Exploiting tools for manipulating insect diapause

Histone acetylation is associated with pupal diapause in cotton bollworm, Helicoverpa armigera

BACKGROUND

Diapause is an environmentally preprogrammed period of arrested development that is important to insect survival and population growth. Histone acetylation, an epigenetic modification, has several biological functions, but its role in agricultural pest diapause is unknown. In this study, we investigated the role of histone H3 acetylation in the diapause of Helicoverpa armigera.

RESULTS

The histone H3 gene of H. armigera was cloned, and multiple sequence alignment of amino acids revealed that the potential lysine acetylation sites were highly conserved across species. Investigation of histone H3 acetylation levels in diapause- and nondiapause-type pupae showed that acetylation levels were down-regulated in diapause-type pupae and were lower in diapausing pupae compared to nondiapause pupae. By screening the genome, six histone acetyltransferase (HAT) and eight histone deacetylase (HDAC) genes responsible for antagonizing catalytic histone acetylation modifications were identified in H. armigera, and most of them exhibited different expression patterns between diapause- and nondiapause-type pupae. To elucidate the effect of histone H3 acetylation on diapause in H. armigera, the diapause pupae were injected with the histone acetylation activator trichostatin A (TSA). The results indicated that TSA injection increased the levels of histone H3 acetylation, causing the diapausing pupae to revert to development. Furthermore, transcriptome analysis revealed that 259 genes were affected by TSA injection, including genes associated with metabolism, resistance, and immunological responses.

CONCLUSION

These results suggest that histone acetylation is inseparably related to the pupal diapause of H. armigera, which promises to be a potential target for pest control. © 2023 Society of Chemical Industry.

Insect diapause: from a rich history to an exciting future

Diapause, a stage-specific developmental arrest, is widely exploited by insects to bridge unfavorable seasons. Considerable progress has been made in understanding the ecology, physiology and evolutionary implications of insect diapause, yet intriguing questions remain. A more complete understanding of diapause processes on Earth requires a better geographic spread of investigations, including more work in the tropics and at high latitudes. Questions surrounding energy management and trade-offs between diapause and non-diapause remain understudied. We know little about how maternal effects direct the diapause response, and regulators of prolonged diapause are also poorly understood. Numerous factors that were recently linked to diapause are still waiting to be placed in the regulatory network leading from photoreception to engagement of the diapause program. These factors include epigenetic processes and small noncoding RNAs, and emerging data also suggest a role for the microbiome in diapause regulation. Another intriguing feature of diapause is the complexity of the response, resulting in a diverse suite of responses that comprise the diapause syndrome. Select transcription factors likely serve as master switches turning on these diverse responses, but we are far from understanding the full complexity. The richness of species displaying diapause offers a platform for seeking common components of a 'diapause toolbox'. Across latitudes, during invasion events and in a changing climate, diapause offers grand opportunities to probe evolutionary change and speciation. At a practical level, diapause responses can be manipulated for insect control and long-term storage. Diapausing insects also contain a treasure trove of pharmacological compounds and offer promising models for human health.