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Researchers discover that the presence of reproductive females activates sperm production in fruit flies

A study recently published reveals in male 'Drosophila' flies that the cells of their reproductive organs are activated to increase sperm production after sensing the presence of females through pheromones emitted by them.
This work describes for the first time how the social context intervenes in the functioning of the testes and contributes to the knowledge of the causes and factors that affect male fertility.

A study led by the Andalusian Center for Developmental Biology (CABD), a joint center of the Spanish National Research Council (CSIC), the Pablo de Olavide University (UPO) and the Andalusian Regional Government (JA), has analyzed for the first time how the social context affects the correct functioning of the testis. This work, published in the journal Cell Reports, shows in the species Drosophila melanogaster, known as fruit flies, how sperm production only increases when potential reproductive partners are detected, which represents an advance in the study of possible similar mechanisms that could affect reproductive health in humans.



Salvador C. Herrera and Javier Martín-Díaz, the authors

Reproduction is a fundamental process in the animal kingdom; however, for it to occur, coordination is necessary between social behavior, i.e., in the search for a mate, courtship and mating, and physiological behavior, such as energy mobilization or dietary change, in addition to gamete production.

So far, the symbiosis between social signals and gametogenesis in females has been extensively studied. However, its existence remained largely unknown in males. In this project, led by Salvador Herrera, Ramón y Cajal researcher at the CABD, the male Drosophila fly was used as a model. To obtain concrete results, a protocol was tested in which individual males were selected and maintained in a virgin state and isolated from any females in order to subsequently study the effects of living with three females that had not previously mated.

The work shows that the presence of the female, a potential reproductive partner, is detected by the male due to sex pheromones secreted by the females, which induces an activation of testicular stem cells leading to increased sperm production.
In addition, it has been possible to describe the interorganic signaling that triggers the testicular response: the brain produces and releases more octopamine (a molecule derived from amino acid metabolism), the homologue of adrenaline in insects, and the muscles generate a stress signal, TNF-α factor.

Although the fly is a distant organism from humans, by describing for the first time how the social context affects fertility in males, new possibilities open up to study whether similar mechanisms affect human reproductive health and can improve it. This could be a breakthrough in better understanding the causes and factors involved in the progressive and accelerated decline in male fertility observed worldwide, since, according to studies, sperm counts have declined by more than 50% in the last 50 years.

“This study is the first to describe how the social context affects the functioning of the testis, causing sperm production to increase only when potential reproductive partners are detected. This mechanism makes it possible to optimize the energy expenditure involved in producing sperm. It is also an example of how the social context or situations of isolation affect our physiology”, remarks CABD researcher Javier Martín-Díaz.

A stem cell activation state coupling spermatogenesis with social interactions in Drosophila males Martin-Diaz, Javier and C. Herrera, Salvador Cell Reports. DOI: 10.1016/j.celrep.2024.114647


This press release was written in collaboration with the CSIC Andalucia and CSIC communication departments