RESUMEN

Small-scale farming of edible insects could help combat public health challenges such as protein energy malnutrition and anemia, but reliable low-cost feeds for insects are needed. In resource-limited contexts, where grains such as maize are prohibitively costly for use as insect feed, the feasibility of insect farming may depend on finding alternatives. Here, we explore the potential to modify plentiful maize crop residue with edible mushroom mycelium to generate a low-cost feed adjunct for the farmed two-spotted cricket, Gryllus bimaculatus. Mushroom farming, like insect agriculture, is versatile; it can yield nutritious food while increasing system circularity by utilizing lignocellulosic residues from row crops as inputs. Pleurotus ostreatus, is an edible basidiomycete capable of being cultivated on corn stover (Zea mays). Mushroom harvest results in abundant "spent" substrate, which we investigated as a candidate feed ingredient. We created six cricket feeds containing fermented Pleurotus substrate plus an unfermented control, measuring cricket mass, mortality, and maturation weekly to evaluate cricket growth performance impacts of both fungal fermentation duration and mushroom formation. Pasteurized corn stover was inoculated with P. ostreatus mycelium and fermented for 0, 2, 3, 4, or 8 weeks. Some 4 and 8-week substrates were induced to produce mushrooms through manipulations of temperature, humidity, and light conditions. Dried fermented stover (40%) was added to a 1:1 corn/soy grain mix and fed to crickets ad libitum for 44 days. The unfermented control group showed higher survivorship compared to several fermented diets. Control group mass yield was higher for 2 out of 6 fermented diets. Little variation in cricket iron content was observed via ICP-spectrometry across feeds, averaging 2.46 mg/100 g. To determine bioavailability, we conducted in vitro Caco-2 human colon epithelial cell absorption assays, showing that iron in crickets fed fruiting-induced substrates was more bioavailable than in unfruited groups. Despite more bioavailable iron in crickets reared on post-fruiting substrates, we conclude that Pleurotus-fermented stover is an unsuitable feed ingredient for G. bimaculatus due to high mortality, variability in growth responses within treatments, and low mass yield.

RESUMEN

Gryllus bimaculatus (De Geer) is a large-bodied cricket distributed throughout Africa and Southern Eurasia where it is often wild-harvested as human food. Outside its native range, culturing G. bimaculatus is feasible due to its dietary plasticity, rapid reproductive cycle, lack of diapause requirement, tolerance for high-density rearing, and robustness against pathogens. Thus, G. bimaculatus can be a versatile model for studies of insect physiology, behavior, embryology, or genetics. Cultural parameters, such as stocking density, within-cage refugia, photoperiod, temperature, relative humidity, and diet, all impact cricket growth, behavior, and gene expression and should be standardized. In the burgeoning literature on farming insects for human consumption, these crickets are frequently employed to evaluate candidate feed admixtures derived from crop residues, food-processing byproducts, and other low-cost waste streams. To support ongoing experiments evaluating G. bimaculatus growth performance and nutritional quality in response to variable feed substrates, a comprehensive set of standard protocols for breeding, upkeep, handling, measurement, and euthanasia in the laboratory was developed and is presented here. An industry-standard cricket feed has proven nutritionally adequate and functionally appropriate for the long-term maintenance of cricket breeding stocks, as well as for use as an experimental control feed. Rearing these crickets at a density of 0.005 crickets/cm3 in screen-topped 29.3 L polyethylene cages at an average temperature of 27 °C on a 12 light (L)/12 dark (D) photoperiod, with moistened coconut coir serving both as hydration source and oviposition medium has successfully sustained healthy crickets over a 2-year span. Following these methods, crickets in a controlled experiment yielded an average mass of 0.724 g 0.190 g at harvest, with 89% survivorship and 68.2% sexual maturation between stocking (22 days) and harvest (65 days).

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RESUMEN

Con el propósito de desarrollar un protocolo para la multiplicación del clon de banano ´FHIA-18´ (AAAB) en sistema de inmersión temporal, se definieron como objetivos del trabajo determinar el efecto del tiempo (5, 10 y 15 minutos) y la frecuencia de inmersión (3, 6 y 8 horas por día), así como la influencia de diferentes combinaciones de reguladores del crecimiento (2,0; 3,0 y 4,0 mg.L-1 de 6-BAP y 2,0; 2,5; 3,0; 3,5 y 4,0 mg.L-1 de 6 AIA), el efecto del volumen de medio de cultivo por planta (20, 30, 40 y 50 ml/explante) y la densidad de explantes por frasco de cultivo (30, 50, 70 y 90 explantes/frasco) para incrementar el coeficiente de multiplicación. Con el empleo de un tiempo de 10 minutos y una frecuencia de inmersión cada tres horas, se alcanzaron los mejores resultados en cuanto al número de explantes obtenidos. Con este tiempo y frecuencia de inmersión los explantes presentaron el mayor diámetro del pseudotallo. Para cada frasco de 10,0 L se inocularon 70 explantes y la renovación con 2800 ml de medio de cultivo (40 ml/explante) con un tiempo de cultivo de 21 días permitió alcanzar la mayor productividad del material en fase de multiplicación. Además al utilizar las sales MS suplementadas con 3,0 mg.L-1 de 6-BAP; 2,0 mg.L-1 de AIA; 10,0 mg.L-1 de ácido ascórbico, se logró disminuir el crecimiento innecesario de los tallos y hojas de los brotes en la fase de multiplicación y por lo tanto un mayor número de explantes.

In order to develop a protocol for multiplication of Banana clone 'FHIA-18' (AAAB) in temporary immersion systems, the following working objectives were defined: to determine the effect of immersion time (5, 10 and 15 minutes) and frequency (3, 6 and 8 hours per day), as well as, the influence of different combinations of growth regulators (2,0; 3,0 and 4,0 mg.L-1 de 6-BAP and 2,0; 2,5; 3,0; 3,5 and 4,0 mg.L-1 de 6 AIA), the volume effect of culture medium plants (20, 30, 40 and 50 ml/explant) and explants density per culture flask (30, 50, 70 y 90 explants/flask) to increase the multiplication coefficient. With 10 minutes immersion time and an immersion frequency every three hours, the best results were achieved in relation to the number of explants obtained. With this immersion time and frequency, explants showed the highest pseudostem diameter. Seventy explants were inoculated in each 10,0 L culture flask. The highest productivity at the multiplication phase was achieved with a culture medium renewal of 2800 ml (40 ml/explants), and a 21 day culture time. In addition to using MS salts supplemented with 3.5 mg.L-1 of 6-BAP, 1.30 mg.L-1 of IAA, 10.0 mg.L-1 ascorbic acid, the unnecessary growth of stems and leaves of shoots in the multiplication phase was reduced and; therefore, a greater number per explant.

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