference gene to confirm the PCR products. The regression curve (y = −3.394 x + 42.521; R2 = 0.994, d.f. 14) between Ct values and Log DNA concentrations of Gryllodes sigillatus resulted in an efficiency of 96.4%. The severity of the technological processing treatments and the matrix structure affected the intensity of the PCR signal with the same amount of insect DNA as observed by different y-intercepts of the three-regression lines for RoGS, ACGS, and GSS. The real-time PCR method resulted in robust and sensitive outcomes able to detect low amounts of GS DNA (5 g/100 g) in a complex matrix, making it suitable for detecting the presence or absence of labeled Gryllodes sigillatus material both in feed and food.

The effects of exposure to predators on personality and plasticity

Past experiences are known to affect average behavior but effects on “animal personality”, and plasticity are less well studied. To determine whether experience with predators influences these aspects, we compared the behavior of Gryllodes sigillatus before and after exposure to live predators. We found that emergence from shelter and distance moved during open-field trials (activity) changed after exposure, with individuals becoming less likely to emerge from shelters but more active when deprived of shelter. We also found that plasticity in activity increased after exposure to predators and some indications that differences among individuals (i.e. “personality”) in emergence from shelter and the amount of an arena investigated increased after exposure. Our results demonstrate that experience with predators affects not only the average behavior of individuals but also how individuals differ from each other—and their own prior behavior—even when all individuals have the same experiences.

Cricket (Gryllodes sigillatus) meal fed to healthy adult dogs does not affect general health and minimally impacts apparent total tract digestibility

Insects can serve as a novel high-quality protein source for pet foods. However, there is an absence of research investigating the use of insects in pet food. The study objective was to evaluate the apparent total tract digestibility and possible health effects of diets containing graded levels of cricket (Gryllodes sigillatus) meal fed to healthy adult dogs. Thirty-two adult Beagles were randomly assigned to one of four dietary treatments: 0%, 8%, 16%, or 24% cricket meal. Dogs were fed their respective diet for a total of 29 d with a 6-d collection phase. Fecal samples were collected daily during the collection phase to measure total fecal output as well as apparent total tract digestibility for dry matter (DM), organic matter, crude protein, fat, total dietary fiber, and gross energy. Blood samples were taken prior to the study and on day 29 for hematology and chemistry profiles. Data were analyzed in a mixed model including the fixed effects of diet and sex. Total fecal output increased on both an as-is (P = 0.030) and DM basis (P = 0.024). The apparent total tract digestibility of each nutrient decreased (P &lt; 0.001) with the increasing level of cricket meal inclusion. All blood values remained within desired reference intervals indicating healthy dogs. Slight fluctuations in blood urea nitrogen (P = 0.037) and hemoglobin (P = 0.044) levels were observed but were not considered of biological significance. Even with the decrease in digestibility with the inclusion of cricket meal, diets remained highly digestible at greater than 80% total apparent digestibility. In conclusion, crickets were demonstrated to be an acceptable ingredient for dog diets.