Female butterflies keep breeding going despite the shortage of males: study

Washington: Despite the declining population of male monarch butterflies, females are successfully carrying out mating and breeding in East Africa.

Researchers have found that some female monarch butterflies have been carrying a parasite called spiroplasma that kills their male offspring. This has led to a very small male population. In some areas, the male proportion dropped below 10%.

However, contrary to expectations, female butterflies have still mated about 1.5 times on average regardless of how many males were around. Experts think that the remaining males are working hard to breed with most of the available females.

Only 10-20% of the female monarch population has remained unmated.

The study is being described as an important part of research-based conservation. "It seems that monarch butterflies are very good at finding each other and mating. The proportion of males in butterfly populations fluctuates throughout the year. But, we found consistent evidence of female breeding success all year round," said Professor Richard ffrench-Constant from the University of Exeter.

According to Professor ffrench-Constant, other butterfly species have evolved resistance to parasites. The researchers are hoping that the monarch butterfly can become a symbol of conservation across Africa because severe drought in East Africa has led to a food crisis for humans and damaged biodiversity and ecosystems.

"The future of the monarch butterfly is tied to that of the continent. They live in savanna habitats. When there is rain, they thrive. When there is no rain, there are no butterflies, no cattle, and no food for humans. Humanity must tackle the climate and environment crisis to secure the future."

Dr Ian Gordon of the University of Rwanda said that the breeding success of female monarchs might explain how the male-killing parasite can be successfully transmitted in a population where males are rare. He added that if the entire population was infected, monarch butterflies will produce no more princes and the parasite will die out along with the butterflies.

The parasite infection is currently confined to a subsection of the East African contact zone where prevailing winds converge and bring flying insects together. The scientists are looking forward to conducting further research on why some monarch butterflies are remaining uninfected and why the outbreak is confined to a certain area.

The study was conducted by researchers at the universities of Exeter, Rwanda, and Edinburg and the Dian Fossey Gorilla Fund.