The expansion of some biofuel crops may unwittingly increase the risk of mosquito-borne disease by altering the insects' life cycle, a study suggests.

 

The so-called first-generation biofuel crops, most notably maize, are increasingly being replaced by second-generation biofuel crops, such as perennial grasses, which require less energy, water, fertilizers and pesticides to thrive.

 

Yet ecological changes brought about by large-scale biofuel farming may alter the transmission of vector-borne diseases, by affecting vector behavior, survival and abundance, for example.

 

In the paper published in this month’s edition of Global Change Biology — Bioenergy, researchers from the University of Illinois, United States, looked at the egg-laying behavior of Aedes aegypti and Aedes albopictus, in water that contained leaves of different types of biofuel crops in laboratory experiments, as may happen in the field.

 

They show that leaves from different types of biofuel crops can affect the chemical properties of the water in which mosquitoes lay their eggs, as well as the mosquitoes’ preference for where to lay eggs and the survival of those eggs.

 

The researchers show, for example, that more eggs reached adulthood when they were laid in water that was infused with leaf material from the second-generation biofuel crops, switch grass and Miscanthus, than that infused with maize leaves.

 

But they add that these crops are also expected to improve wildlife diversity, which may reduce infection prevalence by redirecting mosquito bites to other hosts.

 

The study highlights the "critical need for full life-cycle and environmental impact assessments of crops and agricultural practices".