6 September 2006

Gravity Equations Useful In Modeling Earthbound Phenomena

by Kate Melville

According to researchers from Penn State University and the University of Virginia, the spread of diseases by insects can be described by equations like those used to describe the force of gravity between planetary objects.

The researchers explained that insects tend to transmit diseases in the course of feeding on plants, and their movement between plants is influenced by plant quality and the distance between plants, or, how far they'll have to travel to get to the next meal. "It turns out insects are more likely to move shorter distances between better plants," write the authors in The American Naturalist.

"Interestingly, then, the probability of disease being passed between two plants goes up if they are closer and/or better, which parallels the stronger gravity between closer and larger planets."

In this case, the researchers tracked a fungal disease spread by bees and moths in the course of pollinating and feeding on nectar from white campion flowers. As predicted, the disease was more likely to spread shorter distances between plants that had many flowers.

"This implies that knowledge of insect behavior can lead to better prediction of where disease will spread," explained researcher Ottar Bjornstad. In fact, these patterns are not limited to diseases of plants or diseases carried by insects. Bjornstad and colleagues have previously shown that similar patterns describe the spread of diseases between cities.

Source: University of Chicago Press Journals