Cricket: The third domesticated insect

Preparing eugregarine parasites and their cricket host Acheta domesticus as a model for gregarine infection studies

The increasing global demand for house crickets (Acheta domesticus) necessitates effective health measures. Despite their abundance, the effects of gregarines on these hosts remain underexplored. We present a method for controlled gregarine infection and maintenance of gregarine-free cricket populations. This system, adapted from prior work, is essential for experiments on gregarine infection dynamics, providing insights into parasite evolution and host-parasite interactions within the Apicomplexa group. This protocol includes rearing and maintenance of gregarine-free cricket populations for experimental purposes, gregarine production for oocyst solution and cricket infection, and gregarine infection assessment.

The genome assembly and annotation of the cricket Gryllus longicercus

The order Orthoptera includes insects such as grasshoppers, katydids, and crickets, among which there are important species for ecosystem stability and pollination, as well as research organisms in different fields such as neurobiology, ecology, and evolution. Crickets, with more than 2,400 described species, are emerging as novel model research organisms, for their diversity, worldwide distribution, regeneration capacity, and their characteristic acoustic communication. Here we report the assembly and annotation of the first New World cricket, that of Gryllus longicercus Weissman & Gray 2019. The genome assembly, generated by combining 44.54 Gb of long reads from PacBio and 120.44 Gb of short Illumina reads, has a length of 1.85 Gb. The genome annotation yielded 19,715 transcripts from 14,789 gene models.

The Fatty Acid Compositions, Irritation Properties, and Potential Applications of Teleogryllus mitratus Oil in Nanoemulsion Development

This study aimed to characterize and investigate the potential of the oils from Gryllus bimaculatus, Teleogryllus mitratus, and Acheta domesticus to be used in nanoemulsions. The oils were extracted by a cold press method and characterized for their fatty acid profiles. Their irritation effects on the chorioallantoic membrane (CAM) were evaluated, along with investigations of solubility and the required hydrophilic-lipophilic balance (RHLB). Various parameters impacting nanoemulsion generation using high-pressure homogenization were investigated. The findings revealed that G. bimaculatus yielded the highest oil content (24.58% w/w), followed by T. mitratus (20.96% w/w) and A. domesticus (15.46% w/w). Their major fatty acids were palmitic, oleic, and linoleic acids. All oils showed no irritation, suggesting safety for topical use. The RHLB values of each oil were around six-seven. However, they could be successfully developed into nanoemulsions using various surfactants. All cricket oils could be used for the nanoemulsion preparation, but T. mitratus yielded the smallest internal droplet size with acceptable PDI and zeta potential. Nanoemulsion was found to significantly enhance the antioxidant and anti-skin wrinkle of the T. mitratus oil. These findings pointed to the possible use of cricket oils in nanoemulsions, which could be used in various applications, including topical and cosmetic formulations.

Combinatorial expression of ebony and tan generates body color variation from nymph through adult stages in the cricket, Gryllus bimaculatus

Insect body colors and patterns change markedly during development in some species as they adapt to their surroundings. The contribution of melanin and sclerotin pigments, both of which are synthesized from dopamine, to cuticle tanning has been well studied. Nevertheless, little is known about how insects alter their body color patterns. To investigate this mechanism, the cricket Gryllus bimaculatus, whose body color patterns change during postembryonic development, was used as a model in this study. We focused on the ebony and tan genes, which encode enzymes that catalyze the synthesis and degradation, respectively, of the precursor of yellow sclerotin N-β-alanyl dopamine (NBAD). Expression of the G. bimaculatus (Gb) ebony and tan transcripts tended to be elevated just after hatching and the molting period. We found that dynamic alterations in the combined expression levels of Gb'ebony and Gb'tan correlated with the body color transition from the nymphal stages to the adult. The body color of Gb'ebony knockout mutants generated by CRISPR/Cas9 systemically darkened. Meanwhile, Gb'tan knockout mutants displayed a yellow color in certain areas and stages. The phenotypes of the Gb'ebony and Gb'tan mutants probably result from an over-production of melanin and yellow sclerotin NBAD, respectively. Overall, stage-specific body color patterns in the postembryonic stages of the cricket are governed by the combinatorial expression of Gb'ebony and Gb'tan. Our findings provide insights into the mechanism by which insects evolve adaptive body coloration at each developmental stage.