Search Results (8)

Watermeal (Wolffia globosa) is an emerging sustainable feed ingredient, valued for its rapid growth, high protein content, and rich nutrient profile, offering great potential to improve the efficiency and sustainability of edible cricket production systems through efficient resource use and reduced environmental impact. This study aimed to evaluate the effects of replacing commercial cricket feed with dried watermeal and to determine the optimal substitution level for the production performance of two-spotted crickets (Gryllus bimaculatus). Seven dietary treatments were tested, namely 0% (control; T1), 10% (T2), 25% (T3), 50% (T4), 75% (T5), 90% (T6), and 100% (T7). Crickets were reared for four weeks in an open system with 6 replicates per treatment, with each containing 120 nymphs. Body weight, feed intake, and survival rate were recorded weekly, and a production index was calculated at the end of the trial. Results showed average growth rates ranging from 7.40 to 28.20 mg/day, feed conversion ratios (FCR) between 1.03 and 1.68, survival rates of 29.28% to 69.73%, and production index values from 24.00 to 128.30. A significant decline in production efficiency (p < 0.05) was observed at substitution levels of 75% and above, with the 100% watermeal group showing the lowest production efficiency (p < 0.05), likely due to nutrient imbalances and indigestible compounds. Segmented regression analysis identified 36.7% as the optimal level of watermeal supplementation. In terms of body composition, crickets fed diets containing up to 50% watermeal (10%, 25%, and 50%) showed crude protein, crude fat, crude fiber, and ash contents comparable to those fed the commercial diet. This finding suggests that dried watermeal can replace up to 50% of the commercial cricket feed without negatively affecting growth performance, survival, or nutritional quality, with 36.7% identified as the optimal replacement level for maximizing production efficiency. Full article

This study aimed to determine the influence and optimal conditions of incubation temperature and relative humidity (RH) on the egg hatchability patterns of two-spotted (Gryllus bimaculatus) and house (Acheta domesticus) crickets. Experiment I involved 100 cricket eggs per hatching box for each species, with six replications for each controlled incubation temperature of 23, 25, 27, 29, 30, 31, 32, and 33 °C at 70% RH. Experiment II used all the same procedures as Experiment I, except for incubation temperatures of 29, 30, 31, and 32 °C tested with varied RH levels of 65%, 70%, and 75%. In Experiment I, two-spotted crickets (9.47 ± 1.99 days) exhibited faster hatching than house crickets (13.70 ± 2.78 days). Additionally, the onset of hatching decreased with higher incubation temperatures for both types of crickets. In Experiment II, an incubation temperature of 31 °C and 70% RH resulted in a hatching rate of 79.75% for two-spotted crickets, with hatching beginning in 6 days. For house cricket eggs, the optimal conditions of 30 °C and 65–75% RH led to a peak daily hatching rate of 62.00–65.50% and hatching onset in 12 days. Thus, this study established the optimal incubation temperature and RH for egg hatching of two-spotted and house crickets. Full article

Food safety for cricket production is a crucial factor in producing edible crickets with safety for consumers and sustainability for two-spotted (Gryllus bimaculatus) as well as house (Acheta domesticus) cricket production. This study was conducted by simultaneously rearing two cricket species, comprising two-spotted crickets (G. bimaculatus) and house crickets (A. domesticus). A total of 16 rearing crates were used for the present study, which were allocated into 8 rearing crates for each studied cricket species, including paper egg cartons. Cricket eggs were incubated in the rearing crates. Once the crickets hatched, tap water and powdered feed were provided ad libitum throughout the experiment. At the end of this study (35 and 42 days for the two-spotted and house crickets, respectively), all crickets were harvested, rinsed in tap water, and boiled in water for 5 min. During the rearing and harvesting processes, samples were collected from various potential contamination points for bacteria, including E. coli and Salmonella spp. There were samples of the initial input (feed, drinking water, and staff hands), rearing environment (water pipe, crate wall, living cartons, frass, and cricket surface), and harvesting crickets (harvested, washed, and boiled crickets), with a 2-week sampling interval, except for the last round of sampling for the two-spotted crickets. Subsequently, all samples were submitted to isolate and identify contaminated bacteria. The samples from the last round of sampling for both kinds of crickets were submitted to quantify the level of contamination for E. coli and Salmonella spp., including antimicrobial resistance by the disk diffusion method for the positive isolate. The results showed that bacterial contamination was found in the rearing of both cricket species, primarily involving Klebsiella spp. and Enterobacter spp., mainly found in prepared drinking water and the water pipes of drinking water supply equipment, which are potential sources of contamination with cricket frass. E. coli was found in 4.8% and 4.3% of the two-spotted and house crickets, respectively, while no presence of Salmonella spp. was detected in any submitted samples. The quantification of E. coli and Salmonella spp. indicated E. coli contamination near the water pipe and the frass of two-spotted crickets, but Salmonella spp. was undetectable in both two-spotted and house crickets. The antimicrobial resistance of isolated E. coli mainly involved penicillin G, amoxicillin, ampicillin, erythromycin, lincomycin, and tiamulin. Thus, good farm management with proper sanitation practices (such as cleaning and keeping the environment dry), as well as boiling crickets during the harvesting process, may help ensure the safety of edible cricket production. Full article

This study aimed to investigate the potential of using field two-spotted cricket Gryllus bimaculatus as the main protein source in fish feed for striped snakehead (Channa striata) juveniles. A 10-week feeding effect on growth performance, feed utilization, digestibility of major nutrients, including amino acids, and physiological outputs of nitrogen and phosphorus were determined. A total of 225 C. striata juvenile fish (Initial weight, 15.0 ± 0.1 g) were randomly distributed into three dietary groups in triplicate (25 fish per rectangular aquarium within a semi-recirculating system). Each group was hand-fed one of the experimental diets containing the graded level of a cricket meal (CM) replacing 0%, 50%, and 100% (CM_0%, CM_50%, and CM_100%, respectively) of fish meal (FM) protein component. The results showed that growth performance and protein retention tended to increase with increasing dietary CM levels, whereas the waste outputs of nitrogen (N) and phosphorus (P) decreased. Apparent net protein utilization (ANPU) and P retention values increased with increasing levels of cricket meal inclusion level in the diet. There was a significant reduction in both N and P solid waste and dissolved waste output for snakehead with increased CM inclusion. There were significant effects of CM level on fish whole-body composition in terms of elevated protein and fat content. In conclusion, the CM is a viable alternative protein source for aquaculture feeds and can be included up to 100% as a replacement for FM without compromising the growth performance of striped snakehead Channa striata juveniles. This may also have a more favorable impact, with the potential to reduce N and P loading to the environment. Full article

Genome annotation is critically important data that can support research. Draft genome annotations cover representative genes; however, they often do not include genes that are expressed only in limited tissues and stages, or genes with low expression levels. Neuropeptides are responsible for regulation of various physiological and biological processes. A recent study disclosed the genome draft of the two-spotted cricket Gryllus bimaculatus, which was utilized to understand the intriguing physiology and biology of crickets. Thus far, only two of the nine reported neuropeptides in G. bimaculatus were annotated in the draft genome. Even though de novo assembly using transcriptomic analyses can comprehensively identify neuropeptides, this method does not follow those annotations on the genome locus. In this study, we performed the annotations based on the reference mapping, de novo transcriptome assembly, and manual curation. Consequently, we identified 41 neuropeptides out of 43 neuropeptides, which were reported in the insects. Further, 32 of the identified neuropeptides on the genomic loci in G. bimaculatus were annotated. The present annotation methods can be applicable for the neuropeptide annotation of other insects. Furthermore, the methods will help to generate useful infrastructures for studies relevant to neuropeptides. Full article

Neuropeptides play vital roles in energy homeostasis in insects and other animals. Although the importance of the regulatory network of neuropeptides in feeding and metabolism has been illuminated, a complete understanding of the mechanisms has not been addressed as many factors are involved in the regulation. CCHamide-2 is a newly identified brain-gut neuropeptide that regulates feeding behavior in several insect species including Drosophila melanogaster. However, little is known about the mechanisms controlling the feeding-related behavior and metabolic functions modulated by CCHamide-2 in other insects. In this study, we addressed the functions of CCHamide-2 in the two-spotted cricket, Gryllus bimaculatus, which was used as the experimental material to research the mechanisms of feeding and metabolism in this omnivorous insect species. Knockdown crickets by RNA interference against GbCCHamide-2R increased the amount of food intake, while injection of chemically synthetic GbCCHamide-2 peptide reduced the amount of food intake. Further, knockdown and peptide injection experiments revealed that GbCCHamide-2 signaling increased the concentrations of circulating lipids and carbohydrates, and the carbohydrate-rich diet increased the transcript levels of GbCCHa-2R. Moreover, GbCCHa-2 injection decreased the transcript level of Gbilp. By contrast, GbCCHamide-2 signaling did not affect nymphal growth or the transcript level of GbAKH, as well as feeding preferences. Taken together, CCHamide-2 signaling in G. bimaculatus regulates food intake associated with alterations in lipid and carbohydrate levels in hemolymph. Full article

Arthropods, including insects, convert sterols into cholesterol due to the inability to synthesise cholesterol de novo. 24-dehydrocholesterol reductase (DHCR24) plays an important role in the conversion. Not only involving the cholesterol biosynthesis in vertebrates, DHCR24 is required for the conversion of desmosterol into cholesterol in phytophagous insects. The current study extensively examined DHCR24 in omnivorous insects, which feed on both plants and animals, using Gryllus bimaculatus as the experimental model. We identified cDNAs encoding two homologues of DHCR24 from G. bimaculatus, which were designated as GbDHCR24-1 and GbDHCR24-2. Both homologues contained the flavin adenine dinucleotide binding domain, which is a feature of DHCR24. Quantitative polymerase chain reaction revealed that among tissues of adult crickets, fat body and anterior midgut expressed high levels of GbDHCR24s. Both fat body and anterior midgut demonstrated DHCR24 activities in which one of the functions is the conversion of desmosterol into cholesterol in vitro. Knockdown of GbDHCR24-1 significantly reduced the conversion activity in the anterior midgut while knockdown of the GbDHCR24-2 did not. Additionally, the accumulation of desmosterol was detected in a feeding experiment with a specific DHCR24 inhibitor, azacosterol. We finally concluded that GbDHCR24-1 is the major enzyme that facilitates the desmosterol-to-cholesterol-conversion in crickets. Full article

Natural pathogen pressure is an important factor that shapes the host immune defense mechanism. The current study primarily aimed to explore the molecular basis of the natural immune defense mechanism of a sporadic pest, Gryllus bimaculatus, during swarming by constructing cDNA libraries of the female mid-gut, male mid-gut, testes, and ovaries. The Illumina HiSeq platform generated an average of 7.9 G, 11.77 G, 10.07 G, and 10.07 G bases of outputs from the male mid-gut, female mid-gut, testes, and ovaries and libraries, respectively. The transcriptome of two-spotted field crickets was assembled into 233,172 UniGenes, which yielded approximately 163.58 million reads. On the other hand, there were 43,055 genes in common that were shared among all the biological samples. Gene Ontology analysis successfully annotated 492 immune-related genes, which comprised mainly Pattern Recognition Receptors (62 genes), Signal modulators (57 genes), Signal transduction (214 genes), Effectors (36 genes), and another immune-related 123 genes. In summary, the identified wide range of immune-related genes from G. bimaculatus indicates the existence of a sophisticated and specialized broad spectrum immune mechanism against invading pathogens, which provides, for the first time, insights into the molecular mechanism of disease resistance among two-spotted field crickets. Full article