Farmers around the world produced approximately 60 billion pounds of mangoes (Mangifera indica) in 2004, according to the latest available figures. That's a bounty for fruit lovers and fruit flies (Anastrepha spp.) alike. Now Agricultural Research Service (ARS) entomologist David A. Jenkins has found a low-tech solution for reducing fruit fly infestations in mangoes.
Jenkins works at the ARS Tropical Agricultural Research Station in Mayaguez, Puerto Rico. Naturalized and ornamental mango trees are widespread in Puerto Rico, and ripe mangoes often fall from these trees and remain uncollected for several days. This provides fruit flies with ample breeding opportunities.
In his study, Jenkins and his team collected ripe mangoes that had fallen to the ground. One group of mangoes was shaded--either by a tree or a cloth--and left outside. A second group was stored indoors. A third group was left exposed to full sunlight, and a fourth group was covered with a black plastic garbage bag and then left in full sunlight.
The researchers recorded ambient temperatures and the internal fruit temperatures of all the mangoes several times daily. On clear days, the two sun-kissed groups of mangoes had internal temperatures peaks ranging from 126° F to 138° F. Even on cloudy days, their core temperatures peaked at 122° F. These were well above the 77° F peaks in the indoor mangoes and the 99° F peaks in the shaded mangoes.
After three days, the outdoor mango groups were moved inside and monitored for the emergence of larvae and pupae. Jenkins observed that mangoes stored indoors almost always produced many more larvae than the groups of mangoes that had been basking in the sun.
In areas where mango is not being grown commercially, ripe mangoes that have fallen from the tree remain shaded on the ground until they are gathered up and removed. When fruit flies use these mangos for breeding, the shade keeps the fruit’s core temperatures from reaching peaks lethal to the pests.
Removing the fruit from the shade of backyard trees, along with other strategies, may help reduce fruit fly breeding opportunities and support existing strategies to control fruit flies in commercial produce.
ARS is a scientific research agency of the U.S. Department of Agriculture.