The melanin pigment gene black mediates body pigmentation and courtship behavior in the German cockroach Blattella germanica

Authors: GONG, LANG-LANG - Guizhou University; MA, YUN-FENG - Guizhou University; ZHANG, MENG-QI - Guizhou University; FENG, HONG-YAN - Guizhou University; ZHOU, YAN-YUNTAO - Guizhou University; ZHAO, YA-QIN - Guizhou University; Hull, Joe; DEWER, YOUSSEF - Agricultural Research Center Of Egypt; HE, MING - Guizhou University; HE, PENG - Guizhou University

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2024
Publication Date: 4/16/2024
Citation: Gong, L., Ma, Y., Zhang, M., Feng, H., Zhou, Y., Zhao, Y., Hull, J.J., Dewer, Y., He, M., He, P. 2024. The melanin pigment gene black mediates body pigmentation and courtship behavior in the German cockroach Blattella germanica. Bulletin of Entomological Research. 114(2):271-280. https://doi.org/10.1017/S0007485324000166.
DOI: https://doi.org/10.1017/S0007485324000166

Interpretive Summary: For insects, body coloration typically involves genes linked with melanization and sclerotization (hardening of the cuticle), two processes essential for insect development. Consequently, genes related to these functions have been proposed as candidates for development as pest management targets. One of the genes in this pathway encodes an aspartate decarboxylase termed black that typically plays a crucial role in generating many of the precursor molecules that contribute to insect body coloration. Reduction in the availability of this enzyme in the German cockroach resulted in adults that were largely black in color rather than the typical caramel coloration. The reduction also disrupted normal wing development in a subset of the adults and largely blocked stereotypical male behaviors associated with mating. The study confirmed the conserved role of the black gene in insect body coloration and revealed the importance of the gene for cockroach development and mating behaviors. These findings suggest that strategies specifically targeting the black gene in cockroaches may be useful for suppressing future populations.

Technical Abstract: Genes involved in melanin production directly impact insect pigmentation and can affect diverse physiology and behaviors. The role these genes have on sex behavior, however, is unclear. In the present study, the crucial melanin pigment gene black was functionally characterized in an urban pest, the German cockroach, Blatella germanica. RNAi knockdown of B. germanica black (Bgblack) had no effect on survival, but did result in black pigmentation of the thorax, abdomen, head, wings, legs, antennae, and cercus due to cuticular accumulation of melanin. Sex-specific variation in the pigmentation pattern was apparent, with females exhibiting darker coloration on the abdomen and thorax than males. Bgblack knockdown also resulted in wing deformation and negatively impacted the contact sex pheromone-based courtship behavior of males. This study provides evidence for black function in multiple aspects of B. germanica biology and opens new avenues of exploration for novel pest control strategies.