Transcriptomic responses of females to consumption of nuptial food gifts as a potential mediator of sexual conflict in decorated crickets

The impact of microplastics on tissue-specific gene expression in the tropical house cricket, Gryllodes sigillatus

Microplastics are ubiquitous in our environment, resulting in animal exposure and consumption via food, water, and air. Animals that consume microplastics may suffer from physiological effects like immunotoxicity or mitochondrial dysfunction, but how specific tissues may differentially respond to plastic consumption is poorly understood, particularly in terrestrial insects. Here, we measured transcriptomic responses of tissues (midgut, hindgut, fat body and ovaries) to microplastic consumption in a generalist ground-dwelling insect, the tropical house cricket, Gryllodes sigillatus. Using this approach, we provide insights on how microplastics may impact specific organ systems. We generated a de novo transcriptome, a useful resource for further studies on this emerging model insect, that we then used to infer differential gene expression due to microplastic consumption in individual organs. Ingestion of microplastics elicited unique changes in gene expression depending on the tissue of focus, with notable differentially-expressed genes related to survival and stress pathways as well as those related to metabolism, immunity, and cancer.

A High-Quality Reference Genome and Comparative Genomics of the Widely Farmed Banded Cricket (Gryllodes sigillatus) Identifies Selective Breeding Targets

Farmed insects have gained attention as an alternative, sustainable source of protein with a lower carbon footprint than traditional livestock. We present a high-quality reference genome for one of the most commonly farmed insects, the banded cricket Gryllodes sigillatus. In addition to its agricultural importance, G. sigillatus is also a model in behavioural and evolutionary ecology research on reproduction and mating systems. We report comparative genomic analyses that clarify the banded cricket's evolutionary history, identify gene family expansions and contractions unique to this lineage, associate these with agriculturally important traits, and identify targets for genome-assisted breeding efforts. The high-quality G. sigillatus genome assembly plus accompanying comparative genomic analyses serve as foundational resources for both applied and basic research on insect farming and behavioural biology, enabling researchers to pinpoint trait-associated genetic variants, unravel functional pathways governing those phenotypes, and accelerate selective breeding efforts to increase the efficacy of large-scale insect farming operations.

Sexually antagonistic coevolution of the male nuptial gift and female feeding behaviour in decorated crickets

The evolution of nuptial gifts has traditionally been considered a harmonious affair, providing benefits to both mating partners. There is growing evidence, however, that receiving a nuptial gift can be actively detrimental to the female. In decorated crickets (Gryllodes sigillatus), males produce a gelatinous spermatophylax that enhances sperm transfer but provides little nutritional benefit and hinders female post-copulatory mate choice. Here, we examine the sexually antagonistic coevolution of the spermatophylax and the female feeding response to this gift in G. sigillatus maintained in experimental populations with either a male-biased or female-biased adult sex ratio. After 25 generations, males evolving in male-biased populations produced heavier spermatophylaxes with a more manipulative combination of free amino acids than those evolving in female-biased populations. Moreover, when the spermatophylax originated from the same selection regime, females evolving in male-biased populations always had shorter feeding durations than those evolving in female-biased populations, indicating the evolution of greater resistance. Across populations, female feeding duration increased with the mass and manipulative combination of free amino acids in the spermatophylax, suggesting sexually antagonistic coevolution. Collectively, our work demonstrates a key role for interlocus sexual conflict and sexually antagonistic coevolution in the mating system of G. sigillatus.

Induction of Multiple Immune Signaling Pathways in Gryllodes sigillatus Crickets during Overt Viral Infections

Despite decades of focus on crickets (family: Gryllidae) as a popular commodity and model organism, we still know very little about their immune responses to microbial pathogens. Previous studies have measured downstream immune effects (e.g., encapsulation response, circulating hemocytes) following an immune challenge in crickets, but almost none have identified and quantified the expression of immune genes during an active pathogenic infection. Furthermore, the prevalence of covert (i.e., asymptomatic) infections within insect populations is becoming increasingly apparent, yet we do not fully understand the mechanisms that maintain low viral loads. In the present study, we measured the expression of several genes across multiple immune pathways in Gryllodes sigillatus crickets with an overt or covert infection of cricket iridovirus (CrIV). Crickets with overt infections had higher relative expression of key pathway component genes across the Toll, Imd, Jak/STAT, and RNAi pathways. These results suggests that crickets can tolerate low viral infections but can mount a robust immune response during an overt CrIV infection. Moreover, this study provides insight into the immune strategy of crickets following viral infection and will aid future studies looking to quantify immune investment and improve resistance to pathogens.